The sustainable recovery and utilization of sludge bioenergy within a circular economy context has drawn increasing attention,but there is currently a shortage of reliable technology.This study presents an innovative ...The sustainable recovery and utilization of sludge bioenergy within a circular economy context has drawn increasing attention,but there is currently a shortage of reliable technology.This study presents an innovative biotechnology based on free nitrous acid(FNA)to realize sustainable organics recovery from waste activated sludge(WAS)in-situ,driving efficient nitrogen removal from ammonia rich mature landfill leachate by integrating partial nitrification,fermentation,and denitrification process(PN/DN-F/DN).First,ammonia((1708.5±142.9)mg·L^(-1))in mature landfill leachate is oxidized to nitrite in the aerobic stage of a partial nitrification coupling denitrification(PN/DN)sequencing batch reactor(SBR),with nitrite accumulation ratio of 95.4%±2.5%.Then,intermediate effluent(NO_(2)^(-)-N=(1196.9±184.2)mg·L^(-1))of the PN/DN-SBR,along with concentrated WAS(volatile solids(VSs)=(15119.8±2484.2)mg·L^(-1)),is fed into an anoxic reactor for fermentation coupling denitrification process(F/DN).FNA,the protonated form of nitrite,degrades organics in the WAS to the soluble fraction by the biocidal effect,and the released organics are utilized by denitrifiers to drive NOx-reduction.An ultra-fast sludge reduction rate of 4.89 kg·m^(-3)·d^(-1) and nitrogen removal rate of 0.46 kg·m^(-3)·d^(-1) were realized in the process.Finally,F/DN-SBR effluent containing organics is refluxed to PN/DN-SBR for secondary denitrification in the post anoxic stage.After 175 d operation,an average of 19350.6 mg chemical oxygen demand organics were recovered per operational cycle,with 95.2%nitrogen removal and 53.4%sludge reduction.PN/DN-F/DN is of great significance for promoting a paradigm transformation from energy consumption to energy neutral,specifically,the total benefit in equivalent terms of energy was 291.8 kW·h·t^(-1) total solid.展开更多
The present paper reports on extensive investigations using an ultrasomc treatment ot WAS, to study its potential to meet one or all of four objectives： （1） reduce WAS quantities; （2） achieve a better dewaterabil...The present paper reports on extensive investigations using an ultrasomc treatment ot WAS, to study its potential to meet one or all of four objectives： （1） reduce WAS quantities; （2） achieve a better dewaterability; （3） provoke a release of COD from the biosolids, preferably transformed into biodegradable organics and （4） possibly destroy the filamentous micro-organisms responsible for sludge bulking. The experiments are carried out in a batch reactor of volume up to 2.3L. The ultrasonic apparatus consisted of a generator, a converter and a sonotrode, supplied by Alpha Ultrasonics under the brand name of Telsonic. Three different sludge kinds were tested, at approximate concentration （DS/WAS） between 3.5 and 20g·L^-1. The release of COD from the WAS-phase into the filtrate phase is a function of the specific energy-input SE with yields of about 30% achievable at SE-values of 30000 kJ·kg^-1. A major fraction of the COD is transformed into biodegradable organics （BOD）. The reduction of DS-fraction of the sludge is equivalent to the COD-release rates. Although the dry solids content （DS） is reduced, the dewaterability of the sludge is not improved. This reflects itself in a slightly decreased dryness of the filter cake using vacuum filtration, and in increased values of the capillary suction time （CST）. This more difficult dewaterability is the result of considerably reduced floc sizes, offering an extended surface area. More surface water is bound （CST increases） and the filterability decreases due to clogging of the cake. To reach the same dryness as the untreated cake, the required dosage of poly-electrolyte increases proportionally with the level of ultrasound energy supplied. The ultrasonic reduction of filamentous WAS organisms is not conclusive and very little effect is seen at low intensities and short treatment durations. Microscopic analysis of the WAS identified the dominant presence of Actynomyces. Especially the release of COD and its transformation into BOD certainly merit further research.展开更多
Abstract The principles of reduction, stabilization, harmlessness, resource utilization and low carbonization for sludge treatment and disposal were stated, and the ad- vantages and disadvantages of different sludge t...Abstract The principles of reduction, stabilization, harmlessness, resource utilization and low carbonization for sludge treatment and disposal were stated, and the ad- vantages and disadvantages of different sludge treatment methods were analyzed, from which it concluded that sludge treatment should be acted according to the practical circumstances but not blindly followed, by choosing the appropriate way of sludge treatment. Key words Sludge; Sludge treatment; Landfill; Incineration; Digestion; Land use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
In recent years,sewage treatment has become a common concern of cities,and proper sewage treatment will directly benefit cities by facilitating their healthy and fast development. In this study,the principles of sludg...In recent years,sewage treatment has become a common concern of cities,and proper sewage treatment will directly benefit cities by facilitating their healthy and fast development. In this study,the principles of sludge treatment and disposal such as reduction,stabilization,harmlessness,resource utilization,and low carbonization were introduced. Afterwards,the advantages and disadvantages of ways to dispose sewage were analyzed,and some new techniques were also introduced. In a word,it was advisable to treat sewage properly based on actual conditions.展开更多
The Activated Sludge Process(ASP) exhibits highly nonlinear properties. The design of an automatic control system that is robust against disturbance of inlet wastewater flow rate and has short process settling times i...The Activated Sludge Process(ASP) exhibits highly nonlinear properties. The design of an automatic control system that is robust against disturbance of inlet wastewater flow rate and has short process settling times is a challenging matter. The proposed control method is an I-P modi fied controller automatic control system with state variable feedback and control canonical form simulation diagram for the process. A more stable response is achieved with this type of modern control. Settling times of 0.48 days are achieved for the concentration of microorganisms,(reference value step increase of 50 mg·L-1) and 0.01 days for the concentration of oxygen(reference value step increase of 0.1 mg·L-1). Fluctuations of concentrations of oxygen and microorganisms after an inlet disturbance of5 × 103m3·d-1are small. Changes in the reference values of oxygen and microorganisms(increases by 10%, 20% and 30%) show satisfactory response of the system in all cases. Changes in the value of inlet wastewater flow rate disturbance(increases by 10%, 25%, 50% and 100%) are stabilized by the control system in short time. Maximum percent overshoot is also taken in consideration in all cases and the largest value is 25% which is acceptable. The proposed method with I-P controller is better for disturbance rejection and process settling times compared to the same method using PI controller. This method can substitute optimal control systems in ASP.展开更多
Alkaline pretreatment is an effective technology to disintegrate sewage sludge, where alkali dosage and sludge concentration are two important factors. p H value or alkali concentration is usually adjusted in order to...Alkaline pretreatment is an effective technology to disintegrate sewage sludge, where alkali dosage and sludge concentration are two important factors. p H value or alkali concentration is usually adjusted in order to determine a proper dosage of alkali. Our work has found that this is not a good strategy. A new parameter, the ratio of alkali to sludge(Ra/s), is more sensitive in controlling the alkali dosage. The sludge concentration Csand retention time t are two other important factors to consider. The validity of these arguments is confirmed with modeling and experiments. The individual effect of Ra/s, Csand t was studied separately. Then the combined effect of these three factors was evaluated. The sludge disintegration degree of 44.7% was achieved with the optimized factors. Furthermore, an alkaline-microwave combined pretreatment process was carried out under these optimized conditions. A high disintegration degree of 62.3% was achieved while the energy consumption of microwave was much lower than previously reported.展开更多
Municipal sludge is a sedimentation waste produced during the wastewater process in sewage treatment plants.Among recent studies,pilot and field tests showed that chemical conditioning combined with vacuum preloading ...Municipal sludge is a sedimentation waste produced during the wastewater process in sewage treatment plants.Among recent studies,pilot and field tests showed that chemical conditioning combined with vacuum preloading can effectively treat municipal sludge.To further understand the drainage and consolidation characteristics of the conditioning sludge during vacuum preloading,a large deformation nonlinear numerical simulation model based on the equal strain condition was developed to simulate and analyze the pilot and field tests,whereas the simulation results were not satisfactory.The results of the numerical analysis of the pilot test showed that the predicted consolidation degree was greater than that measured by the field tests,which is attributed to the relatively low permeability layer formed during the preloading process of the prefabricated vertical drain.To better reflect the consolidation process of the conditioned sludge,a simplified analysis method considering the low permeability layer around the prefabricated vertical drain was proposed.The initial permeability coefficient of the low permeability layer is determined via numerical simulations using finite difference method.The predicted settlement curve was in good agreement with the measured results,which indicated that the numerical simulation based on the equal strain condition considering the relatively low permeability layer can better analyze the consolidation process of ferric chloride-conditioning sludge with vacuum preloading.展开更多
As a byproduct of water treatment,drinking water treatment aluminum sludge(DWTAS)has challenges related to imperfect treatment and disposal,which has caused potential harm to human health and the environment.In this p...As a byproduct of water treatment,drinking water treatment aluminum sludge(DWTAS)has challenges related to imperfect treatment and disposal,which has caused potential harm to human health and the environment.In this paper,heat treatment DWTAS as a supplement cementitious material was used to prepare a green cementing material.The results show that the 800℃ is considered as the optimum heat treatment temperature for DWTAS.DWTAS-800℃ is fully activated after thermal decomposition to form incompletely crystallized highly activeγ-Al_(2)O_(3) and active SiO_(2).The addition of DWTAS promoted the formation of ettringite and C-(A)-S-H gel,which could make up for the low early compressive strength of cementing materials to a certain extent.When cured for 90 days,the compressive strength of the mortar with 30% DWTAS-800℃ reached 44.86 MPa.The dynamic process was well simulated by Krstulovi′c-Dabi′c hydration kinetics model.This study provided a methodology for the fabrication of environmentally friendly and cost-effective compound cementitiousmaterials and proposed a“waste-to-resource”strategy for the sustainable management of typical solid wastes.展开更多
Wastewater sludge creates a difficult environmental problem for many large cities.This study developed a three-phase innovative strategy for sludge treatment and reduction,including thermal hydrolysis,fungal fermentat...Wastewater sludge creates a difficult environmental problem for many large cities.This study developed a three-phase innovative strategy for sludge treatment and reduction,including thermal hydrolysis,fungal fermentation,and anaerobic digestion.Increasing the temperature during the treatment from 140 to 180℃ significantly improved the sludge reduction and organic release efficiencies(p<0.05,one-way analysis of variance(ANOVA)for the triplicate experiments at each temperature).After two cycles of thermal hydrolysis,the overall volatile solid reduction ratios of the sludge were 36.6%,47.7%,and 58.5%for treatment at 140,160,and 180℃,respectively,and the total organic carbon(TOC)conversion efficiency reached 28.0%,38.0%,and 45.1%,respectively.The highest concentrations of carbohydrates and proteins were obtained at 160℃ in sludge liquor,whereas the amount of humic substances significantly increased for the treatment at 180℃(p<0.05,one-way ANOVA for the triplicate experiments at each temperature)due to the Maillard reaction.Fungal fermentation of the hydrolyzed sludge liquor with Aspergillus niger converted the waste organics to valuable fiber materials.The biomass concentration of fungal hyphae reached 1.30 and 1.27 g·L^(-1) in the liquor of sludge treated at 140 and 160C,corresponding to organic conversion ratios of 24.6%and 24.0%,respectively.The fungal hyphae produced from the sludge liquor can be readily used for making papers or similar value-added fibrous products.The paper sheets made of hyphae fibers had a dense structure and strong strength with a tensile strength of 10.75 N·m·g^(-1).Combining fungal fermentation and anaerobic digestion,the overall organic utilization efficiency can exceed 75%for the liquor of sludge treated at 160℃.展开更多
The rapid global spread of coronavirus disease 2019(COVID-19)has promoted concern over human pathogens and their significant threats to public health security.The monitoring and control of human pathogens in public sa...The rapid global spread of coronavirus disease 2019(COVID-19)has promoted concern over human pathogens and their significant threats to public health security.The monitoring and control of human pathogens in public sanitation and health facilities are of great importance.Excessive sludge is an inevitable byproduct of sewage that contains human and animal feces in wastewater treatment plants(WWTPs).It is an important sink of different pollutants and pathogens,and the proper treatment and disposal of sludge are important to minimize potential risks to the environment and public health.However,there is a lack of comprehensive analysis of the diversity,exposure risks,assessment methods and inactivation techniques of pathogenic microorganisms in sludge.Based on this consideration,this review summarizes the control performance of pathogenic microorganisms such as enterovirus,Salmonella spp.,and Escherichia coli by different sludge treatment technologies,including composting,anaerobic digestion,aerobic digestion,and microwave irradiation,and the mechanisms of pathogenic microorganism inactivation in sludge treatment processes are discussed.Additionally,this study reviews the diversity,detection methods,and exposure risks of pathogenic microorganisms in sludge.This review advances the quantitative assessment of pathogenic microorganism risks involved in sludge reuse and is practically valuable to optimize the treatment and disposal of sludge for pathogenic microorganism control.展开更多
Millions of tons of waste activated sludge（WAS） produced from biological wastewater treatment processes cause severe adverse environmental consequences. A better understanding of WAS composition is thus very critica...Millions of tons of waste activated sludge（WAS） produced from biological wastewater treatment processes cause severe adverse environmental consequences. A better understanding of WAS composition is thus very critical for sustainable sludge management. In this work, the occurrence and distribution of several fundamental sludge constituents were explored in WAS samples from nine full-scale wastewater treatment plants（WWTPs） of Beijing, China. Among all the components investigated, active heterotrophic biomass was dominant in the samples（up to 9478 mg/L）, followed by endogenous residues（6736 mg/L）,extracellular polymeric substances（2088 mg/L）, and intracellular storage products（464 mg/L）among others. Moreover, significant differences（p 〈 0.05） were observed in composition profiles of sludge samples among the studied WWTPs. To identify the potential parameters affecting the variable fractions of sludge components, wastewater source as well as design and operational parameters of WWTPs were studied using statistical methods. The findings indicated that the component fraction of sewage sludge depends more on wastewater treatment alternatives than on wastewater characteristics among other parameters. A principal component analysis was conducted, which further indicated that there was a greater proportion of residual inert biomass in the sludge produced by the combined system of the conventional anaerobic/anoxic/oxic process and a membrane bioreactor. Additionally, a much longer solids retention time was also found to influence the sludge composition and induce an increase in both endogenous inert residues and extracellular polymeric substances in the sludge.展开更多
High-solid anaerobic digestion(HS-AD)has been applied extensively during the last few decades for treating various organic wastes,such as agricultural wastes,organic fractions of municipal solid wastes,and kitchen was...High-solid anaerobic digestion(HS-AD)has been applied extensively during the last few decades for treating various organic wastes,such as agricultural wastes,organic fractions of municipal solid wastes,and kitchen wastes.However,the application of HS-AD to the processing of sewage sludge(SS)remains limited,which is largely attributable to its poor process stability and performance.Extensive research has been conducted to attempt to surmount these limitations.In this review,the main factors affecting process stability and performance in the HS-AD of SS are comprehensively reviewed,and the improved methods in current use,such as HS sludge pre-treatment and anaerobic co-digestion with other organic wastes,are summarised.Besides,this paper also discusses the characteristics of substance transformation in the HS-AD of SS with and without thermal pre-treatment.Research has shown that the HS effect is due to the presence of high concentrations of substances that may inhibit the function of anaerobic microorganisms,and that it also results in poor mass transfer,a low diffusion coefficient,and high viscosity.Finally,knowledge gaps in the current research on HS-AD of SS are identified.Based on these,it proposes that future efforts should be devoted to standardising the definition of HS sludge,revealing the law of migration and transformation of pollutants,describing the metabolic pathways by which specific substances are degraded,and establishing accurate mathematical models.Moreover,developing green sludge dewatering agents,obtaining high value-added products,and revealing effects of the above two on HS-AD of SS can also be considered in future.展开更多
基金supported by the Beijing Natural Science Foundation (8222040)Key Program of National Natural Science Foundation of China (52131004)+4 种基金Young Elite Scientists Sponsorship Program by China association for science and technology (CAST,YESS20220508)Young Elite Scientists Sponsorship Program by Beijing Association for Science and Technology (BAST,BYESS2023183)Innovation and Entrepreneurship Leading Team Project in Guangzhou (CYLJTD-201607)Key Research and Developmental Program of Shandong Province (2020CXGC011404)Cultivating Fund of Faculty of Environment and Life,Beijing University of Technology (PY202302).
文摘The sustainable recovery and utilization of sludge bioenergy within a circular economy context has drawn increasing attention,but there is currently a shortage of reliable technology.This study presents an innovative biotechnology based on free nitrous acid(FNA)to realize sustainable organics recovery from waste activated sludge(WAS)in-situ,driving efficient nitrogen removal from ammonia rich mature landfill leachate by integrating partial nitrification,fermentation,and denitrification process(PN/DN-F/DN).First,ammonia((1708.5±142.9)mg·L^(-1))in mature landfill leachate is oxidized to nitrite in the aerobic stage of a partial nitrification coupling denitrification(PN/DN)sequencing batch reactor(SBR),with nitrite accumulation ratio of 95.4%±2.5%.Then,intermediate effluent(NO_(2)^(-)-N=(1196.9±184.2)mg·L^(-1))of the PN/DN-SBR,along with concentrated WAS(volatile solids(VSs)=(15119.8±2484.2)mg·L^(-1)),is fed into an anoxic reactor for fermentation coupling denitrification process(F/DN).FNA,the protonated form of nitrite,degrades organics in the WAS to the soluble fraction by the biocidal effect,and the released organics are utilized by denitrifiers to drive NOx-reduction.An ultra-fast sludge reduction rate of 4.89 kg·m^(-3)·d^(-1) and nitrogen removal rate of 0.46 kg·m^(-3)·d^(-1) were realized in the process.Finally,F/DN-SBR effluent containing organics is refluxed to PN/DN-SBR for secondary denitrification in the post anoxic stage.After 175 d operation,an average of 19350.6 mg chemical oxygen demand organics were recovered per operational cycle,with 95.2%nitrogen removal and 53.4%sludge reduction.PN/DN-F/DN is of great significance for promoting a paradigm transformation from energy consumption to energy neutral,specifically,the total benefit in equivalent terms of energy was 291.8 kW·h·t^(-1) total solid.
文摘The present paper reports on extensive investigations using an ultrasomc treatment ot WAS, to study its potential to meet one or all of four objectives： （1） reduce WAS quantities; （2） achieve a better dewaterability; （3） provoke a release of COD from the biosolids, preferably transformed into biodegradable organics and （4） possibly destroy the filamentous micro-organisms responsible for sludge bulking. The experiments are carried out in a batch reactor of volume up to 2.3L. The ultrasonic apparatus consisted of a generator, a converter and a sonotrode, supplied by Alpha Ultrasonics under the brand name of Telsonic. Three different sludge kinds were tested, at approximate concentration （DS/WAS） between 3.5 and 20g·L^-1. The release of COD from the WAS-phase into the filtrate phase is a function of the specific energy-input SE with yields of about 30% achievable at SE-values of 30000 kJ·kg^-1. A major fraction of the COD is transformed into biodegradable organics （BOD）. The reduction of DS-fraction of the sludge is equivalent to the COD-release rates. Although the dry solids content （DS） is reduced, the dewaterability of the sludge is not improved. This reflects itself in a slightly decreased dryness of the filter cake using vacuum filtration, and in increased values of the capillary suction time （CST）. This more difficult dewaterability is the result of considerably reduced floc sizes, offering an extended surface area. More surface water is bound （CST increases） and the filterability decreases due to clogging of the cake. To reach the same dryness as the untreated cake, the required dosage of poly-electrolyte increases proportionally with the level of ultrasound energy supplied. The ultrasonic reduction of filamentous WAS organisms is not conclusive and very little effect is seen at low intensities and short treatment durations. Microscopic analysis of the WAS identified the dominant presence of Actynomyces. Especially the release of COD and its transformation into BOD certainly merit further research.
基金Supported by the Science and Technology Planning Project of Chongqing Municipality(cstc2011pt-gc80019)the Plan for the Construction of Technical Research and Development Base of Chongqing Municipality(cstc2014gjhz20001)the International Science&Technology Cooperation Program of China(2015DFR70390)~~
文摘Abstract The principles of reduction, stabilization, harmlessness, resource utilization and low carbonization for sludge treatment and disposal were stated, and the ad- vantages and disadvantages of different sludge treatment methods were analyzed, from which it concluded that sludge treatment should be acted according to the practical circumstances but not blindly followed, by choosing the appropriate way of sludge treatment. Key words Sludge; Sludge treatment; Landfill; Incineration; Digestion; Land use
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 Science and Technology Planning Project of Chongqing City,China(cstc2011pt-gc80019)Science and Technology Research and Development Base Construction Plan of Chongqing City,China(cstc2014gjhz20001)+1 种基金International Science&Technology Cooperation Program of China(2015DFR70390)National Special Science and Technology Project for Water Pollution Control and Management(2017ZX07403002)
文摘In recent years,sewage treatment has become a common concern of cities,and proper sewage treatment will directly benefit cities by facilitating their healthy and fast development. In this study,the principles of sludge treatment and disposal such as reduction,stabilization,harmlessness,resource utilization,and low carbonization were introduced. Afterwards,the advantages and disadvantages of ways to dispose sewage were analyzed,and some new techniques were also introduced. In a word,it was advisable to treat sewage properly based on actual conditions.
文摘The Activated Sludge Process(ASP) exhibits highly nonlinear properties. The design of an automatic control system that is robust against disturbance of inlet wastewater flow rate and has short process settling times is a challenging matter. The proposed control method is an I-P modi fied controller automatic control system with state variable feedback and control canonical form simulation diagram for the process. A more stable response is achieved with this type of modern control. Settling times of 0.48 days are achieved for the concentration of microorganisms,(reference value step increase of 50 mg·L-1) and 0.01 days for the concentration of oxygen(reference value step increase of 0.1 mg·L-1). Fluctuations of concentrations of oxygen and microorganisms after an inlet disturbance of5 × 103m3·d-1are small. Changes in the reference values of oxygen and microorganisms(increases by 10%, 20% and 30%) show satisfactory response of the system in all cases. Changes in the value of inlet wastewater flow rate disturbance(increases by 10%, 25%, 50% and 100%) are stabilized by the control system in short time. Maximum percent overshoot is also taken in consideration in all cases and the largest value is 25% which is acceptable. The proposed method with I-P controller is better for disturbance rejection and process settling times compared to the same method using PI controller. This method can substitute optimal control systems in ASP.
基金the National Natural Science Foundation of China(51078234)Shenzhen R&D fund(JCYJ20140418193546101)Shenzhen University R&D fund(T201203)
文摘Alkaline pretreatment is an effective technology to disintegrate sewage sludge, where alkali dosage and sludge concentration are two important factors. p H value or alkali concentration is usually adjusted in order to determine a proper dosage of alkali. Our work has found that this is not a good strategy. A new parameter, the ratio of alkali to sludge(Ra/s), is more sensitive in controlling the alkali dosage. The sludge concentration Csand retention time t are two other important factors to consider. The validity of these arguments is confirmed with modeling and experiments. The individual effect of Ra/s, Csand t was studied separately. Then the combined effect of these three factors was evaluated. The sludge disintegration degree of 44.7% was achieved with the optimized factors. Furthermore, an alkaline-microwave combined pretreatment process was carried out under these optimized conditions. A high disintegration degree of 62.3% was achieved while the energy consumption of microwave was much lower than previously reported.
基金acknowledge the financial support from The National Natural Science Foundation No.Gk321002Foundation of Nanjing Hydraulic Research Institute No.Y320012.
文摘Municipal sludge is a sedimentation waste produced during the wastewater process in sewage treatment plants.Among recent studies,pilot and field tests showed that chemical conditioning combined with vacuum preloading can effectively treat municipal sludge.To further understand the drainage and consolidation characteristics of the conditioning sludge during vacuum preloading,a large deformation nonlinear numerical simulation model based on the equal strain condition was developed to simulate and analyze the pilot and field tests,whereas the simulation results were not satisfactory.The results of the numerical analysis of the pilot test showed that the predicted consolidation degree was greater than that measured by the field tests,which is attributed to the relatively low permeability layer formed during the preloading process of the prefabricated vertical drain.To better reflect the consolidation process of the conditioned sludge,a simplified analysis method considering the low permeability layer around the prefabricated vertical drain was proposed.The initial permeability coefficient of the low permeability layer is determined via numerical simulations using finite difference method.The predicted settlement curve was in good agreement with the measured results,which indicated that the numerical simulation based on the equal strain condition considering the relatively low permeability layer can better analyze the consolidation process of ferric chloride-conditioning sludge with vacuum preloading.
基金This work is supported by the National Key Research and Development Program of China(No.2022YFC3203203)the Outstanding Youth Science Foundation of Shaanxi Province(No.2023-JC-JQ-36)the National Natural Science Foundation of China(No.52300121).
文摘As a byproduct of water treatment,drinking water treatment aluminum sludge(DWTAS)has challenges related to imperfect treatment and disposal,which has caused potential harm to human health and the environment.In this paper,heat treatment DWTAS as a supplement cementitious material was used to prepare a green cementing material.The results show that the 800℃ is considered as the optimum heat treatment temperature for DWTAS.DWTAS-800℃ is fully activated after thermal decomposition to form incompletely crystallized highly activeγ-Al_(2)O_(3) and active SiO_(2).The addition of DWTAS promoted the formation of ettringite and C-(A)-S-H gel,which could make up for the low early compressive strength of cementing materials to a certain extent.When cured for 90 days,the compressive strength of the mortar with 30% DWTAS-800℃ reached 44.86 MPa.The dynamic process was well simulated by Krstulovi′c-Dabi′c hydration kinetics model.This study provided a methodology for the fabrication of environmentally friendly and cost-effective compound cementitiousmaterials and proposed a“waste-to-resource”strategy for the sustainable management of typical solid wastes.
基金This work was supported by the Shenzhen Municipal Science and Technology Innovation Council of the Shenzhen Government(JCYJ20170307153821435 and JCYJ20180508152004176)the National Natural Science Foundation of China(51678333)+1 种基金the Research Grants Council of the Hong Kong Government(17261916,T21-711/16R)the Development and Reform Commission of Shenzhen Municipality(Urban Water Recycling and Environment Safety Program).
文摘Wastewater sludge creates a difficult environmental problem for many large cities.This study developed a three-phase innovative strategy for sludge treatment and reduction,including thermal hydrolysis,fungal fermentation,and anaerobic digestion.Increasing the temperature during the treatment from 140 to 180℃ significantly improved the sludge reduction and organic release efficiencies(p<0.05,one-way analysis of variance(ANOVA)for the triplicate experiments at each temperature).After two cycles of thermal hydrolysis,the overall volatile solid reduction ratios of the sludge were 36.6%,47.7%,and 58.5%for treatment at 140,160,and 180℃,respectively,and the total organic carbon(TOC)conversion efficiency reached 28.0%,38.0%,and 45.1%,respectively.The highest concentrations of carbohydrates and proteins were obtained at 160℃ in sludge liquor,whereas the amount of humic substances significantly increased for the treatment at 180℃(p<0.05,one-way ANOVA for the triplicate experiments at each temperature)due to the Maillard reaction.Fungal fermentation of the hydrolyzed sludge liquor with Aspergillus niger converted the waste organics to valuable fiber materials.The biomass concentration of fungal hyphae reached 1.30 and 1.27 g·L^(-1) in the liquor of sludge treated at 140 and 160C,corresponding to organic conversion ratios of 24.6%and 24.0%,respectively.The fungal hyphae produced from the sludge liquor can be readily used for making papers or similar value-added fibrous products.The paper sheets made of hyphae fibers had a dense structure and strong strength with a tensile strength of 10.75 N·m·g^(-1).Combining fungal fermentation and anaerobic digestion,the overall organic utilization efficiency can exceed 75%for the liquor of sludge treated at 160℃.
基金sponsored by the National Natural Science Foundation of China(Grant Nos.51925807,52091542)the Excellent Innovation Project of Research Center for Eco-Environmental Sciences(CAS RCEES-EEI-2019-02).
文摘The rapid global spread of coronavirus disease 2019(COVID-19)has promoted concern over human pathogens and their significant threats to public health security.The monitoring and control of human pathogens in public sanitation and health facilities are of great importance.Excessive sludge is an inevitable byproduct of sewage that contains human and animal feces in wastewater treatment plants(WWTPs).It is an important sink of different pollutants and pathogens,and the proper treatment and disposal of sludge are important to minimize potential risks to the environment and public health.However,there is a lack of comprehensive analysis of the diversity,exposure risks,assessment methods and inactivation techniques of pathogenic microorganisms in sludge.Based on this consideration,this review summarizes the control performance of pathogenic microorganisms such as enterovirus,Salmonella spp.,and Escherichia coli by different sludge treatment technologies,including composting,anaerobic digestion,aerobic digestion,and microwave irradiation,and the mechanisms of pathogenic microorganism inactivation in sludge treatment processes are discussed.Additionally,this study reviews the diversity,detection methods,and exposure risks of pathogenic microorganisms in sludge.This review advances the quantitative assessment of pathogenic microorganism risks involved in sludge reuse and is practically valuable to optimize the treatment and disposal of sludge for pathogenic microorganism control.
基金supported by the National Natural Science Foundation of China(Nos.51408589 and 51138009)State Key Joint Laboratory of Environment Simulation and Pollution Control of China(Research Center for Eco-Environmental Sciences,Chinese Academy of Sciences,No.14Z03ESPCR)Youth Innovation Promotion Association of the Chinese Academy of Sciences
文摘Millions of tons of waste activated sludge（WAS） produced from biological wastewater treatment processes cause severe adverse environmental consequences. A better understanding of WAS composition is thus very critical for sustainable sludge management. In this work, the occurrence and distribution of several fundamental sludge constituents were explored in WAS samples from nine full-scale wastewater treatment plants（WWTPs） of Beijing, China. Among all the components investigated, active heterotrophic biomass was dominant in the samples（up to 9478 mg/L）, followed by endogenous residues（6736 mg/L）,extracellular polymeric substances（2088 mg/L）, and intracellular storage products（464 mg/L）among others. Moreover, significant differences（p 〈 0.05） were observed in composition profiles of sludge samples among the studied WWTPs. To identify the potential parameters affecting the variable fractions of sludge components, wastewater source as well as design and operational parameters of WWTPs were studied using statistical methods. The findings indicated that the component fraction of sewage sludge depends more on wastewater treatment alternatives than on wastewater characteristics among other parameters. A principal component analysis was conducted, which further indicated that there was a greater proportion of residual inert biomass in the sludge produced by the combined system of the conventional anaerobic/anoxic/oxic process and a membrane bioreactor. Additionally, a much longer solids retention time was also found to influence the sludge composition and induce an increase in both endogenous inert residues and extracellular polymeric substances in the sludge.
基金This work was financially supported by the National Natural Science Foundation of China(NSFC)(Grant Nos.51978498 and 51538008)the Support Program of Postdoctoral Innovative Talents(BX20190239)+1 种基金the China Postdoctoral Science Foundation(2020M671227)the National Key R&D Program of China(2019YFC1906301).
文摘High-solid anaerobic digestion(HS-AD)has been applied extensively during the last few decades for treating various organic wastes,such as agricultural wastes,organic fractions of municipal solid wastes,and kitchen wastes.However,the application of HS-AD to the processing of sewage sludge(SS)remains limited,which is largely attributable to its poor process stability and performance.Extensive research has been conducted to attempt to surmount these limitations.In this review,the main factors affecting process stability and performance in the HS-AD of SS are comprehensively reviewed,and the improved methods in current use,such as HS sludge pre-treatment and anaerobic co-digestion with other organic wastes,are summarised.Besides,this paper also discusses the characteristics of substance transformation in the HS-AD of SS with and without thermal pre-treatment.Research has shown that the HS effect is due to the presence of high concentrations of substances that may inhibit the function of anaerobic microorganisms,and that it also results in poor mass transfer,a low diffusion coefficient,and high viscosity.Finally,knowledge gaps in the current research on HS-AD of SS are identified.Based on these,it proposes that future efforts should be devoted to standardising the definition of HS sludge,revealing the law of migration and transformation of pollutants,describing the metabolic pathways by which specific substances are degraded,and establishing accurate mathematical models.Moreover,developing green sludge dewatering agents,obtaining high value-added products,and revealing effects of the above two on HS-AD of SS can also be considered in future.
