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2025 Vol. 43, No. 6
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2025, 43(6): 1-12.
doi: 10.13205/j.hjgc.202506001
Abstract:
Urban sludge treatment and disposal in China have entered a new phase， shifting from simple treatment to resource utilization. The application of stabilized sludge in land use has been shown to positively contribute to the accumulation and sequestration of soil organic carbon （SOC）. This paper reviewed the methods， standards， and mechanisms of SOC response in sludge land use， and found that sludge land use not only improved soil properties but also effectively enhanced SOC content. By comparing different application methods， it was found that the combined approach integrating landscaping and ecological restoration demonstrated significant development potential. The mechanisms underlying the impact of sludge land use on SOC were further summarized， including aspects of sludge organic matter composition， physicochemical processes， and microbial drivers. In terms of physicochemical process， sludge application significantly altered soil structure and pH， thereby influencing SOC transformation and sequestration. Regarding microbial processes， changes in microbial communities and functions following sludge application are key factors affecting SOC turnover， with microbial residues playing a critical role in SOC accumulation. By systematically reviewing relevant research progress domestically and internationally， this study can provide theoretical support and guidance for the sustainable management and land use of sludge.
Urban sludge treatment and disposal in China have entered a new phase， shifting from simple treatment to resource utilization. The application of stabilized sludge in land use has been shown to positively contribute to the accumulation and sequestration of soil organic carbon （SOC）. This paper reviewed the methods， standards， and mechanisms of SOC response in sludge land use， and found that sludge land use not only improved soil properties but also effectively enhanced SOC content. By comparing different application methods， it was found that the combined approach integrating landscaping and ecological restoration demonstrated significant development potential. The mechanisms underlying the impact of sludge land use on SOC were further summarized， including aspects of sludge organic matter composition， physicochemical processes， and microbial drivers. In terms of physicochemical process， sludge application significantly altered soil structure and pH， thereby influencing SOC transformation and sequestration. Regarding microbial processes， changes in microbial communities and functions following sludge application are key factors affecting SOC turnover， with microbial residues playing a critical role in SOC accumulation. By systematically reviewing relevant research progress domestically and internationally， this study can provide theoretical support and guidance for the sustainable management and land use of sludge.
2025, 43(6): 13-23.
doi: 10.13205/j.hjgc.202506002
Abstract:
Microbial nutrient stimulant （MNS） is a product separated and extracted from activated sludge through alkaline thermal hydrolysis technology， which is rich in plant essential nutrients （C， N， P， K） and stimulant substances， thereby enabling sludge resource treatment and sustainable agricultural development simultaneously. This study established three treatments： blank control （CK）， chemical fertilizer （CF）， and microbial nutrient stimulants （MNS）， to evaluate the synergistic enhancement effects of MNS on soybean quality and soil quality. The results showed that， compared with CF， MNS improved the yield and quality of soybean. Specifically， protein， fatty acid， and amino acid content in soybean grains increased by 1.71%， 17.96% and 10.58%， respectively. Moreover， the MNS application also improved soil fertility， with increases in organic matter （+13.73%）， available P （+28.66%）， and available K （+44.18%）， while ammonium nitrogen content decreased （-10.34%）. The MNS modulated the rhizosphere microbiome， enriching functional taxa such as Azohydromonas， Chloroflexaceae， and Sphingomonas， thereby increasing the abundance of rhizosphere metabolites， including arachidonic acid， tryptophan， and stigmasterol. This enhancement promoted carbon-nitrogen cycling and nutrient release in the rhizosphere. The study demonstrates that applying MNS can regulate the interactions among soybean roots， soil， and microorganisms， thereby improving both soybean quality and soil health.
Microbial nutrient stimulant （MNS） is a product separated and extracted from activated sludge through alkaline thermal hydrolysis technology， which is rich in plant essential nutrients （C， N， P， K） and stimulant substances， thereby enabling sludge resource treatment and sustainable agricultural development simultaneously. This study established three treatments： blank control （CK）， chemical fertilizer （CF）， and microbial nutrient stimulants （MNS）， to evaluate the synergistic enhancement effects of MNS on soybean quality and soil quality. The results showed that， compared with CF， MNS improved the yield and quality of soybean. Specifically， protein， fatty acid， and amino acid content in soybean grains increased by 1.71%， 17.96% and 10.58%， respectively. Moreover， the MNS application also improved soil fertility， with increases in organic matter （+13.73%）， available P （+28.66%）， and available K （+44.18%）， while ammonium nitrogen content decreased （-10.34%）. The MNS modulated the rhizosphere microbiome， enriching functional taxa such as Azohydromonas， Chloroflexaceae， and Sphingomonas， thereby increasing the abundance of rhizosphere metabolites， including arachidonic acid， tryptophan， and stigmasterol. This enhancement promoted carbon-nitrogen cycling and nutrient release in the rhizosphere. The study demonstrates that applying MNS can regulate the interactions among soybean roots， soil， and microorganisms， thereby improving both soybean quality and soil health.
2025, 43(6): 24-33.
doi: 10.13205/j.hjgc.202506003
Abstract:
Biochar can effectively improve sludge digestion efficiency and stabilize heavy metals. In this study， biochar was prepared from poplar sawdust under anoxic conditions at 300℃， 500℃ and 700℃， respectively， and the effects of biochar addition on municipal sludge anaerobic digestion efficiency，as well as the contents， chemical speciation， and ecological risks of heavy metals（Cu， As， Ni， Cr and Pb）were investigated. The results showed that biochar addition could contribute to maintaining the stability of pH level and alleviating ammonia nitrogen accumulation in the anaerobic digestion system， and the cumulative methane production increased by 80.55% to 132.52% compared to the control group. Biochar prepared at 700℃ with a dosage of 20 g/L was better than other preparing conditions in promoting anaerobic digestion efficiency. After biochar addition， the content of heavy metals in anaerobically digested sludge increased by 4.79% to 85.54% compared to the control group， both the single-factor pollution index （PI i ） and the Nemerow pollution index （NPI） of heavy metals in the digested sludge increased in varying degrees， but the PI i and NPI values were still less than 1 （indicating a clean level）. In addition， the proportion of heavy metals existed in acid-soluble/exchangeable fraction decreased， while the residual fraction increased in the anaerobically digested sludge with biochar addition. The risk index（RI） value of heavy metals was 58 at a biochar （500 ℃） dosage of 20 g/L， which was 47.75% lower than that of the control group. The potential ecological risks of heavy metals in anaerobically digested sludge could be effectively controlled by biochar addition.
Biochar can effectively improve sludge digestion efficiency and stabilize heavy metals. In this study， biochar was prepared from poplar sawdust under anoxic conditions at 300℃， 500℃ and 700℃， respectively， and the effects of biochar addition on municipal sludge anaerobic digestion efficiency，as well as the contents， chemical speciation， and ecological risks of heavy metals（Cu， As， Ni， Cr and Pb）were investigated. The results showed that biochar addition could contribute to maintaining the stability of pH level and alleviating ammonia nitrogen accumulation in the anaerobic digestion system， and the cumulative methane production increased by 80.55% to 132.52% compared to the control group. Biochar prepared at 700℃ with a dosage of 20 g/L was better than other preparing conditions in promoting anaerobic digestion efficiency. After biochar addition， the content of heavy metals in anaerobically digested sludge increased by 4.79% to 85.54% compared to the control group， both the single-factor pollution index （PI i ） and the Nemerow pollution index （NPI） of heavy metals in the digested sludge increased in varying degrees， but the PI i and NPI values were still less than 1 （indicating a clean level）. In addition， the proportion of heavy metals existed in acid-soluble/exchangeable fraction decreased， while the residual fraction increased in the anaerobically digested sludge with biochar addition. The risk index（RI） value of heavy metals was 58 at a biochar （500 ℃） dosage of 20 g/L， which was 47.75% lower than that of the control group. The potential ecological risks of heavy metals in anaerobically digested sludge could be effectively controlled by biochar addition.
2025, 43(6): 34-40.
doi: 10.13205/j.hjgc.202506004
Abstract:
This research focuses on four types of sludge collected from three wastewater treatment plants in Wuxi. An analysis was conducted on the sludge quality indicators resulting from diverse wastewater treatment methodologies， and an investigation was undertaken into the impact of varying chemical dosage proportions on sludge dewaterability. The findings indicated that the key factors affecting sludge dewatering performance were sludge solid content， protein and polysaccharide contents in extracellular polymeric substances （EPS）， and sludge specific resistance to filtration （SRF）. Based on a uniform experimental design and a linear regression model， a linear relationship was established between the dosage of chemicals and the capillary suction time （CST）， organic matter content， and solid content of sludge. The model validation results showed that within the range of the dosage ratio （lime： 13% to 25%； PAM： 1‰ to 9‰）， the standard error of the equation was below 1.5， indicating good applicability of this model. This study provides a rigorous scientific basis for the application of sludge dewatering agents， thereby enhancing dewatering efficiency， reducing treatment costs， and promoting sustainable sludge management and disposal practices.
This research focuses on four types of sludge collected from three wastewater treatment plants in Wuxi. An analysis was conducted on the sludge quality indicators resulting from diverse wastewater treatment methodologies， and an investigation was undertaken into the impact of varying chemical dosage proportions on sludge dewaterability. The findings indicated that the key factors affecting sludge dewatering performance were sludge solid content， protein and polysaccharide contents in extracellular polymeric substances （EPS）， and sludge specific resistance to filtration （SRF）. Based on a uniform experimental design and a linear regression model， a linear relationship was established between the dosage of chemicals and the capillary suction time （CST）， organic matter content， and solid content of sludge. The model validation results showed that within the range of the dosage ratio （lime： 13% to 25%； PAM： 1‰ to 9‰）， the standard error of the equation was below 1.5， indicating good applicability of this model. This study provides a rigorous scientific basis for the application of sludge dewatering agents， thereby enhancing dewatering efficiency， reducing treatment costs， and promoting sustainable sludge management and disposal practices.
2025, 43(6): 41-50.
doi: 10.13205/j.hjgc.202506005
Abstract:
With the increase in China's sewage treatment capacity， the amount of residue sludge generated during the wastewater treatment process has also been increasing gradually. The issue of sludge treatment urgently needs to be addressed， and sludge dewatering is a key link. The high water content in sludge brings many difficulties to subsequent treatment and increases treatment costs. This paper provides a comprehensive overview of sludge dewatering technologies， including mechanical dewatering and sludge drying， while analyzing the advantages and disadvantages in practical applications. A systematic study was conducted to investigate the factors affecting sludge dewatering performance， clarifying the action mechanisms of various factors， including extracellular polymeric substances （EPS） and colloidal particles. In addition， the physical， chemical， and biological conditioning methods and their effects were comprehensively introduced. For each method， multiple application methods and their effects were listed， providing a comprehensive reference for sludge treatment. On this basis， future directions for sludge dewatering were prospected with a focus on resource utilization and low-carbonization， mainly including technological innovation and collaborative treatment， aiming to provide a reference for sludge treatment and promote the sustainable development in sludge treatment and disposal.
With the increase in China's sewage treatment capacity， the amount of residue sludge generated during the wastewater treatment process has also been increasing gradually. The issue of sludge treatment urgently needs to be addressed， and sludge dewatering is a key link. The high water content in sludge brings many difficulties to subsequent treatment and increases treatment costs. This paper provides a comprehensive overview of sludge dewatering technologies， including mechanical dewatering and sludge drying， while analyzing the advantages and disadvantages in practical applications. A systematic study was conducted to investigate the factors affecting sludge dewatering performance， clarifying the action mechanisms of various factors， including extracellular polymeric substances （EPS） and colloidal particles. In addition， the physical， chemical， and biological conditioning methods and their effects were comprehensively introduced. For each method， multiple application methods and their effects were listed， providing a comprehensive reference for sludge treatment. On this basis， future directions for sludge dewatering were prospected with a focus on resource utilization and low-carbonization， mainly including technological innovation and collaborative treatment， aiming to provide a reference for sludge treatment and promote the sustainable development in sludge treatment and disposal.
2025, 43(6): 51-64.
doi: 10.13205/j.hjgc.202506006
Abstract:
The production of volatile fatty acids （VFAs） through anaerobic fermentation of sludge represents a promising route for the resource utilization of sludge. VFAs are not only precursors for a variety of industrial products but also serve as supplementary carbon sources in biological wastewater treatment processes. Nevertheless， its widespread application is hampered by factors such as low acid production yields and instability of the fermentation process. Consequently， investigating strategies to enhance the efficiency of sludge fermentation for acid production and the application potential of the fermentation broth has become a focal point in research. Current research predominantly focuses on the mechanisms and influencing factors of sludge fermentation for acid production， with a notable gap in the systematic summary of enhancement methods for sludge acid production and the subsequent applications of the fermentation broth. This paper provides an overview of the mechanisms of anaerobic fermentation of sludge for acid production and provides a comprehensive summary of the advantages and limitations of four common enhancement strategies for sludge acid production： pretreatment， membrane technology， alkaline fermentation， and co-fermentation. Additionally， it introduces on the application pathways of the sludge fermentation broth under the aforementioned enhancement strategies， including its use as a raw material for synthesizing polyhydroxyalkanoates （PHAs）， medium-chain fatty acids （MCFAs）， and bioenergy， as well as its potential in the preparation of microbial fuel cells （MFC） and as a carbon source for nitrogen and phosphorus removal in wastewater treatment. Finally， the paper identifies the challenges and deficiencies in the current techniques for enhancing sludge acid production and the application fields of the fermentation broth， and offers insights into future research directions， aiming to provide a reference for improving the recovery rate of sludge resources and the utilization efficiency of fermentation products.
The production of volatile fatty acids （VFAs） through anaerobic fermentation of sludge represents a promising route for the resource utilization of sludge. VFAs are not only precursors for a variety of industrial products but also serve as supplementary carbon sources in biological wastewater treatment processes. Nevertheless， its widespread application is hampered by factors such as low acid production yields and instability of the fermentation process. Consequently， investigating strategies to enhance the efficiency of sludge fermentation for acid production and the application potential of the fermentation broth has become a focal point in research. Current research predominantly focuses on the mechanisms and influencing factors of sludge fermentation for acid production， with a notable gap in the systematic summary of enhancement methods for sludge acid production and the subsequent applications of the fermentation broth. This paper provides an overview of the mechanisms of anaerobic fermentation of sludge for acid production and provides a comprehensive summary of the advantages and limitations of four common enhancement strategies for sludge acid production： pretreatment， membrane technology， alkaline fermentation， and co-fermentation. Additionally， it introduces on the application pathways of the sludge fermentation broth under the aforementioned enhancement strategies， including its use as a raw material for synthesizing polyhydroxyalkanoates （PHAs）， medium-chain fatty acids （MCFAs）， and bioenergy， as well as its potential in the preparation of microbial fuel cells （MFC） and as a carbon source for nitrogen and phosphorus removal in wastewater treatment. Finally， the paper identifies the challenges and deficiencies in the current techniques for enhancing sludge acid production and the application fields of the fermentation broth， and offers insights into future research directions， aiming to provide a reference for improving the recovery rate of sludge resources and the utilization efficiency of fermentation products.
2025, 43(6): 65-76.
doi: 10.13205/j.hjgc.202506007
Abstract:
The residual sludge anaerobic digestate is characterized by high nitrogen and phosphorus content and a low C/N ratio， which is not suitable for direct biological treatment. Microalgae can be used as a pre-treatment technology for residual sludge anaerobic digestate as a fast-growing， renewable source of biomass energy. The immobilized Chlorella vulgaris has a good performance in nitrogen and phosphorus removal in residual sludge anaerobic digestate. In this study， sodium alginate （SA） was used as a carrier， powdered activated carbon （PAC） as an adsorbent and calcium chloride （CaCl2） as a cross-linking agent， and the effects of the proportional concentrations of the three additives on the properties of immobilized Chlorella vulgaris， such as mass transfer， stability and specific growth rate were analyzed. The immobilization conditions were optimized through orthogonal test to investigate the optimal proportions and effectiveness in nitrogen and phosphorus removal from residual sludge anaerobic digestate. The results showed that when the concentration of SA， PAC， and CaCl2 was 2.5%， 4.5%， and 0.2%， the specific growth rate， material mass transfer， and mechanical properties of the immobilized Chlorella vulgaris were optimal. The removal efficiencies of NH4+-N， TP， and COD by immobilized Chlorella vulgaris in the residual sludge anaerobic digestate were 96.70%， 51.30%， and 52.92%， which were 3.13%， 17.05%， and 8.53% higher than those of the suspension Chlorella vulgaris group， respectively. While the removal efficiencies of NH4+-N， TP， and COD were only 22.93%， 14.89%， and 8.12% by the adsorption of PAC and SA without Chlorella vulgaris. As the reuse times increased， the specific growth rate of immobilized Chlorella vulgaris and the removal efficiencies of NH4+-N， COD， and TP decreased. In addition， the removal efficiencies of TN and TP in the residual sludge anaerobic digestate by immobilized Chlorella vulgaris were affected by N/P ratio， and the concentration of Ca2+ and COD. When N/P ratio was 14：1， the removal efficiencies of TN and TP were the highest （91.23%， 86.54%）. With an increasing Ca2+ concentration， the algal density of immobilized Chlorella vulgaris showed an increasing-decreasing trend. When Ca2+ concentration was 0 to 20 mg/L， it had little effect on TN removal efficiency， while that of TP was positively correlated with Ca2+ concentration， and the best removal efficiency of TP was 90.0% when the Ca2+ concentration was 40 mg/L. When the COD concentration was 600 mg/L， the removal efficiencies of TN and TP were 84.39 % and 83.50 %， respectively， which were 46.24 and 11.75 percentage points higher than those of the 1200 mg/L COD group. The results can provide theoretical and technical support for the treatment of residual sludge anaerobic digestate.
The residual sludge anaerobic digestate is characterized by high nitrogen and phosphorus content and a low C/N ratio， which is not suitable for direct biological treatment. Microalgae can be used as a pre-treatment technology for residual sludge anaerobic digestate as a fast-growing， renewable source of biomass energy. The immobilized Chlorella vulgaris has a good performance in nitrogen and phosphorus removal in residual sludge anaerobic digestate. In this study， sodium alginate （SA） was used as a carrier， powdered activated carbon （PAC） as an adsorbent and calcium chloride （CaCl2） as a cross-linking agent， and the effects of the proportional concentrations of the three additives on the properties of immobilized Chlorella vulgaris， such as mass transfer， stability and specific growth rate were analyzed. The immobilization conditions were optimized through orthogonal test to investigate the optimal proportions and effectiveness in nitrogen and phosphorus removal from residual sludge anaerobic digestate. The results showed that when the concentration of SA， PAC， and CaCl2 was 2.5%， 4.5%， and 0.2%， the specific growth rate， material mass transfer， and mechanical properties of the immobilized Chlorella vulgaris were optimal. The removal efficiencies of NH4+-N， TP， and COD by immobilized Chlorella vulgaris in the residual sludge anaerobic digestate were 96.70%， 51.30%， and 52.92%， which were 3.13%， 17.05%， and 8.53% higher than those of the suspension Chlorella vulgaris group， respectively. While the removal efficiencies of NH4+-N， TP， and COD were only 22.93%， 14.89%， and 8.12% by the adsorption of PAC and SA without Chlorella vulgaris. As the reuse times increased， the specific growth rate of immobilized Chlorella vulgaris and the removal efficiencies of NH4+-N， COD， and TP decreased. In addition， the removal efficiencies of TN and TP in the residual sludge anaerobic digestate by immobilized Chlorella vulgaris were affected by N/P ratio， and the concentration of Ca2+ and COD. When N/P ratio was 14：1， the removal efficiencies of TN and TP were the highest （91.23%， 86.54%）. With an increasing Ca2+ concentration， the algal density of immobilized Chlorella vulgaris showed an increasing-decreasing trend. When Ca2+ concentration was 0 to 20 mg/L， it had little effect on TN removal efficiency， while that of TP was positively correlated with Ca2+ concentration， and the best removal efficiency of TP was 90.0% when the Ca2+ concentration was 40 mg/L. When the COD concentration was 600 mg/L， the removal efficiencies of TN and TP were 84.39 % and 83.50 %， respectively， which were 46.24 and 11.75 percentage points higher than those of the 1200 mg/L COD group. The results can provide theoretical and technical support for the treatment of residual sludge anaerobic digestate.
2025, 43(6): 77-85.
doi: 10.13205/j.hjgc.202506008
Abstract:
This study explored the impact of hydrothermal carbonization（HTC） reaction conditions， including reaction temperature， reaction time， and reaction medium on the properties of HMs in sewage sludge. Experimental investigations demonstrated that HTC enriched HMs in the hydrochar， transforming them from unstable fractions （F1/F2/F3） to more stable fractions （F4/F5）. The stabilization degree correlated positively with reaction intensity， with temperature playing a more significant role. The results revealed that HTC greatly reduced the ecological toxicity of HMs. Under neutral conditions， Zn， Cu， Cr， and Ni exhibited low risk levels， while Mn remained at a medium level. The use of 2% H2SO4 as the reaction medium at 220°C for 1 hour was identified as the optimal condition， wherein all HMs in the hydrochar achieved low-risk levels. Furthermore， HTC also reduced leaching toxicity， as measured by SPLP， TCLP， and PBET. This suggests that HTC is a promising technology for the safe and effective disposal of sewage sludge， as it transforms sludge into a low-risk material. The comprehensive analysis of HMs migration， transformation， and ecotoxicity under different HTC conditions provides valuable insights for future research and practical applications.
This study explored the impact of hydrothermal carbonization（HTC） reaction conditions， including reaction temperature， reaction time， and reaction medium on the properties of HMs in sewage sludge. Experimental investigations demonstrated that HTC enriched HMs in the hydrochar， transforming them from unstable fractions （F1/F2/F3） to more stable fractions （F4/F5）. The stabilization degree correlated positively with reaction intensity， with temperature playing a more significant role. The results revealed that HTC greatly reduced the ecological toxicity of HMs. Under neutral conditions， Zn， Cu， Cr， and Ni exhibited low risk levels， while Mn remained at a medium level. The use of 2% H2SO4 as the reaction medium at 220°C for 1 hour was identified as the optimal condition， wherein all HMs in the hydrochar achieved low-risk levels. Furthermore， HTC also reduced leaching toxicity， as measured by SPLP， TCLP， and PBET. This suggests that HTC is a promising technology for the safe and effective disposal of sewage sludge， as it transforms sludge into a low-risk material. The comprehensive analysis of HMs migration， transformation， and ecotoxicity under different HTC conditions provides valuable insights for future research and practical applications.
2025, 43(6): 86-94.
doi: 10.13205/j.hjgc.202506009
Abstract:
Municipal sewage sludge enriches resources and pollutants during the sewage treatment process. As the final pollution control stage of sewage treatment， sludge treatment and disposal not only contribute to non-negligible carbon emissions， but also hold considerable potential for resource and energy recovery. This study systematically analyzed the the composition of carbon emissions from process units and the carbon emission characteristics of mainstream technical routes for sludge treatment and disposal. From the perspectives of greenhouse gas emission reduction， energy saving and consumption reduction， energy and resource recovery， etc.， this study discussed the carbon emission reduction technologies for the 3 mainstream technical routes including anaerobic digestion + land use， aerobic fermentation + land use， and incineration + building material utilization. It also summarized new energy and resource utilization technologies with application prospects. In the end， this study put forward some future development directions for sludge treatment and disposal.
Municipal sewage sludge enriches resources and pollutants during the sewage treatment process. As the final pollution control stage of sewage treatment， sludge treatment and disposal not only contribute to non-negligible carbon emissions， but also hold considerable potential for resource and energy recovery. This study systematically analyzed the the composition of carbon emissions from process units and the carbon emission characteristics of mainstream technical routes for sludge treatment and disposal. From the perspectives of greenhouse gas emission reduction， energy saving and consumption reduction， energy and resource recovery， etc.， this study discussed the carbon emission reduction technologies for the 3 mainstream technical routes including anaerobic digestion + land use， aerobic fermentation + land use， and incineration + building material utilization. It also summarized new energy and resource utilization technologies with application prospects. In the end， this study put forward some future development directions for sludge treatment and disposal.
2025, 43(6): 95-104.
doi: 10.13205/j.hjgc.202506010
Abstract:
To handle the complicated influent， petrochemical wastewater treatment facilities are usually designed as a long process including multiple treatment stages. The traditional operation strategy of such plants mainly relies on the experiences of the operators. It usually takes considerable of time and cost to find the optimum operating conditions， and carries unpredictable risks of non-compliance. The use of mechanistic models for simulating the biological processes has been widely applied in optimizing municipal wastewater treatment plants. It’s more challenging to calibrate the mechanistic models for applications in industrial wastewater treatment. This project used BioWin， a process modeling software， to develop and calibrate a model for simulating biological processes， including anaerobic digestion， pure oxygen aeration systems， surface aeration process， and membrane reactors， at a petrochemical wastewater treatment plant in Tianjin. The calibrated model was used to conduct scenarios analyses， systematically optimizing the wastewater treatment facilities to reduce the operational cost and operator workload.
To handle the complicated influent， petrochemical wastewater treatment facilities are usually designed as a long process including multiple treatment stages. The traditional operation strategy of such plants mainly relies on the experiences of the operators. It usually takes considerable of time and cost to find the optimum operating conditions， and carries unpredictable risks of non-compliance. The use of mechanistic models for simulating the biological processes has been widely applied in optimizing municipal wastewater treatment plants. It’s more challenging to calibrate the mechanistic models for applications in industrial wastewater treatment. This project used BioWin， a process modeling software， to develop and calibrate a model for simulating biological processes， including anaerobic digestion， pure oxygen aeration systems， surface aeration process， and membrane reactors， at a petrochemical wastewater treatment plant in Tianjin. The calibrated model was used to conduct scenarios analyses， systematically optimizing the wastewater treatment facilities to reduce the operational cost and operator workload.
2025, 43(6): 105-114.
doi: 10.13205/j.hjgc.202506011
Abstract:
Mechanical vibration has been proven to be an effective and energy-saving method for controling MBR membrane fouling in many lab-scale and pilot-scale studies. The Beijing Doudian Wastewater Treatment Plant （WWTP） is the first project treating real municipal wastewater with vibrating MBR （V-MBR） and air sparging MBR （AS-MBR） processes in parallel around the world. During two years of operation， data showed that when the COD/TN ratio of the influent was as low as 5， the TN concentration in the effluent of the V-MBR process was at least 4 mg/L lower than that of the AS-MBR process. The COD， NH4+-N， and TP concentrations in the effluents of two processes were comparable. The difference in endogenous nitrogen removal in the V-MBR membrane tank and endogenous nitrogen release in the AS-MBR membrane tank contributed to approximately 70% of the enhanced nitrogen removal capacity in the V-MBR process. The nitrification， denitrification， phosphorus release， and phosphorus uptake rates of the V-MBR sludge were 18%， 19%， 19%， and 14% higher than those of the AS-MBR sludge， respectively. Nitrosomonas and Nitrospira were the main nitrfiers. Denitratisoma， Terrimonas， and Thauera were the main denitrifiers. Dechloromonas and Ca. Accumulibacter were the main phosphorus-accumulating organisms （PAO）. The comparative abundances of nitrifiers， denitrifiers， and PAOs in the V-MBR sludge were all higher than those in the AS-MBR sludge. The energy consumption of the V-MBR process was 0.35 kW·h/m3， which was 0.13 kW·h/m3 lower than that of the AS-MBR. The energy consumption difference between the vibrating motor of the V-MBR and the air-sparging blower of the AS-MBR accounted for 85% of the total energy saving. The chemical cost for phosphorus removal in the V-MBR process was 33.3% lower than that in the AS-MBR process. The V-MBR process demonstrated evident advantages in enhancing nitrogen and phosphorus removal while saving energy. The mechanical structure of the vibrating devices could be further optimized.
Mechanical vibration has been proven to be an effective and energy-saving method for controling MBR membrane fouling in many lab-scale and pilot-scale studies. The Beijing Doudian Wastewater Treatment Plant （WWTP） is the first project treating real municipal wastewater with vibrating MBR （V-MBR） and air sparging MBR （AS-MBR） processes in parallel around the world. During two years of operation， data showed that when the COD/TN ratio of the influent was as low as 5， the TN concentration in the effluent of the V-MBR process was at least 4 mg/L lower than that of the AS-MBR process. The COD， NH4+-N， and TP concentrations in the effluents of two processes were comparable. The difference in endogenous nitrogen removal in the V-MBR membrane tank and endogenous nitrogen release in the AS-MBR membrane tank contributed to approximately 70% of the enhanced nitrogen removal capacity in the V-MBR process. The nitrification， denitrification， phosphorus release， and phosphorus uptake rates of the V-MBR sludge were 18%， 19%， 19%， and 14% higher than those of the AS-MBR sludge， respectively. Nitrosomonas and Nitrospira were the main nitrfiers. Denitratisoma， Terrimonas， and Thauera were the main denitrifiers. Dechloromonas and Ca. Accumulibacter were the main phosphorus-accumulating organisms （PAO）. The comparative abundances of nitrifiers， denitrifiers， and PAOs in the V-MBR sludge were all higher than those in the AS-MBR sludge. The energy consumption of the V-MBR process was 0.35 kW·h/m3， which was 0.13 kW·h/m3 lower than that of the AS-MBR. The energy consumption difference between the vibrating motor of the V-MBR and the air-sparging blower of the AS-MBR accounted for 85% of the total energy saving. The chemical cost for phosphorus removal in the V-MBR process was 33.3% lower than that in the AS-MBR process. The V-MBR process demonstrated evident advantages in enhancing nitrogen and phosphorus removal while saving energy. The mechanical structure of the vibrating devices could be further optimized.
2025, 43(6): 115-126.
doi: 10.13205/j.hjgc.202506012
Abstract:
The difficulty in real-time regulation of large sewage treatment plants leads to long-term risk of exceeding the pollution emission standards， and process simulation software is urgently needed to guide the standard operation. Taking an A2/O process sewage treatment plant in the north China as the research object， a suitable model was established using BioWin6.0. Simulation-based operational optimization was carried out to meet the requirements of the Class IV specified in standard GB 3838—2002 for surface water， and the recommended operation parameters for the four seasons were obtained through TN （total nitrogen）-prioritized and TP （total phosphorus）-prioritized simulations， respectively. Taking winter as an example， the recommended operation parameters for TN control in winter were verified. The results showed that the three indexes of COD， NH4+-N， and TP were stably superior to the Class IV standard for surface water. It was noteworthy that the simulated effluent TN was reduced by up to 21.2% compared to the original level，while the simulated effluent TP was reduced by up to 15.6%， even better than the Class III standard for surface water. This demonstrates that there is still much room for upgrading the operation of this plant. The recommended operation parameters for the four seasons can provide reference and guidance for large sewage treatment plants to reduce costs and increase efficiency.
The difficulty in real-time regulation of large sewage treatment plants leads to long-term risk of exceeding the pollution emission standards， and process simulation software is urgently needed to guide the standard operation. Taking an A2/O process sewage treatment plant in the north China as the research object， a suitable model was established using BioWin6.0. Simulation-based operational optimization was carried out to meet the requirements of the Class IV specified in standard GB 3838—2002 for surface water， and the recommended operation parameters for the four seasons were obtained through TN （total nitrogen）-prioritized and TP （total phosphorus）-prioritized simulations， respectively. Taking winter as an example， the recommended operation parameters for TN control in winter were verified. The results showed that the three indexes of COD， NH4+-N， and TP were stably superior to the Class IV standard for surface water. It was noteworthy that the simulated effluent TN was reduced by up to 21.2% compared to the original level，while the simulated effluent TP was reduced by up to 15.6%， even better than the Class III standard for surface water. This demonstrates that there is still much room for upgrading the operation of this plant. The recommended operation parameters for the four seasons can provide reference and guidance for large sewage treatment plants to reduce costs and increase efficiency.
2025, 43(6): 127-137.
doi: 10.13205/j.hjgc.202506013
Abstract:
In this paper，Graphene oxide （GO） was reduced with Fe（Ⅱ） using sodium borohydride （NaBH4） to prepare rGO/Fe（0） composites. The rGO/Fe（0） composites were characterized using SEM， XPS， FT-IR， XRD， and BET characterization techniques. The adsorption kinetics， thermodynamics， and isotherm models were used to investigate the adsorption-reduction performance of rGO/Fe（0） on Cr（Ⅵ） and the mechanism. The adsorption-reduction performance of Cr（Ⅵ） by the rGO/Fe（0） composite was investigated by combining adsorption kinetics， thermodynamics， and isotherm models. The results showed that the specific surface area （20.03 m2/g） of rGO/Fe（0） increased by 111.1%， the pore volume （0.08 cm3/g） increased by 162.5%， and the pore size （16.45 nm） increased by 21.7% compared to that of rGO. The rGO/Fe（0） adsorbed and reduced Cr（Ⅵ） to Cr（Ⅲ）， which was immobilized on the surface by rGO， and the remaining portion of Cr（Ⅲ） diffused into solution. At pH=3， the removal of Cr（Ⅵ） by rGO/Fe（0） was 28.75 mg/g， of which 23.91 mg/g was reduced， and the Cr（Ⅲ） concentration in the solution was 11.54 mg/L. Electrostatic attraction， reduction and complexation are the main mechanisms of Cr（Ⅵ） removal by rGO/Fe（0）. The removal efficiency of Cr（Ⅵ） by rGO/Fe（0） was 57.5%， of which the contribution of the reduction reaction was 83.2%， indicating that the main mechanism of Cr（Ⅵ） removal by rGO/Fe（0） was the reduction reaction， while Fe（0） was oxidized to Fe（Ⅱ） and Fe（Ⅲ）. The recycling results showed a 17.6 percentage points reduction in Cr（Ⅵ） removal by rGO/Fe（0） after four reuse cycles. rGO/Fe（0） removed 79.5 % of Cr（Ⅵ） from the actual effluent.
In this paper，Graphene oxide （GO） was reduced with Fe（Ⅱ） using sodium borohydride （NaBH4） to prepare rGO/Fe（0） composites. The rGO/Fe（0） composites were characterized using SEM， XPS， FT-IR， XRD， and BET characterization techniques. The adsorption kinetics， thermodynamics， and isotherm models were used to investigate the adsorption-reduction performance of rGO/Fe（0） on Cr（Ⅵ） and the mechanism. The adsorption-reduction performance of Cr（Ⅵ） by the rGO/Fe（0） composite was investigated by combining adsorption kinetics， thermodynamics， and isotherm models. The results showed that the specific surface area （20.03 m2/g） of rGO/Fe（0） increased by 111.1%， the pore volume （0.08 cm3/g） increased by 162.5%， and the pore size （16.45 nm） increased by 21.7% compared to that of rGO. The rGO/Fe（0） adsorbed and reduced Cr（Ⅵ） to Cr（Ⅲ）， which was immobilized on the surface by rGO， and the remaining portion of Cr（Ⅲ） diffused into solution. At pH=3， the removal of Cr（Ⅵ） by rGO/Fe（0） was 28.75 mg/g， of which 23.91 mg/g was reduced， and the Cr（Ⅲ） concentration in the solution was 11.54 mg/L. Electrostatic attraction， reduction and complexation are the main mechanisms of Cr（Ⅵ） removal by rGO/Fe（0）. The removal efficiency of Cr（Ⅵ） by rGO/Fe（0） was 57.5%， of which the contribution of the reduction reaction was 83.2%， indicating that the main mechanism of Cr（Ⅵ） removal by rGO/Fe（0） was the reduction reaction， while Fe（0） was oxidized to Fe（Ⅱ） and Fe（Ⅲ）. The recycling results showed a 17.6 percentage points reduction in Cr（Ⅵ） removal by rGO/Fe（0） after four reuse cycles. rGO/Fe（0） removed 79.5 % of Cr（Ⅵ） from the actual effluent.
2025, 43(6): 138-146.
doi: 10.13205/j.hjgc.202506014
Abstract:
With the introduction of China's national requirement of "Zero Liquid Discharge"， thermal evaporation has emerged as a pivotal technology for minimizing industrial high-salinity wastewater. This process relies on the efficiency and durability of the wastewater heat exchanger， which unfortunately faces significant challenges in surface scaling. The existence of scaling deposits increases the scaling thermal resistance （Rf） of the heat exchanger and reduces its operational efficiency. The scaling problem has become the main obstacle to the rapid development of evaporation crystallization process. In this study， based on the characteristics of the modified epoxy resin coating materials with good corrosion resistance and anti-scaling efficiency， a two-step method （etching and dipping） was used to prepare a coating on the metal substrate surface to obtain a hydrophobic metal substrate with superior anti-scaling efficiency. The modified epoxy coating， with a thickness measured in microns， achieved a water contact angle of approximately （137±1.5）°， indicating a high hydrophobicity. Extensive testing in three different saline solutions revealed a substantial reduction in scaling deposits， with all samples exhibiting a decrease rate of over 50%. Notably， the average scaling rate remained consistently below 0.02 mg/（cm2·h）， and an obvious scale induction period was observed. After 168 hours of continuous exposure to scaling condition， the coated substrates maintained over 45% of their initial anti-scaling efficiency. The polymer aluminum substrate developed in this study stands out for its exceptional hydrophobic and anti-scaling characteristics. It effectively withstands the corrosive effects of industrial high-salinity wastewater， thereby enhancing the reliability and longevity of the evaporation process. This breakthrough in coating technology not only addresses a critical challenge in thermal evaporation but also paves the way for sustainable and efficient high-salinity wastewater treatment practices in compliance with the "Zero Liquid Discharge" requirement.
With the introduction of China's national requirement of "Zero Liquid Discharge"， thermal evaporation has emerged as a pivotal technology for minimizing industrial high-salinity wastewater. This process relies on the efficiency and durability of the wastewater heat exchanger， which unfortunately faces significant challenges in surface scaling. The existence of scaling deposits increases the scaling thermal resistance （Rf） of the heat exchanger and reduces its operational efficiency. The scaling problem has become the main obstacle to the rapid development of evaporation crystallization process. In this study， based on the characteristics of the modified epoxy resin coating materials with good corrosion resistance and anti-scaling efficiency， a two-step method （etching and dipping） was used to prepare a coating on the metal substrate surface to obtain a hydrophobic metal substrate with superior anti-scaling efficiency. The modified epoxy coating， with a thickness measured in microns， achieved a water contact angle of approximately （137±1.5）°， indicating a high hydrophobicity. Extensive testing in three different saline solutions revealed a substantial reduction in scaling deposits， with all samples exhibiting a decrease rate of over 50%. Notably， the average scaling rate remained consistently below 0.02 mg/（cm2·h）， and an obvious scale induction period was observed. After 168 hours of continuous exposure to scaling condition， the coated substrates maintained over 45% of their initial anti-scaling efficiency. The polymer aluminum substrate developed in this study stands out for its exceptional hydrophobic and anti-scaling characteristics. It effectively withstands the corrosive effects of industrial high-salinity wastewater， thereby enhancing the reliability and longevity of the evaporation process. This breakthrough in coating technology not only addresses a critical challenge in thermal evaporation but also paves the way for sustainable and efficient high-salinity wastewater treatment practices in compliance with the "Zero Liquid Discharge" requirement.
Single-molecule sensing of aliphatic monohydrogen-substituted polycarboxylic acid positional isomers
2025, 43(6): 147-153.
doi: 10.13205/j.hjgc.202506015
Abstract:
Per- and polyfluorinated carboxylic acids （PFCAs） and their isomers have emerged as critical environmental concerns in recent years due to their structural diversity， extreme persistence， and substantial environmental risks. These compounds， characterized by strong carbon-fluorine bonds， are ubiquitously detected in water systems， soil， and even biological tissues， posing significant risks to ecosystems and human health. Current analytical techniques， such as liquid chromatography-mass spectrometry （LC-MS）， heavily depend on standardized reference materials for isomer identification. However， the lack of commercially available isomer-specific standards severely limits their capacity to achieve precise differentiation and quantification of PFCA isomers， particularly in complex environmental matrices. To address this challenge， single-molecule sensing （SMS）， which rely on the linear correlation of analyte volume and blockade current， offer a promising approach for PFCA detection without requiring standard samples. However， the capability of SMS to resolve PFCA isomers still requires further validation. Taking aliphatic monohydrogen-substituted PFCA positional isomers as an example， this study developed a novel single-molecule algorithm incorporating frequency modulation and multi-dimensional feature extraction. This approach enable 100% accurate recognition of the above PFCA isomers using a wild-type Aerolysin nanopore. The method leverages the unique electrical signatures generated by the interaction of the isomers with the nanopore， which are then analyzed using sophisticated signal processing techniques to differentiate between the isomers with high precision.
Per- and polyfluorinated carboxylic acids （PFCAs） and their isomers have emerged as critical environmental concerns in recent years due to their structural diversity， extreme persistence， and substantial environmental risks. These compounds， characterized by strong carbon-fluorine bonds， are ubiquitously detected in water systems， soil， and even biological tissues， posing significant risks to ecosystems and human health. Current analytical techniques， such as liquid chromatography-mass spectrometry （LC-MS）， heavily depend on standardized reference materials for isomer identification. However， the lack of commercially available isomer-specific standards severely limits their capacity to achieve precise differentiation and quantification of PFCA isomers， particularly in complex environmental matrices. To address this challenge， single-molecule sensing （SMS）， which rely on the linear correlation of analyte volume and blockade current， offer a promising approach for PFCA detection without requiring standard samples. However， the capability of SMS to resolve PFCA isomers still requires further validation. Taking aliphatic monohydrogen-substituted PFCA positional isomers as an example， this study developed a novel single-molecule algorithm incorporating frequency modulation and multi-dimensional feature extraction. This approach enable 100% accurate recognition of the above PFCA isomers using a wild-type Aerolysin nanopore. The method leverages the unique electrical signatures generated by the interaction of the isomers with the nanopore， which are then analyzed using sophisticated signal processing techniques to differentiate between the isomers with high precision.
2025, 43(6): 154-165.
doi: 10.13205/j.hjgc.202506016
Abstract:
Developing and utilizing unconventional water resources—rainwater resources，is an important way to alleviate the contradiction between water supply and demand. Electric flocculation can significantly accelerate sediment settling， improve water quality in a short period， and avoid the problem of low efficiency in rainwater utilization caused by long natural flocculation time. Indoor experiments were designed to investigate the effects of current density， electrode spacing， initial sediment concentration， and reaction time on sediment settling. The turbidity removal efficiency and floc particle size energy consumption were selected as evaluation indicators， and 128 sets of experiments were completed. Response surface methodology was used to verify and optimize parameter combinations. The results showed that， according to the distribution of sediment and changes in turbidity in the solution， the reaction time of 0 to 10 minutes was the early stage of flocculation， and the removal of sediment particles mainly relied on natural sedimentation. The reaction time of 20 to 40 minutes was the late stage of flocculation， during which the aluminum acid complex adsorbed and combined with sediment particles， dominating the coagulation and sedimentation of small sediment particles. When the current density was low （10 A/m2）， the turbidity removal efficiency increased slowly， whereas at a high current density （40 A/m2）， the turbidity removal efficiency initially increased rapidly and then decreased. When the initial sediment concentration was low （1 g/L）， the turbidity removal efficiency was low， and the electrocoagulation effect was not fully performed. However， when the initial sediment concentration was high （3 g/L）， the turbidity removal efficiency also remained low， because excessive sediment led to insufficient floc formation. The bubbles generated by electrolysis increased the probability of contact between aluminum acid complexes and particles. In addition， the ratio of aluminum acid complexes to sediment concentration was the main factor affecting the flocculation effect. This was particularly evident when the current density exceeded 10 A/m2 and the electrolysis time reached 20 to 25 minutes， the flocculation effect was improvedmost significantly. Response surface methodology optimization showed that under the operating conditions of a current density of 30 A/m2， an initial concentration of 2.4 g/L， and a reaction time of 37 minutes， the turbidity removal efficiency in sediment solution by electrocoagulation reached 91.28%. The treatment cost was 0.02 yuan per ton of water， with a power consumption of 0.06 kW·h. This study provides valuable references for the design and application of electrocoagulation and rainwater resource utilization systems.
Developing and utilizing unconventional water resources—rainwater resources，is an important way to alleviate the contradiction between water supply and demand. Electric flocculation can significantly accelerate sediment settling， improve water quality in a short period， and avoid the problem of low efficiency in rainwater utilization caused by long natural flocculation time. Indoor experiments were designed to investigate the effects of current density， electrode spacing， initial sediment concentration， and reaction time on sediment settling. The turbidity removal efficiency and floc particle size energy consumption were selected as evaluation indicators， and 128 sets of experiments were completed. Response surface methodology was used to verify and optimize parameter combinations. The results showed that， according to the distribution of sediment and changes in turbidity in the solution， the reaction time of 0 to 10 minutes was the early stage of flocculation， and the removal of sediment particles mainly relied on natural sedimentation. The reaction time of 20 to 40 minutes was the late stage of flocculation， during which the aluminum acid complex adsorbed and combined with sediment particles， dominating the coagulation and sedimentation of small sediment particles. When the current density was low （10 A/m2）， the turbidity removal efficiency increased slowly， whereas at a high current density （40 A/m2）， the turbidity removal efficiency initially increased rapidly and then decreased. When the initial sediment concentration was low （1 g/L）， the turbidity removal efficiency was low， and the electrocoagulation effect was not fully performed. However， when the initial sediment concentration was high （3 g/L）， the turbidity removal efficiency also remained low， because excessive sediment led to insufficient floc formation. The bubbles generated by electrolysis increased the probability of contact between aluminum acid complexes and particles. In addition， the ratio of aluminum acid complexes to sediment concentration was the main factor affecting the flocculation effect. This was particularly evident when the current density exceeded 10 A/m2 and the electrolysis time reached 20 to 25 minutes， the flocculation effect was improvedmost significantly. Response surface methodology optimization showed that under the operating conditions of a current density of 30 A/m2， an initial concentration of 2.4 g/L， and a reaction time of 37 minutes， the turbidity removal efficiency in sediment solution by electrocoagulation reached 91.28%. The treatment cost was 0.02 yuan per ton of water， with a power consumption of 0.06 kW·h. This study provides valuable references for the design and application of electrocoagulation and rainwater resource utilization systems.
2025, 43(6): 166-176.
doi: 10.13205/j.hjgc.202506017
Abstract:
Exposure assessment is a key component in site-specific human health risk assessments and plays a significant role in establishment of environmental standards and the formulation of soil remediation goals. Refined exposure assessment has been one of the research hotspots in human health risk assessment in recent years.This paper integrates domestic and international research and technical documents on heavy metal exposure assessment， sorting out the methods and techniques of refined exposure assessment of soil heavy metals at sites from both conceptual models and computational models. The refinement of the conceptual model includes the accurate identification and detailed depiction of risk sources， exposure scenarios， exposure pathways， and risk receptors. The refinement of risk sources requires acquiring information on chemical forms of heavy metals， soil particle size composition， and soil physical and chemical properties. The refinement of exposure scenario translation includes delineation of the site impact range， detailed classification of planned land use， and micro-scenario setting. The refinement of exposure pathways involves screening and specific settings according to different exposure scenarios. The refinement of risk receptors involves specific settings for long-term， medium-term， and short-term receptors， as well as special receptors. The refinement of computational models includes the optimization of computational tools， the optimization of exposure parameters， and the application of probabilistic models. The optimization of computational tools involves the selection of computational models and the combined use of conventional heavy metal exposure models and blood lead models. The optimization of exposure parameters not only uses local parameters as much as possible but also improves the accuracy of some exposure dose parameters through in vitro testing methods or parameter simulation technology. In vitro testing technology mainly refers to bioavailability testing technology. Parameter simulation technology includes soil oral intake simulation technology based on behavioral patterns， air particulate matter concentration simulation technology， etc.Probability models use the probability expression of datasets to replace individual data， which can better address the uncertainties in parameters and risk values brought about by individual differences. Based on the current application status and existing problems of heavy metal exposure assessment at contaminated sites， this paper proposes future prospects such as constructing an exposure assessment system based on refined conceptual models of contaminated sites， expanding related indicators and multi-source data to optimize the calculation results of exposure assessment models， and applying dynamic monitoring technology to support modern site environmental management， to promote the development of theory and technology for refined exposure assessment of heavy metals in site soils.
Exposure assessment is a key component in site-specific human health risk assessments and plays a significant role in establishment of environmental standards and the formulation of soil remediation goals. Refined exposure assessment has been one of the research hotspots in human health risk assessment in recent years.This paper integrates domestic and international research and technical documents on heavy metal exposure assessment， sorting out the methods and techniques of refined exposure assessment of soil heavy metals at sites from both conceptual models and computational models. The refinement of the conceptual model includes the accurate identification and detailed depiction of risk sources， exposure scenarios， exposure pathways， and risk receptors. The refinement of risk sources requires acquiring information on chemical forms of heavy metals， soil particle size composition， and soil physical and chemical properties. The refinement of exposure scenario translation includes delineation of the site impact range， detailed classification of planned land use， and micro-scenario setting. The refinement of exposure pathways involves screening and specific settings according to different exposure scenarios. The refinement of risk receptors involves specific settings for long-term， medium-term， and short-term receptors， as well as special receptors. The refinement of computational models includes the optimization of computational tools， the optimization of exposure parameters， and the application of probabilistic models. The optimization of computational tools involves the selection of computational models and the combined use of conventional heavy metal exposure models and blood lead models. The optimization of exposure parameters not only uses local parameters as much as possible but also improves the accuracy of some exposure dose parameters through in vitro testing methods or parameter simulation technology. In vitro testing technology mainly refers to bioavailability testing technology. Parameter simulation technology includes soil oral intake simulation technology based on behavioral patterns， air particulate matter concentration simulation technology， etc.Probability models use the probability expression of datasets to replace individual data， which can better address the uncertainties in parameters and risk values brought about by individual differences. Based on the current application status and existing problems of heavy metal exposure assessment at contaminated sites， this paper proposes future prospects such as constructing an exposure assessment system based on refined conceptual models of contaminated sites， expanding related indicators and multi-source data to optimize the calculation results of exposure assessment models， and applying dynamic monitoring technology to support modern site environmental management， to promote the development of theory and technology for refined exposure assessment of heavy metals in site soils.
2025, 43(6): 177-187.
doi: 10.13205/j.hjgc.202506018
Abstract:
In recent years，a compulsory domestic waste classification system has been implemented in China， and conflicts between this new system and the existing municipal sanitation system have begun to emerge. In order to analyze the impact of waste classification on municipal solid waste collection volume， based on the system dynamics theory， VENSIM software was used to analyze the key factors affecting the production volume of municipal solid waste， draw a causal loop diagram， establish a stock flow model， and predict collection trends under different social scenarios， including epidemics and mandatory domestic waste classification policies. Using Beijing and Shenzhen as representative cities from northern and southern China respectively， this study analyzed the data from 2010 to 2020， and projected municipal solid waste collection trends for 2021 to 2035 under four scenarios：no-pandemic with no waste classification， business-as-usual baseline， waste reduction， and slow recovery. The results showed that the epidemic and social factors such as pandemic containment measures and waste classification policies had a significant reduction effect on both per capita generation （adjusted by waste-producing population） and total collection volume. Under the waste reduction scenario， measures such as increasing waste disposal fees and promoting pre-processed vegetables are projected to reduce the annual per capita waste production in Beijing and Shenzhen by 16.3% and 17.8% respectively by 2025， with cumulative reductions of 11.2% and 24.0% over the following decade. If the current classification system is maintained， municipal solid waste collection volumes in Beijing and Shenzhen will reach 12.2751 and 12.0433 million tons in 2035， respectively， representing reductions of 12.9% and 17.5% compared to the no-classification scenario.
In recent years，a compulsory domestic waste classification system has been implemented in China， and conflicts between this new system and the existing municipal sanitation system have begun to emerge. In order to analyze the impact of waste classification on municipal solid waste collection volume， based on the system dynamics theory， VENSIM software was used to analyze the key factors affecting the production volume of municipal solid waste， draw a causal loop diagram， establish a stock flow model， and predict collection trends under different social scenarios， including epidemics and mandatory domestic waste classification policies. Using Beijing and Shenzhen as representative cities from northern and southern China respectively， this study analyzed the data from 2010 to 2020， and projected municipal solid waste collection trends for 2021 to 2035 under four scenarios：no-pandemic with no waste classification， business-as-usual baseline， waste reduction， and slow recovery. The results showed that the epidemic and social factors such as pandemic containment measures and waste classification policies had a significant reduction effect on both per capita generation （adjusted by waste-producing population） and total collection volume. Under the waste reduction scenario， measures such as increasing waste disposal fees and promoting pre-processed vegetables are projected to reduce the annual per capita waste production in Beijing and Shenzhen by 16.3% and 17.8% respectively by 2025， with cumulative reductions of 11.2% and 24.0% over the following decade. If the current classification system is maintained， municipal solid waste collection volumes in Beijing and Shenzhen will reach 12.2751 and 12.0433 million tons in 2035， respectively， representing reductions of 12.9% and 17.5% compared to the no-classification scenario.
2025, 43(6): 188-196.
doi: 10.13205/j.hjgc.202506019
Abstract:
To address the research shortages， as well as the low accuracy and high missed detection rate of existing activated sludge microbial detection algorithms， an improved YOLOv5-based microbial detection method was proposed. The K-Means++ algorithm was used to generate the most suitable anchor frame group for this dataset. The original C3 module in the YOLOv5 backbone network was replaced with the C3GC module to enhance feature extraction. In addition， the feature pyramid fusion coordinate attention mechanism in the neck network and the global-to-spatial aggregation module were employed to strengthen the fusion of feature information. Based on the actual collected microbial data of activated sludge， the training and test datasets were constructed using a data augmentation method. The improved algorithm achieved a recall rate of 97.4%， an average accuracy of 99.2%， and a model size of only 23.5MB on the test dataset， which demonstrated a certain improvement in accuracy and regression rate compared to the original YOLOv5 model and other mainstream detection models and variants， while meeting the requirements for rapid deployment on mobile terminals. The experimental data showed that the improved model sacrificed a small amount of detection speed in exchange for a significant improvement in accuracy and regression rate， proving the effectiveness of the improvement. This study provides a valuable reference for the development of artificial intelligence in the field of environmental governance and serves as an example for the advancement of intelligent equipment.
To address the research shortages， as well as the low accuracy and high missed detection rate of existing activated sludge microbial detection algorithms， an improved YOLOv5-based microbial detection method was proposed. The K-Means++ algorithm was used to generate the most suitable anchor frame group for this dataset. The original C3 module in the YOLOv5 backbone network was replaced with the C3GC module to enhance feature extraction. In addition， the feature pyramid fusion coordinate attention mechanism in the neck network and the global-to-spatial aggregation module were employed to strengthen the fusion of feature information. Based on the actual collected microbial data of activated sludge， the training and test datasets were constructed using a data augmentation method. The improved algorithm achieved a recall rate of 97.4%， an average accuracy of 99.2%， and a model size of only 23.5MB on the test dataset， which demonstrated a certain improvement in accuracy and regression rate compared to the original YOLOv5 model and other mainstream detection models and variants， while meeting the requirements for rapid deployment on mobile terminals. The experimental data showed that the improved model sacrificed a small amount of detection speed in exchange for a significant improvement in accuracy and regression rate， proving the effectiveness of the improvement. This study provides a valuable reference for the development of artificial intelligence in the field of environmental governance and serves as an example for the advancement of intelligent equipment.
2025, 43(6): 197-203.
doi: 10.13205/j.hjgc.202506020
Abstract:
Incineration is an effective way for solid waste treatment， with grate incinerators being the most widely used equipment. As a tool， CFD is widely used in the waste incinerator design and optimization， the typical model is coupled by FLIC and FLUENT. However， it cannot fully consider the combustion process and can only be coupled manually， which results in significant errors. This study developed an optimized bed model and compared ot with the FLIC model.In addition， the calculation results from the two models were compared and analyzed. Furthermore， CFD simulations were performed for a 900 t/d incinerator using the optimized bed model coupled with STAR CCM via an automatic coupling method. Finally， the optimization algorithm of SHERPA was used to optimize the air distribution of the incinerator. The optimization results showed that the thermal burn-off rate decreased from 3.1% to 0.25%， and the fuel combustion became more complete； the residence time of flue gas above 850℃ in the furnace increased from 4.22 s to 4.55 s， which was more conducive to the removal of dioxins. Overall， the simulation calculation achieved ideal optimization effects and provide an improved CFD method for waste incinerator design.
Incineration is an effective way for solid waste treatment， with grate incinerators being the most widely used equipment. As a tool， CFD is widely used in the waste incinerator design and optimization， the typical model is coupled by FLIC and FLUENT. However， it cannot fully consider the combustion process and can only be coupled manually， which results in significant errors. This study developed an optimized bed model and compared ot with the FLIC model.In addition， the calculation results from the two models were compared and analyzed. Furthermore， CFD simulations were performed for a 900 t/d incinerator using the optimized bed model coupled with STAR CCM via an automatic coupling method. Finally， the optimization algorithm of SHERPA was used to optimize the air distribution of the incinerator. The optimization results showed that the thermal burn-off rate decreased from 3.1% to 0.25%， and the fuel combustion became more complete； the residence time of flue gas above 850℃ in the furnace increased from 4.22 s to 4.55 s， which was more conducive to the removal of dioxins. Overall， the simulation calculation achieved ideal optimization effects and provide an improved CFD method for waste incinerator design.
2025, 43(6): 204-213.
doi: 10.13205/j.hjgc.202506022
Abstract:
In recent years， along with the advancement of circular economy construction and the elevation of solid waste harmless treatment， a series of projects producing solid recovered fuel （SRF） from municipal solid waste（MSW） have been successively launched in China. In order to clarify the environmental impacts of MSW-SRF incineration for power generation and to reveal the difference in environmental impacts caused by different SRF preparation processes， OpenLCA software was used to conduct a "cradle-to-grave" life cycle assessment of SRF prepared by three typical short processes： mechanical separation， biological drying and high-pressure extrusion-biological drying. At the same time， the life cycle assessment of MSW incineration for power generation was also carried out as a comparison. Taking 1 ton of MSW as the functional unit， the ReCiPe 2016 method was applied to evaluate the life cycle environmental impacts of SRF incineration from 3 aspects： human health damage， ecosystem damage， and resource consumption. Additionally， the key life cycle processes contributing to these environmental impacts were revealed. The results showed that the environmental impacts of SRF incineration were mainly caused by the emission of CO2 and pollutants in the incineration flue gas， while the environmental impacts of material transportation and SRF preparation were relatively insignificant. The main environmental impacts caused by SRF incineration power generation were climate change and particulate matter formation， while the environmental benefits included reduced terrestrial ecological toxicity and lower fossil energy consumption. Among the three SRF preparation processes， the high-pressure extrusion-biological drying process was the least harmful to the environment. Compared with the direct incineration of MSW， the high-pressure extrusion-biological drying SRF incineration could reduce the damage to human health by 11.7%， reduced the ecosystem damage by 462.4%， and increase the resources saving effect by 81.4%. The result revealed the environmental impacts of various processes for MSW-SRF preparation， providing data support and theoretical basis for the selection and optimization of MSW-SRF production processes.
In recent years， along with the advancement of circular economy construction and the elevation of solid waste harmless treatment， a series of projects producing solid recovered fuel （SRF） from municipal solid waste（MSW） have been successively launched in China. In order to clarify the environmental impacts of MSW-SRF incineration for power generation and to reveal the difference in environmental impacts caused by different SRF preparation processes， OpenLCA software was used to conduct a "cradle-to-grave" life cycle assessment of SRF prepared by three typical short processes： mechanical separation， biological drying and high-pressure extrusion-biological drying. At the same time， the life cycle assessment of MSW incineration for power generation was also carried out as a comparison. Taking 1 ton of MSW as the functional unit， the ReCiPe 2016 method was applied to evaluate the life cycle environmental impacts of SRF incineration from 3 aspects： human health damage， ecosystem damage， and resource consumption. Additionally， the key life cycle processes contributing to these environmental impacts were revealed. The results showed that the environmental impacts of SRF incineration were mainly caused by the emission of CO2 and pollutants in the incineration flue gas， while the environmental impacts of material transportation and SRF preparation were relatively insignificant. The main environmental impacts caused by SRF incineration power generation were climate change and particulate matter formation， while the environmental benefits included reduced terrestrial ecological toxicity and lower fossil energy consumption. Among the three SRF preparation processes， the high-pressure extrusion-biological drying process was the least harmful to the environment. Compared with the direct incineration of MSW， the high-pressure extrusion-biological drying SRF incineration could reduce the damage to human health by 11.7%， reduced the ecosystem damage by 462.4%， and increase the resources saving effect by 81.4%. The result revealed the environmental impacts of various processes for MSW-SRF preparation， providing data support and theoretical basis for the selection and optimization of MSW-SRF production processes.
2025, 43(6): 214-227.
doi: 10.13205/j.hjgc.202506023
Abstract:
The treatment of domestic waste in China has undergone three stages： informal landfill， sanitary landfill， incineration as the main stage， and landfill as the auxiliary stage. So far， there are still some informal landfills that have not been properly disposed of and treated. This article focuses on the current pollution situation of informal landfills in China that have not been appropriately tackled. Based on the literature review， the current situation of multiple informal landfills， both domestic and overseas， is summarized， and the waste characteristics of informal landfills in different regions are analyzed and expounded. The impact of informal landfills on the surrounding environment in different regions is compared and summarized. In addition， the waste excavation process， site pollution control process， and site restoration technology of informal landfills were summarized and analyzed. The current situation and treatment， and disposal technology of informal landfills were analyzed and summarized. The research results show that multiple informal landfills， both domestically and internationally， have caused pollution to the surrounding environment. The pollution control technologies for informal landfills mainly include four main methods： in-situ sealing， aerobic accelerated stabilization， off-site relocation， and screening treatment. Informal landfill site restoration technology mainly refers to the process of sealing off the site area and then carrying out ecological restoration and treatment， mainly for the landscaping of the site. On this basis， this article proposes prospects for the development of future informal landfill treatment and disposal technologies， as well as ecological restoration processes， to provide reference for effective pollution prevention and control in informal landfills.
The treatment of domestic waste in China has undergone three stages： informal landfill， sanitary landfill， incineration as the main stage， and landfill as the auxiliary stage. So far， there are still some informal landfills that have not been properly disposed of and treated. This article focuses on the current pollution situation of informal landfills in China that have not been appropriately tackled. Based on the literature review， the current situation of multiple informal landfills， both domestic and overseas， is summarized， and the waste characteristics of informal landfills in different regions are analyzed and expounded. The impact of informal landfills on the surrounding environment in different regions is compared and summarized. In addition， the waste excavation process， site pollution control process， and site restoration technology of informal landfills were summarized and analyzed. The current situation and treatment， and disposal technology of informal landfills were analyzed and summarized. The research results show that multiple informal landfills， both domestically and internationally， have caused pollution to the surrounding environment. The pollution control technologies for informal landfills mainly include four main methods： in-situ sealing， aerobic accelerated stabilization， off-site relocation， and screening treatment. Informal landfill site restoration technology mainly refers to the process of sealing off the site area and then carrying out ecological restoration and treatment， mainly for the landscaping of the site. On this basis， this article proposes prospects for the development of future informal landfill treatment and disposal technologies， as well as ecological restoration processes， to provide reference for effective pollution prevention and control in informal landfills.
