Mathematical models and simulation are considered a powerful tool in engineering practice. Those tools are becoming increasingly used for the improvement of wastewater treatment plants design because the conceptual de...Mathematical models and simulation are considered a powerful tool in engineering practice. Those tools are becoming increasingly used for the improvement of wastewater treatment plants design because the conceptual design is complex and ill-defined. In this paper, three alternatives: 1) complete mix activated sludge without nitrogen removal (CAS);2) complete mix activated sludge with nitrogen removal (CAS-N) and;3) membrane bioreactor (MBR) processes were designed into two steps: first concept design to calculate the size of process units, then second implement modeling and simulation to improve the accuracy of the conceptual design. In brief, the treatment process design has been verified by using the activated sludge model No. 1 (ASM1) in GPS-X (v.7) simulation software. This application helps not only in sizing the treatment units but also in understanding the plant’s capacity. In the same time, it can assist in studying the future expansion works required for increased hydraulic and organic loadings. For this purpose, Tikrit WWTP was selected as a case study. The used model was validated by comparing the designed values of the plant and the modeling data. The verification of the obtained results from both hand calculations and the results of the program showed a good agreement. A significant difference in the volume of secondary treatment was obtained from design calculations, where the CAS without denitrification system was 9244 m3 (aerobic and secondary tanks), CAS with denitrification system was 11,324 m3 (anoxic, aerobic and secondary tanks) and for MBR system was 7468 m3 (anoxic, aerobic and immersed membrane tanks). From the obtained results point of view, it can be concluded that mathematical models can be considered as worthy tools to complement the established wastewater treatment plant design procedures.展开更多
Concentrations of polychlorinated biphenyls (PCBs) have been measured in sewage sludge samples from 8 urban wastewater treatment plants in Beijing, China. The PCB congeners were analyzed by isotope dilution high res...Concentrations of polychlorinated biphenyls (PCBs) have been measured in sewage sludge samples from 8 urban wastewater treatment plants in Beijing, China. The PCB congeners were analyzed by isotope dilution high resolution gas chromatography/high resolution mass spectrometry method. The concentration of PCBs ranged from 65.6 to 157 ng/g dry weight (dw), with a mean value of 101 ng/g dw. The dioxin-like PCB WHO-TEQs (World Health Organization-Toxic Equivalents) of the sludge were lower than 1 pg /g dw. Consequently, all the concentrations of PCBs in sludge samples were below the upper limit for land application according to the Chinese legislation law for agriculture use. The PCB homologue profiles in sludge samples were dominated by tri-CBs and tetra- CBs. Similar distributions have been found in one of the Chinese PCB commercial products. The patterns of dioxin-like and indicator congeners observed in this study were quite similar in all samples. The predominant congener for dioxin-like and indicator PCBs were PCB-118 and PCB-28, respectively, while PCB-126 had the highest TEQ value.展开更多
We investigated the communities of ammonia-oxidizing bacteria (AOB) in activated sludge collected from eight wastewater treatment systems using polymerase chain reaction (PCR) followed by terminal restriction frag...We investigated the communities of ammonia-oxidizing bacteria (AOB) in activated sludge collected from eight wastewater treatment systems using polymerase chain reaction (PCR) followed by terminal restriction fragment length polymorphism (T-RFLP), cloning, and sequencing of the α-subunit of the ammonia monooxygenase gene (amoA). The T-RFLP fingerprint analyses showed that different wastewater treatment systems harbored distinct AOB communities. However, there was no remarkable difference among the AOB T- RFLP profiles from different parts of the same system. The T-RFLP fingerprints showed that a full-scale wastewater treatment plant (WWTP) contained a larger number of dominant AOB species than a pilot-scale reactor. The source of influent affected the AOB community, and the WWTPs treating domestic wastewater contained a higher AOB diversity than those receiving mixed domestic and industrial wastewater. However, the AOB community structure was little affected by the treatment process in this study. Phylogenetic analysis of the cloned amoA genes clearly indicated that all the dominant AOB in the systems was closely related to Nitrosomonas spp. not to Nitrosospira spp. Members of the Nitrosomonas oligotropha and Nitrosomonas communis clusters were found in all samples, while members of Nitrosomonas europaea cluster occurred in some systems.展开更多
[ Objective ] The study aimed at treating wastewater treatment plant (WWTP) effluent by using bio-film reactor with filamentous bamboo as bio-carrier. [ Method] With the aid of a continuous flow reactor, a bio-film ...[ Objective ] The study aimed at treating wastewater treatment plant (WWTP) effluent by using bio-film reactor with filamentous bamboo as bio-carrier. [ Method] With the aid of a continuous flow reactor, a bio-film reactor using filamentous bamboo as bio-carrier was used to treat WWTP effluent with low C/N ratio, and the removal effects of CODc,, TN (total nitrogen), and NO3--N in the wastewater were analyzed.[ Result ] The average removal rates of CODcr, TN, and NO3- -N reached 47.7%, 23.6% and 34.5% when the C/N ratio of influent was around 2. In addi- tion, a stable bio-film was formed very well in the secondary effluent with low C/N ratio and hardly degradable organic pollutants. The pollutants could be removed effectively because of the excellent surface characteristics and compositions of filamentous bamboo. [ Conclusion] The research provides a new method to treat WWTP effluent with low C/N ratio.展开更多
Glucocorticoids(GCs) are a group of endocrine-disrupting compounds(EDCs) frequently prescribed against various medical conditions.Recently,GCs have been shown to be effective in managing septic shock in patients infec...Glucocorticoids(GCs) are a group of endocrine-disrupting compounds(EDCs) frequently prescribed against various medical conditions.Recently,GCs have been shown to be effective in managing septic shock in patients infected with the 2019 novel coronavirus(COVID-19).Due to colossal consumption and potential risks to aquatic organisms,GCs have immensely attracted the focus of the scientific research community as a water pollutant.Therefore,the aim of this paper is to review the current knowledge on the occurrence of various GCs in the aquatic environment and their removal during wastewater treatment.A variety of GCs are ubiquitous in surface water,hospital wastewater,and sewage water worldwide.And the minimum concentration in volume is below 0.01 ng/L,and the maximum one is 10 000 ng/L,and enter the environment through hospital and urban wastewater discharging.Compared with natural GCs,higher risks to aquatic environments could be induced by synthetic GCs.The current activated sludge processes used in wastewater treatment plants(WWTPs) are not fully effective in eliminating GCs,some of which may further increase the risk of GC in the environment.In comparison with the aerobic process in WWTPs,the anaerobic and anoxic processes were found to be more efficient for GC degradation.Of the studied GCs,fluticasone propionate,clobetasol propionate,fluocinolone acetonide,and triamcinolone acetonide need more attention due to their low removal efficiencies and strong toxicity.Among the advanced treatment processes,reverse osmosis,ultraviolet irradiation,CaO_(2),and plasma could achieve significant GC activity removal while micro/ultra-filtration,chlorination,and ozonation were less efficient.展开更多
Microplastics, plastic pieces of ≤5 mm in size, are ubiquitous in ther environment and can be found in both terrestrial and aquatic ecosystems. This manuscript reviews the literature on the fate of microplastics in w...Microplastics, plastic pieces of ≤5 mm in size, are ubiquitous in ther environment and can be found in both terrestrial and aquatic ecosystems. This manuscript reviews the literature on the fate of microplastics in wastewater treatment and briefly highlights novel developments in the removal of microplastics from aqueous systems.展开更多
Antimicrobial resistance(AMR)has emerged as a significant challenge in human health.Wastewater treatment plants(WWTPs),acting as a link between human activities and the environment,create ideal conditions for the sele...Antimicrobial resistance(AMR)has emerged as a significant challenge in human health.Wastewater treatment plants(WWTPs),acting as a link between human activities and the environment,create ideal conditions for the selection and spread of antibiotic resistance genes(ARGs)and antibioticresistant bacteria(ARB).Unfortunately,current treatment processes are ineffective in removing ARGs,resulting in the release of large quantities of ARB and ARGs into the aquatic environment through WWTP effluents.This,in turn,leads to their dispersion and potential transmission to human through water and the food chain.To safeguard human and environmental health,it is crucial to comprehend the mechanisms by which WWTP effluent discharge influences the distribution and diffusion of ARGs in downstream waterbodies.In this study,we examine the latest researches on the antibiotic resistome in various waterbodies that have been exposed to WWTP effluent,highlighting the key influencing mechanisms.Furthermore,recommendations for future research and management strategies to control the dissemination of ARGs from WWTPs to the environment are provided,with the aim to achieve the“One Health”objective.展开更多
Microplastic pollution has become a worldwide issue.The discharge of sewage treatment plants(STPs)or wastewater treatment plant(WWTPs)is an important way for microplastics to enter the environment.This study reviewed ...Microplastic pollution has become a worldwide issue.The discharge of sewage treatment plants(STPs)or wastewater treatment plant(WWTPs)is an important way for microplastics to enter the environment.This study reviewed the sources and occurrence characteristics(type,size,color and components)of microplastics in domestic and foreign sewage plants.It elaborated the removal principles of microplastics by primary,secondary and tertiary treatments.In addition,the removal effects of various treatment units and different processes on microplastics were summarized.In the future,the removal mechanism of microplastics in sewage treatment plants should be discussed in more depth,so as to further improve the removal rate of microplastics by optimizing and transforming traditional sewage treatment processes.Therefore,it is necessary to develop new technologies/processes specifically for the removal of microplastics and promote them to practical applications.展开更多
Wastewaters from the chemical industry are usually of high-strength and may contain minor inhibitory and recalcitrant organics that are at times not readily identifiable. This paper describes the experience of a biolo...Wastewaters from the chemical industry are usually of high-strength and may contain minor inhibitory and recalcitrant organics that are at times not readily identifiable. This paper describes the experience of a biological waste water treatment plant (WWTP) processing a COD concentration of 43000 mg·L^-1 wastewater from an oxochemical manufacturing plant. Stage improvements of the plant process by dilution of the inhibitory influent using other chemical wastewater streams resulting in a synergistic process effect, and removal of inhibitory organics by phase separation via acidification, effectively achieved process optimization producing a high quality effluent. In particular, the COD removal efficiency of granular sludge based anaerobic reactors increased from 56% to 90%. The final effluent COD decreased from 250mg·L^-1 to 50mg·L^-1, consistently meeting the COD concentration of 100 mg·L^-1 regulatory discharge limit. The success of the process enhancements supports the hypothesis that long-chain quaternary carboxylic acids act as substrate inhibitors in the biological process.展开更多
The question of wastewater treatment and control is reflected from a very specific viewpoint: the low priority given to accurate and useful measurements within wastewater treatment. The matter is discussed from four v...The question of wastewater treatment and control is reflected from a very specific viewpoint: the low priority given to accurate and useful measurements within wastewater treatment. The matter is discussed from four various perspectives, that may be labelled “Legal understanding”;“Needs for accurate measurement results already in the planning and design stage”;“The measurement problem and human behaviour”;“The understanding of the short term and long term dynamics and changes in pollution and flow loads on a wastewater treatment plant (WWTP)”. All these aspects bring about much improved needs for an accurate and frequent measurement scheme both for pollutants and flows entering a WWTP. The conclusion is stated as follows: A far more and well elaborated on-line measurement system at the plants would become a needed tool for improved water environment protection at lower costs.展开更多
The combined submerged biofilm ( SBF)-activated sludge (AS) process for treatment of municipal wastewater in a small city in China is described in this paper. The process exhibited high removal efficiencies for ca...The combined submerged biofilm ( SBF)-activated sludge (AS) process for treatment of municipal wastewater in a small city in China is described in this paper. The process exhibited high removal efficiencies for carbonaceous substances, nitrogen and phosphorus which mainly took place in the combined SBF-AS biore- actor. The SBF-AS bioreactor was divided into pre-anoxic, anaerobic, anoxic and aerobic zones from inlet to outlet, in which fixed biofilm carriers were packed. Excellent performance had been obtained under normal operating conditions in more than one year of operation in Dong' e municipal WWTP, Shandong province, with mean removal efficiencies of BOD5 93.4%, COD 88%, SS 92%, NH4 - N 82. 1%, TP 75% and TN 66.7%, and quite high effluent quality such as BOD5 6 to 10 rag/L, COD 20 to 40 rag/L, SS 5 to 10 rag/L, TN 10 to 20 rag/L, NH4 - N 4 to 8 mg/L and TP 0. 6 to 1.0 mg/L. The effluent was reused multi-purposely, such as toilet flushing, green belt watering and artificial lake pounding. Simultaneous nitrification and denitrification took place due to the DO gradient in biofilm in aerobic zone of the SBF-AS bioreactor, which made TN removal efficiency improved remarkably in system. Some activated sludge was returned from final clarifiers to the bioreactor for phosphorus removal. The process had the advantages of low investment and low operational/ maintenance (O/M) costs, low sludge yield and was preferably employed in small towns and cities.展开更多
Dewatered municipal sludge samples were collected from five municipal wastewater treatment plants (WWTPs) and one industrial WWTP in Guangzhou, China. A number of agricultural parameters and total metal concentratio...Dewatered municipal sludge samples were collected from five municipal wastewater treatment plants (WWTPs) and one industrial WWTP in Guangzhou, China. A number of agricultural parameters and total metal concentrations in the sludge were determined. Metal speciation was also studied. The results showed that sewage sludge had high organic carbon, and was rich in such nutrients as N and P. The concentrations of Mn, Zn, and Cu were the highest, followed by Ni, Pb, and Cr, Cd had the lowest concentration. In addition, the concentrations of the aforementioned heavy metals in the sludge samples were higher than those recorded in the background data for crop soils. With the exception of Cu and Cd from site S1, and Ni from sites S1, $2, and $5, all other metal concentrations conformed to permissible levels prescribed by the national application standard of acid soil in China (GB 18918--2002). The results of the BCR sequential extraction showed that the concentrations of Mn and Zn were predominant in acid-soluble/exchangeable and reducible fractions. Cu was principally distributed in oxidizable and residual fractions, whereas Cr was present in oxidizable and residual fractions, Pb was found in the state of residual fractions, and the distribution of Ni and Cd did not show significant characteristics.展开更多
文摘Mathematical models and simulation are considered a powerful tool in engineering practice. Those tools are becoming increasingly used for the improvement of wastewater treatment plants design because the conceptual design is complex and ill-defined. In this paper, three alternatives: 1) complete mix activated sludge without nitrogen removal (CAS);2) complete mix activated sludge with nitrogen removal (CAS-N) and;3) membrane bioreactor (MBR) processes were designed into two steps: first concept design to calculate the size of process units, then second implement modeling and simulation to improve the accuracy of the conceptual design. In brief, the treatment process design has been verified by using the activated sludge model No. 1 (ASM1) in GPS-X (v.7) simulation software. This application helps not only in sizing the treatment units but also in understanding the plant’s capacity. In the same time, it can assist in studying the future expansion works required for increased hydraulic and organic loadings. For this purpose, Tikrit WWTP was selected as a case study. The used model was validated by comparing the designed values of the plant and the modeling data. The verification of the obtained results from both hand calculations and the results of the program showed a good agreement. A significant difference in the volume of secondary treatment was obtained from design calculations, where the CAS without denitrification system was 9244 m3 (aerobic and secondary tanks), CAS with denitrification system was 11,324 m3 (anoxic, aerobic and secondary tanks) and for MBR system was 7468 m3 (anoxic, aerobic and immersed membrane tanks). From the obtained results point of view, it can be concluded that mathematical models can be considered as worthy tools to complement the established wastewater treatment plant design procedures.
基金supported by the Key Project of Chinese Academy of Sciences (No. KZCX2-YW-420)the National Basic Research Program (973) of China (No.2009CB421606)the National Natural Science Foundation of China (No. 20621703)
文摘Concentrations of polychlorinated biphenyls (PCBs) have been measured in sewage sludge samples from 8 urban wastewater treatment plants in Beijing, China. The PCB congeners were analyzed by isotope dilution high resolution gas chromatography/high resolution mass spectrometry method. The concentration of PCBs ranged from 65.6 to 157 ng/g dry weight (dw), with a mean value of 101 ng/g dw. The dioxin-like PCB WHO-TEQs (World Health Organization-Toxic Equivalents) of the sludge were lower than 1 pg /g dw. Consequently, all the concentrations of PCBs in sludge samples were below the upper limit for land application according to the Chinese legislation law for agriculture use. The PCB homologue profiles in sludge samples were dominated by tri-CBs and tetra- CBs. Similar distributions have been found in one of the Chinese PCB commercial products. The patterns of dioxin-like and indicator congeners observed in this study were quite similar in all samples. The predominant congener for dioxin-like and indicator PCBs were PCB-118 and PCB-28, respectively, while PCB-126 had the highest TEQ value.
基金supported by the Key Projects in National Science & Technology Pillar Program during the Eleventh Five-Year Plan Period (No.2006BAC19B01-02)the Mega-projects of Science Research for Water (No.2008ZX07313-3)the Program of Introducing Talents of Discipline to Universities
文摘We investigated the communities of ammonia-oxidizing bacteria (AOB) in activated sludge collected from eight wastewater treatment systems using polymerase chain reaction (PCR) followed by terminal restriction fragment length polymorphism (T-RFLP), cloning, and sequencing of the α-subunit of the ammonia monooxygenase gene (amoA). The T-RFLP fingerprint analyses showed that different wastewater treatment systems harbored distinct AOB communities. However, there was no remarkable difference among the AOB T- RFLP profiles from different parts of the same system. The T-RFLP fingerprints showed that a full-scale wastewater treatment plant (WWTP) contained a larger number of dominant AOB species than a pilot-scale reactor. The source of influent affected the AOB community, and the WWTPs treating domestic wastewater contained a higher AOB diversity than those receiving mixed domestic and industrial wastewater. However, the AOB community structure was little affected by the treatment process in this study. Phylogenetic analysis of the cloned amoA genes clearly indicated that all the dominant AOB in the systems was closely related to Nitrosomonas spp. not to Nitrosospira spp. Members of the Nitrosomonas oligotropha and Nitrosomonas communis clusters were found in all samples, while members of Nitrosomonas europaea cluster occurred in some systems.
基金Supported by the Scientific Research Foundation for Postgraduates of ZhengZhou University (A1003) Open Foundation of Provincial Key Laboratory of Environmental Material and Environmental Engineering (K11027)
文摘[ Objective ] The study aimed at treating wastewater treatment plant (WWTP) effluent by using bio-film reactor with filamentous bamboo as bio-carrier. [ Method] With the aid of a continuous flow reactor, a bio-film reactor using filamentous bamboo as bio-carrier was used to treat WWTP effluent with low C/N ratio, and the removal effects of CODc,, TN (total nitrogen), and NO3--N in the wastewater were analyzed.[ Result ] The average removal rates of CODcr, TN, and NO3- -N reached 47.7%, 23.6% and 34.5% when the C/N ratio of influent was around 2. In addi- tion, a stable bio-film was formed very well in the secondary effluent with low C/N ratio and hardly degradable organic pollutants. The pollutants could be removed effectively because of the excellent surface characteristics and compositions of filamentous bamboo. [ Conclusion] The research provides a new method to treat WWTP effluent with low C/N ratio.
基金National Natural Science Foundation of China (No. 52270062)Natural Science Foundation of Shanghai,China (No. 22ZR1402800)+1 种基金Shanghai Rising-Star Program,China (No. 23QC1400800)Shenzhen Science and Technology Program,China (No. JSGG20220606141402005)。
文摘Glucocorticoids(GCs) are a group of endocrine-disrupting compounds(EDCs) frequently prescribed against various medical conditions.Recently,GCs have been shown to be effective in managing septic shock in patients infected with the 2019 novel coronavirus(COVID-19).Due to colossal consumption and potential risks to aquatic organisms,GCs have immensely attracted the focus of the scientific research community as a water pollutant.Therefore,the aim of this paper is to review the current knowledge on the occurrence of various GCs in the aquatic environment and their removal during wastewater treatment.A variety of GCs are ubiquitous in surface water,hospital wastewater,and sewage water worldwide.And the minimum concentration in volume is below 0.01 ng/L,and the maximum one is 10 000 ng/L,and enter the environment through hospital and urban wastewater discharging.Compared with natural GCs,higher risks to aquatic environments could be induced by synthetic GCs.The current activated sludge processes used in wastewater treatment plants(WWTPs) are not fully effective in eliminating GCs,some of which may further increase the risk of GC in the environment.In comparison with the aerobic process in WWTPs,the anaerobic and anoxic processes were found to be more efficient for GC degradation.Of the studied GCs,fluticasone propionate,clobetasol propionate,fluocinolone acetonide,and triamcinolone acetonide need more attention due to their low removal efficiencies and strong toxicity.Among the advanced treatment processes,reverse osmosis,ultraviolet irradiation,CaO_(2),and plasma could achieve significant GC activity removal while micro/ultra-filtration,chlorination,and ozonation were less efficient.
文摘Microplastics, plastic pieces of ≤5 mm in size, are ubiquitous in ther environment and can be found in both terrestrial and aquatic ecosystems. This manuscript reviews the literature on the fate of microplastics in wastewater treatment and briefly highlights novel developments in the removal of microplastics from aqueous systems.
基金supported by the National Natural Science Foundation of China(Grant Nos.51938001,52170185 and 52070111)the China Postdoctoral Science Foundation(No.2022M721815)。
文摘Antimicrobial resistance(AMR)has emerged as a significant challenge in human health.Wastewater treatment plants(WWTPs),acting as a link between human activities and the environment,create ideal conditions for the selection and spread of antibiotic resistance genes(ARGs)and antibioticresistant bacteria(ARB).Unfortunately,current treatment processes are ineffective in removing ARGs,resulting in the release of large quantities of ARB and ARGs into the aquatic environment through WWTP effluents.This,in turn,leads to their dispersion and potential transmission to human through water and the food chain.To safeguard human and environmental health,it is crucial to comprehend the mechanisms by which WWTP effluent discharge influences the distribution and diffusion of ARGs in downstream waterbodies.In this study,we examine the latest researches on the antibiotic resistome in various waterbodies that have been exposed to WWTP effluent,highlighting the key influencing mechanisms.Furthermore,recommendations for future research and management strategies to control the dissemination of ARGs from WWTPs to the environment are provided,with the aim to achieve the“One Health”objective.
基金Supported by Project of National Natural Science Foundation of China(42007317)Project of Guangdong Basic and Applied Basic Research Foundation(2019A1515110272)+1 种基金Outstanding Young Teachers'Scientific Research Ability Improvement Program Funding Project of Zhaoqing University(YQ202105)Innovation and Entrepreneurship Training Program for College Students(202210580015).
文摘Microplastic pollution has become a worldwide issue.The discharge of sewage treatment plants(STPs)or wastewater treatment plant(WWTPs)is an important way for microplastics to enter the environment.This study reviewed the sources and occurrence characteristics(type,size,color and components)of microplastics in domestic and foreign sewage plants.It elaborated the removal principles of microplastics by primary,secondary and tertiary treatments.In addition,the removal effects of various treatment units and different processes on microplastics were summarized.In the future,the removal mechanism of microplastics in sewage treatment plants should be discussed in more depth,so as to further improve the removal rate of microplastics by optimizing and transforming traditional sewage treatment processes.Therefore,it is necessary to develop new technologies/processes specifically for the removal of microplastics and promote them to practical applications.
文摘Wastewaters from the chemical industry are usually of high-strength and may contain minor inhibitory and recalcitrant organics that are at times not readily identifiable. This paper describes the experience of a biological waste water treatment plant (WWTP) processing a COD concentration of 43000 mg·L^-1 wastewater from an oxochemical manufacturing plant. Stage improvements of the plant process by dilution of the inhibitory influent using other chemical wastewater streams resulting in a synergistic process effect, and removal of inhibitory organics by phase separation via acidification, effectively achieved process optimization producing a high quality effluent. In particular, the COD removal efficiency of granular sludge based anaerobic reactors increased from 56% to 90%. The final effluent COD decreased from 250mg·L^-1 to 50mg·L^-1, consistently meeting the COD concentration of 100 mg·L^-1 regulatory discharge limit. The success of the process enhancements supports the hypothesis that long-chain quaternary carboxylic acids act as substrate inhibitors in the biological process.
文摘The question of wastewater treatment and control is reflected from a very specific viewpoint: the low priority given to accurate and useful measurements within wastewater treatment. The matter is discussed from four various perspectives, that may be labelled “Legal understanding”;“Needs for accurate measurement results already in the planning and design stage”;“The measurement problem and human behaviour”;“The understanding of the short term and long term dynamics and changes in pollution and flow loads on a wastewater treatment plant (WWTP)”. All these aspects bring about much improved needs for an accurate and frequent measurement scheme both for pollutants and flows entering a WWTP. The conclusion is stated as follows: A far more and well elaborated on-line measurement system at the plants would become a needed tool for improved water environment protection at lower costs.
文摘The combined submerged biofilm ( SBF)-activated sludge (AS) process for treatment of municipal wastewater in a small city in China is described in this paper. The process exhibited high removal efficiencies for carbonaceous substances, nitrogen and phosphorus which mainly took place in the combined SBF-AS biore- actor. The SBF-AS bioreactor was divided into pre-anoxic, anaerobic, anoxic and aerobic zones from inlet to outlet, in which fixed biofilm carriers were packed. Excellent performance had been obtained under normal operating conditions in more than one year of operation in Dong' e municipal WWTP, Shandong province, with mean removal efficiencies of BOD5 93.4%, COD 88%, SS 92%, NH4 - N 82. 1%, TP 75% and TN 66.7%, and quite high effluent quality such as BOD5 6 to 10 rag/L, COD 20 to 40 rag/L, SS 5 to 10 rag/L, TN 10 to 20 rag/L, NH4 - N 4 to 8 mg/L and TP 0. 6 to 1.0 mg/L. The effluent was reused multi-purposely, such as toilet flushing, green belt watering and artificial lake pounding. Simultaneous nitrification and denitrification took place due to the DO gradient in biofilm in aerobic zone of the SBF-AS bioreactor, which made TN removal efficiency improved remarkably in system. Some activated sludge was returned from final clarifiers to the bioreactor for phosphorus removal. The process had the advantages of low investment and low operational/ maintenance (O/M) costs, low sludge yield and was preferably employed in small towns and cities.
基金Project(51308132) supported by the National Natural Science Foundation of ChinaProject(2012B050300023) supported by the Scientific and Technological Planning Project of Guangdong Province,China+1 种基金Project(LYM11059) supported by the Foundation for Distinguished Young Talents in Higher Education of Guangdong,ChinaProjects(2011B090400161,2011B090400144) supported by the Cooperation Foundation for Industry,University and Research Institute,Guangdong Province and Ministry of Education of China
文摘Dewatered municipal sludge samples were collected from five municipal wastewater treatment plants (WWTPs) and one industrial WWTP in Guangzhou, China. A number of agricultural parameters and total metal concentrations in the sludge were determined. Metal speciation was also studied. The results showed that sewage sludge had high organic carbon, and was rich in such nutrients as N and P. The concentrations of Mn, Zn, and Cu were the highest, followed by Ni, Pb, and Cr, Cd had the lowest concentration. In addition, the concentrations of the aforementioned heavy metals in the sludge samples were higher than those recorded in the background data for crop soils. With the exception of Cu and Cd from site S1, and Ni from sites S1, $2, and $5, all other metal concentrations conformed to permissible levels prescribed by the national application standard of acid soil in China (GB 18918--2002). The results of the BCR sequential extraction showed that the concentrations of Mn and Zn were predominant in acid-soluble/exchangeable and reducible fractions. Cu was principally distributed in oxidizable and residual fractions, whereas Cr was present in oxidizable and residual fractions, Pb was found in the state of residual fractions, and the distribution of Ni and Cd did not show significant characteristics.