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2022 Vol. 40, No. 10
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2022, 40(10): 1-8,79.
doi: 10.13205/j.hjgc.202210001
Abstract:
The water resources, water supply and usage, sewage treatment and reuse, and water reuse potential in 9 provinces (autonomous regions) and 68 selected cities in the Yellow River basin were systematically analyzed. In 2020, the total amount of reclaimed water used by the 68 selected cities in the Yellow River basin was 1.81 billion m3, and it was estimated that there was a potential growth of 2.20~2.59 billion m3 per year in the future. There were significant differences in the quantity and rate of reclaimed water use among the selected cities in the Yellow River basin. The water reuse rate of 11 upstream cities was less than 25%, and of 20 middle and downstream cities was less than 30%, which was below the national planning target. It was necessary to further develop the reclaimed water use for cities, such as Lanzhou and Baotou in the upper reaches of the Yellow River, Yulin, Taiyuan, Jiyuan, and Tai'an in the middle and lower reaches. In the future, it's necessary to further expand water reuse in terms of applications, especially in industrial use. Also, it is required to enhance the planning of reclaimed water allocation and use, water reuse classification, data collection, etc.
The water resources, water supply and usage, sewage treatment and reuse, and water reuse potential in 9 provinces (autonomous regions) and 68 selected cities in the Yellow River basin were systematically analyzed. In 2020, the total amount of reclaimed water used by the 68 selected cities in the Yellow River basin was 1.81 billion m3, and it was estimated that there was a potential growth of 2.20~2.59 billion m3 per year in the future. There were significant differences in the quantity and rate of reclaimed water use among the selected cities in the Yellow River basin. The water reuse rate of 11 upstream cities was less than 25%, and of 20 middle and downstream cities was less than 30%, which was below the national planning target. It was necessary to further develop the reclaimed water use for cities, such as Lanzhou and Baotou in the upper reaches of the Yellow River, Yulin, Taiyuan, Jiyuan, and Tai'an in the middle and lower reaches. In the future, it's necessary to further expand water reuse in terms of applications, especially in industrial use. Also, it is required to enhance the planning of reclaimed water allocation and use, water reuse classification, data collection, etc.
2022, 40(10): 9-14.
doi: 10.13205/j.hjgc.202210002
Abstract:
In this paper, domestic sewage with low carbon to nitrogen ratio was taken as the research object, and the SBR reactor was used to quickly start the partial nitrification by reducing the stirring time in aerobic stage. The nitrogen removal law of typical operating cycles was studied, and the realization of partial nitrification was further verified from the perspective of microorganisms. After reducing the aerobic stirring time by 50%, the nitrite accumulation rate (NAR) increased from 36.05% to 54.06%. After stopping aerobic stirring, the NAR increased to 90.17%, and it continued to operate stably in this state. In a typical operation cycle, SBR had a good ammonia nitrogen removal effect and high NAR. The removal rate of NH4+-N reached 89.46% and the NAR of effluent reached 89.13%. The detection result of quantitative real-time PCR (q-PCR) showed that after 140 days of population optimization, the contents of ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) in the sludge accounted for 70.3% and 2.1% of the total bacteria, respectively. The realization of partial nitrification was verified from the perspective of molecular biology.
In this paper, domestic sewage with low carbon to nitrogen ratio was taken as the research object, and the SBR reactor was used to quickly start the partial nitrification by reducing the stirring time in aerobic stage. The nitrogen removal law of typical operating cycles was studied, and the realization of partial nitrification was further verified from the perspective of microorganisms. After reducing the aerobic stirring time by 50%, the nitrite accumulation rate (NAR) increased from 36.05% to 54.06%. After stopping aerobic stirring, the NAR increased to 90.17%, and it continued to operate stably in this state. In a typical operation cycle, SBR had a good ammonia nitrogen removal effect and high NAR. The removal rate of NH4+-N reached 89.46% and the NAR of effluent reached 89.13%. The detection result of quantitative real-time PCR (q-PCR) showed that after 140 days of population optimization, the contents of ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria (NOB) in the sludge accounted for 70.3% and 2.1% of the total bacteria, respectively. The realization of partial nitrification was verified from the perspective of molecular biology.
2022, 40(10): 15-23,70.
doi: 10.13205/j.hjgc.202210003
Abstract:
The effects of long-term exposure to sulfamethoxazole (SMX) on nitrogen removal performance and microbial community in sequence batch bioreactor (SBR) were studied. The results showed that the removal effect of organic matter and NH4+-N by SBR didn't change significantly after long-term exposure to a 6 mg/L SMX environment. The average removal rate of COD was (92.57±0.92)%, and that of NH4+-N reached (98.71±0.34)%. The effluent concentrations of NO2--N and NO3--N increased with the increase in operation time. On the 104th day, the specific oxygen consumption rate (SOUR), specific ammonia oxidation rate (SAOR), specific nitrate oxidation rate (SNOR), specific nitrate reduction rate (SNRR), and specific nitrite reduction rate (SNIRR) decreased by 23.33%, 24.47%, 28.29%, 14.97% and 15.81%, compared with those before adding SMX. With the existence of SMX, the contents of extracellular polymeric substance (EPS), loosely bound extracellular polymeric substance (LB-EPS) and tightly bound extracellular polymeric substance (TB-EPS), protein (PN) and polysaccharide (PS) increased with the increase of operation time, and PN/PS showed an upward trend. The production of reactive oxygen species (ROS) and lactate dehydrogenase (LDH) increased with the increase of running time. 6 mg/L SMX could reduce the richness and increase the diversity of the microbial community in activated sludge, and decrease the relative abundance of Proteobacteria, Chloroflexi, and Gammaproteobacteria, thus affecting the nitrogen removal performance of SBR.
The effects of long-term exposure to sulfamethoxazole (SMX) on nitrogen removal performance and microbial community in sequence batch bioreactor (SBR) were studied. The results showed that the removal effect of organic matter and NH4+-N by SBR didn't change significantly after long-term exposure to a 6 mg/L SMX environment. The average removal rate of COD was (92.57±0.92)%, and that of NH4+-N reached (98.71±0.34)%. The effluent concentrations of NO2--N and NO3--N increased with the increase in operation time. On the 104th day, the specific oxygen consumption rate (SOUR), specific ammonia oxidation rate (SAOR), specific nitrate oxidation rate (SNOR), specific nitrate reduction rate (SNRR), and specific nitrite reduction rate (SNIRR) decreased by 23.33%, 24.47%, 28.29%, 14.97% and 15.81%, compared with those before adding SMX. With the existence of SMX, the contents of extracellular polymeric substance (EPS), loosely bound extracellular polymeric substance (LB-EPS) and tightly bound extracellular polymeric substance (TB-EPS), protein (PN) and polysaccharide (PS) increased with the increase of operation time, and PN/PS showed an upward trend. The production of reactive oxygen species (ROS) and lactate dehydrogenase (LDH) increased with the increase of running time. 6 mg/L SMX could reduce the richness and increase the diversity of the microbial community in activated sludge, and decrease the relative abundance of Proteobacteria, Chloroflexi, and Gammaproteobacteria, thus affecting the nitrogen removal performance of SBR.
2022, 40(10): 24-31.
doi: 10.13205/j.hjgc.202210004
Abstract:
Based on 16S rRNA genes-Illumina MiSeq high-throughput sequencing, this study aimed to investigate the effects of FA concentrations of 0, 0.2, 1, 4, 10, 15, 25, 50 mg/L on phosphorus removal efficiency and bacterial community structure of an EBPR system. Results indicated that when the concentration of FA was 0.2 mg/L, it promoted the phosphorus removal of the EBPR system; and when the concentration of FA was 1~50 mg/L, it inhibited the phosphorus removal of the EBPR system. The relative abundance of Proteobacteria increased with the increase of FA concentration. The relative abundance of Gammaproteobacteria was positively correlated with the FA concentration at the class level. At the genus level, the relative abundance of Tetrasphaera was more consistent with the effect of FA on phosphorus removal performance than Ca. Accumulibacter. LEfSe analysis showed that the biomarkers of Low, Mid and High were Chloroflexi, Bacteroidetes and Betaproteobacteriales, respectively. This study clarified the process of the effect of FA on the EBPR system, deepened the understanding of the bacterial community structure during the phosphorus removal process of the EBPR system, and provided a reference for the in-depth study of the inhibition mechanism of biological phosphorus removal.
Based on 16S rRNA genes-Illumina MiSeq high-throughput sequencing, this study aimed to investigate the effects of FA concentrations of 0, 0.2, 1, 4, 10, 15, 25, 50 mg/L on phosphorus removal efficiency and bacterial community structure of an EBPR system. Results indicated that when the concentration of FA was 0.2 mg/L, it promoted the phosphorus removal of the EBPR system; and when the concentration of FA was 1~50 mg/L, it inhibited the phosphorus removal of the EBPR system. The relative abundance of Proteobacteria increased with the increase of FA concentration. The relative abundance of Gammaproteobacteria was positively correlated with the FA concentration at the class level. At the genus level, the relative abundance of Tetrasphaera was more consistent with the effect of FA on phosphorus removal performance than Ca. Accumulibacter. LEfSe analysis showed that the biomarkers of Low, Mid and High were Chloroflexi, Bacteroidetes and Betaproteobacteriales, respectively. This study clarified the process of the effect of FA on the EBPR system, deepened the understanding of the bacterial community structure during the phosphorus removal process of the EBPR system, and provided a reference for the in-depth study of the inhibition mechanism of biological phosphorus removal.
STUDY ON THE EFFECTIVENESS OF TEXTILE DYING SLUDGE BIOCHAR IN TREATING REFRACTORY ORGANIC WASTEWATER
2022, 40(10): 32-39.
doi: 10.13205/j.hjgc.202210005
Abstract:
The sludge-based carbon (SC) was prepared from textile dyeing sludge, and the impact of carbonization temperature and reaction time on the adsorption capacity of SC treating refractory industrial wastewater were investigated. Simultaneously the adsorption preference of SC and commercial activated carbon (CAC) was compared and studied. The results indicate that the SC derived from higher carbonization temperature can own more specific surface area, pore volume and deeper graphitization degree which facilitate its adsorption capacity. The SC-900℃ owns more than 90% mesoporous pore volume and it's specific surface area reaches 140.65 m2/g. The chemical oxygen demand (COD) removal rate of SC-900℃ treating coking wastewater and digest filtrate is as effective as 70% that of CAC. Besides, the SC-900℃(89.56%)present superior decolorizing effect than CAC(16.70%)when treating high chromaticity digestion filtrate. The macromolecular pollutants can be rapidly adsorbed by SC, the adsorption equilibrium time of SC-900℃(≤ 120 min) treating digestion filtrate is significantly lower than that of CAC(>24 h); Especially, the humus-like macromolecular compounds containing chromogenic functional groups could be selectively absorbed in the mesoporous (3.8~5.4 nm) of SC. At last, some guidance suggestions for industrialization application of SC to treat refractory industrial wastewater are put forward based on above research results.
The sludge-based carbon (SC) was prepared from textile dyeing sludge, and the impact of carbonization temperature and reaction time on the adsorption capacity of SC treating refractory industrial wastewater were investigated. Simultaneously the adsorption preference of SC and commercial activated carbon (CAC) was compared and studied. The results indicate that the SC derived from higher carbonization temperature can own more specific surface area, pore volume and deeper graphitization degree which facilitate its adsorption capacity. The SC-900℃ owns more than 90% mesoporous pore volume and it's specific surface area reaches 140.65 m2/g. The chemical oxygen demand (COD) removal rate of SC-900℃ treating coking wastewater and digest filtrate is as effective as 70% that of CAC. Besides, the SC-900℃(89.56%)present superior decolorizing effect than CAC(16.70%)when treating high chromaticity digestion filtrate. The macromolecular pollutants can be rapidly adsorbed by SC, the adsorption equilibrium time of SC-900℃(≤ 120 min) treating digestion filtrate is significantly lower than that of CAC(>24 h); Especially, the humus-like macromolecular compounds containing chromogenic functional groups could be selectively absorbed in the mesoporous (3.8~5.4 nm) of SC. At last, some guidance suggestions for industrialization application of SC to treat refractory industrial wastewater are put forward based on above research results.
2022, 40(10): 40-48.
doi: 10.13205/j.hjgc.202210006
Abstract:
In this paper, the CuO/g-C3N4 was synthesized by the hydrothermal-calcination method, and its basic properties were characterized by X-ray diffractometer, scanning electron microscope, infrared absorption spectroscopy and X-ray energy spectroscopy. Under different parameters, CuO/g-C3N4 activated peroxodisulfate (PDS) system to remove organic pollutants (methyl orange, MO). The results of activation experiments show that CuO/g-C3N4 has a significant effect on activating PDS and degrading MO. Through the optimization experiment, it can be seen that under the conditions of 8 h of hydrothermal time of catalyst, 10% of CuO composite ratio, initial concentration of catalyst in the reaction system of 1.00 g/L, initial concentration of PDS of 4 mmol/L and pH=3, the degradation rate of internal MO is as high as 99.20% in 30min. Further mechanism exploration verified that sulfate radicals (SO4-·) and hydroxyl radicals (·OH) on the surface of the catalyst are the main active substances that degrade MO, and a small amount of superoxide radicals (·O2-) participate in them. The catalyst was repeated 5 times, and the degradation rate of MO remained above 90% after activating PDS, indicating that the catalyst had a good stability.
In this paper, the CuO/g-C3N4 was synthesized by the hydrothermal-calcination method, and its basic properties were characterized by X-ray diffractometer, scanning electron microscope, infrared absorption spectroscopy and X-ray energy spectroscopy. Under different parameters, CuO/g-C3N4 activated peroxodisulfate (PDS) system to remove organic pollutants (methyl orange, MO). The results of activation experiments show that CuO/g-C3N4 has a significant effect on activating PDS and degrading MO. Through the optimization experiment, it can be seen that under the conditions of 8 h of hydrothermal time of catalyst, 10% of CuO composite ratio, initial concentration of catalyst in the reaction system of 1.00 g/L, initial concentration of PDS of 4 mmol/L and pH=3, the degradation rate of internal MO is as high as 99.20% in 30min. Further mechanism exploration verified that sulfate radicals (SO4-·) and hydroxyl radicals (·OH) on the surface of the catalyst are the main active substances that degrade MO, and a small amount of superoxide radicals (·O2-) participate in them. The catalyst was repeated 5 times, and the degradation rate of MO remained above 90% after activating PDS, indicating that the catalyst had a good stability.
2022, 40(10): 49-54.
doi: 10.13205/j.hjgc.202210007
Abstract:
Tetrahydroxymethyl phosphorus chloride (THPC) in tannery wastewater has the characteristics of stable structure and inhibition of wastewater treatment microorganisms, and the traditional biochemical treatment technologies cannot treat this kind of wastewater effectively. In this study, Fenton oxidation method was used to treat refractory organic phosphorus tetrahydroxymethyl phosphorus chloride (THPC) in tannery wastewater. The effects of H2O2 dosage, pH, m (Fe2+)/m (H2O2), reaction time and UV wavelength on the removal of total phosphorus and COD were investigated, and the kinetic model of total phosphorus degradation was established and analyzed. The results showed that when pH=4, H2O2 dosage=6667 mg/L, m (Fe2+)/m (H2O2)=1 and reaction time=80 min, the removal rates of total phosphorus and COD reached 43% and 83% respectively; it was found that UV assisted Fenton system (wavelength=185 nm) could improve the oxidation effect of THPC; the kinetic model showed that the dosage of hydrogen peroxide (q=1.065) was higher than that of organic matter (a=0.858), indicating that the reaction rate of Fenton oxidative degradation of total phosphorus was mainly controlled by the dosage of H2O2.
Tetrahydroxymethyl phosphorus chloride (THPC) in tannery wastewater has the characteristics of stable structure and inhibition of wastewater treatment microorganisms, and the traditional biochemical treatment technologies cannot treat this kind of wastewater effectively. In this study, Fenton oxidation method was used to treat refractory organic phosphorus tetrahydroxymethyl phosphorus chloride (THPC) in tannery wastewater. The effects of H2O2 dosage, pH, m (Fe2+)/m (H2O2), reaction time and UV wavelength on the removal of total phosphorus and COD were investigated, and the kinetic model of total phosphorus degradation was established and analyzed. The results showed that when pH=4, H2O2 dosage=6667 mg/L, m (Fe2+)/m (H2O2)=1 and reaction time=80 min, the removal rates of total phosphorus and COD reached 43% and 83% respectively; it was found that UV assisted Fenton system (wavelength=185 nm) could improve the oxidation effect of THPC; the kinetic model showed that the dosage of hydrogen peroxide (q=1.065) was higher than that of organic matter (a=0.858), indicating that the reaction rate of Fenton oxidative degradation of total phosphorus was mainly controlled by the dosage of H2O2.
2022, 40(10): 55-61.
doi: 10.13205/j.hjgc.202210008
Abstract:
The effect of NH4+-N shock on pollutants' removal efficiency of the micro-pressure reactor (MPR) was investigated by increasing the single cycle instantaneous influent NH4+-N concentration to 40 and 50 mg/L and shocking the MPR. The results showed that the MPR had a good pollutant removal effect under conventional load. The degradation epoch of the shock cycle showed that in the influent 40 mg/L NH4+-N shock cycle, the influent concentrations of COD, NH4+-N, and TP were 192.58, 40.96, and 2.52 mg/L, and the effluent concentrations were 38.16, 0.70, and 0.26 mg/L, respectively, with no significant changes in the removal effect, and the effluent TN concentration increased to 16.04 mg/L. When the NH4+-N concentration shock was increased to 50 mg/L, the NH4+-N degradation rate remained unchanged and the denitrification rate increased during the impact cycle, and the effluent NH4+-N and TN concentrations increased to 4.95 and 17.62 mg/L. TN degradation was mainly affected by the lack of carbon source, and there was no change in TP removal effect. The above results showed that the nitrogen removal performance of the MPR system recovered within 1 cycle after the impact of NH4+-N, indicating a reversible short-term effect on the nitrogen removal system. An irreversible long-term effect on the phosphorus removal system was observed.
The effect of NH4+-N shock on pollutants' removal efficiency of the micro-pressure reactor (MPR) was investigated by increasing the single cycle instantaneous influent NH4+-N concentration to 40 and 50 mg/L and shocking the MPR. The results showed that the MPR had a good pollutant removal effect under conventional load. The degradation epoch of the shock cycle showed that in the influent 40 mg/L NH4+-N shock cycle, the influent concentrations of COD, NH4+-N, and TP were 192.58, 40.96, and 2.52 mg/L, and the effluent concentrations were 38.16, 0.70, and 0.26 mg/L, respectively, with no significant changes in the removal effect, and the effluent TN concentration increased to 16.04 mg/L. When the NH4+-N concentration shock was increased to 50 mg/L, the NH4+-N degradation rate remained unchanged and the denitrification rate increased during the impact cycle, and the effluent NH4+-N and TN concentrations increased to 4.95 and 17.62 mg/L. TN degradation was mainly affected by the lack of carbon source, and there was no change in TP removal effect. The above results showed that the nitrogen removal performance of the MPR system recovered within 1 cycle after the impact of NH4+-N, indicating a reversible short-term effect on the nitrogen removal system. An irreversible long-term effect on the phosphorus removal system was observed.
2022, 40(10): 62-70.
doi: 10.13205/j.hjgc.202210009
Abstract:
For the low carbon nitrogen ratio (C/N) of rural domestic sewage limited the denitrification course, a sequencing batch reactor (SBR) process enhanced by composite solid carbon sources (SCS-SBR) was used to improve the treatment efficiency of rural domestic sewage (compost of water diversion project sewage and village sewage). The unique functional bacterial community was also thoroughly examined during the operation of SCS-SBR. The denitrification capacity of the SBR process could be effectively improved by incorporating composite solid carbon sources (PHBV+straw). The experimental results showed that the effluent COD, NH4+-N and TN concentrations remained below 25.0, 0.4, and 5.0 mg/L throughout the stable operation of the SCS-SBR process, respectively, and TN removal efficiency of village sewage reached 83.1%. Following the addition of SCS to SBR, Illumina sequencing analysis revealed that some unique functional bacteria were screened out. In contrast to the nitrifying bacteria (Nitrosomonas) and the denitrifying bacteria (Pseudomonas) in the traditional activated sludge, the nitrifying bacteria in the SCS-SBR process was norank_f_JG30-KF-CM45, and the denitrifying functional bacteria were Thermomonas and Rubrivax. The relative abundance of Thermomonas increased from undetectable in the stage without solid carbon sources (AS1 and AS2), to 2.54% and 7.55% in the stage with solid carbon sources (SCS1 and SCS2), respectively. Furthermore, the relative abundance of an aerobic and oxygen stress-tolerant bacteria in the activated sludge, Nakamurella decreased dramatically from 44.52% and 57.66% in AS1 and AS2, to 1.06% and 0.86% in SCS1 and SCS2, respectively, indicating that microorganisms that cannot utilize solid carbon sources in the process were gradually eliminated. In conclusion, composite solid carbon sources (PHBV+straw) could eliminate the flaws of liquid carbon sources, improve the denitrification capacity of the SBR process and efficiently screen the functional microorganisms in the system. This study provides a theoretical basis and technical support for rural domestic sewage treatment.
For the low carbon nitrogen ratio (C/N) of rural domestic sewage limited the denitrification course, a sequencing batch reactor (SBR) process enhanced by composite solid carbon sources (SCS-SBR) was used to improve the treatment efficiency of rural domestic sewage (compost of water diversion project sewage and village sewage). The unique functional bacterial community was also thoroughly examined during the operation of SCS-SBR. The denitrification capacity of the SBR process could be effectively improved by incorporating composite solid carbon sources (PHBV+straw). The experimental results showed that the effluent COD, NH4+-N and TN concentrations remained below 25.0, 0.4, and 5.0 mg/L throughout the stable operation of the SCS-SBR process, respectively, and TN removal efficiency of village sewage reached 83.1%. Following the addition of SCS to SBR, Illumina sequencing analysis revealed that some unique functional bacteria were screened out. In contrast to the nitrifying bacteria (Nitrosomonas) and the denitrifying bacteria (Pseudomonas) in the traditional activated sludge, the nitrifying bacteria in the SCS-SBR process was norank_f_JG30-KF-CM45, and the denitrifying functional bacteria were Thermomonas and Rubrivax. The relative abundance of Thermomonas increased from undetectable in the stage without solid carbon sources (AS1 and AS2), to 2.54% and 7.55% in the stage with solid carbon sources (SCS1 and SCS2), respectively. Furthermore, the relative abundance of an aerobic and oxygen stress-tolerant bacteria in the activated sludge, Nakamurella decreased dramatically from 44.52% and 57.66% in AS1 and AS2, to 1.06% and 0.86% in SCS1 and SCS2, respectively, indicating that microorganisms that cannot utilize solid carbon sources in the process were gradually eliminated. In conclusion, composite solid carbon sources (PHBV+straw) could eliminate the flaws of liquid carbon sources, improve the denitrification capacity of the SBR process and efficiently screen the functional microorganisms in the system. This study provides a theoretical basis and technical support for rural domestic sewage treatment.
2022, 40(10): 71-79.
doi: 10.13205/j.hjgc.202210010
Abstract:
The eutrophication and algal blooms of Lake Taihu, a large shallow lake in eastern China, have always been one of the important water problems that troubled the high-quality development of this region. The uneven distribution of water resources and relatively high concentration of some nutrients have seriously restricted the healthy development of the ecological environment of Lake Taihu. Based on the monthly observation data of water quality and meteorology of Lake Taihu from 1999 to 2019, a Chl-a prediction model ARIMA(1, 1, 1)(0, 1, 1)12 based on covariates (total nitrogen, total phosphorus, permanganate index, precipitation, water diversion and drainage volume) was established in this paper. An optimization strategy of water diversion and drainage schemes was proposed to decline the risk of algal blooms outbreak in Lake Taihu under the future normal year scenario. Results showed that the ARIMA(1, 1, 1)(0, 1, 1)12 model could effectively predict the monthly Chl-a concen trations of Lake Taihu. In the preset future scenario, the nutrient content of water can be effectively reduced by synchronously increasing both water diversion and drainage. The key to the optimization of water diversion and drainage scheme is rational allocation of seasonal water resources, and based on meeting water safety, adeptly enhancing both diversion and drainage in winter and spring could improve the water dynamic and nutritional salt discharge.
The eutrophication and algal blooms of Lake Taihu, a large shallow lake in eastern China, have always been one of the important water problems that troubled the high-quality development of this region. The uneven distribution of water resources and relatively high concentration of some nutrients have seriously restricted the healthy development of the ecological environment of Lake Taihu. Based on the monthly observation data of water quality and meteorology of Lake Taihu from 1999 to 2019, a Chl-a prediction model ARIMA(1, 1, 1)(0, 1, 1)12 based on covariates (total nitrogen, total phosphorus, permanganate index, precipitation, water diversion and drainage volume) was established in this paper. An optimization strategy of water diversion and drainage schemes was proposed to decline the risk of algal blooms outbreak in Lake Taihu under the future normal year scenario. Results showed that the ARIMA(1, 1, 1)(0, 1, 1)12 model could effectively predict the monthly Chl-a concen trations of Lake Taihu. In the preset future scenario, the nutrient content of water can be effectively reduced by synchronously increasing both water diversion and drainage. The key to the optimization of water diversion and drainage scheme is rational allocation of seasonal water resources, and based on meeting water safety, adeptly enhancing both diversion and drainage in winter and spring could improve the water dynamic and nutritional salt discharge.
2022, 40(10): 80-87,175.
doi: 10.13205/j.hjgc.202210011
Abstract:
This study aimed to solve the sludge treatment issues caused by kitchen waste entering the municipal network. This study used kitchen waste to produce the primary sludge (PS), then mixed it with different amounts of residual sludge (RS) to produce the mixed sewage sludge(MSS). The pyrolysis performance and evolved gas properties of mixed sewage sludge containing food waste were evaluated by TG-FTIR. The mass loss could be divided into 3 stages:initial dehydration, major decomposition, and continuous slight decomposition. With the increase of PS proportion, the reaction rate and pyrolysis characteristic parameter (CPI) got improved, and the reaction time got reduced, thus improving the performance of sewage sludge pyrolysis. The interactions between PS and RS varied at different temperatures, the low-temperature region (<300℃) was almost non-interactive, the medium temperature region (300~550℃) was mutually promoting, and the high-temperature region (550~850℃) was mutually inhibiting. FTIR detected 6 main gaseous products and functional groups of CH4, CO2, H2O, CO, CO and SO2. The results showed that the production of evolved gases and functional groups were increased with the increase of PS percentage, and CO2 was the main gaseous product. The interactions were not only reflected in the mass loss process but also in the product evolution process, and PS50RS50 showed the most obvious mutual promotion effect, which could be considered as the best ratio. With the increase of temperature, the products generally reached the maximum in the range of 500~600℃, which can be considered as the best pyrolysis temperature.
This study aimed to solve the sludge treatment issues caused by kitchen waste entering the municipal network. This study used kitchen waste to produce the primary sludge (PS), then mixed it with different amounts of residual sludge (RS) to produce the mixed sewage sludge(MSS). The pyrolysis performance and evolved gas properties of mixed sewage sludge containing food waste were evaluated by TG-FTIR. The mass loss could be divided into 3 stages:initial dehydration, major decomposition, and continuous slight decomposition. With the increase of PS proportion, the reaction rate and pyrolysis characteristic parameter (CPI) got improved, and the reaction time got reduced, thus improving the performance of sewage sludge pyrolysis. The interactions between PS and RS varied at different temperatures, the low-temperature region (<300℃) was almost non-interactive, the medium temperature region (300~550℃) was mutually promoting, and the high-temperature region (550~850℃) was mutually inhibiting. FTIR detected 6 main gaseous products and functional groups of CH4, CO2, H2O, CO, CO and SO2. The results showed that the production of evolved gases and functional groups were increased with the increase of PS percentage, and CO2 was the main gaseous product. The interactions were not only reflected in the mass loss process but also in the product evolution process, and PS50RS50 showed the most obvious mutual promotion effect, which could be considered as the best ratio. With the increase of temperature, the products generally reached the maximum in the range of 500~600℃, which can be considered as the best pyrolysis temperature.
2022, 40(10): 88-97.
doi: 10.13205/j.hjgc.202210012
Abstract:
In this paper, the microalgae-fungus (Chlorella-Ganoderma) symbiotic system was chosen as the research object, and the effects of different CO2 concentrations on simultaneous purification of biogas slurry and biogas were investigated under the induction of two concentrations of synthetic unicolactone (GR24, 10-7, 10-9 mol/L). Under the induction of GR24, the metabolism and photosynthesis of microalgae in the microalgae-fungal system were enhanced, which made the algal-bacterial symbiosis grow rapidly and further enhanced the purification performance of the system. In addition, GR24 enhanced CO2 removal performance of the co-culture system by increasing the activity of carbonic anhydrase in microalgae cells. The results showed that the optimal GR24 concentration was 10-9 mol/L, and the CO2 concentration was 45%. Under these optimal conditions, the average removal rates of COD, TN and TP were (83.37±8.04)%, (82.07±7.74)% and (85.43±8.26)%, respectively, and the average removal rate of CO2 in biogas was (62.07±5.94)%.
In this paper, the microalgae-fungus (Chlorella-Ganoderma) symbiotic system was chosen as the research object, and the effects of different CO2 concentrations on simultaneous purification of biogas slurry and biogas were investigated under the induction of two concentrations of synthetic unicolactone (GR24, 10-7, 10-9 mol/L). Under the induction of GR24, the metabolism and photosynthesis of microalgae in the microalgae-fungal system were enhanced, which made the algal-bacterial symbiosis grow rapidly and further enhanced the purification performance of the system. In addition, GR24 enhanced CO2 removal performance of the co-culture system by increasing the activity of carbonic anhydrase in microalgae cells. The results showed that the optimal GR24 concentration was 10-9 mol/L, and the CO2 concentration was 45%. Under these optimal conditions, the average removal rates of COD, TN and TP were (83.37±8.04)%, (82.07±7.74)% and (85.43±8.26)%, respectively, and the average removal rate of CO2 in biogas was (62.07±5.94)%.
2022, 40(10): 98-104,111.
doi: 10.13205/j.hjgc.202210013
Abstract:
Based on the parameters of cement kiln thermal conditions and the basic principle of response surface design, a study on the thermal decomposition law and influencing factors of BDE-209 was carried out, and the debromination path of BDE-209 was analyzed. The results showed that the content of PBDEs in flue gas decreased with the decrease of bromine substitution number. Different PBDEs monomers were significantly influenced by different factors, and the concentration of BDE-209 in the flue gas was mainly influenced by the original concentration and temperature in the sample, while the concentrations of nine and octa-BDE were mainly affected by the interaction of temperature and oxygen. Combining the literature study with the experiment results, it was assumed that the main debromination pathways of BDE-209 including two main degradation paths under the thermal conditions of the cement kiln. The main path to generate nine brominated diphenyl ether was to remove one bromine from BDE-209 to generate BDE-207. The main path to generate octabromodiphenyl ether was to remove one bromine from BDE-209 to generate BDE-206, and then remove one bromine from BDE-206 to generate BDE-203. The clarification of the thermal decomposition law of BDE-209 and the influencing factors could provide theoretical support for the disposal of waste containing PBDEs in cement kilns under thermal working conditions.
Based on the parameters of cement kiln thermal conditions and the basic principle of response surface design, a study on the thermal decomposition law and influencing factors of BDE-209 was carried out, and the debromination path of BDE-209 was analyzed. The results showed that the content of PBDEs in flue gas decreased with the decrease of bromine substitution number. Different PBDEs monomers were significantly influenced by different factors, and the concentration of BDE-209 in the flue gas was mainly influenced by the original concentration and temperature in the sample, while the concentrations of nine and octa-BDE were mainly affected by the interaction of temperature and oxygen. Combining the literature study with the experiment results, it was assumed that the main debromination pathways of BDE-209 including two main degradation paths under the thermal conditions of the cement kiln. The main path to generate nine brominated diphenyl ether was to remove one bromine from BDE-209 to generate BDE-207. The main path to generate octabromodiphenyl ether was to remove one bromine from BDE-209 to generate BDE-206, and then remove one bromine from BDE-206 to generate BDE-203. The clarification of the thermal decomposition law of BDE-209 and the influencing factors could provide theoretical support for the disposal of waste containing PBDEs in cement kilns under thermal working conditions.
2022, 40(10): 105-111.
doi: 10.13205/j.hjgc.202210014
Abstract:
Clean combustion is the main way for the efficient energy utilization of pyrolysis oil of organic solid wastes. The content of aromatic hydrocarbons accounted for about 30% of pyrolysis oil from all-steel waste tires. The thermal value and viscosity of the pyrolysis oil were similar to that of diesel, but the flash point was much lower, only 20℃. In this study, combustion experiments were carried out in a self-designed furnace, and the characteristics of the combustion temperature and flue gas emission of pyrolysis oil were studied. It was found that the combustion temperature reached the highest when the excess air ratio was 1.3. When the excess air ratio increased to 1.4, CO content in the flue gas dropped to 0. NOx content increased with the increase of excess air ratio. When the excess air ratio exceeded 1.3, SO2 content decreased substantially. The increase of injection oil pressure could increase the combustion temperature, making the combustion more adequate, reducing CO content in the flue gas, and promoting the generation of thermal NOx. When the pressure rose from 1.5 MPa to 1.75 MPa, the combustion temperature, the CO content and the NOx content varied the most. The increase of the nozzle orifice diameter could increase the atomization cone angle, expand the oil fog to contact with the air at a larger angle, and CO content dropped accordingly. Meanwhile, the increase of atomization cone angle could reduce the spray penetration distance, which shortened the flame length and the residence time of flue gas in high-temperature area, and reduced NOx content.
Clean combustion is the main way for the efficient energy utilization of pyrolysis oil of organic solid wastes. The content of aromatic hydrocarbons accounted for about 30% of pyrolysis oil from all-steel waste tires. The thermal value and viscosity of the pyrolysis oil were similar to that of diesel, but the flash point was much lower, only 20℃. In this study, combustion experiments were carried out in a self-designed furnace, and the characteristics of the combustion temperature and flue gas emission of pyrolysis oil were studied. It was found that the combustion temperature reached the highest when the excess air ratio was 1.3. When the excess air ratio increased to 1.4, CO content in the flue gas dropped to 0. NOx content increased with the increase of excess air ratio. When the excess air ratio exceeded 1.3, SO2 content decreased substantially. The increase of injection oil pressure could increase the combustion temperature, making the combustion more adequate, reducing CO content in the flue gas, and promoting the generation of thermal NOx. When the pressure rose from 1.5 MPa to 1.75 MPa, the combustion temperature, the CO content and the NOx content varied the most. The increase of the nozzle orifice diameter could increase the atomization cone angle, expand the oil fog to contact with the air at a larger angle, and CO content dropped accordingly. Meanwhile, the increase of atomization cone angle could reduce the spray penetration distance, which shortened the flame length and the residence time of flue gas in high-temperature area, and reduced NOx content.
2022, 40(10): 112-119.
doi: 10.13205/j.hjgc.202210015
Abstract:
Aiming at the problems of low available phosphorus content of kitchen waste compost and the limited mobilization efficiency of adding low-grade rock phosphate, this study explored the effect of different exogenous additives on phosphorus transformation in phosphorus-rich kitchen waste composting, by adding successively surfactants (CSP), phosphate-solubilizing bacteria (CMSP) and biochar (CBMSP) based on adding rock phosphate (CP). The results showed that:1) compared to CP, the increment of available phosphorus after 35 days of aerobic composting increased by 2.00%, 9.00% and 39.00% in CSP, CMSP and CBMSP treatments, respectively. The addition of phosphate-solubilizing bacteria, biochar and surfactants significantly promoted the mobilization efficiency of insoluble phosphorus to 16.00% (P<0.05); 2) the number of bacteria in compost products treated by CMSP was significantly higher than that of CP(P<0.05), which increased to 1.85 times that of CP. The addition of biochar further improved the abundance of actinobacteria and fungi in kitchen waste compost products, up to 1.56 times and 10.66 times of CP respectively. These indicated that adding surfactants, biochar and phosphate-solubilizing bacteria together could improve the microbial growth environment in compost and promote microbial growth; 3) correlation analysis showed that microbial biomass phosphorus (MBP) was significantly correlated with available phosphorus and fungi abundance in CMSP and CBMSP (P<0.01). The synergistic addition of surfactants, phosphate-solubilizing bacteria inoculation and biochar could promote the mobilization of insoluble rock phosphate by enhancing the accumulation of microbial biomass phosphorus. This study could effectively improve the utilization efficiency of compost nutrient resources and insoluble phosphorus.
Aiming at the problems of low available phosphorus content of kitchen waste compost and the limited mobilization efficiency of adding low-grade rock phosphate, this study explored the effect of different exogenous additives on phosphorus transformation in phosphorus-rich kitchen waste composting, by adding successively surfactants (CSP), phosphate-solubilizing bacteria (CMSP) and biochar (CBMSP) based on adding rock phosphate (CP). The results showed that:1) compared to CP, the increment of available phosphorus after 35 days of aerobic composting increased by 2.00%, 9.00% and 39.00% in CSP, CMSP and CBMSP treatments, respectively. The addition of phosphate-solubilizing bacteria, biochar and surfactants significantly promoted the mobilization efficiency of insoluble phosphorus to 16.00% (P<0.05); 2) the number of bacteria in compost products treated by CMSP was significantly higher than that of CP(P<0.05), which increased to 1.85 times that of CP. The addition of biochar further improved the abundance of actinobacteria and fungi in kitchen waste compost products, up to 1.56 times and 10.66 times of CP respectively. These indicated that adding surfactants, biochar and phosphate-solubilizing bacteria together could improve the microbial growth environment in compost and promote microbial growth; 3) correlation analysis showed that microbial biomass phosphorus (MBP) was significantly correlated with available phosphorus and fungi abundance in CMSP and CBMSP (P<0.01). The synergistic addition of surfactants, phosphate-solubilizing bacteria inoculation and biochar could promote the mobilization of insoluble rock phosphate by enhancing the accumulation of microbial biomass phosphorus. This study could effectively improve the utilization efficiency of compost nutrient resources and insoluble phosphorus.
2022, 40(10): 120-125,133.
doi: 10.13205/j.hjgc.202210016
Abstract:
The demand for the harmless treatment of combustible solid waste (CSW) is increasing, and the incineration method can effectively realize the resource utilization, reduction and harmlessness of CSW. The thermochemical properties of CSW are of great significance in the organization of the combustion process. Due to the diversity of sources and types of CSW, the characterization of the thermochemical properties of CSW, especially CSW mixture is an urgent problem. If some typical CSW is used as "pseudo-components", the thermochemical characteristics of other CSW can be simplified, efficiently and systematically characterized. In this study, the principal component analysis (PCA) method was used to reduce the dimension, and then the CSW was classified with the selection of the pseudo-components based on the criteria of completeness, independence and certainty, as well as the central criteria and the simple criteria. Finally, eight species including latex gloves, hard plastic bags, PE, PET, starch, lignin, cellulose and hemicellulose were selected as pseudo-components. And the above several pseudo-components had been characterized by thermogravimetric analysis, based on this, a method for characterizing the heat conversion unit of CSW was established. Fitting industrial CSW, which gray relation grade was as high as 0.989, the practicability and accuracy of the method of dimension reduction and clustering were verified. This study established a method for characterizing the thermal conversion of CSW, which could provide a reference for the thermal conversion and disposal of CSW.
The demand for the harmless treatment of combustible solid waste (CSW) is increasing, and the incineration method can effectively realize the resource utilization, reduction and harmlessness of CSW. The thermochemical properties of CSW are of great significance in the organization of the combustion process. Due to the diversity of sources and types of CSW, the characterization of the thermochemical properties of CSW, especially CSW mixture is an urgent problem. If some typical CSW is used as "pseudo-components", the thermochemical characteristics of other CSW can be simplified, efficiently and systematically characterized. In this study, the principal component analysis (PCA) method was used to reduce the dimension, and then the CSW was classified with the selection of the pseudo-components based on the criteria of completeness, independence and certainty, as well as the central criteria and the simple criteria. Finally, eight species including latex gloves, hard plastic bags, PE, PET, starch, lignin, cellulose and hemicellulose were selected as pseudo-components. And the above several pseudo-components had been characterized by thermogravimetric analysis, based on this, a method for characterizing the heat conversion unit of CSW was established. Fitting industrial CSW, which gray relation grade was as high as 0.989, the practicability and accuracy of the method of dimension reduction and clustering were verified. This study established a method for characterizing the thermal conversion of CSW, which could provide a reference for the thermal conversion and disposal of CSW.
2022, 40(10): 126-133.
doi: 10.13205/j.hjgc.202210017
Abstract:
Electrothermal regeneration is a kind of activated carbon material regeneration method with a short treating time, strong versatility and low energy consumption, and it has attracted much attention in the field of volatile organic compounds treatment, indoor air purification and chemical protection. In this paper, we used activated carbon fiber mesh to fill the adsorption bed, and systematically studied the effects of energizing voltage, specific velocity of purge gas, and bed water adsorption on the electrothermal behavior of the adsorption bed. The results showed that:setting the energizing voltage to 50 V and inputting 1 W·h electrical energy for the drying bed, the bed could rise to 144.6℃, which was 63.8℃ higher than that at 20 V. Increasing the specific velocity of purge gas reduced the temperature at the end of the electrothermal process and prolong the heating time. There was a temperature rise platform in the water adsorption bed during electric heating. Under the conditions of a voltage of 40 V and a specific speed of purge gas flow of 0.08 L/(min·cm2), the heating platform could last up to 30 minutes according to different water adsorption rates. In addition, the energizing voltage and purge gas could affect the temperature and duration of the heating platform.
Electrothermal regeneration is a kind of activated carbon material regeneration method with a short treating time, strong versatility and low energy consumption, and it has attracted much attention in the field of volatile organic compounds treatment, indoor air purification and chemical protection. In this paper, we used activated carbon fiber mesh to fill the adsorption bed, and systematically studied the effects of energizing voltage, specific velocity of purge gas, and bed water adsorption on the electrothermal behavior of the adsorption bed. The results showed that:setting the energizing voltage to 50 V and inputting 1 W·h electrical energy for the drying bed, the bed could rise to 144.6℃, which was 63.8℃ higher than that at 20 V. Increasing the specific velocity of purge gas reduced the temperature at the end of the electrothermal process and prolong the heating time. There was a temperature rise platform in the water adsorption bed during electric heating. Under the conditions of a voltage of 40 V and a specific speed of purge gas flow of 0.08 L/(min·cm2), the heating platform could last up to 30 minutes according to different water adsorption rates. In addition, the energizing voltage and purge gas could affect the temperature and duration of the heating platform.
2022, 40(10): 134-140.
doi: 10.13205/j.hjgc.202210018
Abstract:
In order to explore the application effect of engineered modification, phytoremediation, passivation remediation, antagonism remediation, and the passivation-antagonism remediation technology at safe utilization project of cadmium polluted wheat field in sewage irrigation areas, we studied the wheat grain Cd content, soil Cd content and degree of wheat Cd enrichment after the 5 kinds of techniques applied in a typical sewage irrigation area in Henan. The results showed that:a single or composite treatment of passivation and antagonism could remediate the pollution of Cd in wheat by affecting the enrichment of Cd in wheat grain and the content of Cd in soil; Cd content in wheat grain was significantly reduced by 38% after appropriate application of phosphorus A or B and iron material composites, and the Cd content was significantly reduced by 27% to 48% after appropriate application of phosphorus materials B in wheat grain, and both restorative effects were remarkable; other techniques had some restorative effect, but not significant. The Cd enrichment coefficient of wheat (PUFCd) could be used as one indicating index to evaluate the effect of technology application on cadmium polluted wheat field safe utilization project in the sewage irrigation area.
In order to explore the application effect of engineered modification, phytoremediation, passivation remediation, antagonism remediation, and the passivation-antagonism remediation technology at safe utilization project of cadmium polluted wheat field in sewage irrigation areas, we studied the wheat grain Cd content, soil Cd content and degree of wheat Cd enrichment after the 5 kinds of techniques applied in a typical sewage irrigation area in Henan. The results showed that:a single or composite treatment of passivation and antagonism could remediate the pollution of Cd in wheat by affecting the enrichment of Cd in wheat grain and the content of Cd in soil; Cd content in wheat grain was significantly reduced by 38% after appropriate application of phosphorus A or B and iron material composites, and the Cd content was significantly reduced by 27% to 48% after appropriate application of phosphorus materials B in wheat grain, and both restorative effects were remarkable; other techniques had some restorative effect, but not significant. The Cd enrichment coefficient of wheat (PUFCd) could be used as one indicating index to evaluate the effect of technology application on cadmium polluted wheat field safe utilization project in the sewage irrigation area.
2022, 40(10): 141-149.
doi: 10.13205/j.hjgc.202210019
Abstract:
A new method for rapid and non-destructive detection of Ruditapes Philippinarum contaminated by heavy metals has been proposed in this paper, which is based on hyperspectral image technology and machine learning algorithm. Firstly, the hyperspectral images of Ruditapes Philippinarum were collected and preprocessed by three preprocessing methods. Then the dimension of hyperspectral image data was reduced by Linear Discriminant Analysis (LDA). Finally, heavy metal-contaminated Ruditapes Philippinarum was detected by the Support Vector Machine (SVM). For binary classification of single heavy metal-contaminated samples and healthy samples, the accuracy of LDA-SVM model for detecting heavy metal-contaminated samples was higher than 99.33%. For multi-classification of Cd, Cu, Pb and Zn-contaminated samples and healthy samples, the accuracy was more than 93.33%. The experimental results showed that LDA-SVM model could realize rapid and non-destructive detection of Ruditapes Philippinarum contaminated by heavy metals. Moreover, the performance of LDA-SVM model was not affected by preprocessing methods and model parameters, and the model had strong robustness.
A new method for rapid and non-destructive detection of Ruditapes Philippinarum contaminated by heavy metals has been proposed in this paper, which is based on hyperspectral image technology and machine learning algorithm. Firstly, the hyperspectral images of Ruditapes Philippinarum were collected and preprocessed by three preprocessing methods. Then the dimension of hyperspectral image data was reduced by Linear Discriminant Analysis (LDA). Finally, heavy metal-contaminated Ruditapes Philippinarum was detected by the Support Vector Machine (SVM). For binary classification of single heavy metal-contaminated samples and healthy samples, the accuracy of LDA-SVM model for detecting heavy metal-contaminated samples was higher than 99.33%. For multi-classification of Cd, Cu, Pb and Zn-contaminated samples and healthy samples, the accuracy was more than 93.33%. The experimental results showed that LDA-SVM model could realize rapid and non-destructive detection of Ruditapes Philippinarum contaminated by heavy metals. Moreover, the performance of LDA-SVM model was not affected by preprocessing methods and model parameters, and the model had strong robustness.
2022, 40(10): 150-155,168.
doi: 10.13205/j.hjgc.202210020
Abstract:
Engineered smoldering technology, based on smoldering mechanism, is a self-sustaining treatment technology for active remediation, aiming at medias such as heavy (low volatility) oil sludge or petroleum hydrocarbon contaminated soil that are highly contaminated by organics and difficult to degrade and treat. Its R&D and practice are still at an early stage in China. Treatment of the stocked oil sludge at a coking plant in Hubei province was the debut of engineered smoldering technology for the treatment of oil sludge in China. A pilot test was conducted first to determine the pre-treatment approach, reagent dosage, and process conditions of smoldering treatment. Step I of the demonstration project was pre-treatment through a "chemical conditioning+plate-frame pressure filtration" process for dewatering and mass reduction; Step II was a treatment process with 4 sets of ex-situ engineered smoldering equipment. The moisture of oil sludge was reduced to around 50% through pre-treatment, total mass was reduced by 90% and the removal rate of the concerned contaminants in oil sludge exceeded 98% after smoldering treatment, meeting the acceptance standard of this project.
Engineered smoldering technology, based on smoldering mechanism, is a self-sustaining treatment technology for active remediation, aiming at medias such as heavy (low volatility) oil sludge or petroleum hydrocarbon contaminated soil that are highly contaminated by organics and difficult to degrade and treat. Its R&D and practice are still at an early stage in China. Treatment of the stocked oil sludge at a coking plant in Hubei province was the debut of engineered smoldering technology for the treatment of oil sludge in China. A pilot test was conducted first to determine the pre-treatment approach, reagent dosage, and process conditions of smoldering treatment. Step I of the demonstration project was pre-treatment through a "chemical conditioning+plate-frame pressure filtration" process for dewatering and mass reduction; Step II was a treatment process with 4 sets of ex-situ engineered smoldering equipment. The moisture of oil sludge was reduced to around 50% through pre-treatment, total mass was reduced by 90% and the removal rate of the concerned contaminants in oil sludge exceeded 98% after smoldering treatment, meeting the acceptance standard of this project.
2022, 40(10): 156-161.
doi: 10.13205/j.hjgc.202210021
Abstract:
In this paper, the flow velocity, temperature, ammonia concentration, and flow direction of flue gas in the SCR denitration system of a 330 MW coal-fired power unit were simulated by three-dimensional numerical simulation, and then the numerical simulation results were verified by a physical model. The results showed that the trapezoidal micromixer had the advantages of simple processing, large disturbance range, large pressure loss, and great influence on the downstream velocity field; the twisted vane micromixer had lower resistance and effect on the downstream velocity field, but smaller disturbance range and higher requirements on the installation angle. The comprehensive performance of hexagonal micromixer was between trapezoidal micromixer and twisted vane micromixer. The hexagonal micromixer could better realize the mixing of NH3 and flue gas, and the uniformity of downstream velocity field and NH3 concentration met the design requirements.
In this paper, the flow velocity, temperature, ammonia concentration, and flow direction of flue gas in the SCR denitration system of a 330 MW coal-fired power unit were simulated by three-dimensional numerical simulation, and then the numerical simulation results were verified by a physical model. The results showed that the trapezoidal micromixer had the advantages of simple processing, large disturbance range, large pressure loss, and great influence on the downstream velocity field; the twisted vane micromixer had lower resistance and effect on the downstream velocity field, but smaller disturbance range and higher requirements on the installation angle. The comprehensive performance of hexagonal micromixer was between trapezoidal micromixer and twisted vane micromixer. The hexagonal micromixer could better realize the mixing of NH3 and flue gas, and the uniformity of downstream velocity field and NH3 concentration met the design requirements.
2022, 40(10): 162-168.
doi: 10.13205/j.hjgc.202210022
Abstract:
Aiming at the problems of unstable operation and unqualified emission of small heat treatment furnaces for the disposal of rural domestic wastes, a new type of pyrolysis gasification incinerator for rural solid wastes was introduced, and the dioxins emission characteristics of flue gas and slag in a novel 30 t/d solid wastes gasification system were studied. The results were as follows:the emission of dioxin from slag was 0.723 μg I-TEQ/kg, which met the requirements of Standard of Pollution Control on the Landfill Site of Municipal Solid Waste (GB 16889-2008). When spraying activated carbon normally, the concentration of dioxin in tail flue gas was 0.029 ng I-TEQ/Nm3, lower than the dioxin emission limitation of Standard for Pollution Control on the Municipal Solid Waste Incineration (GB 18485-2014). The original emission concentration of dioxin from flue gas in the gasification and combustion process was low, and low-temperature heterogeneous synthesis reaction was the main source of dioxin in flue gas of the furnace. Furthermore, high chlorinated PCDD/Fs was dominant in mass concentration distribution, and 2,3,4,7,8-PeCDF played an important role in total toxic equivalent. Besides, spraying activated carbon had a good removal effect on dioxins. This study provided a demonstration for the standardized disposal of pyrolysis and gasification for rural domestic wastes, and a reference for dioxin emission control of the pyrolysis and gasification furnace.
Aiming at the problems of unstable operation and unqualified emission of small heat treatment furnaces for the disposal of rural domestic wastes, a new type of pyrolysis gasification incinerator for rural solid wastes was introduced, and the dioxins emission characteristics of flue gas and slag in a novel 30 t/d solid wastes gasification system were studied. The results were as follows:the emission of dioxin from slag was 0.723 μg I-TEQ/kg, which met the requirements of Standard of Pollution Control on the Landfill Site of Municipal Solid Waste (GB 16889-2008). When spraying activated carbon normally, the concentration of dioxin in tail flue gas was 0.029 ng I-TEQ/Nm3, lower than the dioxin emission limitation of Standard for Pollution Control on the Municipal Solid Waste Incineration (GB 18485-2014). The original emission concentration of dioxin from flue gas in the gasification and combustion process was low, and low-temperature heterogeneous synthesis reaction was the main source of dioxin in flue gas of the furnace. Furthermore, high chlorinated PCDD/Fs was dominant in mass concentration distribution, and 2,3,4,7,8-PeCDF played an important role in total toxic equivalent. Besides, spraying activated carbon had a good removal effect on dioxins. This study provided a demonstration for the standardized disposal of pyrolysis and gasification for rural domestic wastes, and a reference for dioxin emission control of the pyrolysis and gasification furnace.
2022, 40(10): 169-175.
doi: 10.13205/j.hjgc.202210023
Abstract:
Based on characteristics of wastewater and resource recovery, a zero liquid discharge process of flue gas desulfurization wastewater, combined with graded salt separation pretreatment, membrane concentration and electrolytic chlorine production unit, was constructed. A pilot-scale experiment was conducted for 35 d at a flow rate of 500 L/d. The results suggested that effective removal of pollutants and resource recovery could be achieved with suspended solid, Mg2+, SO2-4 and Ca2+ removal of 100%, 96.6%, 99.8% and 98.9%. The purity of CaSO4, Mg(OH)2, ettringite and CaCO3 precipitate were 86.9%, 99.8%, 88.3% and 99.9%, which were suitable to be utilized as desulfurization gypsum, dephosphorization agent, flame retardant and desulfurizer. NaClO obtained from electrolytic chlorine production could satisfy the requirement of type A, class Ⅲ in China's National Standard GB 19106-2013, which was applicable to disinfection, sterilization and water treatment.
Based on characteristics of wastewater and resource recovery, a zero liquid discharge process of flue gas desulfurization wastewater, combined with graded salt separation pretreatment, membrane concentration and electrolytic chlorine production unit, was constructed. A pilot-scale experiment was conducted for 35 d at a flow rate of 500 L/d. The results suggested that effective removal of pollutants and resource recovery could be achieved with suspended solid, Mg2+, SO2-4 and Ca2+ removal of 100%, 96.6%, 99.8% and 98.9%. The purity of CaSO4, Mg(OH)2, ettringite and CaCO3 precipitate were 86.9%, 99.8%, 88.3% and 99.9%, which were suitable to be utilized as desulfurization gypsum, dephosphorization agent, flame retardant and desulfurizer. NaClO obtained from electrolytic chlorine production could satisfy the requirement of type A, class Ⅲ in China's National Standard GB 19106-2013, which was applicable to disinfection, sterilization and water treatment.
2022, 40(10): 176-182,191.
doi: 10.13205/j.hjgc.202210024
Abstract:
In response to the special requirements for water environment quality improvement in the Taihu Lake Basin, this article focused on the printing and dyeing industry in the Taihu Lake Basin, and built an enterprise advanced in production technology and equipment, resource and energy utilization, pollutant generation, economic benefits, process equipment, treatment effects, and management level. The evaluation index system for performance, and printing and dyeing products were refined into 4 categories from 5 categories in the Water Pollutant Discharge Standard for Textile Dyeing and Finishing Industry (GB 4287-2012). The study found that the pollutants discharge load limit per unit product calculated and strictly obtained using four methods including enterprise monitoring data, industry standards, environmental statistics and pollutant discharge permit declaration data was far lower than the current national emission limit. On this basis, a complete technical plan was formed, which could provide a basis for the determination of pollution permit limits for this industry and other industries based on advanced technologies, and provide technical support for the implementation of the pollution permit system.
In response to the special requirements for water environment quality improvement in the Taihu Lake Basin, this article focused on the printing and dyeing industry in the Taihu Lake Basin, and built an enterprise advanced in production technology and equipment, resource and energy utilization, pollutant generation, economic benefits, process equipment, treatment effects, and management level. The evaluation index system for performance, and printing and dyeing products were refined into 4 categories from 5 categories in the Water Pollutant Discharge Standard for Textile Dyeing and Finishing Industry (GB 4287-2012). The study found that the pollutants discharge load limit per unit product calculated and strictly obtained using four methods including enterprise monitoring data, industry standards, environmental statistics and pollutant discharge permit declaration data was far lower than the current national emission limit. On this basis, a complete technical plan was formed, which could provide a basis for the determination of pollution permit limits for this industry and other industries based on advanced technologies, and provide technical support for the implementation of the pollution permit system.
2022, 40(10): 183-191.
doi: 10.13205/j.hjgc.202210025
Abstract:
Mining urban mineral resource deposits to compensate for the shortage of primary mineral resources is of great significance. The key to this problem is to estimate urban mineral deposits accurately. This research focused on the residence buildings and estimated the potential mineral deposits on a community scale. In this paper, Huilongguan community in Beijing was chosen as an example, and the in-use stock of 662 residence buildings in 21 communities was estimated quantitatively. Mineral deposits were estimated according to the life cycle of China's residence building, and the number of recoverable resources was calculated furthermore. Annual greenhouse gas emissions of current buildings were also estimated. The results showed that:1) potential deposits of mineral resources were large and the total amount in 21 communities reached 7.293 million tons; 2) buildings of 562 frame and 70 shear wall structures took 95.48% of the whole, and their greenhouse gas emissions were much higher than brick-concrete structure buildings. Environmental pressure would be greater as frame and shear wall structure buildings become dominant in the future; 3) the estimated recyclable materials deposit were 3.658 million tons and might have beneficial resource, and environmental effects through classified treatment and recycling.
Mining urban mineral resource deposits to compensate for the shortage of primary mineral resources is of great significance. The key to this problem is to estimate urban mineral deposits accurately. This research focused on the residence buildings and estimated the potential mineral deposits on a community scale. In this paper, Huilongguan community in Beijing was chosen as an example, and the in-use stock of 662 residence buildings in 21 communities was estimated quantitatively. Mineral deposits were estimated according to the life cycle of China's residence building, and the number of recoverable resources was calculated furthermore. Annual greenhouse gas emissions of current buildings were also estimated. The results showed that:1) potential deposits of mineral resources were large and the total amount in 21 communities reached 7.293 million tons; 2) buildings of 562 frame and 70 shear wall structures took 95.48% of the whole, and their greenhouse gas emissions were much higher than brick-concrete structure buildings. Environmental pressure would be greater as frame and shear wall structure buildings become dominant in the future; 3) the estimated recyclable materials deposit were 3.658 million tons and might have beneficial resource, and environmental effects through classified treatment and recycling.
2022, 40(10): 192-202,241.
doi: 10.13205/j.hjgc.202210026
Abstract:
In order to systematically understand the removal efficiency of antibiotic resistance genes (ARGs) in sludge during anaerobic digestion and clarify the degradation mechanism of antibiotic resistance genes, this paper reviewed the effects of several common anaerobic digestion intensification processes, such as thermophilic anaerobic digestion, pretreatment technologies and additives injection on ARGs removal, taking the global research progress into account. It was found that the fate of ARGs was mainly related to the selective pressure in the sludge, the abundance of the host bacteria, the efficiency of horizontal gene transfer and the resistance mechanism of ARGs. Anaerobic digestion and its intensification processes mainly achieved an efficient reduction of ARGs by destroying the sludge cell structure, reducing the abundance of host bacteria and reducing the risk of horizontal gene transfer.
In order to systematically understand the removal efficiency of antibiotic resistance genes (ARGs) in sludge during anaerobic digestion and clarify the degradation mechanism of antibiotic resistance genes, this paper reviewed the effects of several common anaerobic digestion intensification processes, such as thermophilic anaerobic digestion, pretreatment technologies and additives injection on ARGs removal, taking the global research progress into account. It was found that the fate of ARGs was mainly related to the selective pressure in the sludge, the abundance of the host bacteria, the efficiency of horizontal gene transfer and the resistance mechanism of ARGs. Anaerobic digestion and its intensification processes mainly achieved an efficient reduction of ARGs by destroying the sludge cell structure, reducing the abundance of host bacteria and reducing the risk of horizontal gene transfer.
2022, 40(10): 203-214.
doi: 10.13205/j.hjgc.202210027
Abstract:
Anammox technology has great application prospects for nitrogen removal in mainstream wastewater treatment plants (WWTPs). It has significant advantages in terms of high efficiency and energy saving, sludge reduction and greenhouse gas emission reduction, and has become the research focus and hot spot in the mainstream wastewater treatment field. This article summarized the mainstream wastewater Anammox process, analyzed the possible reasons for the presence of anaerobic ammonia-oxidizing bacteria (AAOB) in the general wastewater, and conducted an in-depth analysis on low temperature, nitrite and nitrogen removal efficiency that hindered the realization of Anammox, and proposed countermeasures to realize mainstream Anammox. It considered that the realization of high-latitude mainstream Anammox was more suitable for use of PDA (partial denitrification coupled with Anammox). A process route to achieve mainstream Anammox was proposed. AAOB biological characteristics analysis, the formation mechanism and function of PDA granular sludge/biofilm, pilot test and field application of PDA process, and realization of mainstream WWTPs PDA in situ were considered the focus of future mainstream Anammox.
Anammox technology has great application prospects for nitrogen removal in mainstream wastewater treatment plants (WWTPs). It has significant advantages in terms of high efficiency and energy saving, sludge reduction and greenhouse gas emission reduction, and has become the research focus and hot spot in the mainstream wastewater treatment field. This article summarized the mainstream wastewater Anammox process, analyzed the possible reasons for the presence of anaerobic ammonia-oxidizing bacteria (AAOB) in the general wastewater, and conducted an in-depth analysis on low temperature, nitrite and nitrogen removal efficiency that hindered the realization of Anammox, and proposed countermeasures to realize mainstream Anammox. It considered that the realization of high-latitude mainstream Anammox was more suitable for use of PDA (partial denitrification coupled with Anammox). A process route to achieve mainstream Anammox was proposed. AAOB biological characteristics analysis, the formation mechanism and function of PDA granular sludge/biofilm, pilot test and field application of PDA process, and realization of mainstream WWTPs PDA in situ were considered the focus of future mainstream Anammox.
2022, 40(10): 215-223.
doi: 10.13205/j.hjgc.202210028
Abstract:
Waste pyrolysis technology is an effective mean to convert waste into energy. Waste pyrolysis kinetics is the study on the reaction mechanism of waste pyrolysis, the mathematical expressions of the reaction rate, and the influencing factors. The study of waste pyrolysis kinetics is of great significance for the prediction of waste pyrolysis results and the design and simulation of waste pyrolysis equipment. This article aims to provide an overview of the research on waste pyrolysis kinetics, mainly summarizing various models and methods for calculating mathematical expressions for waste pyrolysis reaction rates, and describing the applications, advantages, and disadvantages of these methods. Moreover, this article summarizes the research on the factors influencing the kinetic parameters of waste pyrolysis in recent years. It is found that factors including conversion rate, additives, and feedstock components, affect waste pyrolysis kinetic parameters and are of great help for the application of waste pyrolysis.
Waste pyrolysis technology is an effective mean to convert waste into energy. Waste pyrolysis kinetics is the study on the reaction mechanism of waste pyrolysis, the mathematical expressions of the reaction rate, and the influencing factors. The study of waste pyrolysis kinetics is of great significance for the prediction of waste pyrolysis results and the design and simulation of waste pyrolysis equipment. This article aims to provide an overview of the research on waste pyrolysis kinetics, mainly summarizing various models and methods for calculating mathematical expressions for waste pyrolysis reaction rates, and describing the applications, advantages, and disadvantages of these methods. Moreover, this article summarizes the research on the factors influencing the kinetic parameters of waste pyrolysis in recent years. It is found that factors including conversion rate, additives, and feedstock components, affect waste pyrolysis kinetic parameters and are of great help for the application of waste pyrolysis.
2022, 40(10): 224-232.
doi: 10.13205/j.hjgc.202210029
Abstract:
After the ultra-low emission transformation of China's active coal-fired power plants, the NOx emission of some of them doesn't meet the standard. In order to solve the practical problems of the projects in coal-fired power plants, we summarized the research status of numerical simulation of SCR denitration system in coal-fired power plants. The research shows that in order to further improve the accuracy of numerical simulation of SCR denitration system, non-uniform flue gas inlet boundary conditions and coke combustion model based on ash layer suppression should be adopted; the relationship between the thickness of the deflector and the flue gas flow characteristics in the flue should be considered in the reconstruction of the deflector; the transformation of the ammonia injection system and mixer is an important reason for the high transformation cost and induced draft fan energy consumption. The comparative study between the engineering transformation and the increased cost of energy consumption after the transformation and the cost saved on catalyst will be a hot research direction in the future. The technical route for the engineering transformation of SCR denitration system in coal-fired power plants is proposed, which can provide theoretical guidance and technical support for the engineering practice.
After the ultra-low emission transformation of China's active coal-fired power plants, the NOx emission of some of them doesn't meet the standard. In order to solve the practical problems of the projects in coal-fired power plants, we summarized the research status of numerical simulation of SCR denitration system in coal-fired power plants. The research shows that in order to further improve the accuracy of numerical simulation of SCR denitration system, non-uniform flue gas inlet boundary conditions and coke combustion model based on ash layer suppression should be adopted; the relationship between the thickness of the deflector and the flue gas flow characteristics in the flue should be considered in the reconstruction of the deflector; the transformation of the ammonia injection system and mixer is an important reason for the high transformation cost and induced draft fan energy consumption. The comparative study between the engineering transformation and the increased cost of energy consumption after the transformation and the cost saved on catalyst will be a hot research direction in the future. The technical route for the engineering transformation of SCR denitration system in coal-fired power plants is proposed, which can provide theoretical guidance and technical support for the engineering practice.
2022, 40(10): 233-241.
doi: 10.13205/j.hjgc.202210030
Abstract:
Ecological integrity includes physical, chemical and biological integrity, therefore, based on a systematic understanding of the connotation of ecological integrity, the specific evaluation methods of biological, physical and chemical integrity were analyzed in depth, including the biological integrity index method, the predictive model method, the qualitative habitat evaluation index and the physical habitat index, etc. The advantages and limitations of different evaluation methods were compared and analyzed, and the monitoring indicators and scope of application of different methods were clarified. The advantages and limitations of different evaluation methods were compared and analyzed, and the required monitoring indicators and the scope of application of different methods were clarified. In addition, the methods and cases of water ecological integrity assessment of typical watersheds that had been carried out internationally so far were synthesized. Finally, the current problems of ecological integrity assessment were pointed out given the current environmental management needs of watershed water and ecological quality assessment, and several suggestions were proposed for the future work of water and ecological quality assessment.
Ecological integrity includes physical, chemical and biological integrity, therefore, based on a systematic understanding of the connotation of ecological integrity, the specific evaluation methods of biological, physical and chemical integrity were analyzed in depth, including the biological integrity index method, the predictive model method, the qualitative habitat evaluation index and the physical habitat index, etc. The advantages and limitations of different evaluation methods were compared and analyzed, and the monitoring indicators and scope of application of different methods were clarified. The advantages and limitations of different evaluation methods were compared and analyzed, and the required monitoring indicators and the scope of application of different methods were clarified. In addition, the methods and cases of water ecological integrity assessment of typical watersheds that had been carried out internationally so far were synthesized. Finally, the current problems of ecological integrity assessment were pointed out given the current environmental management needs of watershed water and ecological quality assessment, and several suggestions were proposed for the future work of water and ecological quality assessment.
