The abundance of microplastics(MPs)in wastewater from three wastewater treatment plants(WWTPs)were determined in Hangzhou,Zhejiang Province,China.The MPs abundance was 140-350 particles per litre in the influent and 1...The abundance of microplastics(MPs)in wastewater from three wastewater treatment plants(WWTPs)were determined in Hangzhou,Zhejiang Province,China.The MPs abundance was 140-350 particles per litre in the influent and 10-30 particles per litre in the effluent.Four shapes of MPs in the influent were observed,while mainly only debris was left in the effluent.The percentage of small(<100μm),medium(100-500μm),and large-sized(≥500μm)plastics in the raw leachate of the three WWTPs were 54.3%,8.6%,and 37.1%,28.6%,64.3%,and 7.1%,and 41.4%,24.1%,and 34.5%,respectively.Mainly only the size of≤100μm was left in the effluent of all.The removal efficiencies of MPs in a range of 78.6%to 96.6%were achieved.Polypropylene,polystyrene,polyethylene,polyethylene terephthalate and polyvinyl chloride were the main types and detected in all wastewater samples,accounting for over 75%of all types.The plastic components contained in different industrial wastewater were more complex.The distribution of MPs was significantly positively correlated with most conventional indicators such as chemical oxygen demead,ammonia nitrogen,and total phosphorus,but not with heavy metals.Similar wastewater,different treatment processes,or similar processes but different wastewater(industrial wastewater proportion varied)could all lead to differences in MPs removal.The MPs abundance measured in this experiment was similar to some previous studies,but relatively high.The three WWTPs can discharge up to 6.0×10^(-8)-1.8×10^(-9) plastics of MPs per day,which poses potential ecological risks.This study indicates that the source control of MPs and optimizing the process design of existing WWTPs are crucial for preventing and controlling MPs pollution.展开更多
Oxytetracycline(OTC) and tetracycline(TC) are the most common TC antibiotics used in human and veterinary medicine.Residual amounts of these antibiotics in manure pose a potential threat to public and ecological healt...Oxytetracycline(OTC) and tetracycline(TC) are the most common TC antibiotics used in human and veterinary medicine.Residual amounts of these antibiotics in manure pose a potential threat to public and ecological health as a result of the potential for them to be released to the environment following land application of manure from animals treated with antibiotics.We investigated the degradation of OTC and TC during anaerobic composting.We tested the effects of temperature and antibiotic concentration on degradation rates in a control and in manure spiked with TCs.We examined changes in p H,biological degradation material(BDM),and moisture corresponding with antibiotic degradation of TCs in the swine manure.Results showed that the OTC and TC concentrations decreased by between 68.54% and 95.50% in all nine treatments following 14 days of anaerobic composting,and the highest removal ef ficiencies were observed at an incubation temperature of 55°C and initial concentrations of 10.36 μg·g^(-1),and 5.96 μg·g^(-1) of OTC and TC,respectively,which were degraded by 95.50%,and 90.06%.During composting at 55 °C and at added concentrations of 5 μg·g^(-1),OTC decreased rapidly,and the time required for50% and 90% degradation was 4.1 and 9.8 days,respectively;for TC,these values were 4.4 and 14.0 days,respectively.Removal ef ficiencies for all TCs correlated well with moisture content of the manure.These results show that composting may be a practical and useful means to reduce concentrations of OTC and TC in swine manure prior to its land application.展开更多
Transformations of di-n-butyl phthalate(DBP) and di(2-ethylhexyl) phthalate(DEHP) have been investigated in anaerobic/anoxic/oxic(A/A/O) leachate treatment processes. Although the DBP removal processes are different w...Transformations of di-n-butyl phthalate(DBP) and di(2-ethylhexyl) phthalate(DEHP) have been investigated in anaerobic/anoxic/oxic(A/A/O) leachate treatment processes. Although the DBP removal processes are different when the DBP initial concentration is different, the overall system DBP removal efficiencies are high(N 94%).DEHP is much more difficult to remove than DBP. The removal efficiency of DEHP is approximately 75%–78%.The results of mass balance calculations indicate that approximately 33.7%–50.7% of the DBP is degraded by the activated sludge, 48.9%–64.9% accumulates in the system, and 0.4%–1.4% is contained in the final effluent. Approximately 15.0%–19.0% of the DEHP is degraded by activated microcosms, 75.8%–79.0% accumulates in the system, and 5.2%–6.0% is contained in the final effluent. Biodegradation and adsorption to the activated sludge are the main mechanisms for DBP removal and adsorption to the activated sludge is the main mechanism for DEHP removal. The different removal mechanisms of the two PAEs may be related to their different molecular structures. However, PAEs are not really removed when they adsorb onto the sludge. Therefore, methods for decreasing PAEs adsorption and increasing the biodegradation efficiencies of the leachate treatment processes should be further investigated.展开更多
In this work,we constructed a three-dimensional electrochemical system(3D-ECO),which included the cathode and anode electrode plates,as well as the screening of three-dimensional particle electrodes and parameter opti...In this work,we constructed a three-dimensional electrochemical system(3D-ECO),which included the cathode and anode electrode plates,as well as the screening of three-dimensional particle electrodes and parameter opti-mization,for the degradation of landfill leachate(LL)containing elevated levels of tetracycline(TC),and explored its mechanism of action.Firstly,titanium-based ruthenium-iridium(Ti/RuO_(2)-IrO_(2)),titanium-based ruthenium-iridium-platinum(Ti/Pt-RuO_(2)-IrO_(2)),and titanium-based tin-antimony(Ti/SnO_(2)-Sb_(2)O_(3))were employed as an-odes in the electrocatalytic oxidation system,with titanium and stainless steel plates serving as cathodes,to construct the optimal two-dimensional electrocatalytic oxidation system(2D-ECO)through cross-comparison ex-periments.Subsequently,using granular activated carbon(GAC),coconut shell biochar(CBC),walnut shell carbon(WBC),and bamboo charcoal(BBC)as particle electrodes,a 3D-ECO system was developed.The influence of var-ious operational parameters on treating TC-containing LL was investigated.The optimal operating parameters obtained from the study was:pH=5,current density of 30 mA/cm^(2),particle dosage of 7 g/L,particle size ranging from 1.70 to 2.00 mm,and electrode spacing of 4 cm.Under these conditions,the COD removal rate of 3D-ECO within three hours was 90.25%,the TC removal rate was 72.41%,and the NH_(3)-N removal rate was 39.52%.The removal of TC followed a pseudo-first-order kinetic model.Additionally,degradation mechanisms were elucidated through electron paramagnetic resonance(EPR)spectrometer and Tert-Butanol(TBA)quenching experiments,indicating that the degradation primarily occurred through a non-radical(1O_(2))pathway.This re-search offers a comprehensive analysis of the simultaneous breakdown of intricate LL matrices and TC,enhancing our comprehension of the degradation processes and underlying mechanisms.展开更多
基金funded by the National Natural Science Foundation of China(42477406,51878617)the horizontal scientific research project(KYY-HX-20220803)the Engineering Research Center of Ministry of Education for Renewable Energy Infrastructure Construction Technology。
文摘The abundance of microplastics(MPs)in wastewater from three wastewater treatment plants(WWTPs)were determined in Hangzhou,Zhejiang Province,China.The MPs abundance was 140-350 particles per litre in the influent and 10-30 particles per litre in the effluent.Four shapes of MPs in the influent were observed,while mainly only debris was left in the effluent.The percentage of small(<100μm),medium(100-500μm),and large-sized(≥500μm)plastics in the raw leachate of the three WWTPs were 54.3%,8.6%,and 37.1%,28.6%,64.3%,and 7.1%,and 41.4%,24.1%,and 34.5%,respectively.Mainly only the size of≤100μm was left in the effluent of all.The removal efficiencies of MPs in a range of 78.6%to 96.6%were achieved.Polypropylene,polystyrene,polyethylene,polyethylene terephthalate and polyvinyl chloride were the main types and detected in all wastewater samples,accounting for over 75%of all types.The plastic components contained in different industrial wastewater were more complex.The distribution of MPs was significantly positively correlated with most conventional indicators such as chemical oxygen demead,ammonia nitrogen,and total phosphorus,but not with heavy metals.Similar wastewater,different treatment processes,or similar processes but different wastewater(industrial wastewater proportion varied)could all lead to differences in MPs removal.The MPs abundance measured in this experiment was similar to some previous studies,but relatively high.The three WWTPs can discharge up to 6.0×10^(-8)-1.8×10^(-9) plastics of MPs per day,which poses potential ecological risks.This study indicates that the source control of MPs and optimizing the process design of existing WWTPs are crucial for preventing and controlling MPs pollution.
基金Supported by the Innovative Team Foundation of Zhejiang Province(2013TD12)the International Science and Technology Cooperation Program of China(2014DFE90040)the Significant Science and Technology Project of Zhejiang Province(2015C33006)
文摘Oxytetracycline(OTC) and tetracycline(TC) are the most common TC antibiotics used in human and veterinary medicine.Residual amounts of these antibiotics in manure pose a potential threat to public and ecological health as a result of the potential for them to be released to the environment following land application of manure from animals treated with antibiotics.We investigated the degradation of OTC and TC during anaerobic composting.We tested the effects of temperature and antibiotic concentration on degradation rates in a control and in manure spiked with TCs.We examined changes in p H,biological degradation material(BDM),and moisture corresponding with antibiotic degradation of TCs in the swine manure.Results showed that the OTC and TC concentrations decreased by between 68.54% and 95.50% in all nine treatments following 14 days of anaerobic composting,and the highest removal ef ficiencies were observed at an incubation temperature of 55°C and initial concentrations of 10.36 μg·g^(-1),and 5.96 μg·g^(-1) of OTC and TC,respectively,which were degraded by 95.50%,and 90.06%.During composting at 55 °C and at added concentrations of 5 μg·g^(-1),OTC decreased rapidly,and the time required for50% and 90% degradation was 4.1 and 9.8 days,respectively;for TC,these values were 4.4 and 14.0 days,respectively.Removal ef ficiencies for all TCs correlated well with moisture content of the manure.These results show that composting may be a practical and useful means to reduce concentrations of OTC and TC in swine manure prior to its land application.
基金funded by the National Natural Science Foundation of China(51678531,51878617).
文摘Transformations of di-n-butyl phthalate(DBP) and di(2-ethylhexyl) phthalate(DEHP) have been investigated in anaerobic/anoxic/oxic(A/A/O) leachate treatment processes. Although the DBP removal processes are different when the DBP initial concentration is different, the overall system DBP removal efficiencies are high(N 94%).DEHP is much more difficult to remove than DBP. The removal efficiency of DEHP is approximately 75%–78%.The results of mass balance calculations indicate that approximately 33.7%–50.7% of the DBP is degraded by the activated sludge, 48.9%–64.9% accumulates in the system, and 0.4%–1.4% is contained in the final effluent. Approximately 15.0%–19.0% of the DEHP is degraded by activated microcosms, 75.8%–79.0% accumulates in the system, and 5.2%–6.0% is contained in the final effluent. Biodegradation and adsorption to the activated sludge are the main mechanisms for DBP removal and adsorption to the activated sludge is the main mechanism for DEHP removal. The different removal mechanisms of the two PAEs may be related to their different molecular structures. However, PAEs are not really removed when they adsorb onto the sludge. Therefore, methods for decreasing PAEs adsorption and increasing the biodegradation efficiencies of the leachate treatment processes should be further investigated.
基金supported by the National Natural Science Foundation of China(Nos.42477406 and 51878617)the Horizontal Scientific Research Project(No.KYY-HX-20220803)the Engineering Research Center of Ministry of Education for Renewable Energy Infrastructure Construction Technology.
文摘In this work,we constructed a three-dimensional electrochemical system(3D-ECO),which included the cathode and anode electrode plates,as well as the screening of three-dimensional particle electrodes and parameter opti-mization,for the degradation of landfill leachate(LL)containing elevated levels of tetracycline(TC),and explored its mechanism of action.Firstly,titanium-based ruthenium-iridium(Ti/RuO_(2)-IrO_(2)),titanium-based ruthenium-iridium-platinum(Ti/Pt-RuO_(2)-IrO_(2)),and titanium-based tin-antimony(Ti/SnO_(2)-Sb_(2)O_(3))were employed as an-odes in the electrocatalytic oxidation system,with titanium and stainless steel plates serving as cathodes,to construct the optimal two-dimensional electrocatalytic oxidation system(2D-ECO)through cross-comparison ex-periments.Subsequently,using granular activated carbon(GAC),coconut shell biochar(CBC),walnut shell carbon(WBC),and bamboo charcoal(BBC)as particle electrodes,a 3D-ECO system was developed.The influence of var-ious operational parameters on treating TC-containing LL was investigated.The optimal operating parameters obtained from the study was:pH=5,current density of 30 mA/cm^(2),particle dosage of 7 g/L,particle size ranging from 1.70 to 2.00 mm,and electrode spacing of 4 cm.Under these conditions,the COD removal rate of 3D-ECO within three hours was 90.25%,the TC removal rate was 72.41%,and the NH_(3)-N removal rate was 39.52%.The removal of TC followed a pseudo-first-order kinetic model.Additionally,degradation mechanisms were elucidated through electron paramagnetic resonance(EPR)spectrometer and Tert-Butanol(TBA)quenching experiments,indicating that the degradation primarily occurred through a non-radical(1O_(2))pathway.This re-search offers a comprehensive analysis of the simultaneous breakdown of intricate LL matrices and TC,enhancing our comprehension of the degradation processes and underlying mechanisms.
