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
Diatomite is a kind of natural low-cost mineral material. It has a number of unique physical properties and has been widely used as an adsorbent in wastewater treatment. This study was conducted to investigate the aer...Diatomite is a kind of natural low-cost mineral material. It has a number of unique physical properties and has been widely used as an adsorbent in wastewater treatment. This study was conducted to investigate the aerobic biodegradation of coal gasification wastewater with and without diatomite addition. Experimental results indicated that diatomite added in the activated sludge system could promote the biomass and also enhance the performance of the sludge settling. The average mixed-liquor volatile suspended solids （MLVSS） is increased from 4055 mg.L^-1 to 4518 mg.L^-1 and the average settling volume （SV） are changed only from 45.9% to 47.1%. Diatomite additive could enhance the efficiency of chemical oxygen demand （COD） and total phenols removal from the wastewater. The COD removal increased from 73.3% to near 80% and the total phenols removal increased from 81.4% to 85.8%. The mechanisms of the increase of biomass and pollutants removal may correlates to the improvement of bioavailability and sludge settlement characteristics by diatomite added. Micrograph of the sludge in the diatomite-activated sludge system indicated that the diatomite added could be the carrier of the microbe and also affect the biomass and pollutant removal.展开更多
To investigate the influence of salinity variations on the performance of activated sludge systems, treating domestic wastewater. Methods The completely mixed reactor was used and operated in a batch-wis...To investigate the influence of salinity variations on the performance of activated sludge systems, treating domestic wastewater. Methods The completely mixed reactor was used and operated in a batch-wise mode. The activated sludge taken from the Gaobeidian Wastewater Treatment Plant was used as a seeding sludge. Total organic carbon (TOC), oxygen uptake rate (OUR) and suspended solids (SS) were used as parameters to characterize the performance of the treatment systems. TOC was measured using a TOC-analyzer (TOC-5000, Japan). The OUR value was measured with a dissolved oxygen meter (YSI model-58). SS was measured gravimetrically. Results The TOC removal efficiency and the OUR value of activated sludge were not deteriorated when the NaCl shock concentration was less than 0.5 g/L. However, when the NaCl shock concentrations were up to 10g/L and 20 g/L, the OUR of activated sludge was reduced by 35% and TOC removal efficiency was dropped by 30%, compared with the control experiment without NaCl shock loading. Conclusion The effect of NaCl shock loading on the activated sludge wastewater treatment system is dependant upon the NaCl concentrations and the degree of influence can be inferred through the change of substrate utilization rate at different shock NaCl loadings.展开更多
Based on the operation data from a certain wastewater treatment plant(WWTP) in northeast China, the models of back propagation neural network(BP NN) and radial basis function neural network(RBF NN) have been designed ...Based on the operation data from a certain wastewater treatment plant(WWTP) in northeast China, the models of back propagation neural network(BP NN) and radial basis function neural network(RBF NN) have been designed respectively and the ability of convergence and generalization has been analyzed separately. As for BP NN, the effects of numbers of layers and nodes have been studied; as for RBF NN, the influences of the number of nodes and the RBF′s width have been studied. It is concluded that BP NN has converged much slowly in comparison with RBF NN. The conclusion that the RBF NN is suitable for modeling activated sludge system has been drawn. An automatically optimum design program for RBF NN has been developed, through which the RBF NN model of traditional activated sludge system has been established.展开更多
Respirogram technology has been widely applied for aerobic process, however, the response of respirogram to anoxic denitrification is still unclear. To reveal such response may help to design a new method for the eval...Respirogram technology has been widely applied for aerobic process, however, the response of respirogram to anoxic denitrification is still unclear. To reveal such response may help to design a new method for the evaluation of the performance of denitrification. The size distribution of flocs measured at different denitrification moments demonstrated a clear expansion of flocs triggered by denitrification, during which higher specific endogenous and quasi-endogenous respiration rates(SOUReand SOURq) were also observed. Furthermore,SOURqincreases exponentially with the specific denitrification rate(SDNR), suggesting that there should be a maximum SDNR in conventional activated sludge systems. Based on these findings, an index Rq/t, defined as the ratio of quasi-endogenous(OURq) to maximum respiration rate(OURt), is proposed to estimate the denitrification capacity that higher Rq/tindicates higher denitrification potential, which can be readily obtained without complex measurement or analysis, and it offers a novel and promising respirogram-based approach for denitrification estimation and control by taking measures to extend anoxic time to maintain its value at a high level within a certain range.展开更多
A recent study conducted on the four activated systems serving the surrounding communities in the Northern Gauteng revealed the failure of three of these wastewater treatment plants to remove enteric pathogenic bacter...A recent study conducted on the four activated systems serving the surrounding communities in the Northern Gauteng revealed the failure of three of these wastewater treatment plants to remove enteric pathogenic bacteria and protozoan parasites such as Cryptosporidium and Giardia spp. To determine the factors involved in the inadequate performance of the plants, the following parameters were considered： the design characteristic of the plants, the microbiological structure and the physical characteristics of the plants. The results revealed that higher than optimal influent loadings and inadequate aeration systems, observed in Baviaanspoort, Refilwe and Rayton Water Care Works （WCW） increased the composition of filamentous bacteria in flocs and decreased the diversity of protozoan species in the sludge. Sequentially, these resulted in the poor settling properties of the sludge at these plants. However, Zeekoegat WCW showed optimum influent loads and adequate aeration systems. This maintained balance in the microbial community, resulting in good clarification of the sludge.展开更多
Vinasse is the main residue generated during alcohol, sugar and blue rum production by fermentation process. This residue is effluent that could cause serious environmental pollution due to high organic load when is n...Vinasse is the main residue generated during alcohol, sugar and blue rum production by fermentation process. This residue is effluent that could cause serious environmental pollution due to high organic load when is not treated adequately. The aim of this work consists of evaluating the efficiency and application of heterogeneous photocatalysis with TiO2, followed by a biological treatment (activated sludge system) to reduce organic load in the referred effluent. Complete factorial designs indicated the best experimental conditions subsequent to photacatalytic and biological treatments providing a reduction of non-purgeable organic carbon (NPOC) as a variable response. After the photocatalytic process, the sample from the best experiment condition was treated by a biological process in order to verify the degradation efficiency of the effluent organic matter studied according to the hybrid system (Advanced Oxidation Process—Acti- vated Sludge System). This system, which presented more efficiency, had a photochemical treatment of 180 minutes carried out in aerated solutions, pH 9 and effluent in natura, while the biological treatment was performed at pH 8 and sludge concentration of 5 gL–1. The reduction of biochemical oxygen demand (BOD) was >80%.展开更多
Aerobic granules were formed in a conven- tional, continuous flow, completely mixed activated sludge system （CMAS）. The reactor was inoculated with seed sludge containing few filaments and fed with synthetic municip...Aerobic granules were formed in a conven- tional, continuous flow, completely mixed activated sludge system （CMAS）. The reactor was inoculated with seed sludge containing few filaments and fed with synthetic municipal wastewater. The settling time of the sludge and the average dissolved oxygen （DO） of the reactor were 2 h and 4.2 mg. L 1, respectively. The reactor was agitated by a stirrer, with a speed of 250r·min^-1, to ensure good mixing . The granular sludge had good settleability, and the sludge volume index （SVI） was between 50 and 90 mL ·g ^-1. The laser particle analyzer showed the diameter of the granules to be between 0.18 and 1.25 mm. A scanning electron microscope （SEM） investigation revealed the predominance of sphere-like and rod-like bacteria, and only few filaments grew in the granules. The microbial community structure of the granules was also analyzed by polymerase chain reaction-denaturing gradient gel electro- phoresis （PCR-DGGE）. Sequencing analysis indicated the dominant species were α, β, and γ-Proteobacteria, Bacteroidetes, and Firmicutes. The data from the study suggested that aerobic granules could form, if provided with sufficient number of filaments and high shear force. It was also observed that a high height-to-diameter ratio of the reactor and short settling time were not essential for the formation of aerobic granular sludge.展开更多
Popular descriptive multivariate statistical method currently employed is the principal component analyses （PCA） method. PCA is used to develop linear combinations that successively maximize the total variance of a ...Popular descriptive multivariate statistical method currently employed is the principal component analyses （PCA） method. PCA is used to develop linear combinations that successively maximize the total variance of a sample where there is no known group structure. This study aimed at demonstrating the performance evaluation of pilot activated sludge treatment system by inoculating a strain of Pseudomonas capable of degrading malathion which was isolated by enrichment technique. An intensive analytical program was followed for evaluating the efficiency of biosimulator by maintaining the dissolved oxygen （DO） concentration at 4.0 mg/L. Analyses by high performance liquid chromatographic technique revealed that 90% of malathion removal was achieved within 29 h of treatment whereas COD got reduced considerably during the treatment process and mean removal efficiency was found to be 78%. The mean pH values increased gradually during the treatment process ranging from 7.36-8.54. Similarly the mean ammonia-nitrogen （NH3-N） values were found to be fluctuating between 19.425-28.488 mg/L, mean nitrite-nitrogen （NO3-N） ranging between 1.301- 2.940 mg/L and mean nitrate-nitrogen （NO3-N） ranging between 0.0071-0.0711 mg/L. The study revealed that inoculation of bacterial culture under laboratory conditions could be used in bioremediation of environmental pollution caused by xenobiotics. The PCA analyses showed that pH, COD, organic load and total malathion concentration were highly correlated and emerged as the variables controlling the first component, whereas dissolved oxygen, NO3-N and NH3-N governed the second component. The third component repeated the trend exhibited by the first two components.展开更多
With the increasing use of antibiotics and rare earth elements(REE)during the coronavirus disease(COVID-19)pandemic,the co-occurrence of sulfamethoxazole(SMX)and gadolinium(Gd)has increased in wastewater treatment pla...With the increasing use of antibiotics and rare earth elements(REE)during the coronavirus disease(COVID-19)pandemic,the co-occurrence of sulfamethoxazole(SMX)and gadolinium(Gd)has increased in wastewater treatment plants(WWTPs).However,the effects of SMX and Gd exposure on the transmission of antibiotic resistance genes(ARGs)and heavy metal resistance genes(MRGs)remain unknown.This study investigated the impacts of SMX and Gd on the fate of ARGs and MRGs in an activated sludge system.The diversity and relative abundance of ARGs,MRGs,and mobile genetic elements(MGEs)were detected by metagenomic sequencing.The results revealed an increased abundance of ARGs but a decreased abundance of MRGs under the joint effect of SMX and Gd.In addition,Gd alone exerted adverse effects on the proliferation and spread of ARGs and MRGs.However,SMX alone resulted in an increase in the diversity of ARGs and MRGs and promoted the growth of Pseudomonas,Thauera,and Streptomyces in the activated sludge system.Interestingly,a positive correlation was observed between most ARGs and MGEs.These findings provide comprehensive insights into the effects of co-occurring REEs and antibiotics on the fate of ARGs,MRGs,and MGEs,providing evidence to assist in controlling the spread and proliferation of ARGs and MRGs in activated sludge systems.展开更多
We investigated the communities of ammonia-oxidizing bacteria （AOB） in activated sludge collected from eight wastewater treatment systems using polymerase chain reaction （PCR） followed by terminal restriction frag...We investigated the communities of ammonia-oxidizing bacteria （AOB） in activated sludge collected from eight wastewater treatment systems using polymerase chain reaction （PCR） followed by terminal restriction fragment length polymorphism （T-RFLP）, cloning, and sequencing of the α-subunit of the ammonia monooxygenase gene （amoA）. The T-RFLP fingerprint analyses showed that different wastewater treatment systems harbored distinct AOB communities. However, there was no remarkable difference among the AOB T- RFLP profiles from different parts of the same system. The T-RFLP fingerprints showed that a full-scale wastewater treatment plant （WWTP） contained a larger number of dominant AOB species than a pilot-scale reactor. The source of influent affected the AOB community, and the WWTPs treating domestic wastewater contained a higher AOB diversity than those receiving mixed domestic and industrial wastewater. However, the AOB community structure was little affected by the treatment process in this study. Phylogenetic analysis of the cloned amoA genes clearly indicated that all the dominant AOB in the systems was closely related to Nitrosomonas spp. not to Nitrosospira spp. Members of the Nitrosomonas oligotropha and Nitrosomonas communis clusters were found in all samples, while members of Nitrosomonas europaea cluster occurred in some systems.展开更多
In the biofilm and activated sludge combined system, denitrifying bacteria attached on the fibrous carriers in the anoxic tank, while the sludge containing nitrifying and phosphorus removal bacteria was only recircula...In the biofilm and activated sludge combined system, denitrifying bacteria attached on the fibrous carriers in the anoxic tank, while the sludge containing nitrifying and phosphorus removal bacteria was only recirculated between the aerobic and anaerobic tanks. Therefore, the factors affected and restricted nitrification, denitrification and phosphorus removal in a traditional A/A/O process were resolved. This paper describes the optimum operation conditions for nitrogen and phosphorus removal using this system.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
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
Anaerobic ammonia oxidation(Anammox)is an economical and sustainablewastewater nitrogen removal technology,and its application in the mainstream process is the inevitable trend of the development of Anammox.However,ho...Anaerobic ammonia oxidation(Anammox)is an economical and sustainablewastewater nitrogen removal technology,and its application in the mainstream process is the inevitable trend of the development of Anammox.However,how to effectively enriching Anammox bacteria from the activated sludge remains challenging and restricts its extensive applications.In this study,the rapid and efficient enrichment of Anammox bacteriawas achieved by raising the reflux ratio and nitrogen loading rate(NLR)using conventional activated sludge as the inoculant.In the screening phase(days 1–90),the reflux ratio was increased to discharge partial floc sludge,resulting in the relative abundance of Candidatus Brocadiaceae increased from0.04%to 22.54%,which effectively reduced thematrix and spatial competition between other microorganisms and Anammox bacteria.On day 90,the stoichiometric ratio of the Anammox process closely approached the theoretical value of 1:1.32:0.26,indicating that the Anammox reaction was the primary nitrogen removal process in the system.In the enrichment phase(days 91–238),the NLR increased from 0.43 to 1.20 kgN/(m^(3)·d)and removal efficiency was 71.89%,resulting in the relative abundance of Candidatus Brocadiaceae increased to 61.27%on day 180.The reactor operated steadily from days 444 to 498,maintaining the nitrogen removal rate(NRR)of 3.00 kgN/(m^(3)·d)and achieving successful sludge granulation with the particle size of 392.4μm.In short,this study provided a simple and efficient approach for enriching Anammox bacteria from the activated sludge,supporting to start an Anammox process efficiently.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
The effect of mid-stage pulping wastewater(as shock load)on micro-aerobic magnetic activated sludge system was studied.Micro-aerobic activated sludge systems with and without magnetic particles were shocked with mid-s...The effect of mid-stage pulping wastewater(as shock load)on micro-aerobic magnetic activated sludge system was studied.Micro-aerobic activated sludge systems with and without magnetic particles were shocked with mid-stage wastewater for 16 days.“Recovery”experiments were conducted by using simulated wastewater for 12 days.Upon the addition of mid-stage wastewater,CODCr removal pertaining to the use of magnetic particles reached 71.57%and remained above 80%in the“recovery”experiment.However,the efficiency of the reactor in the absence of magnetic particles was only 37.29%,and reached about 40%in the“recovery”experiment.After the micro-aerobic activated sludge was shocked,the flocculation performance and surface properties of the sludge were analyzed,and the results showed that all indicators of the reactors in the presence of magnetic particles were superior to those of reactors without magnetic particles.After 12 days of“recovery”,the indicators of the sludge pertaining to the reactors containing magnetic particles“recovered”completely.展开更多
In this paper, starting from the action mechanism of environmental osmotic pressure and microorganisms in activated sludge, a wastewater sample from a wastewater treatment plant was selected to determine the impact of...In this paper, starting from the action mechanism of environmental osmotic pressure and microorganisms in activated sludge, a wastewater sample from a wastewater treatment plant was selected to determine the impact of chloride ion concentration on its wastewater treatment effect, and mixed solutions with different chloride ion concentrations were prepared to test the nitrification and denitrification effects, and the comprehensive evaluation of sludge activity and drainage water quality was realized. The research results show that the microorganisms contained in activated sludge have certain chloride ion tolerance ability, but when the chloride ion concentration changes abruptly or exceeds the limit value, it will damage the microorganisms and reduce the sludge activity and the treatment effect. In the actual production process, measures such as A2O-MBBR improvement process, activated sludge domestication method, wastewater dilution and other chemical substances addition can also be introduced in combination with the actual production requirements to effectively adjust the chloride ion concentration, reduce the impact of chloride ion on sludge activity and improve the system treatment efficiency.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
This paper researched a promising biological treatment of methyl violet waste water by methods of activated sludge.Effects of temperature and pH were studied on this process.Kinetic equation ...This paper researched a promising biological treatment of methyl violet waste water by methods of activated sludge.Effects of temperature and pH were studied on this process.Kinetic equation of the substrate biodegradation was investigated in the experimental range.It was studied and simulated that flow within the bubble region of this bioreactor according to the κ ε two fluid equation.Simulation results agree well with experimental data.展开更多
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 Shanghai Committee of Education (07ZZ158)
文摘Diatomite is a kind of natural low-cost mineral material. It has a number of unique physical properties and has been widely used as an adsorbent in wastewater treatment. This study was conducted to investigate the aerobic biodegradation of coal gasification wastewater with and without diatomite addition. Experimental results indicated that diatomite added in the activated sludge system could promote the biomass and also enhance the performance of the sludge settling. The average mixed-liquor volatile suspended solids （MLVSS） is increased from 4055 mg.L^-1 to 4518 mg.L^-1 and the average settling volume （SV） are changed only from 45.9% to 47.1%. Diatomite additive could enhance the efficiency of chemical oxygen demand （COD） and total phenols removal from the wastewater. The COD removal increased from 73.3% to near 80% and the total phenols removal increased from 81.4% to 85.8%. The mechanisms of the increase of biomass and pollutants removal may correlates to the improvement of bioavailability and sludge settlement characteristics by diatomite added. Micrograph of the sludge in the diatomite-activated sludge system indicated that the diatomite added could be the carrier of the microbe and also affect the biomass and pollutant removal.
基金The work was supported by the National Natural Science Foundation of China (Grant No. 29637010 59978020 50325824).
文摘To investigate the influence of salinity variations on the performance of activated sludge systems, treating domestic wastewater. Methods The completely mixed reactor was used and operated in a batch-wise mode. The activated sludge taken from the Gaobeidian Wastewater Treatment Plant was used as a seeding sludge. Total organic carbon (TOC), oxygen uptake rate (OUR) and suspended solids (SS) were used as parameters to characterize the performance of the treatment systems. TOC was measured using a TOC-analyzer (TOC-5000, Japan). The OUR value was measured with a dissolved oxygen meter (YSI model-58). SS was measured gravimetrically. Results The TOC removal efficiency and the OUR value of activated sludge were not deteriorated when the NaCl shock concentration was less than 0.5 g/L. However, when the NaCl shock concentrations were up to 10g/L and 20 g/L, the OUR of activated sludge was reduced by 35% and TOC removal efficiency was dropped by 30%, compared with the control experiment without NaCl shock loading. Conclusion The effect of NaCl shock loading on the activated sludge wastewater treatment system is dependant upon the NaCl concentrations and the degree of influence can be inferred through the change of substrate utilization rate at different shock NaCl loadings.
文摘Based on the operation data from a certain wastewater treatment plant(WWTP) in northeast China, the models of back propagation neural network(BP NN) and radial basis function neural network(RBF NN) have been designed respectively and the ability of convergence and generalization has been analyzed separately. As for BP NN, the effects of numbers of layers and nodes have been studied; as for RBF NN, the influences of the number of nodes and the RBF′s width have been studied. It is concluded that BP NN has converged much slowly in comparison with RBF NN. The conclusion that the RBF NN is suitable for modeling activated sludge system has been drawn. An automatically optimum design program for RBF NN has been developed, through which the RBF NN model of traditional activated sludge system has been established.
基金supported by the National Natural Science Foundation of China (Nos. 51878539, 52070149)the Technology Innovation and Level Promotion Project of Shanghai State-owned Assets Supervision and Administration Commission (No. 2018001)。
文摘Respirogram technology has been widely applied for aerobic process, however, the response of respirogram to anoxic denitrification is still unclear. To reveal such response may help to design a new method for the evaluation of the performance of denitrification. The size distribution of flocs measured at different denitrification moments demonstrated a clear expansion of flocs triggered by denitrification, during which higher specific endogenous and quasi-endogenous respiration rates(SOUReand SOURq) were also observed. Furthermore,SOURqincreases exponentially with the specific denitrification rate(SDNR), suggesting that there should be a maximum SDNR in conventional activated sludge systems. Based on these findings, an index Rq/t, defined as the ratio of quasi-endogenous(OURq) to maximum respiration rate(OURt), is proposed to estimate the denitrification capacity that higher Rq/tindicates higher denitrification potential, which can be readily obtained without complex measurement or analysis, and it offers a novel and promising respirogram-based approach for denitrification estimation and control by taking measures to extend anoxic time to maintain its value at a high level within a certain range.
文摘A recent study conducted on the four activated systems serving the surrounding communities in the Northern Gauteng revealed the failure of three of these wastewater treatment plants to remove enteric pathogenic bacteria and protozoan parasites such as Cryptosporidium and Giardia spp. To determine the factors involved in the inadequate performance of the plants, the following parameters were considered： the design characteristic of the plants, the microbiological structure and the physical characteristics of the plants. The results revealed that higher than optimal influent loadings and inadequate aeration systems, observed in Baviaanspoort, Refilwe and Rayton Water Care Works （WCW） increased the composition of filamentous bacteria in flocs and decreased the diversity of protozoan species in the sludge. Sequentially, these resulted in the poor settling properties of the sludge at these plants. However, Zeekoegat WCW showed optimum influent loads and adequate aeration systems. This maintained balance in the microbial community, resulting in good clarification of the sludge.
基金Fundacao de Amparo a Pes- quisa do Estado de Sao Paulo
文摘Vinasse is the main residue generated during alcohol, sugar and blue rum production by fermentation process. This residue is effluent that could cause serious environmental pollution due to high organic load when is not treated adequately. The aim of this work consists of evaluating the efficiency and application of heterogeneous photocatalysis with TiO2, followed by a biological treatment (activated sludge system) to reduce organic load in the referred effluent. Complete factorial designs indicated the best experimental conditions subsequent to photacatalytic and biological treatments providing a reduction of non-purgeable organic carbon (NPOC) as a variable response. After the photocatalytic process, the sample from the best experiment condition was treated by a biological process in order to verify the degradation efficiency of the effluent organic matter studied according to the hybrid system (Advanced Oxidation Process—Acti- vated Sludge System). This system, which presented more efficiency, had a photochemical treatment of 180 minutes carried out in aerated solutions, pH 9 and effluent in natura, while the biological treatment was performed at pH 8 and sludge concentration of 5 gL–1. The reduction of biochemical oxygen demand (BOD) was >80%.
基金Acknowledgements This research was supported by the National Natural Science Foundation of China （Grant No. 50878180）.
文摘Aerobic granules were formed in a conven- tional, continuous flow, completely mixed activated sludge system （CMAS）. The reactor was inoculated with seed sludge containing few filaments and fed with synthetic municipal wastewater. The settling time of the sludge and the average dissolved oxygen （DO） of the reactor were 2 h and 4.2 mg. L 1, respectively. The reactor was agitated by a stirrer, with a speed of 250r·min^-1, to ensure good mixing . The granular sludge had good settleability, and the sludge volume index （SVI） was between 50 and 90 mL ·g ^-1. The laser particle analyzer showed the diameter of the granules to be between 0.18 and 1.25 mm. A scanning electron microscope （SEM） investigation revealed the predominance of sphere-like and rod-like bacteria, and only few filaments grew in the granules. The microbial community structure of the granules was also analyzed by polymerase chain reaction-denaturing gradient gel electro- phoresis （PCR-DGGE）. Sequencing analysis indicated the dominant species were α, β, and γ-Proteobacteria, Bacteroidetes, and Firmicutes. The data from the study suggested that aerobic granules could form, if provided with sufficient number of filaments and high shear force. It was also observed that a high height-to-diameter ratio of the reactor and short settling time were not essential for the formation of aerobic granular sludge.
文摘Popular descriptive multivariate statistical method currently employed is the principal component analyses （PCA） method. PCA is used to develop linear combinations that successively maximize the total variance of a sample where there is no known group structure. This study aimed at demonstrating the performance evaluation of pilot activated sludge treatment system by inoculating a strain of Pseudomonas capable of degrading malathion which was isolated by enrichment technique. An intensive analytical program was followed for evaluating the efficiency of biosimulator by maintaining the dissolved oxygen （DO） concentration at 4.0 mg/L. Analyses by high performance liquid chromatographic technique revealed that 90% of malathion removal was achieved within 29 h of treatment whereas COD got reduced considerably during the treatment process and mean removal efficiency was found to be 78%. The mean pH values increased gradually during the treatment process ranging from 7.36-8.54. Similarly the mean ammonia-nitrogen （NH3-N） values were found to be fluctuating between 19.425-28.488 mg/L, mean nitrite-nitrogen （NO3-N） ranging between 1.301- 2.940 mg/L and mean nitrate-nitrogen （NO3-N） ranging between 0.0071-0.0711 mg/L. The study revealed that inoculation of bacterial culture under laboratory conditions could be used in bioremediation of environmental pollution caused by xenobiotics. The PCA analyses showed that pH, COD, organic load and total malathion concentration were highly correlated and emerged as the variables controlling the first component, whereas dissolved oxygen, NO3-N and NH3-N governed the second component. The third component repeated the trend exhibited by the first two components.
基金supported by the National Key R&D Program of China(No.2019YFC0408500).
文摘With the increasing use of antibiotics and rare earth elements(REE)during the coronavirus disease(COVID-19)pandemic,the co-occurrence of sulfamethoxazole(SMX)and gadolinium(Gd)has increased in wastewater treatment plants(WWTPs).However,the effects of SMX and Gd exposure on the transmission of antibiotic resistance genes(ARGs)and heavy metal resistance genes(MRGs)remain unknown.This study investigated the impacts of SMX and Gd on the fate of ARGs and MRGs in an activated sludge system.The diversity and relative abundance of ARGs,MRGs,and mobile genetic elements(MGEs)were detected by metagenomic sequencing.The results revealed an increased abundance of ARGs but a decreased abundance of MRGs under the joint effect of SMX and Gd.In addition,Gd alone exerted adverse effects on the proliferation and spread of ARGs and MRGs.However,SMX alone resulted in an increase in the diversity of ARGs and MRGs and promoted the growth of Pseudomonas,Thauera,and Streptomyces in the activated sludge system.Interestingly,a positive correlation was observed between most ARGs and MGEs.These findings provide comprehensive insights into the effects of co-occurring REEs and antibiotics on the fate of ARGs,MRGs,and MGEs,providing evidence to assist in controlling the spread and proliferation of ARGs and MRGs in activated sludge systems.
基金supported by the Key Projects in National Science & Technology Pillar Program during the Eleventh Five-Year Plan Period (No.2006BAC19B01-02)the Mega-projects of Science Research for Water (No.2008ZX07313-3)the Program of Introducing Talents of Discipline to Universities
文摘We investigated the communities of ammonia-oxidizing bacteria （AOB） in activated sludge collected from eight wastewater treatment systems using polymerase chain reaction （PCR） followed by terminal restriction fragment length polymorphism （T-RFLP）, cloning, and sequencing of the α-subunit of the ammonia monooxygenase gene （amoA）. The T-RFLP fingerprint analyses showed that different wastewater treatment systems harbored distinct AOB communities. However, there was no remarkable difference among the AOB T- RFLP profiles from different parts of the same system. The T-RFLP fingerprints showed that a full-scale wastewater treatment plant （WWTP） contained a larger number of dominant AOB species than a pilot-scale reactor. The source of influent affected the AOB community, and the WWTPs treating domestic wastewater contained a higher AOB diversity than those receiving mixed domestic and industrial wastewater. However, the AOB community structure was little affected by the treatment process in this study. Phylogenetic analysis of the cloned amoA genes clearly indicated that all the dominant AOB in the systems was closely related to Nitrosomonas spp. not to Nitrosospira spp. Members of the Nitrosomonas oligotropha and Nitrosomonas communis clusters were found in all samples, while members of Nitrosomonas europaea cluster occurred in some systems.
文摘In the biofilm and activated sludge combined system, denitrifying bacteria attached on the fibrous carriers in the anoxic tank, while the sludge containing nitrifying and phosphorus removal bacteria was only recirculated between the aerobic and anaerobic tanks. Therefore, the factors affected and restricted nitrification, denitrification and phosphorus removal in a traditional A/A/O process were resolved. This paper describes the optimum operation conditions for nitrogen and phosphorus removal using this system.
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 Natural Science Foundation of China(No.52070149)Shaanxi Innovative Research Team for Key Science and Technology(No.2023-CXTD-36)+1 种基金Shaanxi Province Key Program for International S&T Cooperation Projects(No.2024GH-ZDXM-04)the Bureau of Science and Technology of Xi’an City of China(No.23SFSF0011).
文摘Anaerobic ammonia oxidation(Anammox)is an economical and sustainablewastewater nitrogen removal technology,and its application in the mainstream process is the inevitable trend of the development of Anammox.However,how to effectively enriching Anammox bacteria from the activated sludge remains challenging and restricts its extensive applications.In this study,the rapid and efficient enrichment of Anammox bacteriawas achieved by raising the reflux ratio and nitrogen loading rate(NLR)using conventional activated sludge as the inoculant.In the screening phase(days 1–90),the reflux ratio was increased to discharge partial floc sludge,resulting in the relative abundance of Candidatus Brocadiaceae increased from0.04%to 22.54%,which effectively reduced thematrix and spatial competition between other microorganisms and Anammox bacteria.On day 90,the stoichiometric ratio of the Anammox process closely approached the theoretical value of 1:1.32:0.26,indicating that the Anammox reaction was the primary nitrogen removal process in the system.In the enrichment phase(days 91–238),the NLR increased from 0.43 to 1.20 kgN/(m^(3)·d)and removal efficiency was 71.89%,resulting in the relative abundance of Candidatus Brocadiaceae increased to 61.27%on day 180.The reactor operated steadily from days 444 to 498,maintaining the nitrogen removal rate(NRR)of 3.00 kgN/(m^(3)·d)and achieving successful sludge granulation with the particle size of 392.4μm.In short,this study provided a simple and efficient approach for enriching Anammox bacteria from the activated sludge,supporting to start an Anammox process efficiently.
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the State Key Laboratory of Pulp and Paper Engineering(201522)Shandong Provincial Natural Science Foundation of China(ZR2017MC032)the Natural Science Project of Guangdong Education Department(2015KTSCX140).
文摘The effect of mid-stage pulping wastewater(as shock load)on micro-aerobic magnetic activated sludge system was studied.Micro-aerobic activated sludge systems with and without magnetic particles were shocked with mid-stage wastewater for 16 days.“Recovery”experiments were conducted by using simulated wastewater for 12 days.Upon the addition of mid-stage wastewater,CODCr removal pertaining to the use of magnetic particles reached 71.57%and remained above 80%in the“recovery”experiment.However,the efficiency of the reactor in the absence of magnetic particles was only 37.29%,and reached about 40%in the“recovery”experiment.After the micro-aerobic activated sludge was shocked,the flocculation performance and surface properties of the sludge were analyzed,and the results showed that all indicators of the reactors in the presence of magnetic particles were superior to those of reactors without magnetic particles.After 12 days of“recovery”,the indicators of the sludge pertaining to the reactors containing magnetic particles“recovered”completely.
文摘In this paper, starting from the action mechanism of environmental osmotic pressure and microorganisms in activated sludge, a wastewater sample from a wastewater treatment plant was selected to determine the impact of chloride ion concentration on its wastewater treatment effect, and mixed solutions with different chloride ion concentrations were prepared to test the nitrification and denitrification effects, and the comprehensive evaluation of sludge activity and drainage water quality was realized. The research results show that the microorganisms contained in activated sludge have certain chloride ion tolerance ability, but when the chloride ion concentration changes abruptly or exceeds the limit value, it will damage the microorganisms and reduce the sludge activity and the treatment effect. In the actual production process, measures such as A2O-MBBR improvement process, activated sludge domestication method, wastewater dilution and other chemical substances addition can also be introduced in combination with the actual production requirements to effectively adjust the chloride ion concentration, reduce the impact of chloride ion on sludge activity and improve the system treatment efficiency.
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.
文摘This paper researched a promising biological treatment of methyl violet waste water by methods of activated sludge.Effects of temperature and pH were studied on this process.Kinetic equation of the substrate biodegradation was investigated in the experimental range.It was studied and simulated that flow within the bubble region of this bioreactor according to the κ ε two fluid equation.Simulation results agree well with experimental data.
