In this study,the effects of different salinity gradients and addition of compatible solutes on anaerobic treated effluent water qualities,sludge characteristics and microbial communities were investigated.The increas...In this study,the effects of different salinity gradients and addition of compatible solutes on anaerobic treated effluent water qualities,sludge characteristics and microbial communities were investigated.The increase in salinity resulted in a decrease in particle size of the granular sludge,which was concentrated in the range of 0.5-1.0 mm.The content of EPS(extracellular polymeric substances)in the granular sludge gradually increased with increasing salinity and the addition of betaine(a typical compatible solute).Meanwhile,the microbial community structure was significantly affected by salinity,with high salinity reducing the diversity of bacteria.At higher salinity,Patescibacteria and Proteobacteria gradually became the dominant phylum,with relative abundance increasing to 13.53%and 12.16%at 20 g/L salinity.Desulfobacterota and its subordinate Desulfovibrio,which secrete EPS in large quantities,dominated significantly after betaine addition.Their relative abundance reached 13.65%and 7.86%at phylum level and genus level.The effect of these changes on the treated effluent was shown as the average chemical oxygen demand(COD)removal rate decreased from 82.10%to 79.71%,78.01%,68.51%and 64.55%when the salinity gradually increased from 2 g/L to 6,10,16 and 20 g/L.At the salinity of 20 g/L,average COD removal increased to 71.65%by the addition of 2 mmol/L betaine.The gradient elevated salinity and the exogenous addition of betaine played an important role in achieving stability of the anaerobic system in a highly saline environment,which provided a feasible strategy for anaerobic treatment of organic saline wastewater.展开更多
Saccharification of lignocellulosic wastes is the bottleneck of different bio-based chemical industries.Using enzymes for saccharification of lignocellulosic materials has several advantages over using chemicals.In th...Saccharification of lignocellulosic wastes is the bottleneck of different bio-based chemical industries.Using enzymes for saccharification of lignocellulosic materials has several advantages over using chemicals.In the current work,the application of the Maximyze■ enzyme system,which is industrially used in papermaking,was investigated in the saccharification of paper sludge and fiber dust wastes from the tissue paper industry.For optimizing the saccharification process,the effects of the consistency%,enzyme loading,and incubation time were studied and optimized using the Response Surface Methodology.The effect of these factors on the weight loss of paper sludge and total sugars in the hydrolyzate was studied.High-Performance Liquid Chromatography(HPLC)was used to measure the sugars composition of the hydrolyzate.Under the optimized conditions,~90% and~66% of the fiber dust and paper sludge could be hydrolyzed into sugars,respectively.The sugar composition was 80.23% glucose,10.99% xylose,and 8.65% arabinose based on the total sugars in the case of fiber dust.In comparison,80.63% glucose,8.43% xylose,and 10.75% arabinose were detected in the case of paper sludge.The results showed the applicability of the Maximyze Rcommercial enzymes used in the paper industry for efficient saccharification of paper sludge and fiber dust.The presence of non-cellulosic materials in the paper sludge(residual ink,paper additives,and ash)didn’t affect the activity of the enzymes.The study also showed the potential use of fiber dust as a valuable and clean source of sugars that can be used to prepare different bio-based chemicals.展开更多
Anaerobic digestion(AD)is widely employed for sludge stabilization and waste reduction.However,the slow hydrolysis process hinders methane production and leads to prolonged sludge issues.In this study,an efficient and...Anaerobic digestion(AD)is widely employed for sludge stabilization and waste reduction.However,the slow hydrolysis process hinders methane production and leads to prolonged sludge issues.In this study,an efficient and eco-friendly lysozyme pre-treatment method was utilized to address these challenges.By optimizing lysozyme dosage,hydrolysis and cell lysis were maximized.Furthermore,lysozyme combined with hydrothermal pretreatment enhanced overall efficiency.Results indicate that:(1)When lysozyme dosage reached 90 mg/g TS after 240 min of pretreatment,SCOD,soluble polysaccharides,and protein content reached their maxima at 855.00,44.09,and 204.86 mg/L,respectively.This represented an increase of 85.87%,365.58%,and 259.21%compared to the untreated sludge.Threedimensional fluorescence spectroscopy revealed the highest fluorescence intensity in the IV region(soluble microbial product),promoting microbial metabolic activity.(2)Lysozyme combined with hydrothermal pretreatment significantly increased SCOD,soluble proteins,and polysaccharide release from sludge,reducing SCOD release time.Orthogonal experiments identified Group 3 as the most effective for SCOD and soluble polysaccharide release,while Group 9 released the most soluble proteins.The significance order of factors influencing SCOD,soluble proteins,and polysaccharide release is hydrothermal temperature>hydrothermal time>enzymatic digestion time.(3)The lysozyme-assisted hydrothermal pretreatment group exhibited the fastest release and the highest SCOD concentration of 8,135.00 mg/L during anaerobic digestion.Maximum SCOD consumption and cumulative gas production increased by 95.89%and 130.58%,respectively,compared to the control group,allowing gas production to conclude 3 days earlier.展开更多
We read with great interest the investigations conducted by Pourakbar et al.(2024)on the“Stabilization of clay soil using alkali-activated sewage sludge.”The authors have investigated the feasibility of utilizing al...We read with great interest the investigations conducted by Pourakbar et al.(2024)on the“Stabilization of clay soil using alkali-activated sewage sludge.”The authors have investigated the feasibility of utilizing alkali-activated sewage sludge(AASS)as a binder for stabilizing the clayey soil.Sewage sludge(SS)in varying proportions of 1.5%,2%,2.5%,3.5%,and 4.5%was utilized to prepare geopolymer binders using sodium and potassium-based alkali activators.Furthermore,unconfined compressive strength(UCS)and direct shear tests were conducted to examine the strength development of clayey soil stabilized with AASS.While the study presented some intriguing results,we have identified critical concerns regarding(i)the selection of SS as a precursor for alkali activation,(ii)technical inconsistencies associated with the compaction characteristics and microstructural analysis,and(iii)the feasibility of the proposed methodology for practical applications.Through our discussion,we seek to highlight these issues and provide constructive feedback to advance the understanding of alkali activation processes and their implications for soil stabilization.展开更多
As a key step in waste activated sludge(WAS)treatment and disposal,WAS dewatering can minimize the amount of WAS and decrease the costs of transportation,storage management,treatment,and disposal.Advanced oxidation pr...As a key step in waste activated sludge(WAS)treatment and disposal,WAS dewatering can minimize the amount of WAS and decrease the costs of transportation,storage management,treatment,and disposal.Advanced oxidation processes(AOPs)have been widely explored in WAS dewatering due to the excellent oxidizing properties and efficient decomposition capacity since the 21^(st)century.This review outlined the mechanisms of AOPs to improve WAS dewatering and pointed out the shortcomings of the existing mechanisms.Then,the applications of AOPs-based WAS dewatering processes for enhanced WAS dewatering were reviewed,and the intrinsic limitations of AOPs-based WAS dewatering processes in engineering applications were proposed.In addition,an overall review of AOPs-based WAS dewatering researches was also conducted through bibliometric analysis,and future research hotspots in the field of AOPs-based WAS dewatering were proposed.Finally,the positive effects of the AOPs-based WAS dewatering processes on pollutant removal and resource recovery were investigated,and an integrated plan for the harmless disposal of WAS was constructed to achieve a positive reform of the traditional WAS management plan.This review provided theoretical basis and technical reference for the development of efficient,economical,and environmental AOPs for enhanced WAS dewatering to facilitate the application of AOPs in actual WAS dewatering engineering.展开更多
Sedimentation sludge water(SSW),a prominent constituent of wastewater from drinking water treatment plants,has received limited attention in terms of its treatment and utilization likely due to the perceived difficult...Sedimentation sludge water(SSW),a prominent constituent of wastewater from drinking water treatment plants,has received limited attention in terms of its treatment and utilization likely due to the perceived difficulties associated with managing SSW sludge.This study comprehensively evaluated the water quality of SSW by comparing it to a well-documented wastewater(filter backwash water(FBW)).Furthermore,it investigated the pollutant variations in the SSW during pre-sedimentation process,probed the underlying reaction mechanism,and explored the feasibility of employing a pilot-scale coagulation-sedimentation process for SSW treatment.The levels of most water quality parameters were generally comparable between SSW and FBW.During the pre-sedimentation of SSW,significant removal of turbidity,bacterial counts,and dissolved organic matter(DOM)was observed.The characterization of DOM components,molecular weight distributions,and optical properties revealed that the macromolecular proteinaceous biopolymers and humic acids were preferentially removed.The characterization of particulates indicated that high surface energy,zeta potential,and bridging/adsorption/sedimentation/coagulation capacities in aluminum residuals of SSW,underscoring its potential as a coagulant and promoting the generation and sedimentation of inorganic-organic complexes.The coagulation-sedimentation process could effectively remove pollutants from low-turbidity SSW([turbidity]0<15 NTU).These findings provide valuable insights into the water quality dynamics of SSW during the pre-sedimentation process,facilitating the development of SSW quality management and enhancing its reuse rate.展开更多
Cresyl diphenyl phosphate(CDP),an emerging aryl organophosphate ester(OPE),exhibits potential toxic effects and is frequently found in diverse environmental media,thereby raising concerns about environmental pollution...Cresyl diphenyl phosphate(CDP),an emerging aryl organophosphate ester(OPE),exhibits potential toxic effects and is frequently found in diverse environmental media,thereby raising concerns about environmental pollution.Biodegradation demonstrates substantial potential for CDP removal from the environment.This study investigated the biodegradation mechanisms of CDP using anaerobic activated sludge(AnAS).The biodegradation of 1-mg/L CDP followed a first-order kinetic model with a degradation kinetic constant of 0.943 d^(-1),and the addition of different electron acceptors affected the degradation rate.High-resolution mass spectrometry identified seven transformation products(TPs)of CDP.The pathways of CDP degradation in anaerobic conditions were proposed,with carboxylation products being the most dominant intermediate products.The structure of the anaerobic microbial community at different degradation time points in CDP-amended microcosms was examined.The linear discriminant analysis(LDA)of effect size(LEfSe)potentially underscored the pivotal role of Methyloversatilis in CDP biodegradation.Zebrafish embryotoxicity experiments revealed both lethal and morphogenetic impacts of CDP on zebrafish embryos.The survival rate,hatching rate,and body length indicators of zebrafish embryos underscored the detoxification of CDP and its resultant intermediates by AnAS.This study offers new insights into the fate and biodegradation mechanisms of CDP in wastewater treatment plants.展开更多
Sewage sludge in cities of Yangzi River Belt,China,generally exhibits a lower organic content and higher silt contentdue to leakage of drainage system,which caused low bioenergy recovery and carbon emission benefits i...Sewage sludge in cities of Yangzi River Belt,China,generally exhibits a lower organic content and higher silt contentdue to leakage of drainage system,which caused low bioenergy recovery and carbon emission benefits in conventional anaerobic digestion(CAD).Therefore,this paper is on a pilot scale,a bio-thermophilic pretreatment anaerobic digestion(BTPAD)for low organic sludge(volatile solids(VS)of 4%)was operated with a long-term continuous flow of 200 days.The VS degradation rate and CH_(4) yield of BTPAD increased by 19.93%and 53.33%,respectively,compared to those of CAD.The analysis of organic compositions in sludge revealed that BTPAD mainly improved the hydrolysis of proteins in sludge.Further analysis of microbial community proportions by high-throughput sequencing revealed that the short-term bio-thermophilic pretreatment was enriched in Clostridiales,Coprothermobacter and Gelria,was capable of hydrolyzing acidified proteins,and provided more volatile fatty acid(VFA)for the subsequent reaction.Biome combined with fluorescence quantitative polymerase chain reaction(PCR)analysis showed that the number of bacteria with high methanogenic capacity in BTPAD was much higher than that in CAD during the medium temperature digestion stage,indicating that short-term bio-thermophilic pretreatment could provide better methanogenic conditions for BTPAD.Furthermore,the greenhouse gas emission footprint analysis showed that short-term bio-thermophilic pretreatment could reduce the carbon emission of sludge anaerobic digestion system by 19.18%.展开更多
This study embarks on an explorative investigation into the effects of typical concentrations and varying particle sizes of fine grits(FG,the involatile portion of suspended solids)and fine debris(FD,the volatile yet ...This study embarks on an explorative investigation into the effects of typical concentrations and varying particle sizes of fine grits(FG,the involatile portion of suspended solids)and fine debris(FD,the volatile yet unbiodegradable fraction of suspended solids)within the influent on themixed liquor volatile suspended solids(MLVSS)/mixed liquor suspended solids(MLSS)ratio of an activated sludge system.Through meticulous experimentation,it was discerned that the addition of FG or FD,the particle size of FG,and the concentration of FD bore no substantial impact on the pollutant removal efficiency(denoted by the removal rate of COD and ammonia nitrogen)under constant operational conditions.However,a notable decrease in the MLVSS/MLSS ratio was observed with a typical FG concentration of 20 mg/L,with smaller FG particle sizes exacerbating this reduction.Additionally,variations in FD concentrations influenced both MLSS andMLVSS/MLSS ratios;a higher FD concentration led to an increased MLSS and a reduced MLVSS/MLSS ratio,indicating FD accumulation in the system.A predictive model for MLVSS/MLSS was constructed based on quality balance calculations,offering a tool for foreseeing the MLVSS/MLSS ratio under stable long-term influent conditions of FG and FD.This model,validated using data from the BXH wastewater treatment plant(WWTP),showcased remarkable accuracy.展开更多
Steel rolling sludge,an oil-containing waste generated during steel production,was difficult to manage.Prolonged storage poses significant environmental and health hazards.Most steel enterprises in China use steel rol...Steel rolling sludge,an oil-containing waste generated during steel production,was difficult to manage.Prolonged storage poses significant environmental and health hazards.Most steel enterprises in China use steel rolling sludge directly as a raw material for sintering.However,its adhesive nature caused poor mixing with other materials,affecting the quality of the sinter.Herein,the incorporation of steel rolling sludge incineration slag into the sintering process was investigated for experimental purposes.The results indicated that adding 1%incinerated steel rolling sludge to the sintering raw material was feasible.At this proportion,both the yield and the tumbler index of the sinter have improved,primarily due to the oxidation reaction of Fe_(3)O_(4)present in the steel rolling sludge incineration slag during the sintering process,which significantly increases the sensible heat of the sinter and enhances the sintering mineralization reaction.Notably,the addition of steel rolling sludge incineration slag reduced dioxin concentrations in the sintering flue gas.Although CO,NO_(x),and SO_(2)emission concentrations slightly increased,the existing flue gas treatment system effectively controlled their emissions.展开更多
Stainless steel pickling sludge(SSPS)is a by-product of pickling and passivation treatment of stainless steel in the process of stainless steel production.A novel approach for the treatment of the SSPS using the high-...Stainless steel pickling sludge(SSPS)is a by-product of pickling and passivation treatment of stainless steel in the process of stainless steel production.A novel approach for the treatment of the SSPS using the high-temperature nickel-iron blast furnace molten slag(NBFS)was investigated.The results show that the flow temperature of the slag decreases with the increase in the proportion of SSPS.In a certain range,the flow temperature decreases by about 7℃ when the proportion of SSPS increases by 1%.The computational results from FactSage indicate that the addition of SSPS leads to a reduction in MgO content and an increase in CaO and CaSO_(4) contents,which are the reasons for the decrease in the flow temperature.Mortar blocks were prepared by mixing the slag powder prepared by water-quenched slag drying ball milling with 425 Portland cement in a certain proportion.As the proportion of SSPS increased from 0 to 5%,the 7-day strength of mortar blocks increased from 22.32 to 26.98 MPa,and the 28-day strength increased from 37.28 to 41.43 MPa.The 28-day activity index is above 75%,and its activity index meets the requirements of S75 ground granulated blast furnace slag.The industrial application program in the nickel-iron blast furnace with a volume of 550 m^(3) was also put forward,which provides a new way for realizing the resource utilization of SSPS.展开更多
Beryllium-containing sludge(BCS)is a typical hazardous waste from Be smelting,which can cause serious harm to ecology and human health by releasing harmful Be if it is stored long-term in environment.Nonetheless,the o...Beryllium-containing sludge(BCS)is a typical hazardous waste from Be smelting,which can cause serious harm to ecology and human health by releasing harmful Be if it is stored long-term in environment.Nonetheless,the occurrence of Be in BCS is unclear,which seriously hinders the development of pollution control technologies.In order to enhance the understanding of BCS,the occurrence of Be and the microscale interactions with coexisting phases were investigated for the first time.It was found that CaSO_(4)·2H_(2)O and amorphous SiO_(2) are the primary phases of BCS.The simulated experiments of purified materials showed that Be interacted with CaSO_(4)·2H_(2)O and amorphous SiO_(2).Be can enter into the lattice of CaSO_(4)·2H_(2)O mainly as free Be2+.Amorphous SiO_(2) can adsorb Be2+particularly at a pH range of 3–5.The dissolution behavior experiment of BCS shows that about 52%of the Be is readily extracted under acidic conditions,which refers to the Be of independent occurrence.In contrast,the remaining 48%of Be can be extracted only after the CaSO_(4)·2H_(2)O has completely dissolved.Hence,CaSO_(4)·2H_(2)O is identified as the key occurrence phase which determines the highly efficient dissolution of Be.As a result,this study enhances the understanding of BCS and lays the foundation for the development of Be separation technologies.展开更多
Biochar is a massively produced by-product of biomass pyrolysis to obtain renewable energy and has not been fully used. Incomplete separation of sludge and effluent and insufficient denitrification of sewage are two o...Biochar is a massively produced by-product of biomass pyrolysis to obtain renewable energy and has not been fully used. Incomplete separation of sludge and effluent and insufficient denitrification of sewage are two of main factors that influence the efficiency of activated sludge process. In this work, we proposed a new utilization of biochar and investigated the effect of biochar addition on the performance of settleability and denitrification of activated sludge. Results show that the addition of biochar can improve the settleability of activated sludge by changing the physicochemical characteristics of sludge （e.g., flocculating ability, zeta-potential, hydrophobicity, and extracellular polymeric substances constituents）. Moreover, the dissolved organic carbon released from biochar obtained at lower pyrolysis temperature can improve the nitrate removal efficiency to a certain extent.展开更多
[Objective] This study aimed to make use of the limited filamentous sludge bulking characteristics to purify water quality and save energy. [Method] The effects of dissolved oxygen （DO） on sludge bulking were explor...[Objective] This study aimed to make use of the limited filamentous sludge bulking characteristics to purify water quality and save energy. [Method] The effects of dissolved oxygen （DO） on sludge bulking were explored by changing the DO con- centration in the aerobiotic pool of NO system from the low load （0.25 kg COD/（kg MLSS.d）） and the medium to high load （0.55 kgCOD/（kg MLSSod））. [Result] In the NO activated sludge system, when the sludge load was 0.25 kg COD/（kg MLSS.d）, DO=1.5 mg/L, the sludge index was at around 250, while when the sludge load- ing was 0.55 kg COD/（kg MLSS.d）, DO=1.5 mg/L, the sludge index was close to 300, occurring the limited filamentous bulking. The bulked sludge still showed high removal rates to COD, SS, nitrogen and phosphorus. [Conclusion] It could improve the oxygen transfer rate and reduce the aeration rate at low DO conditions to achieve energy-saving.展开更多
An engineering technology for the comprehensive treatments of sewage sludge and mine wastewater in smal town was introduced. As fil ing materials, gangue to fil in the col apse basin, construction waste, household ref...An engineering technology for the comprehensive treatments of sewage sludge and mine wastewater in smal town was introduced. As fil ing materials, gangue to fil in the col apse basin, construction waste, household refuse and ex-cess sludge as wel as clay were mixed with water into organic fil ing soil, turning the waste sludge into useful soil matrix, which solved the difficulties in growing plants in the reclaimed land that lack of organic soil. The col apse basin was de-signed into oxidation pond, wetland and land infiltration system to treat industrial wastewater and domestic wastewater, realizing the up-to-standard release after sewage treatment.展开更多
The optimization of process parameters for the bioconversion of activated sludge by Penicillium corylophilum was investigated using response surface methodology （RSM）. The three parameters namely temperature of 33℃...The optimization of process parameters for the bioconversion of activated sludge by Penicillium corylophilum was investigated using response surface methodology （RSM）. The three parameters namely temperature of 33℃, agitation of 150 r/min, and pH of 5 were chosen as center point from the previous study of fungal treatment. The experimental data on chemical oxygen demand （COD） removal （%） were fitted into a quadratic polynomial model using multiple regression analysis. The optimum process conditions were determined by analyzing response surface three-dimensional surface plot and contour plot and by solving the regression model equation with Design Expert software. Box-Behnken design technique under RSM was used to optimize their interactions, which showed that an incubation temperature of 32.5℃, agitation of 105 r/min, and pH of 5.5 were the best conditions. Under these conditions, the maximum predicted yield of COD removal was 98.43%. These optimum conditions were used to evaluate the trail experiment, and the maximum yield of COD removal was recorded as 98.5%.展开更多
The process of using flat-sheet membrane for simultaneous sludge thickening and digestion （MSTD） was employed. The variations of sludge concentration and rheology were characterized and simulated. Based on mass bala...The process of using flat-sheet membrane for simultaneous sludge thickening and digestion （MSTD） was employed. The variations of sludge concentration and rheology were characterized and simulated. Based on mass balance analysis, mathematical models were developed and successfully used to predict and evaluate the variations of sludge concentration and the digestion efficiency in the MSTD process. The apparent viscosity of sludge could be modeled as functions of mixed liquor suspended solids and shear rates. The sludge in the MSTD process showed both shear-thinning and viscoplastic behaviour, and under various shear rates different rheological models could be chosen to predict their flow behaviour. It was also found that sludge concentration and viscosity had significant correlations with membrane fouling in the MSTD process.展开更多
Hybrid system combines the nature of suspended growth and attached growth has been widely applied to wastewater treatment. In this research, the contributions to N transformation and N2O emission by biofilm and suspen...Hybrid system combines the nature of suspended growth and attached growth has been widely applied to wastewater treatment. In this research, the contributions to N transformation and N2O emission by biofilm and suspended sludge in the hybrid sequencing- batch reactor for a simultaneous nitrification, denitrification and phosphorus removal process were investigated. For the hybrid system, nitrification occurred mostly in the suspended sludge, while the biofilm played the major role in denitrification. The interaction of the biofilm and the suspended sludge in the same reactor resulted in a better overall nitrogen removal performance with simultaneous nitrification and denitrification. However, N2O emission was the main end product of nitrogen removal for the hybrid system; while it was N2 for the biofilm. The relative low N2O emissions from the pure biofilm and the pure suspended sludge corresponded to the relatively high nitrate at the end of the aeration period compared with the hybrid system.展开更多
基金supported by the Guangdong Special Support ProgramProject(No.2021JC060580)the Foshan Innovation Team Project(No.2130218003140).
文摘In this study,the effects of different salinity gradients and addition of compatible solutes on anaerobic treated effluent water qualities,sludge characteristics and microbial communities were investigated.The increase in salinity resulted in a decrease in particle size of the granular sludge,which was concentrated in the range of 0.5-1.0 mm.The content of EPS(extracellular polymeric substances)in the granular sludge gradually increased with increasing salinity and the addition of betaine(a typical compatible solute).Meanwhile,the microbial community structure was significantly affected by salinity,with high salinity reducing the diversity of bacteria.At higher salinity,Patescibacteria and Proteobacteria gradually became the dominant phylum,with relative abundance increasing to 13.53%and 12.16%at 20 g/L salinity.Desulfobacterota and its subordinate Desulfovibrio,which secrete EPS in large quantities,dominated significantly after betaine addition.Their relative abundance reached 13.65%and 7.86%at phylum level and genus level.The effect of these changes on the treated effluent was shown as the average chemical oxygen demand(COD)removal rate decreased from 82.10%to 79.71%,78.01%,68.51%and 64.55%when the salinity gradually increased from 2 g/L to 6,10,16 and 20 g/L.At the salinity of 20 g/L,average COD removal increased to 71.65%by the addition of 2 mmol/L betaine.The gradient elevated salinity and the exogenous addition of betaine played an important role in achieving stability of the anaerobic system in a highly saline environment,which provided a feasible strategy for anaerobic treatment of organic saline wastewater.
基金funding of the current work by the Science,Technology,and Innovation Funding Authority(STDF),Egypt,project no.46104:“Recycling of sludge wastes from paper industry via green technologies”.
文摘Saccharification of lignocellulosic wastes is the bottleneck of different bio-based chemical industries.Using enzymes for saccharification of lignocellulosic materials has several advantages over using chemicals.In the current work,the application of the Maximyze■ enzyme system,which is industrially used in papermaking,was investigated in the saccharification of paper sludge and fiber dust wastes from the tissue paper industry.For optimizing the saccharification process,the effects of the consistency%,enzyme loading,and incubation time were studied and optimized using the Response Surface Methodology.The effect of these factors on the weight loss of paper sludge and total sugars in the hydrolyzate was studied.High-Performance Liquid Chromatography(HPLC)was used to measure the sugars composition of the hydrolyzate.Under the optimized conditions,~90% and~66% of the fiber dust and paper sludge could be hydrolyzed into sugars,respectively.The sugar composition was 80.23% glucose,10.99% xylose,and 8.65% arabinose based on the total sugars in the case of fiber dust.In comparison,80.63% glucose,8.43% xylose,and 10.75% arabinose were detected in the case of paper sludge.The results showed the applicability of the Maximyze Rcommercial enzymes used in the paper industry for efficient saccharification of paper sludge and fiber dust.The presence of non-cellulosic materials in the paper sludge(residual ink,paper additives,and ash)didn’t affect the activity of the enzymes.The study also showed the potential use of fiber dust as a valuable and clean source of sugars that can be used to prepare different bio-based chemicals.
文摘Anaerobic digestion(AD)is widely employed for sludge stabilization and waste reduction.However,the slow hydrolysis process hinders methane production and leads to prolonged sludge issues.In this study,an efficient and eco-friendly lysozyme pre-treatment method was utilized to address these challenges.By optimizing lysozyme dosage,hydrolysis and cell lysis were maximized.Furthermore,lysozyme combined with hydrothermal pretreatment enhanced overall efficiency.Results indicate that:(1)When lysozyme dosage reached 90 mg/g TS after 240 min of pretreatment,SCOD,soluble polysaccharides,and protein content reached their maxima at 855.00,44.09,and 204.86 mg/L,respectively.This represented an increase of 85.87%,365.58%,and 259.21%compared to the untreated sludge.Threedimensional fluorescence spectroscopy revealed the highest fluorescence intensity in the IV region(soluble microbial product),promoting microbial metabolic activity.(2)Lysozyme combined with hydrothermal pretreatment significantly increased SCOD,soluble proteins,and polysaccharide release from sludge,reducing SCOD release time.Orthogonal experiments identified Group 3 as the most effective for SCOD and soluble polysaccharide release,while Group 9 released the most soluble proteins.The significance order of factors influencing SCOD,soluble proteins,and polysaccharide release is hydrothermal temperature>hydrothermal time>enzymatic digestion time.(3)The lysozyme-assisted hydrothermal pretreatment group exhibited the fastest release and the highest SCOD concentration of 8,135.00 mg/L during anaerobic digestion.Maximum SCOD consumption and cumulative gas production increased by 95.89%and 130.58%,respectively,compared to the control group,allowing gas production to conclude 3 days earlier.
文摘We read with great interest the investigations conducted by Pourakbar et al.(2024)on the“Stabilization of clay soil using alkali-activated sewage sludge.”The authors have investigated the feasibility of utilizing alkali-activated sewage sludge(AASS)as a binder for stabilizing the clayey soil.Sewage sludge(SS)in varying proportions of 1.5%,2%,2.5%,3.5%,and 4.5%was utilized to prepare geopolymer binders using sodium and potassium-based alkali activators.Furthermore,unconfined compressive strength(UCS)and direct shear tests were conducted to examine the strength development of clayey soil stabilized with AASS.While the study presented some intriguing results,we have identified critical concerns regarding(i)the selection of SS as a precursor for alkali activation,(ii)technical inconsistencies associated with the compaction characteristics and microstructural analysis,and(iii)the feasibility of the proposed methodology for practical applications.Through our discussion,we seek to highlight these issues and provide constructive feedback to advance the understanding of alkali activation processes and their implications for soil stabilization.
基金funded under the auspices of the National Key Research and Development Program of China(No.2023YFC3207404-01)the Postdoctoral Fellowship Program of CPSF(No.GZC20233450)the Heilongjiang Province Postdoctoral Science Foundation(No.LBHZ23154)。
文摘As a key step in waste activated sludge(WAS)treatment and disposal,WAS dewatering can minimize the amount of WAS and decrease the costs of transportation,storage management,treatment,and disposal.Advanced oxidation processes(AOPs)have been widely explored in WAS dewatering due to the excellent oxidizing properties and efficient decomposition capacity since the 21^(st)century.This review outlined the mechanisms of AOPs to improve WAS dewatering and pointed out the shortcomings of the existing mechanisms.Then,the applications of AOPs-based WAS dewatering processes for enhanced WAS dewatering were reviewed,and the intrinsic limitations of AOPs-based WAS dewatering processes in engineering applications were proposed.In addition,an overall review of AOPs-based WAS dewatering researches was also conducted through bibliometric analysis,and future research hotspots in the field of AOPs-based WAS dewatering were proposed.Finally,the positive effects of the AOPs-based WAS dewatering processes on pollutant removal and resource recovery were investigated,and an integrated plan for the harmless disposal of WAS was constructed to achieve a positive reform of the traditional WAS management plan.This review provided theoretical basis and technical reference for the development of efficient,economical,and environmental AOPs for enhanced WAS dewatering to facilitate the application of AOPs in actual WAS dewatering engineering.
基金supported by the Ministry of Science and Technology of China (Nos.2021YFC3200904,and 2022YFC3203705)the National Natural Science Foundation of China (Nos.52070184,and 52270012)the Nanning Scientific Research and Technology Development Project (No.ZC20223238).
文摘Sedimentation sludge water(SSW),a prominent constituent of wastewater from drinking water treatment plants,has received limited attention in terms of its treatment and utilization likely due to the perceived difficulties associated with managing SSW sludge.This study comprehensively evaluated the water quality of SSW by comparing it to a well-documented wastewater(filter backwash water(FBW)).Furthermore,it investigated the pollutant variations in the SSW during pre-sedimentation process,probed the underlying reaction mechanism,and explored the feasibility of employing a pilot-scale coagulation-sedimentation process for SSW treatment.The levels of most water quality parameters were generally comparable between SSW and FBW.During the pre-sedimentation of SSW,significant removal of turbidity,bacterial counts,and dissolved organic matter(DOM)was observed.The characterization of DOM components,molecular weight distributions,and optical properties revealed that the macromolecular proteinaceous biopolymers and humic acids were preferentially removed.The characterization of particulates indicated that high surface energy,zeta potential,and bridging/adsorption/sedimentation/coagulation capacities in aluminum residuals of SSW,underscoring its potential as a coagulant and promoting the generation and sedimentation of inorganic-organic complexes.The coagulation-sedimentation process could effectively remove pollutants from low-turbidity SSW([turbidity]0<15 NTU).These findings provide valuable insights into the water quality dynamics of SSW during the pre-sedimentation process,facilitating the development of SSW quality management and enhancing its reuse rate.
基金supported by the National Natural Science Foundation of China(Grants No.52270155 and 92047201).
文摘Cresyl diphenyl phosphate(CDP),an emerging aryl organophosphate ester(OPE),exhibits potential toxic effects and is frequently found in diverse environmental media,thereby raising concerns about environmental pollution.Biodegradation demonstrates substantial potential for CDP removal from the environment.This study investigated the biodegradation mechanisms of CDP using anaerobic activated sludge(AnAS).The biodegradation of 1-mg/L CDP followed a first-order kinetic model with a degradation kinetic constant of 0.943 d^(-1),and the addition of different electron acceptors affected the degradation rate.High-resolution mass spectrometry identified seven transformation products(TPs)of CDP.The pathways of CDP degradation in anaerobic conditions were proposed,with carboxylation products being the most dominant intermediate products.The structure of the anaerobic microbial community at different degradation time points in CDP-amended microcosms was examined.The linear discriminant analysis(LDA)of effect size(LEfSe)potentially underscored the pivotal role of Methyloversatilis in CDP biodegradation.Zebrafish embryotoxicity experiments revealed both lethal and morphogenetic impacts of CDP on zebrafish embryos.The survival rate,hatching rate,and body length indicators of zebrafish embryos underscored the detoxification of CDP and its resultant intermediates by AnAS.This study offers new insights into the fate and biodegradation mechanisms of CDP in wastewater treatment plants.
基金supported by the National Key Research and Development Project (Nos.2020YFC1908702 and 2021YFC3200700)the National Natural Science Foundation of China (Nos.52192684 and 52192680).
文摘Sewage sludge in cities of Yangzi River Belt,China,generally exhibits a lower organic content and higher silt contentdue to leakage of drainage system,which caused low bioenergy recovery and carbon emission benefits in conventional anaerobic digestion(CAD).Therefore,this paper is on a pilot scale,a bio-thermophilic pretreatment anaerobic digestion(BTPAD)for low organic sludge(volatile solids(VS)of 4%)was operated with a long-term continuous flow of 200 days.The VS degradation rate and CH_(4) yield of BTPAD increased by 19.93%and 53.33%,respectively,compared to those of CAD.The analysis of organic compositions in sludge revealed that BTPAD mainly improved the hydrolysis of proteins in sludge.Further analysis of microbial community proportions by high-throughput sequencing revealed that the short-term bio-thermophilic pretreatment was enriched in Clostridiales,Coprothermobacter and Gelria,was capable of hydrolyzing acidified proteins,and provided more volatile fatty acid(VFA)for the subsequent reaction.Biome combined with fluorescence quantitative polymerase chain reaction(PCR)analysis showed that the number of bacteria with high methanogenic capacity in BTPAD was much higher than that in CAD during the medium temperature digestion stage,indicating that short-term bio-thermophilic pretreatment could provide better methanogenic conditions for BTPAD.Furthermore,the greenhouse gas emission footprint analysis showed that short-term bio-thermophilic pretreatment could reduce the carbon emission of sludge anaerobic digestion system by 19.18%.
基金supported by the National Special Project for Science and Technology on Water Pollution Control and Management(No.2017ZX07102-003)the Fundamental Research Funds for the Central Universities,and the Research Funds of Renmin University of China(No.2020030257).
文摘This study embarks on an explorative investigation into the effects of typical concentrations and varying particle sizes of fine grits(FG,the involatile portion of suspended solids)and fine debris(FD,the volatile yet unbiodegradable fraction of suspended solids)within the influent on themixed liquor volatile suspended solids(MLVSS)/mixed liquor suspended solids(MLSS)ratio of an activated sludge system.Through meticulous experimentation,it was discerned that the addition of FG or FD,the particle size of FG,and the concentration of FD bore no substantial impact on the pollutant removal efficiency(denoted by the removal rate of COD and ammonia nitrogen)under constant operational conditions.However,a notable decrease in the MLVSS/MLSS ratio was observed with a typical FG concentration of 20 mg/L,with smaller FG particle sizes exacerbating this reduction.Additionally,variations in FD concentrations influenced both MLSS andMLVSS/MLSS ratios;a higher FD concentration led to an increased MLSS and a reduced MLVSS/MLSS ratio,indicating FD accumulation in the system.A predictive model for MLVSS/MLSS was constructed based on quality balance calculations,offering a tool for foreseeing the MLVSS/MLSS ratio under stable long-term influent conditions of FG and FD.This model,validated using data from the BXH wastewater treatment plant(WWTP),showcased remarkable accuracy.
基金supported by the National Natural Science Foundation of China(52204331)Natural Science Foundation of Anhui Province Youth Project(2208085QE145)the Open Project Program of Key Laboratory of Metallurgical Emission Reduction&Resources Recycling(Anhui University of Technology),Ministry of Education(JKF20-03).
文摘Steel rolling sludge,an oil-containing waste generated during steel production,was difficult to manage.Prolonged storage poses significant environmental and health hazards.Most steel enterprises in China use steel rolling sludge directly as a raw material for sintering.However,its adhesive nature caused poor mixing with other materials,affecting the quality of the sinter.Herein,the incorporation of steel rolling sludge incineration slag into the sintering process was investigated for experimental purposes.The results indicated that adding 1%incinerated steel rolling sludge to the sintering raw material was feasible.At this proportion,both the yield and the tumbler index of the sinter have improved,primarily due to the oxidation reaction of Fe_(3)O_(4)present in the steel rolling sludge incineration slag during the sintering process,which significantly increases the sensible heat of the sinter and enhances the sintering mineralization reaction.Notably,the addition of steel rolling sludge incineration slag reduced dioxin concentrations in the sintering flue gas.Although CO,NO_(x),and SO_(2)emission concentrations slightly increased,the existing flue gas treatment system effectively controlled their emissions.
基金supported by the National Key Research and Development Program of China(No.2022YFC3901405)the Excellent Youth Project of Anhui Provincial Natural Science Foundation(No.2408085Y030)Overseas Study Funding Program for Young Faculty of Anhui Province(2023-11).
文摘Stainless steel pickling sludge(SSPS)is a by-product of pickling and passivation treatment of stainless steel in the process of stainless steel production.A novel approach for the treatment of the SSPS using the high-temperature nickel-iron blast furnace molten slag(NBFS)was investigated.The results show that the flow temperature of the slag decreases with the increase in the proportion of SSPS.In a certain range,the flow temperature decreases by about 7℃ when the proportion of SSPS increases by 1%.The computational results from FactSage indicate that the addition of SSPS leads to a reduction in MgO content and an increase in CaO and CaSO_(4) contents,which are the reasons for the decrease in the flow temperature.Mortar blocks were prepared by mixing the slag powder prepared by water-quenched slag drying ball milling with 425 Portland cement in a certain proportion.As the proportion of SSPS increased from 0 to 5%,the 7-day strength of mortar blocks increased from 22.32 to 26.98 MPa,and the 28-day strength increased from 37.28 to 41.43 MPa.The 28-day activity index is above 75%,and its activity index meets the requirements of S75 ground granulated blast furnace slag.The industrial application program in the nickel-iron blast furnace with a volume of 550 m^(3) was also put forward,which provides a new way for realizing the resource utilization of SSPS.
基金supported by the National Natural Science Foundation of China(No.22276219)the foundation for Innovative Research Groups of the National Natural Science Foundation of China(No.52121004)+1 种基金the major program Natural Science Foundation of Hunan Province of China(No.2021JC0001)the Fundamental Research Funds for the Central Universities of Central South University(No.2024ZZTS0063).
文摘Beryllium-containing sludge(BCS)is a typical hazardous waste from Be smelting,which can cause serious harm to ecology and human health by releasing harmful Be if it is stored long-term in environment.Nonetheless,the occurrence of Be in BCS is unclear,which seriously hinders the development of pollution control technologies.In order to enhance the understanding of BCS,the occurrence of Be and the microscale interactions with coexisting phases were investigated for the first time.It was found that CaSO_(4)·2H_(2)O and amorphous SiO_(2) are the primary phases of BCS.The simulated experiments of purified materials showed that Be interacted with CaSO_(4)·2H_(2)O and amorphous SiO_(2).Be can enter into the lattice of CaSO_(4)·2H_(2)O mainly as free Be2+.Amorphous SiO_(2) can adsorb Be2+particularly at a pH range of 3–5.The dissolution behavior experiment of BCS shows that about 52%of the Be is readily extracted under acidic conditions,which refers to the Be of independent occurrence.In contrast,the remaining 48%of Be can be extracted only after the CaSO_(4)·2H_(2)O has completely dissolved.Hence,CaSO_(4)·2H_(2)O is identified as the key occurrence phase which determines the highly efficient dissolution of Be.As a result,this study enhances the understanding of BCS and lays the foundation for the development of Be separation technologies.
文摘Biochar is a massively produced by-product of biomass pyrolysis to obtain renewable energy and has not been fully used. Incomplete separation of sludge and effluent and insufficient denitrification of sewage are two of main factors that influence the efficiency of activated sludge process. In this work, we proposed a new utilization of biochar and investigated the effect of biochar addition on the performance of settleability and denitrification of activated sludge. Results show that the addition of biochar can improve the settleability of activated sludge by changing the physicochemical characteristics of sludge （e.g., flocculating ability, zeta-potential, hydrophobicity, and extracellular polymeric substances constituents）. Moreover, the dissolved organic carbon released from biochar obtained at lower pyrolysis temperature can improve the nitrate removal efficiency to a certain extent.
基金Supported by the National Natural Science Foundation of China(51208068)~~
文摘[Objective] This study aimed to make use of the limited filamentous sludge bulking characteristics to purify water quality and save energy. [Method] The effects of dissolved oxygen （DO） on sludge bulking were explored by changing the DO con- centration in the aerobiotic pool of NO system from the low load （0.25 kg COD/（kg MLSS.d）） and the medium to high load （0.55 kgCOD/（kg MLSSod））. [Result] In the NO activated sludge system, when the sludge load was 0.25 kg COD/（kg MLSS.d）, DO=1.5 mg/L, the sludge index was at around 250, while when the sludge load- ing was 0.55 kg COD/（kg MLSS.d）, DO=1.5 mg/L, the sludge index was close to 300, occurring the limited filamentous bulking. The bulked sludge still showed high removal rates to COD, SS, nitrogen and phosphorus. [Conclusion] It could improve the oxygen transfer rate and reduce the aeration rate at low DO conditions to achieve energy-saving.
基金Supported by the National Natural Science Foundation of China(51208068)~~
文摘An engineering technology for the comprehensive treatments of sewage sludge and mine wastewater in smal town was introduced. As fil ing materials, gangue to fil in the col apse basin, construction waste, household refuse and ex-cess sludge as wel as clay were mixed with water into organic fil ing soil, turning the waste sludge into useful soil matrix, which solved the difficulties in growing plants in the reclaimed land that lack of organic soil. The col apse basin was de-signed into oxidation pond, wetland and land infiltration system to treat industrial wastewater and domestic wastewater, realizing the up-to-standard release after sewage treatment.
文摘The optimization of process parameters for the bioconversion of activated sludge by Penicillium corylophilum was investigated using response surface methodology （RSM）. The three parameters namely temperature of 33℃, agitation of 150 r/min, and pH of 5 were chosen as center point from the previous study of fungal treatment. The experimental data on chemical oxygen demand （COD） removal （%） were fitted into a quadratic polynomial model using multiple regression analysis. The optimum process conditions were determined by analyzing response surface three-dimensional surface plot and contour plot and by solving the regression model equation with Design Expert software. Box-Behnken design technique under RSM was used to optimize their interactions, which showed that an incubation temperature of 32.5℃, agitation of 105 r/min, and pH of 5.5 were the best conditions. Under these conditions, the maximum predicted yield of COD removal was 98.43%. These optimum conditions were used to evaluate the trail experiment, and the maximum yield of COD removal was recorded as 98.5%.
基金supported by the Foundation of Chinese State Key Laboratory of Pollution Control and Resource Reuse for Young Scholars (No. PCRRY08005)by the Science and Technology Commission of Shanghai Municipality (No. 08231200200)
文摘The process of using flat-sheet membrane for simultaneous sludge thickening and digestion （MSTD） was employed. The variations of sludge concentration and rheology were characterized and simulated. Based on mass balance analysis, mathematical models were developed and successfully used to predict and evaluate the variations of sludge concentration and the digestion efficiency in the MSTD process. The apparent viscosity of sludge could be modeled as functions of mixed liquor suspended solids and shear rates. The sludge in the MSTD process showed both shear-thinning and viscoplastic behaviour, and under various shear rates different rheological models could be chosen to predict their flow behaviour. It was also found that sludge concentration and viscosity had significant correlations with membrane fouling in the MSTD process.
文摘Hybrid system combines the nature of suspended growth and attached growth has been widely applied to wastewater treatment. In this research, the contributions to N transformation and N2O emission by biofilm and suspended sludge in the hybrid sequencing- batch reactor for a simultaneous nitrification, denitrification and phosphorus removal process were investigated. For the hybrid system, nitrification occurred mostly in the suspended sludge, while the biofilm played the major role in denitrification. The interaction of the biofilm and the suspended sludge in the same reactor resulted in a better overall nitrogen removal performance with simultaneous nitrification and denitrification. However, N2O emission was the main end product of nitrogen removal for the hybrid system; while it was N2 for the biofilm. The relative low N2O emissions from the pure biofilm and the pure suspended sludge corresponded to the relatively high nitrate at the end of the aeration period compared with the hybrid system.
