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2023 Vol. 41, No. 7
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2023, 41(7): 1-7,13.
doi: 10.13205/j.hjgc.202307001
Abstract:
Anaerobic digestion (AD) is one of the promising approaches to treat sludge for resource recovery and carbon reduction, but the efficiency of resource recovery and carbon reduction varied greatly under different treatment strategies. This work comprehensively evaluated the energy recovery and carbon emissions of four different treatment routes (i.e. conventional anaerobic digestion (R1), hydrothermal pretreatment at 90℃/170℃ (R2), co-digestion (R3) and hydrothermal pretreatment with co-digestion (R4), based on the Intergovernmental Panel on Climate Change (IPCC) methodology. Results indicated that the methane production followed an order of R1 < R290℃ < R2170℃ < R3 < R4, while the net carbon emission followed an order of R3 < R290℃ < R1 < R4 < R2170℃. All routes have achieved the aims of carbon neutrality >100% and negative carbon emissions, due to the self-sufficient heat and electricity. R2170℃ generated 15.4% more methane than R290℃, but simultaneously increased 110% heat consumption and 60.5% carbon emissions (with a proportion of 74.3% indirect carbon emission). R4 produced 6.3% more methane than R3, but also increased 110% heat consumption and 61.9% carbon emissions (with a proportion of 95.9% indirect carbon emission). However, in R3, more than 40.9% methane was generated compared with that of R2170℃, and it also reduced 52.7% heat consumption and 413% carbon emissions. These results implied that the co-digestion showed advantages over hydrothermal pretreatment for sludge anaerobic treatment in view of both energy recovery and carbon emission reduction. A balance between more energy input and increased operational performance should be considered in selecting the optimal sludge treatment route.
Anaerobic digestion (AD) is one of the promising approaches to treat sludge for resource recovery and carbon reduction, but the efficiency of resource recovery and carbon reduction varied greatly under different treatment strategies. This work comprehensively evaluated the energy recovery and carbon emissions of four different treatment routes (i.e. conventional anaerobic digestion (R1), hydrothermal pretreatment at 90℃/170℃ (R2), co-digestion (R3) and hydrothermal pretreatment with co-digestion (R4), based on the Intergovernmental Panel on Climate Change (IPCC) methodology. Results indicated that the methane production followed an order of R1 < R290℃ < R2170℃ < R3 < R4, while the net carbon emission followed an order of R3 < R290℃ < R1 < R4 < R2170℃. All routes have achieved the aims of carbon neutrality >100% and negative carbon emissions, due to the self-sufficient heat and electricity. R2170℃ generated 15.4% more methane than R290℃, but simultaneously increased 110% heat consumption and 60.5% carbon emissions (with a proportion of 74.3% indirect carbon emission). R4 produced 6.3% more methane than R3, but also increased 110% heat consumption and 61.9% carbon emissions (with a proportion of 95.9% indirect carbon emission). However, in R3, more than 40.9% methane was generated compared with that of R2170℃, and it also reduced 52.7% heat consumption and 413% carbon emissions. These results implied that the co-digestion showed advantages over hydrothermal pretreatment for sludge anaerobic treatment in view of both energy recovery and carbon emission reduction. A balance between more energy input and increased operational performance should be considered in selecting the optimal sludge treatment route.
2023, 41(7): 8-13.
doi: 10.13205/j.hjgc.202307002
Abstract:
Carbon capture, utilization and storage (CCUS) is an effective technique to solve global warming issue and achieve the large-scale reduction of greenhouse gas CO2. Nowadays, marine CCUS technology is one of the hot topics, due to its high security for the environment compared to the terrestrial CCUS technology. This paper systematically introduced marine environmental monitoring, the preventive monitoring of CO2 leakage, and the earthquake monitoring of the Tomakomai CCS demonstration project. According to the investigation results, this paper analyzed the applicability of pCO2/DO for CO2 leakage and the influence of earthquakes on CCUS project. Based on the actual state of Chinese marine CCUS, this paper suggests adding a CO2 leakage preventive monitoring system and an earthquake monitoring system. This paper could provide some reference for future marine CCUS projects in China.
Carbon capture, utilization and storage (CCUS) is an effective technique to solve global warming issue and achieve the large-scale reduction of greenhouse gas CO2. Nowadays, marine CCUS technology is one of the hot topics, due to its high security for the environment compared to the terrestrial CCUS technology. This paper systematically introduced marine environmental monitoring, the preventive monitoring of CO2 leakage, and the earthquake monitoring of the Tomakomai CCS demonstration project. According to the investigation results, this paper analyzed the applicability of pCO2/DO for CO2 leakage and the influence of earthquakes on CCUS project. Based on the actual state of Chinese marine CCUS, this paper suggests adding a CO2 leakage preventive monitoring system and an earthquake monitoring system. This paper could provide some reference for future marine CCUS projects in China.
2023, 41(7): 14-21.
doi: 10.13205/j.hjgc.202307003
Abstract:
As a key primary wastewater treatment unit, septic tanks significantly contribute to the carbon emissions of wastewater systems due to the production of greenhouse gases, such as large amounts of methane (CH4) and some nitrous oxide (N2O) from anaerobic reactions. Many studies are therefore calling for the phasing out of septic tanks, but few studies explore the greenhouse effect of septic tanks in-depth and comprehensively. In fact, a review of the greenhouse effect of septic tanks could help point the way to the future of septic tanks. The review shows that there is considerable spatial and temporal variability in both CH4 and N2O emissions from septic tanks, and that the actual N2O emissions need to be further verified; the indirect carbon emissions from routine maintenance and emptying and the potential impact of septic tank removal on subsequent systems in terms of carbon emissions are still worthy of further analysis, from an LCA carbon perspective. In terms of specific greenhouse gas emission capacity, due to the different functions of septic tanks in China and abroad, the domestic estimate is about 8.3 g CH4/(cap·d), lower than the 11.0 g CH4/(cap·d) commonly estimated abroad. Finally, in terms of the shortcomings of the current research, there are generally significant parameter uncertainties and regional heterogeneity in the estimation and accounting studies, and there is a temporary "gap" in the field monitoring studies in China, as well as a lack of online monitoring, resulting in the spatial and temporal variability of greenhouse gases not being described in detail. In this regard, there is an urgent need for extensive monitoring and accounting of septic tanks in China to clarify the phasing out of septic tanks.
As a key primary wastewater treatment unit, septic tanks significantly contribute to the carbon emissions of wastewater systems due to the production of greenhouse gases, such as large amounts of methane (CH4) and some nitrous oxide (N2O) from anaerobic reactions. Many studies are therefore calling for the phasing out of septic tanks, but few studies explore the greenhouse effect of septic tanks in-depth and comprehensively. In fact, a review of the greenhouse effect of septic tanks could help point the way to the future of septic tanks. The review shows that there is considerable spatial and temporal variability in both CH4 and N2O emissions from septic tanks, and that the actual N2O emissions need to be further verified; the indirect carbon emissions from routine maintenance and emptying and the potential impact of septic tank removal on subsequent systems in terms of carbon emissions are still worthy of further analysis, from an LCA carbon perspective. In terms of specific greenhouse gas emission capacity, due to the different functions of septic tanks in China and abroad, the domestic estimate is about 8.3 g CH4/(cap·d), lower than the 11.0 g CH4/(cap·d) commonly estimated abroad. Finally, in terms of the shortcomings of the current research, there are generally significant parameter uncertainties and regional heterogeneity in the estimation and accounting studies, and there is a temporary "gap" in the field monitoring studies in China, as well as a lack of online monitoring, resulting in the spatial and temporal variability of greenhouse gases not being described in detail. In this regard, there is an urgent need for extensive monitoring and accounting of septic tanks in China to clarify the phasing out of septic tanks.
2023, 41(7): 22-29.
doi: 10.13205/j.hjgc.202307004
Abstract:
According to the data from 2000 to 2020, the investigation employed the emission coefficient method provided by IPCC to estimate the total annual carbon emissions of the Pearl River Delta during the study period. Using the STIRPAT model, the influencing factors were categorized into seven dimensions. When analyzing the factors that affected the carbon emissions in the Pearl River Delta, the spatial Dubin model was applied, and eight forecast scenarios were formulated depending on the development goals proposed by Guangdong province. For the prediction of the trend of carbon emissions in the Pearl River Delta, this paper dynamically forecast the situation under different policy plans from 2021 to 2035 on the basis of system dynamics. The research results were as follows:1) under the established policy scenarios, the total carbon emission of the Pearl River Delta would reach its peak in 2030; 2) certain policy interventions could reduce carbon emission, in other words, to achieve carbon peak was inseparable from the active participation of government rather than relaxed management; 3) in the context of single emission reduction policy, the Pearl River Delta would realize the carbon peak in 2025-2030 under most prediction scenarios; 4) the coordinated control of multiple carbon emission reduction policies could accomplish carbon peak in 2024, better than single carbon emission reduction policy. In addition, relying on the consequence of the spatial Dubin model and carbon emission prediction, targeted policy recommendations such as increasing urban greening, paying attention to inter-city spatial connection and policy coordination, optimizing industrial structure, improving power system and strengthening residents' awareness of green consumption were proposed, which would help to achieve carbon peaking.
According to the data from 2000 to 2020, the investigation employed the emission coefficient method provided by IPCC to estimate the total annual carbon emissions of the Pearl River Delta during the study period. Using the STIRPAT model, the influencing factors were categorized into seven dimensions. When analyzing the factors that affected the carbon emissions in the Pearl River Delta, the spatial Dubin model was applied, and eight forecast scenarios were formulated depending on the development goals proposed by Guangdong province. For the prediction of the trend of carbon emissions in the Pearl River Delta, this paper dynamically forecast the situation under different policy plans from 2021 to 2035 on the basis of system dynamics. The research results were as follows:1) under the established policy scenarios, the total carbon emission of the Pearl River Delta would reach its peak in 2030; 2) certain policy interventions could reduce carbon emission, in other words, to achieve carbon peak was inseparable from the active participation of government rather than relaxed management; 3) in the context of single emission reduction policy, the Pearl River Delta would realize the carbon peak in 2025-2030 under most prediction scenarios; 4) the coordinated control of multiple carbon emission reduction policies could accomplish carbon peak in 2024, better than single carbon emission reduction policy. In addition, relying on the consequence of the spatial Dubin model and carbon emission prediction, targeted policy recommendations such as increasing urban greening, paying attention to inter-city spatial connection and policy coordination, optimizing industrial structure, improving power system and strengthening residents' awareness of green consumption were proposed, which would help to achieve carbon peaking.
2023, 41(7): 30-36,60.
doi: 10.13205/j.hjgc.202307005
Abstract:
The cement industry is one of the key industries in China for achieving the goal of carbon neutrality. To reveal the effect of energy saving and emission reduction of cement kiln collaborative disposal waste, this study compared the carbon emissions of cement kiln collaborative disposal of hazardous waste, cement kiln collaborative disposal of domestic waste, cement kiln collaborative disposal of general solid waste, and conventional cement production, based on the whole life cycle theory, and analyzed the carbon emission reduction path of cement industry. The results showed that calcination composed of carbonate and coal consumption was the main source of greenhouse gas emissions, accounting for about 52.37%~62.84%. The amount of CO2 emitted by cement production was in the order of conventional cement production > cement kiln collaborative disposal of domestic waste > cement kiln coordinated disposal of general solid waste > cement kiln coordinated disposal of hazardous waste, which were 883.65 kg/t, 772.67 kg/t, 656.30 kg/t and 609.79 kg/t, respectively, indicating that collaborative disposal of waste had certain advantages in reducing CO2 emissions. Policy control, adjustment of energy structure, the substitution of raw (combustion), energy efficiency improvement technology, waste heat power generation technology and CCUS technology were the main measures to achieve the goal of carbon neutrality in the cement industry. This study could provide basic support for the cement industry to carry out energy conservation and emission reduction.
The cement industry is one of the key industries in China for achieving the goal of carbon neutrality. To reveal the effect of energy saving and emission reduction of cement kiln collaborative disposal waste, this study compared the carbon emissions of cement kiln collaborative disposal of hazardous waste, cement kiln collaborative disposal of domestic waste, cement kiln collaborative disposal of general solid waste, and conventional cement production, based on the whole life cycle theory, and analyzed the carbon emission reduction path of cement industry. The results showed that calcination composed of carbonate and coal consumption was the main source of greenhouse gas emissions, accounting for about 52.37%~62.84%. The amount of CO2 emitted by cement production was in the order of conventional cement production > cement kiln collaborative disposal of domestic waste > cement kiln coordinated disposal of general solid waste > cement kiln coordinated disposal of hazardous waste, which were 883.65 kg/t, 772.67 kg/t, 656.30 kg/t and 609.79 kg/t, respectively, indicating that collaborative disposal of waste had certain advantages in reducing CO2 emissions. Policy control, adjustment of energy structure, the substitution of raw (combustion), energy efficiency improvement technology, waste heat power generation technology and CCUS technology were the main measures to achieve the goal of carbon neutrality in the cement industry. This study could provide basic support for the cement industry to carry out energy conservation and emission reduction.
2023, 41(7): 37-44.
doi: 10.13205/j.hjgc.202307006
Abstract:
With China's food waste production increasing yearly, recycling energy from food waste becomes a key issue in solid waste treatment. In order to explore the carbon emissions and energy usage of several main food waste recycling methods, this paper used the accounting methods recommended by IPCC and related literature to evaluate the carbon offset and energy recovery of four treatment methods, sewage co-treatment, anaerobic digestion, incineration and composting. The results showed that the carbon offset potential of the four treatment methods was -56.9, -88.6, 44.2, and 222.0 kg CO2/t FW, respectively. The energy recovery potential was -116.0, -215.0, 58.9, and 61.0 kW·h/t FW, respectively. According to the sensitivity analysis, the co-treatment and anaerobic digestion mode have strong stability in addition to the technical influence, indicating that co-treatment and anaerobic digestion are ideal resource treatment methods. The incineration method involves a large amount of carbon emissions due to the dehydration process, and the overall stability is poor. Composting can't achieve carbon emission reduction and energy recovery, so its application should be minimized. To sum up, the priority sequence of food waste recycling disposal was anaerobic digestion, sewage co-treatment, incineration and composting.
With China's food waste production increasing yearly, recycling energy from food waste becomes a key issue in solid waste treatment. In order to explore the carbon emissions and energy usage of several main food waste recycling methods, this paper used the accounting methods recommended by IPCC and related literature to evaluate the carbon offset and energy recovery of four treatment methods, sewage co-treatment, anaerobic digestion, incineration and composting. The results showed that the carbon offset potential of the four treatment methods was -56.9, -88.6, 44.2, and 222.0 kg CO2/t FW, respectively. The energy recovery potential was -116.0, -215.0, 58.9, and 61.0 kW·h/t FW, respectively. According to the sensitivity analysis, the co-treatment and anaerobic digestion mode have strong stability in addition to the technical influence, indicating that co-treatment and anaerobic digestion are ideal resource treatment methods. The incineration method involves a large amount of carbon emissions due to the dehydration process, and the overall stability is poor. Composting can't achieve carbon emission reduction and energy recovery, so its application should be minimized. To sum up, the priority sequence of food waste recycling disposal was anaerobic digestion, sewage co-treatment, incineration and composting.
2023, 41(7): 45-52.
doi: 10.13205/j.hjgc.202307007
Abstract:
The carbon emissions from the construction industry account for nearly one-third of the total carbon emissions in China, and the potential for carbon reduction is huge. Aiming at the evaluation of carbon emission and carbon compensation in the demolition stage of the abandoned buildings, the whole life cycle evaluation method was adopted to define the calculation boundary of the demolition stage of abandoned buildings, which was divided into the demolition stage, waste transportation stage and waste disposal stage. Carbon compensation is the reuse stage of construction waste, and the calculation model of carbon emission and carbon compensation was established. Through quantitative analysis, it was concluded that carbon emissions are mainly concentrated in the construction waste disposal stage, accounting for about 75% of the total carbon emissions. The secondary recycling of construction waste could effectively reduce 31.01% of the total carbon emissions in the demolition stage of buildings, which had a good carbon reduction effect. With the increase of the secondary recycling rate of construction waste, the carbon emission of the construction waste disposal stage linearly decreased, the carbon compensation of building materials linearly increased, and the carbon reduction effect was enhanced.
The carbon emissions from the construction industry account for nearly one-third of the total carbon emissions in China, and the potential for carbon reduction is huge. Aiming at the evaluation of carbon emission and carbon compensation in the demolition stage of the abandoned buildings, the whole life cycle evaluation method was adopted to define the calculation boundary of the demolition stage of abandoned buildings, which was divided into the demolition stage, waste transportation stage and waste disposal stage. Carbon compensation is the reuse stage of construction waste, and the calculation model of carbon emission and carbon compensation was established. Through quantitative analysis, it was concluded that carbon emissions are mainly concentrated in the construction waste disposal stage, accounting for about 75% of the total carbon emissions. The secondary recycling of construction waste could effectively reduce 31.01% of the total carbon emissions in the demolition stage of buildings, which had a good carbon reduction effect. With the increase of the secondary recycling rate of construction waste, the carbon emission of the construction waste disposal stage linearly decreased, the carbon compensation of building materials linearly increased, and the carbon reduction effect was enhanced.
2023, 41(7): 53-60.
doi: 10.13205/j.hjgc.202307008
Abstract:
The recycling of shield muck is an important measure in response to China's Carbon Peak and Carbon Neutrality goal in subway construction. In order to quantify the carbon emission intensity and emission reduction potential in the recycling and disposal of subway shield muck, an assessment method of carbon emission from the recycling and disposal of related subway shield muck was established, based on the LCA method. Taking a tunnel section of Shenzhen Metro Line 13 as an example, the process and system for the recycling of subway-related shield muck were sorted out, the management pathway for the recycling on-site muck was clarified, and the carbon emission intensity and carbon reduction potential of recycling and disposal muck were quantified. The results implied that shield muck recycling reduced 4243.13 t of CO2e emission. The preparation of one cubic meter of recycled unburned brick can contribute 239.26 kg of carbon reduction benefits, while the landfill of one cubic meter of shield muck produces 89.42 kg of CO2e. If the shield muck efficient recycling method provided by the case is utilized for Shenzhen Metro, an amount of 770000 tons of CO2e carbon reduction benefits can be achieved by 2035. The study provides theoretical methods and data for the government to formulate the management policy of subway shield muck and promote the recycling of subway shield muck.
The recycling of shield muck is an important measure in response to China's Carbon Peak and Carbon Neutrality goal in subway construction. In order to quantify the carbon emission intensity and emission reduction potential in the recycling and disposal of subway shield muck, an assessment method of carbon emission from the recycling and disposal of related subway shield muck was established, based on the LCA method. Taking a tunnel section of Shenzhen Metro Line 13 as an example, the process and system for the recycling of subway-related shield muck were sorted out, the management pathway for the recycling on-site muck was clarified, and the carbon emission intensity and carbon reduction potential of recycling and disposal muck were quantified. The results implied that shield muck recycling reduced 4243.13 t of CO2e emission. The preparation of one cubic meter of recycled unburned brick can contribute 239.26 kg of carbon reduction benefits, while the landfill of one cubic meter of shield muck produces 89.42 kg of CO2e. If the shield muck efficient recycling method provided by the case is utilized for Shenzhen Metro, an amount of 770000 tons of CO2e carbon reduction benefits can be achieved by 2035. The study provides theoretical methods and data for the government to formulate the management policy of subway shield muck and promote the recycling of subway shield muck.
2023, 41(7): 61-68,85.
doi: 10.13205/j.hjgc.202307009
Abstract:
The estimation of direct CO2 emissions from three major industries and domestic energy consumption in Gansu province from 2000 to 2020 by emission factor method was carried out, to describe and analyze its evolution characteristics. Then we established a BP neural network model and forecasted the CO2 emissions of Gansu province from 2021 to 2030. Finally, a STIRPAT expansion model of influencing factors of CO2 emission in Gansu province was constructed, the influence degree and internal mechanism of each factor on CO2 emissions were quantitatively explored by using multiple regression analysis, and the important influencing factors were further identified by combining random forests. The results showed that:the direct CO2 emission from industrial and domestic energy consumption in Gansu province were generally fluctuating, and the secondary industry accounted for more than 70% of the total CO2 emissions, which was the main source of carbon dioxide emissions. The prediction error of the BP neural network model was 2×10-4, and the correlation coefficient was greater than 0.99, which had high accuracy for predicting CO2 emissions in Gansu province, also it was concluded that the direct CO2 emissions of energy consumption in Gansu province would reach the maximum value in 2026. The driving factors of CO2 emissions in Gansu province were significantly different, the intensity of CO2 emissions, economic development and urban and rural consumption had a greater positive effect on CO2 emissions, and per capita consumption expenditure of urban residents was the main influencing factor. The growth of forest coverage inhibited CO2 emissions, and the reduction of energy intensity contributed to the reduction of CO2 emissions. The adjustment and transformation of the three major industrial structures could lead to a decline in CO2 emissions. The research provided a theoretical basis and scientific basis for Gansu province to promote low-carbon emission reduction.
The estimation of direct CO2 emissions from three major industries and domestic energy consumption in Gansu province from 2000 to 2020 by emission factor method was carried out, to describe and analyze its evolution characteristics. Then we established a BP neural network model and forecasted the CO2 emissions of Gansu province from 2021 to 2030. Finally, a STIRPAT expansion model of influencing factors of CO2 emission in Gansu province was constructed, the influence degree and internal mechanism of each factor on CO2 emissions were quantitatively explored by using multiple regression analysis, and the important influencing factors were further identified by combining random forests. The results showed that:the direct CO2 emission from industrial and domestic energy consumption in Gansu province were generally fluctuating, and the secondary industry accounted for more than 70% of the total CO2 emissions, which was the main source of carbon dioxide emissions. The prediction error of the BP neural network model was 2×10-4, and the correlation coefficient was greater than 0.99, which had high accuracy for predicting CO2 emissions in Gansu province, also it was concluded that the direct CO2 emissions of energy consumption in Gansu province would reach the maximum value in 2026. The driving factors of CO2 emissions in Gansu province were significantly different, the intensity of CO2 emissions, economic development and urban and rural consumption had a greater positive effect on CO2 emissions, and per capita consumption expenditure of urban residents was the main influencing factor. The growth of forest coverage inhibited CO2 emissions, and the reduction of energy intensity contributed to the reduction of CO2 emissions. The adjustment and transformation of the three major industrial structures could lead to a decline in CO2 emissions. The research provided a theoretical basis and scientific basis for Gansu province to promote low-carbon emission reduction.
2023, 41(7): 69-75.
doi: 10.13205/j.hjgc.202307010
Abstract:
In this study, four kinds of native plants in central China including Lolium multifolorum, Alopecurus pratensis L., Pteris vittata L., and Acorus gramineus were selected as research objects. Laboratory hydroponic experiments were conducted to study the purification effect of the combined water pollution of eutrophication and heavy metals. The result showed that all the four plant combinations had good removal effects on TN, TP, Cd and Pb in combined water pollution of eutrophication and heavy metal under different concentration gradients, and different plant combinations presented different removal effects. After 30 days of remediation, the average removal rates of the plant combinations in low concentration sewage for TN, TP, Cd and Pb were 88.68%~93.66%, 64.00%~83.02%, 83.84%~93.62% and 95.07%~98.02%, respectively. And the average removal rates in high concentration sewage were 94.49%~97.11% to TN, 92.85%~94.15% to TP, 63.01%~81.42% to Cd, and 88.56%~91.64% to Pb. The intercropping of Lolium multifolorum and Acorus gramineus had the best treatment performance. The bioconcentration factor of four kinds of plants on Cd and Pb was greater than 1, which meant a strong accumulation ability of plants on heavy metals. The accumulation ability of plants on Cd and Pb in low concentration sewage was far greater than those in high concentration sewage. The enrichment ability of Pb was stronger than Cd for the same plant, significantly.
In this study, four kinds of native plants in central China including Lolium multifolorum, Alopecurus pratensis L., Pteris vittata L., and Acorus gramineus were selected as research objects. Laboratory hydroponic experiments were conducted to study the purification effect of the combined water pollution of eutrophication and heavy metals. The result showed that all the four plant combinations had good removal effects on TN, TP, Cd and Pb in combined water pollution of eutrophication and heavy metal under different concentration gradients, and different plant combinations presented different removal effects. After 30 days of remediation, the average removal rates of the plant combinations in low concentration sewage for TN, TP, Cd and Pb were 88.68%~93.66%, 64.00%~83.02%, 83.84%~93.62% and 95.07%~98.02%, respectively. And the average removal rates in high concentration sewage were 94.49%~97.11% to TN, 92.85%~94.15% to TP, 63.01%~81.42% to Cd, and 88.56%~91.64% to Pb. The intercropping of Lolium multifolorum and Acorus gramineus had the best treatment performance. The bioconcentration factor of four kinds of plants on Cd and Pb was greater than 1, which meant a strong accumulation ability of plants on heavy metals. The accumulation ability of plants on Cd and Pb in low concentration sewage was far greater than those in high concentration sewage. The enrichment ability of Pb was stronger than Cd for the same plant, significantly.
2023, 41(7): 76-85.
doi: 10.13205/j.hjgc.202307011
Abstract:
A metal-organic backbone hybrid foam MIL-100(Fe)/PEO was prepared by the ice-template-freeze-drying method. X-ray diffraction, nitrogen adsorption-desorption, scanning electron microscopy, and TG-DSC techniques were used to characterize the structural morphology and elemental composition of the surface of the hybrid foam. The factors influencing the adsorption performance of the hybrid foam and the adsorption kinetics, adsorption thermodynamics and adsorption isotherm models were analyzed by adsorption experiments, and the stability of the hybrid foam separation and regeneration was studied using recycling stability tests. The results showed that MIL-100(Fe)/PEO hybrid foam had strong mechanical strength and rich porous structure, and retained the properties of MIL-100(Fe) itself. The maximum adsorption of tetracycline (TC) and Cu2+ by MIL-100(Fe)/PEO reached 85.02 mg/g and 87.66 mg/g at a MIL-100(Fe)/PEO dosing of 30 mg, an adsorption time of 12 h, an initial adsorption concentration of 20 mg/L, and neutral pH conditions. The adsorption process of the material followed the proposed secondary kinetics with the Langmuir isothermal adsorption model and was an exothermic, spontaneous process. The removal rates of both TC and Cu2+ by MIL-100(Fe)/PEO were maintained at about 70% after 8 cycles of adsorption. MIL-100(Fe)/PEO heterogeneous foam is an efficient and stable adsorbent and promising in application in the removal of mixed pollutants of tetracycline and Cu2+ from wastewater.
A metal-organic backbone hybrid foam MIL-100(Fe)/PEO was prepared by the ice-template-freeze-drying method. X-ray diffraction, nitrogen adsorption-desorption, scanning electron microscopy, and TG-DSC techniques were used to characterize the structural morphology and elemental composition of the surface of the hybrid foam. The factors influencing the adsorption performance of the hybrid foam and the adsorption kinetics, adsorption thermodynamics and adsorption isotherm models were analyzed by adsorption experiments, and the stability of the hybrid foam separation and regeneration was studied using recycling stability tests. The results showed that MIL-100(Fe)/PEO hybrid foam had strong mechanical strength and rich porous structure, and retained the properties of MIL-100(Fe) itself. The maximum adsorption of tetracycline (TC) and Cu2+ by MIL-100(Fe)/PEO reached 85.02 mg/g and 87.66 mg/g at a MIL-100(Fe)/PEO dosing of 30 mg, an adsorption time of 12 h, an initial adsorption concentration of 20 mg/L, and neutral pH conditions. The adsorption process of the material followed the proposed secondary kinetics with the Langmuir isothermal adsorption model and was an exothermic, spontaneous process. The removal rates of both TC and Cu2+ by MIL-100(Fe)/PEO were maintained at about 70% after 8 cycles of adsorption. MIL-100(Fe)/PEO heterogeneous foam is an efficient and stable adsorbent and promising in application in the removal of mixed pollutants of tetracycline and Cu2+ from wastewater.
2023, 41(7): 86-93,101.
doi: 10.13205/j.hjgc.202307012
Abstract:
Iron-based catalysts have excellent performance in activating persulfate (PS) and are readily available, attracting extensive attention from researchers. However, most of the iron-based catalysts studied at the current stage are powder materials, and there are problems such as easy agglomeration and difficulty in recycling, which restrict their practical application. In this study, a microsphere catalyst (CA-Fe microspheres) with high catalytic activity was prepared using cellulose acetate (CA) as a carrier by droplet microfluidic technology. The morphology, structure and composition of the catalysts were characterized by SEM-EDS, FTIR and BET. The high catalytic degradation of tetracycline hydrochloride (TCH) in aqueous solution was tested by catalytic activation of PS. The effects of initial TCH concentration, the dosage of CA-Fe microspheres and the dosage of PS on TCH degradation were also investigated. The results showed that the CA-Fe microspheres had good activation performance for PS, and TCH could be effectively degraded in the CA-Fe/PS system. In the condition of the initial TCH concentration of 20 mg/L, the PS concentration of 2 mmol/L, and the CA-Fe microspheres dosage of 4 g/L, the degradation rate of TCH was about 85%. The electron paramagnetic resonance (EPR) and free radical quenching studies revealed that both SO4-· and·OH radicals were found in the CA-Fe microspheres/PS system, and the SO4-· radical played a major role in the degradation of TCH. Furthermore, the CA-Fe microspheres exhibited excellent structural stability and recycling performance, and the TCH degradation rate remained 80% above after three cycles. The results can provide a scientific basis for the application of cellulose-based magnetic microspheres/PS catalytic systems in the field of removing antibiotic wastewater.
Iron-based catalysts have excellent performance in activating persulfate (PS) and are readily available, attracting extensive attention from researchers. However, most of the iron-based catalysts studied at the current stage are powder materials, and there are problems such as easy agglomeration and difficulty in recycling, which restrict their practical application. In this study, a microsphere catalyst (CA-Fe microspheres) with high catalytic activity was prepared using cellulose acetate (CA) as a carrier by droplet microfluidic technology. The morphology, structure and composition of the catalysts were characterized by SEM-EDS, FTIR and BET. The high catalytic degradation of tetracycline hydrochloride (TCH) in aqueous solution was tested by catalytic activation of PS. The effects of initial TCH concentration, the dosage of CA-Fe microspheres and the dosage of PS on TCH degradation were also investigated. The results showed that the CA-Fe microspheres had good activation performance for PS, and TCH could be effectively degraded in the CA-Fe/PS system. In the condition of the initial TCH concentration of 20 mg/L, the PS concentration of 2 mmol/L, and the CA-Fe microspheres dosage of 4 g/L, the degradation rate of TCH was about 85%. The electron paramagnetic resonance (EPR) and free radical quenching studies revealed that both SO4-· and·OH radicals were found in the CA-Fe microspheres/PS system, and the SO4-· radical played a major role in the degradation of TCH. Furthermore, the CA-Fe microspheres exhibited excellent structural stability and recycling performance, and the TCH degradation rate remained 80% above after three cycles. The results can provide a scientific basis for the application of cellulose-based magnetic microspheres/PS catalytic systems in the field of removing antibiotic wastewater.
2023, 41(7): 94-101.
doi: 10.13205/j.hjgc.202307013
Abstract:
A strain that could efficiently degrade phenanthrene was isolated from the aerobic sludge. Firstly, the degradation characteristics of phenanthrene with different carbon sources as co-substrates were explored. The results showed that the degradation rate of 30 mg/L phenanthrene reached 95.35% in the co-metabolism system with 80 mg/L phenol as a co-substrate.Compared with the non-co-metabolism system without phenol, the degradation rate of phenanthrene increased by 20.33%, and phenol was also mineralized. The co-metabolism enhancement mechanism of the strain with phenol as a co-substrate was further analyzed based on the cells' physiological response and the related enzymatic expression. It was found that biomass and microbial activity increased significantly, which promoted the secretion of proteins and polysaccharides in extracellular polymeric substances (EPS). And the functional groups of EPS also were changed in the co-metabolism system. In addition, compared with the non-co-metabolism system, the co-metabolism system could advance the expression of dehydrogenase (DHA) activities and dioxygenase (C23O) activities by 12 h, and the activities respectively increased by 0.17 to 3.37 times and 0.84 to 1.71, respectively, times during the degradation process. Therefore, the co-metabolism system with phenol as a co-substrate could effectively improve the degradation rate of phenanthrene, which was of great significance for the efficient degradation of aromatic hydrocarbons.
A strain that could efficiently degrade phenanthrene was isolated from the aerobic sludge. Firstly, the degradation characteristics of phenanthrene with different carbon sources as co-substrates were explored. The results showed that the degradation rate of 30 mg/L phenanthrene reached 95.35% in the co-metabolism system with 80 mg/L phenol as a co-substrate.Compared with the non-co-metabolism system without phenol, the degradation rate of phenanthrene increased by 20.33%, and phenol was also mineralized. The co-metabolism enhancement mechanism of the strain with phenol as a co-substrate was further analyzed based on the cells' physiological response and the related enzymatic expression. It was found that biomass and microbial activity increased significantly, which promoted the secretion of proteins and polysaccharides in extracellular polymeric substances (EPS). And the functional groups of EPS also were changed in the co-metabolism system. In addition, compared with the non-co-metabolism system, the co-metabolism system could advance the expression of dehydrogenase (DHA) activities and dioxygenase (C23O) activities by 12 h, and the activities respectively increased by 0.17 to 3.37 times and 0.84 to 1.71, respectively, times during the degradation process. Therefore, the co-metabolism system with phenol as a co-substrate could effectively improve the degradation rate of phenanthrene, which was of great significance for the efficient degradation of aromatic hydrocarbons.
2023, 41(7): 102-108.
doi: 10.13205/j.hjgc.202307014
Abstract:
Numerical simulation technology is widely used in the remediation of polluted groundwater and usually used in the design stage of remediation technology. However, the accuracy of the model parameters obtained is limited to a certain extent in time and space, so there are many uncertainties in the remediation effect. It is more practical to apply numerical simulation technology to the actual repair process. In combination with the example of groundwater pollution remediation, a three-dimensional numerical model was established to simulate groundwater flow and solute transport, considering the characteristics of land mass such as convection, dispersion, and adsorption. Parameter correcting was performed with monitoring data of water level and quality of several monitoring wells during groundwater restoration. The changing trend of pollutants in groundwater with the development of the groundwater remediation process was analyzed, and the extraction and treatment scheme was adjusted in time, in order to guide the implementation of subsequent groundwater remediation. The results indicated the method of numerical model modification based on the monitoring data, during the restoration process, can truly reflect the characteristics of the groundwater system in the simulation area, and effectively guide the follow-up restoration implementation.
Numerical simulation technology is widely used in the remediation of polluted groundwater and usually used in the design stage of remediation technology. However, the accuracy of the model parameters obtained is limited to a certain extent in time and space, so there are many uncertainties in the remediation effect. It is more practical to apply numerical simulation technology to the actual repair process. In combination with the example of groundwater pollution remediation, a three-dimensional numerical model was established to simulate groundwater flow and solute transport, considering the characteristics of land mass such as convection, dispersion, and adsorption. Parameter correcting was performed with monitoring data of water level and quality of several monitoring wells during groundwater restoration. The changing trend of pollutants in groundwater with the development of the groundwater remediation process was analyzed, and the extraction and treatment scheme was adjusted in time, in order to guide the implementation of subsequent groundwater remediation. The results indicated the method of numerical model modification based on the monitoring data, during the restoration process, can truly reflect the characteristics of the groundwater system in the simulation area, and effectively guide the follow-up restoration implementation.
2023, 41(7): 109-115.
doi: 10.13205/j.hjgc.202307015
Abstract:
In order to explore the effect of the concentration of organic matter on the microscopic animals' movement in activated sludge, the microfauna with ordinary movement modes (the linear swimming type, the curved swimming type and the comprehensive swimming type) were taken as the research object, and the effect of COD concentration on average linear velocity ($\bar V$), average angular velocity ($\bar W$) and average curve velocity ($\bar V$CL) of microfauna were analyzed. The results showed that with the increase of COD concentration, the average angular velocity of curve swimming and fast-moving Frontonia depressa increased by 87.7%. The average angular velocity of Coleps hirtus, which moves very fast, increased by 49.1%. Both average angular velocities of the two curved swimming types were significantly correlated with COD concentration (r=0.921, r=0.955) with a better indicating function. The COD concentration was negatively correlated with the linear velocity of Peranema trichophorum (r=-0.723); it was positively correlated with the linear velocity of Frontonia depressa (r=0.877). Both are with certain indicative function. COD concentration had little effect on Anisonema acinus and Euchlanis sp., but had no significant effect on the curve velocity of Aspidisca lynceus.
In order to explore the effect of the concentration of organic matter on the microscopic animals' movement in activated sludge, the microfauna with ordinary movement modes (the linear swimming type, the curved swimming type and the comprehensive swimming type) were taken as the research object, and the effect of COD concentration on average linear velocity ($\bar V$), average angular velocity ($\bar W$) and average curve velocity ($\bar V$CL) of microfauna were analyzed. The results showed that with the increase of COD concentration, the average angular velocity of curve swimming and fast-moving Frontonia depressa increased by 87.7%. The average angular velocity of Coleps hirtus, which moves very fast, increased by 49.1%. Both average angular velocities of the two curved swimming types were significantly correlated with COD concentration (r=0.921, r=0.955) with a better indicating function. The COD concentration was negatively correlated with the linear velocity of Peranema trichophorum (r=-0.723); it was positively correlated with the linear velocity of Frontonia depressa (r=0.877). Both are with certain indicative function. COD concentration had little effect on Anisonema acinus and Euchlanis sp., but had no significant effect on the curve velocity of Aspidisca lynceus.
2023, 41(7): 116-123,251.
doi: 10.13205/j.hjgc.202307016
Abstract:
In response to the current situation that various raw materials, high costs and complicated process in the preparation of Fe/C catalysts to activate persulfates, four Fe/C catalysts were prepared by a high-temperature carbonization method at different pyrolysis temperatures (700, 800, 900 and 1000℃) using inexpensive and environmentally friendly ferric citrate as raw material, and then characterized by SEM, EDS, BET, XRD, XPS. Four Fe/C catalysts were used for the adsorption and activation of peroxydisulfate (PDS) for the degradation of sulfadiazine (SDZ). After initial screening, Fe/C-800 catalyst obtained at 800℃ was used as the target catalyst for an in-depth study. The performance of its activation of PDS to degrade SDZ and the mechanism of action were analyzed. The results showed that the degradation rate of 98.8% can be achieved for 10 mg/L SDZ by 0.05 g/L Fe/C-800 and 1 mmol/L PDS. The Fe/C-800 catalyst had a wide range of pH, could achieve the efficient degradation of different concentrations of SDZ even at a low dosing rate, and demonstrated good recycling performance. Fe0 and C could promote the conversion of Fe3+ into Fe2+, and the amount of ferri & ferrous iron ions dissolved at the end of the reaction was as low as 0.3182 mg/L. Both free radical and non-free radical pathways existed in the reaction system, in which SO4-·, O2-·, and 1O2 played the dominant roles in the degradation process of SDZ. The study may provide new ideas for the activation of Fe/C non-homogeneous catalysts to degrade organic pollutants by PDS.
In response to the current situation that various raw materials, high costs and complicated process in the preparation of Fe/C catalysts to activate persulfates, four Fe/C catalysts were prepared by a high-temperature carbonization method at different pyrolysis temperatures (700, 800, 900 and 1000℃) using inexpensive and environmentally friendly ferric citrate as raw material, and then characterized by SEM, EDS, BET, XRD, XPS. Four Fe/C catalysts were used for the adsorption and activation of peroxydisulfate (PDS) for the degradation of sulfadiazine (SDZ). After initial screening, Fe/C-800 catalyst obtained at 800℃ was used as the target catalyst for an in-depth study. The performance of its activation of PDS to degrade SDZ and the mechanism of action were analyzed. The results showed that the degradation rate of 98.8% can be achieved for 10 mg/L SDZ by 0.05 g/L Fe/C-800 and 1 mmol/L PDS. The Fe/C-800 catalyst had a wide range of pH, could achieve the efficient degradation of different concentrations of SDZ even at a low dosing rate, and demonstrated good recycling performance. Fe0 and C could promote the conversion of Fe3+ into Fe2+, and the amount of ferri & ferrous iron ions dissolved at the end of the reaction was as low as 0.3182 mg/L. Both free radical and non-free radical pathways existed in the reaction system, in which SO4-·, O2-·, and 1O2 played the dominant roles in the degradation process of SDZ. The study may provide new ideas for the activation of Fe/C non-homogeneous catalysts to degrade organic pollutants by PDS.
2023, 41(7): 124-130.
doi: 10.13205/j.hjgc.202307017
Abstract:
In-situ chemical oxidation high-pressure rotary spray remediation technology has broad application prospects in the remediation of organic contaminated sites. Based on the remediation project of a compound organic contaminated site, the field impact radius test was conducted to evaluate the optimal construction parameters for a high-pressure rotary jet. The indoor pilot test was used to study the impacts of the oxidant dosing ratio and the initial concentration of pollutants on the remediation effect, and the engineering pilot scale application was operated to identify the best oxidant dosing ratio for the site. The results showed that the best construction parameters of the high-pressure rotary jet at the site were rotation speed of 15 r/min, nozzle diameter of 2.5 mm, injection pressure of 25 MPa, and lifting speed of 15 cm/min. The composite oxidant of sodium persulfate activated by sodium hydroxide has good repair effect. The lower the dosage ratio of oxidant and the higher the initial concentrations of pollutants, the higher the pollutant removal rate; when the dosing ratio of oxidant increased to 5%, the concentrations of organic pollutants in the application area of the pilot scale project were reduced to the target values of remediation. The research results have high engineering reference value.
In-situ chemical oxidation high-pressure rotary spray remediation technology has broad application prospects in the remediation of organic contaminated sites. Based on the remediation project of a compound organic contaminated site, the field impact radius test was conducted to evaluate the optimal construction parameters for a high-pressure rotary jet. The indoor pilot test was used to study the impacts of the oxidant dosing ratio and the initial concentration of pollutants on the remediation effect, and the engineering pilot scale application was operated to identify the best oxidant dosing ratio for the site. The results showed that the best construction parameters of the high-pressure rotary jet at the site were rotation speed of 15 r/min, nozzle diameter of 2.5 mm, injection pressure of 25 MPa, and lifting speed of 15 cm/min. The composite oxidant of sodium persulfate activated by sodium hydroxide has good repair effect. The lower the dosage ratio of oxidant and the higher the initial concentrations of pollutants, the higher the pollutant removal rate; when the dosing ratio of oxidant increased to 5%, the concentrations of organic pollutants in the application area of the pilot scale project were reduced to the target values of remediation. The research results have high engineering reference value.
2023, 41(7): 131-137,165.
doi: 10.13205/j.hjgc.202307018
Abstract:
The complexity of aerosol components, structure and morphology challenges the applicability of statistical models for aerosol scattering hygroscopic growth factor under high humidity conditions. Based on the hourly observational data of nephelometer and aethalometer, as well as the simultaneous monitored data of environmental meteorology from October to December, 2017 in Chengdu, the aerosol scattering hygroscopic growth factor was calculated by optical synthesis method. The relative humidity (RH), CBC, CBC/CPM2.5, CPM1/CPM2.5 and CPM2.5/CPM10 were used as input factors (CBC, CPM1, CPM2.5 and CPM10 representing mass concentrations of BC, PM1, PM2.5 and PM10 respectively), and a BP neural network model of aerosol scattering hygroscopic growth factor was proposed. The comparison results of multiple models showed that:the corresponding determination coefficient (R2) of the univariate quadratic polynomial model, bivariate model, multivariate GAM model and BP neural network model for the aerosol hygroscopic growth factor were 0.650, 0.744, 0.792 and 0.870 respectively, and the corresponding determination coefficient (R2) for the simulated values under high humidity conditions of RH>85% were 0.538, 0.638, 0.685 and 0.749, respectively. The BP neural network model of aerosol scattering hygroscopic growth factor achieved the best fitting effect and the simulation error of aerosol scattering hygroscopic growth factor under high humidity condition (RH>85%) was significantly reduced.
The complexity of aerosol components, structure and morphology challenges the applicability of statistical models for aerosol scattering hygroscopic growth factor under high humidity conditions. Based on the hourly observational data of nephelometer and aethalometer, as well as the simultaneous monitored data of environmental meteorology from October to December, 2017 in Chengdu, the aerosol scattering hygroscopic growth factor was calculated by optical synthesis method. The relative humidity (RH), CBC, CBC/CPM2.5, CPM1/CPM2.5 and CPM2.5/CPM10 were used as input factors (CBC, CPM1, CPM2.5 and CPM10 representing mass concentrations of BC, PM1, PM2.5 and PM10 respectively), and a BP neural network model of aerosol scattering hygroscopic growth factor was proposed. The comparison results of multiple models showed that:the corresponding determination coefficient (R2) of the univariate quadratic polynomial model, bivariate model, multivariate GAM model and BP neural network model for the aerosol hygroscopic growth factor were 0.650, 0.744, 0.792 and 0.870 respectively, and the corresponding determination coefficient (R2) for the simulated values under high humidity conditions of RH>85% were 0.538, 0.638, 0.685 and 0.749, respectively. The BP neural network model of aerosol scattering hygroscopic growth factor achieved the best fitting effect and the simulation error of aerosol scattering hygroscopic growth factor under high humidity condition (RH>85%) was significantly reduced.
EVOLUTION CHARACTERISTIC AND KINETIC MODEL FOR FUNCTIONAL GROUPS IN BITUMINOUS COAL DURING PYROLYSIS
2023, 41(7): 138-144.
doi: 10.13205/j.hjgc.202307019
Abstract:
Understanding the mechanism of coal pyrolysis is of great significance to improving coal utilization efficiency and mitigating environmental impact. Fourier transform infrared spectroscopy (FTIR) and gas chromatogram-mass spectrum analyses were used to investigate changes in molecular functional groups and polycyclic aromatic hydrocarbons (PAHs) during pyrolysis of bituminous coal, and then kinetic models were constructed. Results showed that:the relative abundances of aromatic, aliphatic, and heteroatom functional groups decreased as pyrolysis temperature increased. When the temperature was lower than 300℃, the reduction of aromatic and aliphatic functional groups was mainly due to the volatilization of the small molecular groups, while the reduction of oxygen-containing functional groups was due to thermal breakage of self-associating hydroxyl hydrogen bonds; when the temperature was 300~600℃, the functional groups of C-O and aliphatics were decomposed at 300℃ and 400℃, leading to rapid decreases in relative abundances of aromatic, aliphatic and oxygen-containing functional groups. The activation energy of each functional group at high temperature stage was higher than that at low temperature stage. The kinetic models of ·OH and C-O in the whole pyrolysis process followed the second-order reaction mode. Changes in the aliphatic functional groups conformed to the two-phase interface model at 25 to 400℃, and conformed to the second-order reaction model at 400 to 600℃. C=O conformed to the three-way transport mode and the second-order reaction model at 25 to 300℃ and 300 to 600℃, respectively.
Understanding the mechanism of coal pyrolysis is of great significance to improving coal utilization efficiency and mitigating environmental impact. Fourier transform infrared spectroscopy (FTIR) and gas chromatogram-mass spectrum analyses were used to investigate changes in molecular functional groups and polycyclic aromatic hydrocarbons (PAHs) during pyrolysis of bituminous coal, and then kinetic models were constructed. Results showed that:the relative abundances of aromatic, aliphatic, and heteroatom functional groups decreased as pyrolysis temperature increased. When the temperature was lower than 300℃, the reduction of aromatic and aliphatic functional groups was mainly due to the volatilization of the small molecular groups, while the reduction of oxygen-containing functional groups was due to thermal breakage of self-associating hydroxyl hydrogen bonds; when the temperature was 300~600℃, the functional groups of C-O and aliphatics were decomposed at 300℃ and 400℃, leading to rapid decreases in relative abundances of aromatic, aliphatic and oxygen-containing functional groups. The activation energy of each functional group at high temperature stage was higher than that at low temperature stage. The kinetic models of ·OH and C-O in the whole pyrolysis process followed the second-order reaction mode. Changes in the aliphatic functional groups conformed to the two-phase interface model at 25 to 400℃, and conformed to the second-order reaction model at 400 to 600℃. C=O conformed to the three-way transport mode and the second-order reaction model at 25 to 300℃ and 300 to 600℃, respectively.
2023, 41(7): 145-149.
doi: 10.13205/j.hjgc.202307020
Abstract:
In order to improve the methane production performance of food waste and spent mushroom substrate high temperature co-digestion, we set four fermentation groups:control, electro-fermentation, activated carbon, and electro-fermentation+activated carbon. By comparing the cumulative methane yield, electrochemical characteristics, and the stability of anaerobic digestion system, we studied the effects of electro-fermentation and the addition of activated carbon on high-temperature anaerobic co-digestion of food waste and spent mushroom substrate. The results showed that, compared with the control group, the cumulative methane production of electro-fermentation, activated carbon, and electro-fermentation+activated carbon groups increased by 6.2%, 7.6% and 21.9%, respectively; meanwhile, the biodegradability increased by 6.4%, 7.6% and 16.9%, respectively, indicating that electro-fermentation and addition activated carbon could synergistically promote gas production. Both the application of a weak electric field and the addition of activated carbon can reduce the concentration of free ammonia (FAN), and accelerate the transformation and degradation of VFAs by methanogens. The reduction of methanogenic bacteria activity caused by the accumulation of FAN and VFAs in the fermentation system was alleviated. In addition, electro-fermentation, electro-fermentation+activated carbon groups had obvious REDOX peak in the volt-ampere characteristic curve, further illustrating that a weak electric field and adding activated carbon could promote cell proliferation and the electron transfer process, accelerate electrochemical REDOX reaction, and enhance the stability of anaerobic digestion system and the target product yield. This study provides a scientific basis for promoting the development of new cross-research directions of microbiology and electrochemistry, and new ways to food waste resource utilization.
In order to improve the methane production performance of food waste and spent mushroom substrate high temperature co-digestion, we set four fermentation groups:control, electro-fermentation, activated carbon, and electro-fermentation+activated carbon. By comparing the cumulative methane yield, electrochemical characteristics, and the stability of anaerobic digestion system, we studied the effects of electro-fermentation and the addition of activated carbon on high-temperature anaerobic co-digestion of food waste and spent mushroom substrate. The results showed that, compared with the control group, the cumulative methane production of electro-fermentation, activated carbon, and electro-fermentation+activated carbon groups increased by 6.2%, 7.6% and 21.9%, respectively; meanwhile, the biodegradability increased by 6.4%, 7.6% and 16.9%, respectively, indicating that electro-fermentation and addition activated carbon could synergistically promote gas production. Both the application of a weak electric field and the addition of activated carbon can reduce the concentration of free ammonia (FAN), and accelerate the transformation and degradation of VFAs by methanogens. The reduction of methanogenic bacteria activity caused by the accumulation of FAN and VFAs in the fermentation system was alleviated. In addition, electro-fermentation, electro-fermentation+activated carbon groups had obvious REDOX peak in the volt-ampere characteristic curve, further illustrating that a weak electric field and adding activated carbon could promote cell proliferation and the electron transfer process, accelerate electrochemical REDOX reaction, and enhance the stability of anaerobic digestion system and the target product yield. This study provides a scientific basis for promoting the development of new cross-research directions of microbiology and electrochemistry, and new ways to food waste resource utilization.
2023, 41(7): 150-158.
doi: 10.13205/j.hjgc.202307021
Abstract:
The synchronous passivation of soil contaminated with high concentration of heavy metals is a difficulty in soil passivation research. In this paper, the synchronous passivation effect of various inorganic salts modified bentonite on soil contaminated with high concentration of heavy metals was studied. The results showed the modified bentonite prepared by NaCl, KCl, Na2CO3, K2CO3, NaNO3, KNO3, Na3PO4, KH2PO4, KMnO4, K3PO4, NaH2PO4 and NaHCO3 under the same condition had obvious differences in the synchronous passivation effect of multiple heavy metal high concentration composite polluted soil. Na2CO3, K3PO4 and NaH2PO4 were selected, by their performance to optimize the modification conditions. Under the optimal modification conditions, the synchronous passivation effect of NaH2PO4 modified bentonite was the best overall. The reduction rates of available Zn, Pb and Cd reached 26.28%, 28.84% and 31.42%. In the modification process of NaH2PO4, calcium in bentonite particles could be exchanged and new independent crystals of CaHPO4·2H2O could be formed. Meanwhile, bentonite particles have better intercalation, layered structure, fracture structure and wider distribution of Na+. Cation exchange interaction during bentonite modification may further promote the passivation effect of modified bentonite on heavy metals.
The synchronous passivation of soil contaminated with high concentration of heavy metals is a difficulty in soil passivation research. In this paper, the synchronous passivation effect of various inorganic salts modified bentonite on soil contaminated with high concentration of heavy metals was studied. The results showed the modified bentonite prepared by NaCl, KCl, Na2CO3, K2CO3, NaNO3, KNO3, Na3PO4, KH2PO4, KMnO4, K3PO4, NaH2PO4 and NaHCO3 under the same condition had obvious differences in the synchronous passivation effect of multiple heavy metal high concentration composite polluted soil. Na2CO3, K3PO4 and NaH2PO4 were selected, by their performance to optimize the modification conditions. Under the optimal modification conditions, the synchronous passivation effect of NaH2PO4 modified bentonite was the best overall. The reduction rates of available Zn, Pb and Cd reached 26.28%, 28.84% and 31.42%. In the modification process of NaH2PO4, calcium in bentonite particles could be exchanged and new independent crystals of CaHPO4·2H2O could be formed. Meanwhile, bentonite particles have better intercalation, layered structure, fracture structure and wider distribution of Na+. Cation exchange interaction during bentonite modification may further promote the passivation effect of modified bentonite on heavy metals.
2023, 41(7): 159-165.
doi: 10.13205/j.hjgc.202307022
Abstract:
In order to solve the problem of the limited radius of influence (ROI) caused by low soil mass transfer efficiency in the application of traditional tubular soil bioelectrochemical system (SBES), horizontally placed carbon brush integrated with horizontal drilling was used to build a new SBES configuration in this study. A horizontal electronic pathway was constructed to promote the degradation of total petroleum hydrocarbon (TPH), while investigating the maximum ROI. The results showed that carbon fiber brush coupling SBESs removed 46.4% to 49.0% of TPH after 80 days, which was 169.8% to 184.9% and 358.4% to 385% higher than those of vertical SBES and natural attenuation, respectively. Besides, the current production correlated with TPH removal reached a maximum output of 21.7 to 35.8 mA/m2, and the maximum ROI could be 136 to 138 cm, which was 1.48 to 1.50 times in terms of vertical SBES. Therefore, the horizontal carbon fiber brush coupling SBES could enhance the microbial degradation of TPH and expansion of ROI, which provides new technology in SBES engineering applications.
In order to solve the problem of the limited radius of influence (ROI) caused by low soil mass transfer efficiency in the application of traditional tubular soil bioelectrochemical system (SBES), horizontally placed carbon brush integrated with horizontal drilling was used to build a new SBES configuration in this study. A horizontal electronic pathway was constructed to promote the degradation of total petroleum hydrocarbon (TPH), while investigating the maximum ROI. The results showed that carbon fiber brush coupling SBESs removed 46.4% to 49.0% of TPH after 80 days, which was 169.8% to 184.9% and 358.4% to 385% higher than those of vertical SBES and natural attenuation, respectively. Besides, the current production correlated with TPH removal reached a maximum output of 21.7 to 35.8 mA/m2, and the maximum ROI could be 136 to 138 cm, which was 1.48 to 1.50 times in terms of vertical SBES. Therefore, the horizontal carbon fiber brush coupling SBES could enhance the microbial degradation of TPH and expansion of ROI, which provides new technology in SBES engineering applications.
2023, 41(7): 166-174.
doi: 10.13205/j.hjgc.202307023
Abstract:
In this study, petroleum hydrocarbon-degrading strains were isolated and purified from an arsenic-petroleum hydrocarbon composite contaminated site in Hubei Province. 16S rDNA sequencing technology was used to identify the bacteria species. The growth and degradation characteristics of the degrading strain were analyzed, and the actual remediation ability of the degrading strains was tested on the composite contaminated soil. The main conclusions were as follows:Acinetobacter sp. JYZ-03, a highly efficient petroleum hydrocarbon degradation strain resistant to As, was isolated. The optimal growth and degradation conditions were pH of 7, 30℃, salinity of 0.1% and initial inoculation amount of 2%. The degradation rate of petroleum hydrocarbon by strain JYZ-03 was 84.05%. The degradation ability of strain for different petroleum hydrocarbon components was in sequence of long-chain alkane (C26 to C38)>polycyclic aromatic hydrocarbons>branched alkanes>medium and long-chain alkanes (C11 to C25); the actual repairing by the strain achieved a satisfying effect. This study enriches the functional strains for remediation of petroleum hydrocarbon, and provides more options for the remediation of compound-contaminated sites.
In this study, petroleum hydrocarbon-degrading strains were isolated and purified from an arsenic-petroleum hydrocarbon composite contaminated site in Hubei Province. 16S rDNA sequencing technology was used to identify the bacteria species. The growth and degradation characteristics of the degrading strain were analyzed, and the actual remediation ability of the degrading strains was tested on the composite contaminated soil. The main conclusions were as follows:Acinetobacter sp. JYZ-03, a highly efficient petroleum hydrocarbon degradation strain resistant to As, was isolated. The optimal growth and degradation conditions were pH of 7, 30℃, salinity of 0.1% and initial inoculation amount of 2%. The degradation rate of petroleum hydrocarbon by strain JYZ-03 was 84.05%. The degradation ability of strain for different petroleum hydrocarbon components was in sequence of long-chain alkane (C26 to C38)>polycyclic aromatic hydrocarbons>branched alkanes>medium and long-chain alkanes (C11 to C25); the actual repairing by the strain achieved a satisfying effect. This study enriches the functional strains for remediation of petroleum hydrocarbon, and provides more options for the remediation of compound-contaminated sites.
2023, 41(7): 175-183,234.
doi: 10.13205/j.hjgc.202307024
Abstract:
Combined with photoelectric detection technology and UV-Vis absorption spectroscopy in spectral analysis technology, a multi-parameter portable surface water quality detection system was developed, which can quickly detect phosphate, nitrite, and chemical oxygen demand (COD) and ammonia nitrogen on-site. For the substances in the water body that absorb the characteristic wavelengths in the visible range, a camera was used to collect the visible spectrum, and the grayscale image of the visible spectrum image was modelled by a convolutional neural network. The concentration value of substances, whose absorption characteristic wavelength is within the ultraviolet band, was measured by photoelectric detection technology. The established convolutional neural network model was transplanted into ZYNQ, and combined with an ultraviolet photoelectric sensor, the concentration value of the detected substance was displayed on the LCD to realize the portability of the water quality detector. Research indicated that:the prediction value of the convolutional neural network was obtained as the tendency value of sample solution in 8 output types of concentration value, the highest accuracy was 100%, and the lowest was 40%. The highest error of COD concentration value was 10%, proving that the detection system has good practical value.
Combined with photoelectric detection technology and UV-Vis absorption spectroscopy in spectral analysis technology, a multi-parameter portable surface water quality detection system was developed, which can quickly detect phosphate, nitrite, and chemical oxygen demand (COD) and ammonia nitrogen on-site. For the substances in the water body that absorb the characteristic wavelengths in the visible range, a camera was used to collect the visible spectrum, and the grayscale image of the visible spectrum image was modelled by a convolutional neural network. The concentration value of substances, whose absorption characteristic wavelength is within the ultraviolet band, was measured by photoelectric detection technology. The established convolutional neural network model was transplanted into ZYNQ, and combined with an ultraviolet photoelectric sensor, the concentration value of the detected substance was displayed on the LCD to realize the portability of the water quality detector. Research indicated that:the prediction value of the convolutional neural network was obtained as the tendency value of sample solution in 8 output types of concentration value, the highest accuracy was 100%, and the lowest was 40%. The highest error of COD concentration value was 10%, proving that the detection system has good practical value.
2023, 41(7): 184-191.
doi: 10.13205/j.hjgc.202307025
Abstract:
For the problem of leakage identification of water distribution networks, this paper proposed a leakage identification method based on virtual pressure partition. The dimension of the leakage identification problem was reduced by virtual pressure partition of water distribution networks, and the distribution of real leakage flow in the network was optimized by a genetic algorithm. The method was divided into virtual pressure partition and leakage zone identification. Firstly, based on the improved K-means clustering algorithm, the network nodes were divided into different regions with adjacent locations, similar average free water heads and connected topological structures. Secondly, the regional proportional coefficient was taken as the decision variable, and the objective function was to minimize the difference between the simulated value and the measured value at the pressure measuring point, and the real leakage situation of each region was identified. A small verification case was designed based on the No. 8 area of the water distribution network in L Town, Z City, to verify the accuracy of the method in identifying different leakage conditions. Subsequently, the water distribution network in L Town was also used for practical engineering application. The results show that the proposed method divides the nodes well, and the identification results of the serious leakage area in the network are consistent with the actual situation, which can assist in the leakage detection of large water distribution networks.
For the problem of leakage identification of water distribution networks, this paper proposed a leakage identification method based on virtual pressure partition. The dimension of the leakage identification problem was reduced by virtual pressure partition of water distribution networks, and the distribution of real leakage flow in the network was optimized by a genetic algorithm. The method was divided into virtual pressure partition and leakage zone identification. Firstly, based on the improved K-means clustering algorithm, the network nodes were divided into different regions with adjacent locations, similar average free water heads and connected topological structures. Secondly, the regional proportional coefficient was taken as the decision variable, and the objective function was to minimize the difference between the simulated value and the measured value at the pressure measuring point, and the real leakage situation of each region was identified. A small verification case was designed based on the No. 8 area of the water distribution network in L Town, Z City, to verify the accuracy of the method in identifying different leakage conditions. Subsequently, the water distribution network in L Town was also used for practical engineering application. The results show that the proposed method divides the nodes well, and the identification results of the serious leakage area in the network are consistent with the actual situation, which can assist in the leakage detection of large water distribution networks.
2023, 41(7): 192-200.
doi: 10.13205/j.hjgc.202307026
Abstract:
Cu/Al-MCM-41 molecular sieve catalyst modified by Cu and Al was prepared by a one-step hydrothermal synthesis method for desolved oxygen (DO) removal in reclaimed water. The effects of the adding amount of active metal, pH of catalyst preparation, crystallization temperature and crystallization time on the removal rate of DO were investigated. The results revealed that when the molar ratio of Cu/Si and Al/Si were 0.2 and 0.1, respectively, pH was 10.5, and Cu/Al-MCM-41 was crystallized at 140℃ for 36 hours, the removal rate of DO in reclaimed water reached 97.0% after 60 min. Meanwhile, the quality of reclaimed water and simulated water had little influence on the DO removal effect. Carbohydrazide was secondary decomposed into N2 and four hydrogen atoms (H·), under the catalysis of Cu/Al-MCM-41. The increase in the concentration of hydrogen atoms adsorbed on the catalyst surface led to the rapid reduction of DO concentration. The introduction of Cu and Al could significantly increase the acidic sites and enhance the total acidity of catalysts to promote the decomposition of DO, to generate more oxidizing hydroxyl radicals (·OH), which can combine with hydrogen atoms with higher activity and reducibility to form H2O. This speeds up the removal of dissolved oxygen.
Cu/Al-MCM-41 molecular sieve catalyst modified by Cu and Al was prepared by a one-step hydrothermal synthesis method for desolved oxygen (DO) removal in reclaimed water. The effects of the adding amount of active metal, pH of catalyst preparation, crystallization temperature and crystallization time on the removal rate of DO were investigated. The results revealed that when the molar ratio of Cu/Si and Al/Si were 0.2 and 0.1, respectively, pH was 10.5, and Cu/Al-MCM-41 was crystallized at 140℃ for 36 hours, the removal rate of DO in reclaimed water reached 97.0% after 60 min. Meanwhile, the quality of reclaimed water and simulated water had little influence on the DO removal effect. Carbohydrazide was secondary decomposed into N2 and four hydrogen atoms (H·), under the catalysis of Cu/Al-MCM-41. The increase in the concentration of hydrogen atoms adsorbed on the catalyst surface led to the rapid reduction of DO concentration. The introduction of Cu and Al could significantly increase the acidic sites and enhance the total acidity of catalysts to promote the decomposition of DO, to generate more oxidizing hydroxyl radicals (·OH), which can combine with hydrogen atoms with higher activity and reducibility to form H2O. This speeds up the removal of dissolved oxygen.
2023, 41(7): 201-205,240.
doi: 10.13205/j.hjgc.202307027
Abstract:
It is necessary to research and develop a multifunctional composite filter material under the current context of regular epidemic prevention and control. Reduced graphene oxide (rGO) composite functional filter material and the electret air filtration material (PTFE) were chosen for the experimental study. Tests on the filtration characteristics and antibacterial properties and other properties were conducted. Results showed that at the beginning of the filtration experiment, the filtration efficiency of rGO filter material was positively correlated with the change in filtration rate, while the trend of the filtration efficiency of PTFE filter material was opposite, and the filtration efficiency was better than that of rGO filter material overall. In the subsequent experiments, the filtration efficiency of rGO filter material was generally higher than that of PTFE filter material, but the filtration resistance of rGO filter material was about twice that of PTFE filter material. The dust capacity of rGO filter material was far greater than that of PTFE filter material at the wind velocity of 0.05 m/s. In addition, it was found that rGO filter media also had certain antibacterial and bacteriostatic properties. This study provides a reference for the selection of air purifiers and improvement of rGO filter material performance in the post-pandemic era, which also provides a new idea for the subsequent research of composite filter material.
It is necessary to research and develop a multifunctional composite filter material under the current context of regular epidemic prevention and control. Reduced graphene oxide (rGO) composite functional filter material and the electret air filtration material (PTFE) were chosen for the experimental study. Tests on the filtration characteristics and antibacterial properties and other properties were conducted. Results showed that at the beginning of the filtration experiment, the filtration efficiency of rGO filter material was positively correlated with the change in filtration rate, while the trend of the filtration efficiency of PTFE filter material was opposite, and the filtration efficiency was better than that of rGO filter material overall. In the subsequent experiments, the filtration efficiency of rGO filter material was generally higher than that of PTFE filter material, but the filtration resistance of rGO filter material was about twice that of PTFE filter material. The dust capacity of rGO filter material was far greater than that of PTFE filter material at the wind velocity of 0.05 m/s. In addition, it was found that rGO filter media also had certain antibacterial and bacteriostatic properties. This study provides a reference for the selection of air purifiers and improvement of rGO filter material performance in the post-pandemic era, which also provides a new idea for the subsequent research of composite filter material.
2023, 41(7): 206-213,228.
doi: 10.13205/j.hjgc.202307028
Abstract:
By adding a spoiler at the inlet, the problem that the filter paper near the inlet of the upper intake horizontal cartridge dust-collector was easily damaged and invalid, got improved. To determine the best matching scheme of the structural and installation parameters of the spoiler, an orthogonal experiment with three factors and three levels was designed to conduct a CFD numerical simulation. In this experiment, the width of the spoiler b, the installation angle β and the distance from the installation position of the flower plate x, were selected as the factors, and the first order interaction between them was also taken into account. The performance of the spoiler was evaluated by the comprehensive flow distribution coefficient Δ$\overline {{K_\xi }} $, static pressure drop ΔP and ash-hopper particle capture rate η. After variance analysis, single factor analysis and interaction analysis of the experiment result, the parameter matching scheme with better ash-hopper particle capture rate and smaller pressure drop was selected, that was, b=120 mm, β=60° and x=140 mm. With the spoiler, ΔP was still within the appropriate range, Δ$\overline {{K_\xi }} $ decreased by 11.5% and η increased by 19.3%, indicating that the flow uniformity of the filter cartridge and the initial separation effect of particles were improved, which was good for extending the life of filter cartridges.
By adding a spoiler at the inlet, the problem that the filter paper near the inlet of the upper intake horizontal cartridge dust-collector was easily damaged and invalid, got improved. To determine the best matching scheme of the structural and installation parameters of the spoiler, an orthogonal experiment with three factors and three levels was designed to conduct a CFD numerical simulation. In this experiment, the width of the spoiler b, the installation angle β and the distance from the installation position of the flower plate x, were selected as the factors, and the first order interaction between them was also taken into account. The performance of the spoiler was evaluated by the comprehensive flow distribution coefficient Δ$\overline {{K_\xi }} $, static pressure drop ΔP and ash-hopper particle capture rate η. After variance analysis, single factor analysis and interaction analysis of the experiment result, the parameter matching scheme with better ash-hopper particle capture rate and smaller pressure drop was selected, that was, b=120 mm, β=60° and x=140 mm. With the spoiler, ΔP was still within the appropriate range, Δ$\overline {{K_\xi }} $ decreased by 11.5% and η increased by 19.3%, indicating that the flow uniformity of the filter cartridge and the initial separation effect of particles were improved, which was good for extending the life of filter cartridges.
2023, 41(7): 214-221.
doi: 10.13205/j.hjgc.202307029
Abstract:
Underwater trash detection technology is of great significance for automatic trash removal tasks by underwater robots. However, it faces some challenges, such as an unsatisfactory detection rate due to poor underwater light conditions and high computation load. To solve these problems, this paper proposed an improved YOLOv5 model for underwater trash detection. First, in the preprocessing stage, Gamma transform was introduced to improve the grey level and contrast of underwater images for model detection. Meanwhile, the CBAM attention mechanism was embedded in the detection part of the YOLOv5 model to select the information important to underwater trash detection tasks and suppress uncritical information, thus improving the accuracy of the algorithm. Besides, in the neck layer, the traditional convolution module was replaced by the Ghost convolution module to reduce the calculation amount and improve the detection speed. The proposed model was evaluated on an underwater trash dataset in the real environment. Compared with mainstream object detection algorithms, the proposed model achieved the highest detection accuracy of 93.7% in images with a resolution of 640×640, and the calculation time was only 6.7 ms, meeting the requirements of real-time performance. The study results provide a good reference for underwater trash detection.
Underwater trash detection technology is of great significance for automatic trash removal tasks by underwater robots. However, it faces some challenges, such as an unsatisfactory detection rate due to poor underwater light conditions and high computation load. To solve these problems, this paper proposed an improved YOLOv5 model for underwater trash detection. First, in the preprocessing stage, Gamma transform was introduced to improve the grey level and contrast of underwater images for model detection. Meanwhile, the CBAM attention mechanism was embedded in the detection part of the YOLOv5 model to select the information important to underwater trash detection tasks and suppress uncritical information, thus improving the accuracy of the algorithm. Besides, in the neck layer, the traditional convolution module was replaced by the Ghost convolution module to reduce the calculation amount and improve the detection speed. The proposed model was evaluated on an underwater trash dataset in the real environment. Compared with mainstream object detection algorithms, the proposed model achieved the highest detection accuracy of 93.7% in images with a resolution of 640×640, and the calculation time was only 6.7 ms, meeting the requirements of real-time performance. The study results provide a good reference for underwater trash detection.
2023, 41(7): 222-228.
doi: 10.13205/j.hjgc.202307030
Abstract:
The traditional index risk assessment method takes the total amount of heavy metals as the object of determining the environmental risk assessment of contaminated soil, which may underestimate the pollution degree of heavy metals. In this paper, an improved potential ecological risk assessment method based on the available state of heavy metals is proposed. This method can consider both the data discreteness and biological availability, and quantify the pollution risk of volatile organic compounds. Aiming at the regional polluted soil of a chemical enterprise in Dafeng District, Yancheng, the traditional index risk assessment method and the improved potential ecological risk assessment method were compared and analyzed. The results showed that the improved potential ecological assessment method was feasible. The assessment results of the improved method showed that Cr and Cu elements presented a forth level ecological hazard degree, Pb element presented a strong ecological hazard degree, while the potential ecological risk coefficient of Co elements and VOCs reached a very strong ecological hazard degree. The potential ecological risk index RI of the contaminated soil was 4613.43, a very strong ecological hazard degree.
The traditional index risk assessment method takes the total amount of heavy metals as the object of determining the environmental risk assessment of contaminated soil, which may underestimate the pollution degree of heavy metals. In this paper, an improved potential ecological risk assessment method based on the available state of heavy metals is proposed. This method can consider both the data discreteness and biological availability, and quantify the pollution risk of volatile organic compounds. Aiming at the regional polluted soil of a chemical enterprise in Dafeng District, Yancheng, the traditional index risk assessment method and the improved potential ecological risk assessment method were compared and analyzed. The results showed that the improved potential ecological assessment method was feasible. The assessment results of the improved method showed that Cr and Cu elements presented a forth level ecological hazard degree, Pb element presented a strong ecological hazard degree, while the potential ecological risk coefficient of Co elements and VOCs reached a very strong ecological hazard degree. The potential ecological risk index RI of the contaminated soil was 4613.43, a very strong ecological hazard degree.
2023, 41(7): 229-234.
doi: 10.13205/j.hjgc.202307031
Abstract:
The current evaluation standard of domestic waste incineration plants is based on the project construction level and operation management level of the evaluation object. Then comprehensive scoring method is conducted according to the different weights of the two dimensions. Due to the large differences in design parameters between waste incineration power plants, the existing evaluation methods are mainly based on design parameters, and the evaluation objects are evaluated by experts. Index selection doesn't consider the weights from the perspective of energy efficiency and environmental protection indicators, and the expert scoring also has strong subjectivity. Therefore, the evaluation results are one-sided sometimes. By using the Delphi and TOPSIS method and combining them reasonably, this paper gave a comprehensive evaluation method from the aspects of index determination, index evaluation and ranking different planets. First, using the Delphi method, the evaluation indicators were determined from the perspective of energy efficiency and environmental protection, so that the evaluation dimensions gave consideration to both economic and social aspects. Then, using Delphi method, experts ranked the evaluation objects according to the determined evaluation indicators to give the subjective score. The deviation between the actual evaluation index and the ideal solution was objectively scored by the TOPSIS method. The final comprehensive score was calculated according to the different weights of subjective and objective evaluations. This method was proposed to evaluate the operation of multiple waste incineration plants and provide a subjective and objective ranking. It can provide new scoring ideas for the revision of the current evaluation standards for domestic waste incineration plants.
The current evaluation standard of domestic waste incineration plants is based on the project construction level and operation management level of the evaluation object. Then comprehensive scoring method is conducted according to the different weights of the two dimensions. Due to the large differences in design parameters between waste incineration power plants, the existing evaluation methods are mainly based on design parameters, and the evaluation objects are evaluated by experts. Index selection doesn't consider the weights from the perspective of energy efficiency and environmental protection indicators, and the expert scoring also has strong subjectivity. Therefore, the evaluation results are one-sided sometimes. By using the Delphi and TOPSIS method and combining them reasonably, this paper gave a comprehensive evaluation method from the aspects of index determination, index evaluation and ranking different planets. First, using the Delphi method, the evaluation indicators were determined from the perspective of energy efficiency and environmental protection, so that the evaluation dimensions gave consideration to both economic and social aspects. Then, using Delphi method, experts ranked the evaluation objects according to the determined evaluation indicators to give the subjective score. The deviation between the actual evaluation index and the ideal solution was objectively scored by the TOPSIS method. The final comprehensive score was calculated according to the different weights of subjective and objective evaluations. This method was proposed to evaluate the operation of multiple waste incineration plants and provide a subjective and objective ranking. It can provide new scoring ideas for the revision of the current evaluation standards for domestic waste incineration plants.
2023, 41(7): 235-240.
doi: 10.13205/j.hjgc.202307032
Abstract:
The Law of Soil Pollution Prevention and Control of the People's Republic of China has stipulated that we should implement a soil pollution risk control system. However, the risk control system of soil radioactive pollution has not been established, and no screening value of soil radioactive pollution for risk control has been formulated. The research selected 0.01 mSv/a as a screening value to determine dosage guidelines, used RESRAD software program to calculate and deduce the screening values of soil radioactive contamination risk, according to different land-use types, and then compared the calculated results with the nuclide screening values recommend by United States NRC, and determined the soil risk screening values of 9 nuclide species. The research can provide a basis for improving the soil radioactivity risk control standards in China.
The Law of Soil Pollution Prevention and Control of the People's Republic of China has stipulated that we should implement a soil pollution risk control system. However, the risk control system of soil radioactive pollution has not been established, and no screening value of soil radioactive pollution for risk control has been formulated. The research selected 0.01 mSv/a as a screening value to determine dosage guidelines, used RESRAD software program to calculate and deduce the screening values of soil radioactive contamination risk, according to different land-use types, and then compared the calculated results with the nuclide screening values recommend by United States NRC, and determined the soil risk screening values of 9 nuclide species. The research can provide a basis for improving the soil radioactivity risk control standards in China.
2023, 41(7): 241-251.
doi: 10.13205/j.hjgc.202307033
Abstract:
Producing volatile fatty acids (VFAs) by anaerobic fermentation from municipal sludge to strengthen nitrogen and phosphorus removal of urban sewage, is one of the most effective sludge treatment and disposal methods to realize the purpose of treating waste with waste. However, hydrolysis is the limiting step of VFAs production from sludge. Improving sludge hydrolysis efficiency by pretreatment is an efficient way to increase VFAs yield significantly. Many pretreatment strategies have been reported, and the mechanism and impact of enhancing the VFAs production process are different. Therefore, this review summarized and compared the commonly used pre-treatment processes for promoting sludge fermentation to produce VFAs, elaborated on the principles, characteristics, and application effect of each pre-treatment process, compared and analyzed their economic costs, comprehensively analyzed their existing problems, and looked forward to future development directions, in order to provide literature reference for the design and optimization of sludge fermentation acid production engineering schemes.
Producing volatile fatty acids (VFAs) by anaerobic fermentation from municipal sludge to strengthen nitrogen and phosphorus removal of urban sewage, is one of the most effective sludge treatment and disposal methods to realize the purpose of treating waste with waste. However, hydrolysis is the limiting step of VFAs production from sludge. Improving sludge hydrolysis efficiency by pretreatment is an efficient way to increase VFAs yield significantly. Many pretreatment strategies have been reported, and the mechanism and impact of enhancing the VFAs production process are different. Therefore, this review summarized and compared the commonly used pre-treatment processes for promoting sludge fermentation to produce VFAs, elaborated on the principles, characteristics, and application effect of each pre-treatment process, compared and analyzed their economic costs, comprehensively analyzed their existing problems, and looked forward to future development directions, in order to provide literature reference for the design and optimization of sludge fermentation acid production engineering schemes.
2023, 41(7): 252-259,270.
doi: 10.13205/j.hjgc.202307034
Abstract:
At present, aquaculture in China is deeply restricted by the shortage of high-quality feed resources, and the phenomenon of competition for food by human and livestock is becoming increasingly severe, so it is urgently needed to develop unconventional feed resources. Most of the unconventional feed resources are agro-industrial wastes, which are seriously wasted, due to the low direct feeding value. Solid-state fermentation technology is increasingly favored by the feed industry due to its simpler operation, higher yield rate and environmental friendliness. It has been widely used in improving the nutritional value of unconventional feeds and improving animal health. This paper first introduces the status quo of solid-state fermentation technology and common unconventional feed resources, then analyzes the influence of each process parameter on solid-state fermentation, then summarizes the value-added application of unconventional feed resources in solid-state fermentation, and finally puts forward the problems existing in the preparation of feed by solid-state fermentation and prospects the future development direction.
At present, aquaculture in China is deeply restricted by the shortage of high-quality feed resources, and the phenomenon of competition for food by human and livestock is becoming increasingly severe, so it is urgently needed to develop unconventional feed resources. Most of the unconventional feed resources are agro-industrial wastes, which are seriously wasted, due to the low direct feeding value. Solid-state fermentation technology is increasingly favored by the feed industry due to its simpler operation, higher yield rate and environmental friendliness. It has been widely used in improving the nutritional value of unconventional feeds and improving animal health. This paper first introduces the status quo of solid-state fermentation technology and common unconventional feed resources, then analyzes the influence of each process parameter on solid-state fermentation, then summarizes the value-added application of unconventional feed resources in solid-state fermentation, and finally puts forward the problems existing in the preparation of feed by solid-state fermentation and prospects the future development direction.
2023, 41(7): 260-270.
doi: 10.13205/j.hjgc.202307035
Abstract:
Volatile organic compounds (VOCs) are a class of common pollutants. They can enter the environment through industrial and agricultural activities and cause pollution, thus posing a potential threat to the ecological environment and human health. Carbon-based materials are widely used in the research of VOCs pollution prevention and control,due to their advantages and great engineering application potential. Therefore, it is of practical environmental significance to clarify the interaction mechanism between carbon-based materials and VOCs. In this review, the primary sources, hazards and common treatment methods of VOCs were first summarized. Taking carbon-based materials as the primary research object, the adsorption and degradation efficiency of various modified or unmodified carbon-based materials on VOCs were discussed. The possible interaction mechanism between them in the process of adsorption and degradation was described in detail. Then, from the perspective of the physicochemical properties of carbon-based materials and VOCs themselves as well as environmental factors, the factors influencing the adsorption or degradation of VOCs by carbon-based materials were discussed. Finally, the correlation and differences between the two were clarified, and the interaction methods in the process of determining the removal of VOCs were summarized. Based on the in-depth understanding of the efficiency, mechanism and influencing factors in the adsorption and degradation of VOCs by carbon-based materials, this review could provide a deeper understanding of the critical role of carbon-based materials in the VOCs treatment process, which could provide theoretical guidance for the future regulation direction of the structure of carbon-based materials, application performance evaluation and their application in adsorption or degradation of VOCs.
Volatile organic compounds (VOCs) are a class of common pollutants. They can enter the environment through industrial and agricultural activities and cause pollution, thus posing a potential threat to the ecological environment and human health. Carbon-based materials are widely used in the research of VOCs pollution prevention and control,due to their advantages and great engineering application potential. Therefore, it is of practical environmental significance to clarify the interaction mechanism between carbon-based materials and VOCs. In this review, the primary sources, hazards and common treatment methods of VOCs were first summarized. Taking carbon-based materials as the primary research object, the adsorption and degradation efficiency of various modified or unmodified carbon-based materials on VOCs were discussed. The possible interaction mechanism between them in the process of adsorption and degradation was described in detail. Then, from the perspective of the physicochemical properties of carbon-based materials and VOCs themselves as well as environmental factors, the factors influencing the adsorption or degradation of VOCs by carbon-based materials were discussed. Finally, the correlation and differences between the two were clarified, and the interaction methods in the process of determining the removal of VOCs were summarized. Based on the in-depth understanding of the efficiency, mechanism and influencing factors in the adsorption and degradation of VOCs by carbon-based materials, this review could provide a deeper understanding of the critical role of carbon-based materials in the VOCs treatment process, which could provide theoretical guidance for the future regulation direction of the structure of carbon-based materials, application performance evaluation and their application in adsorption or degradation of VOCs.
2023, 41(7): 271-276.
doi: 10.13205/j.hjgc.202307036
Abstract:
The antagonistic or synergistic effect of selenium on the absorption of heavy metal elements by crops is the theoretical support to produce selenium-enriched and low-heavy metal agricultural products in soil-polluted areas. Based on the analysis of the advantages and disadvantages of foliar selenium application, this paper focuses on the possible impact of foliar selenium application on the absorption, accumulation, and redistribution of arsenic in rice. It is considered that, for the foliar sprayed selenium, the ability of leaves to absorb and redistribute selenium, the migration and re-accumulation process of leaf selenium in rice, and the impact of leaf selenium migration, accumulation, and efflux effects on As absorption, upward migration, and accumulation in rice roots are key processes that determine arsenic enrichment in rice. The form of selenium application, the amount of selenium application and the growth period of selenium application are the key factors affecting arsenic accumulation. This paper also proposes the future research direction in this field.
The antagonistic or synergistic effect of selenium on the absorption of heavy metal elements by crops is the theoretical support to produce selenium-enriched and low-heavy metal agricultural products in soil-polluted areas. Based on the analysis of the advantages and disadvantages of foliar selenium application, this paper focuses on the possible impact of foliar selenium application on the absorption, accumulation, and redistribution of arsenic in rice. It is considered that, for the foliar sprayed selenium, the ability of leaves to absorb and redistribute selenium, the migration and re-accumulation process of leaf selenium in rice, and the impact of leaf selenium migration, accumulation, and efflux effects on As absorption, upward migration, and accumulation in rice roots are key processes that determine arsenic enrichment in rice. The form of selenium application, the amount of selenium application and the growth period of selenium application are the key factors affecting arsenic accumulation. This paper also proposes the future research direction in this field.
