Performance of wastewater sludge ecological stabilization

In this article, wastewater sludge ecological stabilization （WWSES） was presented for sludge dewatering, mineralization, and stabilization, as well as for percolate treatment. Two years of pilot scale experimental results indicated that sludge volatile solid, Wiphenyltetrazolium chloride （TTC）-dehydrogenase activity （DHA）, and moisture content as indicators showed the process and degree of sludge stabilization. The observation on dewatering process showed that dried sludge reached a content of 20%-50% total solid after two years of system operation. Sludge TTC-DHA in the first year was obviously lower than that of the second year, and TTC-DHA tended to decrease with an increase in the drying time of the sludge. Total nitrogen, total phosphorus, and organic contents of sludge decreased gradually from the top to the bottom of dried sludge layer. In comparison with natural stands on stands treated with sewage sludge, individual shoot was significantly higher, and coarse protein, coarse fat, and coarse fiber contents in reed roots, stems, and leaves in the system were higher than that of wild reed, especially coarse protein contents of reed roots in the system （7.38%） were obviously higher than that of wild reeds （3.29%）.

Evaluation of fungal potentiality for bioconversion of domestic wastewater sludge

This study was undertaken to screen the filamentous fungi isolated from its relevant habitats(wastewater, sewage sludge and sludge cake) for the bioconversion of domestic wastewater sludge. A total of 35 fungal strains were tested against wastewater sludge (total suspended solids, TSS 1%—5% w/w) to evaluate its potentiality for enhancing the biodegradability and dewaterability using liquid state bioconversion(LSB) process. The strains were divided into five groups i.e. Penicillium, Aspergillus, Trichoderma, Basidiomycete and Miscellaneous, respectively. The strains WWZP1003, SCahmA103, SCahmT105 and PC-9 among their respective groups of Penicillium, Aspergillus, Trichoderma and Basidiomycete played potential roles in terms of separation(formation of pellets/flocs/filaments), biodegradation(removal of COD) and filtration(filterability) of treated domestic wastewater sludge. The Miscellaneous group was not considered due to its unsatisfactory results as compared to the other groups. The pH value was also influenced by the microbial treatment during fermentation process. The filterability of treated sludge was improved by fungal treatment, and lowest filtration time was recorded for the strain WWZP1003 and SCahmA103 of Penicillium and Aspergillus groups respectively compared with other strains.

Thermal Hydrolysis of Wastewater Sludge Followed by Fungal Fermentation for Organic Recovery and Hyphae Fiber Production

Wastewater sludge creates a difficult environmental problem for many large cities.This study developed a three-phase innovative strategy for sludge treatment and reduction,including thermal hydrolysis,fungal fermentation,and anaerobic digestion.Increasing the temperature during the treatment from 140 to 180℃ significantly improved the sludge reduction and organic release efficiencies(p<0.05,one-way analysis of variance(ANOVA)for the triplicate experiments at each temperature).After two cycles of thermal hydrolysis,the overall volatile solid reduction ratios of the sludge were 36.6%,47.7%,and 58.5%for treatment at 140,160,and 180℃,respectively,and the total organic carbon(TOC)conversion efficiency reached 28.0%,38.0%,and 45.1%,respectively.The highest concentrations of carbohydrates and proteins were obtained at 160℃ in sludge liquor,whereas the amount of humic substances significantly increased for the treatment at 180℃(p<0.05,one-way ANOVA for the triplicate experiments at each temperature)due to the Maillard reaction.Fungal fermentation of the hydrolyzed sludge liquor with Aspergillus niger converted the waste organics to valuable fiber materials.The biomass concentration of fungal hyphae reached 1.30 and 1.27 g·L^(-1) in the liquor of sludge treated at 140 and 160C,corresponding to organic conversion ratios of 24.6%and 24.0%,respectively.The fungal hyphae produced from the sludge liquor can be readily used for making papers or similar value-added fibrous products.The paper sheets made of hyphae fibers had a dense structure and strong strength with a tensile strength of 10.75 N·m·g^(-1).Combining fungal fermentation and anaerobic digestion,the overall organic utilization efficiency can exceed 75%for the liquor of sludge treated at 160℃.

Optimization of process parameters for the bioconversion of activated sludge by Penicillium corylophilum, using response surface methodology

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%.

Effect of sulfate on the methanogenic activity of a bacterial culture from a brewery wastewater during glucose degradation

The maximum specific methanogenic activity （SMA） of a sludge originating from a brewery wastewater treatment plant on the degradation of glucose was investigated at various levels of sulfate on a specific loading basis. Batch experiments were conducted in serum bottles at pH 7 and 35℃. A comparison of the values indicates that the SMA of this mixed culture was increased and reached its highest level of 0.128 g CH4 gas COD/（g VSS.d） when biomass was in contact with sulfate at a ratio of 1：0.114 by weight.

Screening of an Effective Degrading Strain for Treatment of Antibiotic Pharmaceutical Wastewater and Determination of Its Biological Properties

In this study,an effective antibiotic-degrading strain NG3 was isolated from activated sludge of antibiotic wastewater treatment.According to the results of morphological,physiological and biochemical identification and phylogenetical analysis of 16S r DNA sequence,the isolated strain belonged to Acinetobacter sp.,which was named Acinetobacter sp.NG3.Moreover,biological properties of the isolated strain were analyzed preliminarily,which provided a basis for the application of Acinetobacter sp.NG3 strain in efficient treatment of antibiotic industrial wastewater.

Effects of acid,acid-ZVI/PMS,Fe(Ⅱ)/PMS and ZVI/PMS conditioning on the wastewater activated sludge(WAS)dewaterability and extracellular polymeric substances(EPS)

The effects of four conditioning approaches:Acid,Acid-zero-valent iron(ZVI)/peroxydisulfate(PMS),Fe(Ⅱ)/PMS and ZVI/PMS,on wastewater activated sludge(WAS)dewatering and organics distribution in supernatant and extracellular polymeric substances(EPS)layers were investigated.The highest reduction in bound water and the most WAS destruction was achieved by Acid-ZVI/PMS,and the optimum conditions were pH 3,ZVI dosage 0.15 g/g dry solid(DS),oxone dosage 0.07 g/g DS and reaction time 10.6 min with the reductions in capillary suction time(CST)and water content(Wc)as 19.67%and 8.49%,respectively.Four conditioning approaches could result in TOC increase in EPS layers and supernatant,and protein(PN)content in tightly bound EPS(TB-EPS).After conditioning,organics in EPS layers could migrate to supernatant.Polysaccharide(PS)was easier to migrate to supernatant than PN.In addition,Acid,Acid-ZVI/PMS or Fe(Ⅱ)/PMS conditioning promoted the release of some polysaccharides containing ring vibrations v P=O,v C-O-C,v C-O-P functional groups from TB-EPS.ESR spectra proved that both radicals of SO4-·and·OH contributed to dewatering and organics transformation and migration.CST value of WAS positively correlated with the ratios of PN/PS in LB-EPS and total EPS,while it negatively correlated with TOC,PN content and PS content in TB-EPS,as well as PS content in supernatant and LB-EPS.BWC negatively correlated to zeta potential and TOC value,PN content,and HA content in supernatant.

Impacts of wastewater sludge amendments in restoring nitrogen cycle in p-nitrophenol contaminated soil

The possible impacts on nitrogen-cycle in a p-nitrophenol （PNP） polluted soil and the effectiveness of wastewater sludge amendments in restoring nitrification potential and urease activity were evaluated by an incubation study. The results indicated that PNP at 250 mg/kg soil inhibited urease activity, nitrification potential, arginine ammonification rate and heterotrophic bacteria counts to some extents. After exposure to PNP, the nitrification potential of the tested soil was dramatically reduced to zero over a period of 30 days. Based on the findings, nitrification potential was postulated as a simple biochemical indicator for PNP pollution in soils. Nitrogen-cycling processes in soils responded positively to the applications of wastewater sludges. A sludge application rate of 200 tons/ha was sufficient for successful biostimulation of these nitrogen processes. The microbial activities in sludge-amended, heavy PNP-polluted soils seemed to recover after 30–45 days, indicating the effectiveness of sludge as a useful soil amendment.

Adsorption behavior of sulfamethazine in an activated sludge process treating swine wastewater

Swine wastewater is an important pollution source of antibiotics entering the aquatic environment. In this work,the adsorption behavior of sulfamethazine（SMN）,a commonlyused sulfonamide antibiotic,on activated sludge from a sequencing batch reactor treating swine wastewater was investigated. The results show that the adsorption of SMN on activated sludge was an initially rapid process and reached equilibrium after 6 hr. The removal efficiency of SMN from the water phase increased with an increasing concentration of mixed liquor suspended solids,while the adsorbed concentration of SMN decreased. Solution pH influenced both the speciation of SMN and the surface properties of activated sludge,thus significantly impacting the adsorption process. A linear partition model could give a good fit for the equilibrium concentrations of SMN at the test temperatures（i.e.,10,20 and 30°C）. The partition coefficient（Kd） was determined to be 100.5 L/kg at 20°C,indicating a quite high adsorption capacity for SMN. Thermodynamic analysis revealed that SMN adsorption on activated sludge was an exothermic process. This study could help to clarify the fate and behavior of sulfonamide antibiotics in the activated sludge process and assess consequent environmental risks arising from sludge disposal as well.

Occurrence,distribution,and potential influencing factors of sewage sludge components derived from nine full-scale wastewater treatment plants of Beijing,China

Millions of tons of waste activated sludge（WAS） produced from biological wastewater treatment processes cause severe adverse environmental consequences. A better understanding of WAS composition is thus very critical for sustainable sludge management. In this work, the occurrence and distribution of several fundamental sludge constituents were explored in WAS samples from nine full-scale wastewater treatment plants（WWTPs） of Beijing, China. Among all the components investigated, active heterotrophic biomass was dominant in the samples（up to 9478 mg/L）, followed by endogenous residues（6736 mg/L）,extracellular polymeric substances（2088 mg/L）, and intracellular storage products（464 mg/L）among others. Moreover, significant differences（p 〈 0.05） were observed in composition profiles of sludge samples among the studied WWTPs. To identify the potential parameters affecting the variable fractions of sludge components, wastewater source as well as design and operational parameters of WWTPs were studied using statistical methods. The findings indicated that the component fraction of sewage sludge depends more on wastewater treatment alternatives than on wastewater characteristics among other parameters. A principal component analysis was conducted, which further indicated that there was a greater proportion of residual inert biomass in the sludge produced by the combined system of the conventional anaerobic/anoxic/oxic process and a membrane bioreactor. Additionally, a much longer solids retention time was also found to influence the sludge composition and induce an increase in both endogenous inert residues and extracellular polymeric substances in the sludge.

Improving sludge dewaterability via Fe^(2+) chelated citrate activated peroxydisulfate oxidation

Citrate (Ct) was chosen as a typical chelator used in the Fe^(2+)-peroxydisulfate (PDS) process to improve sludge dewaterability.The PDS-Fe^(2+)-Ct process exhibited better performance in sludge dewatering than PDS-Fe^(2+).Specifically,with a PDS dosage of 1.2 mmol/g VS,the molar ratio of PDS/Fe^(2+)and Ct/Fe^(2+)were 4:5 and 1:4,respectively,the capillary suction time decreased from 155.8 to 24.8sec,and the sludge cake water content decreased from 82.62%to 64.11%(-0.06MPa).The oxidation led to a reduced negative charge and a decrease in particle size.The enhanced sludge dewaterability and changes of sludge properties were attributed to the decomposition of extracellular polymeric substances,and it was explored by protein,polysaccharide,3D-EEMs,and FT-IR.Additionally,the quenching experiments of radical species demonstrated that SO_(4)-·played a more important role than·OH,and its productivity was improved with the addition of Ct.Moreover,the reasons for the improved productivity of radicals with the addition of Ct were discussed.The results of this study could serve as a basis for improving sludge dewatering using the PDS-Fe^(2+)-Ct process and suggest that the addition of Ct may improve the productivity of SO_(4)-·in the activation o PDS via Fe^(2+).

Efficient treatment of azo dye containing wastewater in a hybrid acidogenic bioreactor stimulated by biocatalyzed electrolysis

In this study, a novel scaled-up hybrid acidogenic bioreactor（HAB） was designed and adopted to evaluate the performance of azo dye（acid red G, ARG） containing wastewater treatment. Principally, HAB is an acidogenic bioreactor coupled with a biocatalyzed electrolysis module. The effects of hydraulic retention time（HRT） and ARG loading rate on the performance of HAB were investigated. In addition, the influent was switched from synthetic wastewater to domestic wastewater to examine the key parameters for the application of HAB. The results showed that the introduction of the biocatalyzed electrolysis module could enhance anoxic decolorization and COD（chemical oxygen demand） removal. The combined process of HAB-CASS presented superior performance compared to a control system without biocatalyzed electrolysis（AB-CASS）. When the influent was switched to domestic wastewater, with an environment having more balanced nutrients and diverse organic matters, the ARG, COD and nitrogen removal efficiencies of HAB-CASS were further improved, reaching 73.3% ± 2.5%, 86.2% ± 3.8% and 93.5% ± 1.6% at HRT of 6 hr, respectively, which were much higher than those of AB-CASS（61.1% ± 4.7%,75.4% ± 5.0% and 82.1% ± 2.1%, respectively）. Moreover, larger TCV/TV（total cathode volume/total volume） for HAB led to higher current and ARG removal. The ARG removal efficiency and current at TCV/TV of 0.15 were 39.2% ± 3.7% and 28.30 ± 1.48 mA,respectively. They were significantly increased to 62.1% ± 2.0% and 34.55 ± 0.83 mA at TCV/TV of 0.25. These results show that HAB system could be used to effectively treat real wastewater.

Bacterial communities in different locations, seasons and segments of a dairy wastewater treatment system consisting of six segments

A dairy wastewater treatment system composed of the 1st segment（no aeration） equipped with a facility for the destruction of milk fat particles, four successive aerobic treatment segments with activated sludge and a final sludge settlement segment was developed. The activated sludge is circulated through the six segments by settling sediments（activated sludge） in the 6th segment and sending the sediments beck to the 1st and 2nd segments.Microbiota was examined using samples from the non-aerated 1st and aerated 2nd segments obtained from two farms using the same system in summer or winter. Principal component analysis showed that the change in microbiota from the 1st to 2nd segments concomitant with effective wastewater treatment is affected by the concentrations of activated sludge and organic matter（biological oxygen demand [BOD]）, and dissolved oxygen（DO） content. Microbiota from five segments（1st and four successive aerobic segments） in one location was also examined. Although the activated sludge is circulating throughout all the segments, microbiota fluctuation was observed. The observed successive changes in microbiota reflected the changes in the concentrations of organic matter and other physicochemical conditions（such as DO）, suggesting that the microbiota is flexibly changeable depending on the environmental condition in the segments. The genera Dechloromonas, Zoogloea and Leptothrix are frequently observed in this wastewater treatment system throughout the analyses of microbiota in this study.

Concentrations and sources of an emerging pollutant, decabromodiphenylethane (DBDPE), in sewage sludge for land application

The presence of an emerging brominated flame retardant, decabromodiphenylethane （DBDPE）, has been confirmed in Spanish sewage sludge. Thirty one samples from different urban wastewater treatment plants （WWTPs） were analyzed for this brominated flame retardant. DBDPE was positively identified and quantified in all samples at lower concentrations （47.0 ± 29.7 ng/g dry weight （dw）; mean ± SD） than those obtained for decabromodiphenyl ether （BDE-209） （290 ± 236 ng/g dw; mean ± SD） in a previous study. Influence of the WWTP characteristics in the pollutant levels was evaluated. No significant correlations were obtained between DBDPE concentrations and the population or sewage sludge production rate associated with the plants, neither wastewater treatment method. Sources of DBDPE in the sludge were also evaluated. Data indicate a common origin for DBDPE and BDE-209, which may be related to leaching processes during the use and disposal of consumer products containing these chemicals. Nevertheless, DBDPE contents are not influenced by industrial activities, which suggests that the infusion of DBDPE commercial mixture is not a source of this chemical into the environment, and indicates that the use of DBDPE in the Spanish industry is still low compared to deca-BDE.

Antibiotic Resistance Genes in the Human-Impacted Environment:A One Health Perspective

Antibiotic resistance and its environmental component are gaining more attention as part of combating the growing healthcare crisis. The One Health framework, promulgated by many global health agencies, recognizes that antimicrobial resistance is a truly inter-domain problem in which human health, animal agriculture, and the environment are the core and interrelated components.This prospectus presents the status and issues relevant to the environmental component of antibiotic resistance, namely, the needs for advancing surveillance methodology: the environmental reservoirs and sources of resistance, namely, urban wastewater treatment plants, aquaculture production systems, soil receiving manure and biosolid, and the atmosphere which includes longer range dispersal.Recently, much work has been done describing antibiotic resistance genes in various environments;now quantitative, mechanistic,and hypothesis-driven studies are needed to identify practices that reduce real risks and maintain the effectiveness of our current antibiotics as long as possible. Advanced deployable detection methods for antibiotic resistance in diverse environmental samples are needed in order to provide the surveillance information to identify risks and define barriers that can reduce risks. Also needed are practices that reduce antibiotic use and thereby reduce selection for resistance, as well as practices that limit the dispersal of or destroy antibiotic-resistant bacteria or their resistance genes that are feasible for these varied environmental domains.