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Centralized sewage treatment plants may not be a sustainable solution for a developing country such as India. Therefore, we conducted for the first time an integrated assessment of the different technologies currently used for sewage treatment in the state of West Bengal, India. Five decentralized sewage treatment plants and one centralized sewage treatment plant located in different parts of Kolkata were evaluated. We compared influent and effluent water quality, energy consumed, capital and operating costs, and treated wastewater reuse potential. F test was used to validate results on the effect of working days and holidays and seasons on treated water quality. Wastewater management strategy was assessed by performance indicators. Our results show that treatment efficiency was lowest in anaerobic plants not because of faulty technology but due to unskilled operation. Therefore, performance improvement of plants is expected if factors such as monitoring, training of staff, regular and scrupulous desludging, reuse aspects, and rational water tariff are implemented earnestly. [ABSTRACT FROM AUTHOR]

Characterization and biological treatment of leachate generated by Borg El-Arab landfill has been carried out. Intensive monitoring of the leachate indicated that it is moderately biodegradable. The BOD/COD ratio is in the range of 0.33–0.45. The ratio of COD:N:P was 100:39:0.3 indicating high nitrogen and low PO 4 -P content. Three experimental sets of treatment schemes were conducted: aerobic, anaerobic and combined anaerobic/aerobic. To assess the impact of the applied organic load on the performance of the treatment processes, the leachate was diluted using sewage. Three different leachate concentrations were used, 5.9%, 25% and 50%. These correspond to average COD values of 1166, 4207 and 7830 mgO 2 /l, respectively. Each treatment scheme was fed with the three dilutions. The same sets of experiments were repeated after pre-treatment using air stripping to remove ammonia nitrogen. The results obtained indicated that ammonia stripping for 6 h after adjusting the pH of the leachate (1:1) at 10, coupled by aerobic treatment via activated sludge for 24 h achieved the best results. Ammonia removal was more than 90%. Corresponding COD and BOD removal values reached 64.4 and 67.2%, respectively. [ABSTRACT FROM AUTHOR]

The paper presents the prospects of using the technology of low-oxygen aerobic wastewater treatment – simultaneous nitrification and denitrification – as energy-efficient solution for construction and reconstruction of wastewater treatment plants for small settlements in the conditions of the Russian Federation. The results of an experiment (the second phase) conducted on a laboratory model of the Oxidation Ditch are described. The paper presents the horizontal model of the Oxidation Ditch that will be used for further experiments. This model differs from previous ones in its hydraulic performance. [ABSTRACT FROM AUTHOR]

A fusant strain T1, which was constructed by protoplast fusion betweenAcinetobactersp. SRL8,Escherichiasp. XBR68 andAcinetobactersp. RC10, could simultaneously decolorize three different dyes, namely reactive brilliant blue XBR, disperse orange SRL, and red base RC. Maximum decolorization of initial 30 mg L−1was achieved at pH 7.0, 35°C and 3% inoculum (v/v) under anaerobic condition during 24 h incubation. The decolorization ratio for XBR, SRL, and RC by the strain T1 could reach 91.5, 87.6, and 65.7%, respectively. Supplementation with appropriate concentration of glucose (0.2%, w/v) in the decolorization reaction system could further enhance decolorization percent. The strain T1 was highly tolerant to three different dyes up to 400 mg L−1. Biological decolorization of the three different dyes by the strain T1 was investigated in a sequential anaerobic/aerobic process. The reaction system was operated at room temperature. The results indicated that over 95% color removal was obtained in anaerobic process and 97.6% COD removal occurred in the aerobic process. [ABSTRACT FROM AUTHOR]

Although a high volume of research on aerobic granular sludge exists in the body of related literature, the determination of biokinetic parameters of aerobic granules using a linear plot for biodegradation of real wastewater has rarely been discussed. Therefore, this study aims to determine the biokinetic parameters of aerobic granules that develop in a sequencing batch reactor (SBR) with sewage as a substrate, using a linear plot. The difference in biokinetic parameter ( k , K s , Y, K d and μ max ) values gathered from five aerobic granules batches were tested as whether it is linearly correlated with the variable organic loading rate (OLR) and reactor height/diameter (H/D) ratio. The R 2 value of 0.97 and 0.82 was obtained from the linear correlation between μ max and reactor H/D ratio, and Y and OLR, respectively. This demonstrates that biomass production (Y and μ max ) proportionally depends on the increase in OLR and reactor H/D ratio. This might be because the effectiveness of the aerobic granules measured by K s are greater in high H/D ratio reactors with values over 315 mg/L as compared to less than 276 mg/L in low H/D ratio reactors. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In this study, the effect of seasonal variations on the performance of combined anaerobic–aerobic system for wastewater treatment was investigated. The pilot plant system consists of packed bed anaerobic sludge blanket, followed by a biological aerated filter. The packing material in both units was a non-woven polyester fabric. The system was operated for more than two years at ambient temperature. The results indicated that the performance of the pilot plant was very satisfactory during the whole seasons. However, in summer, slightly better results were achieved for chemical oxygen demand, biological oxygen demand, total suspended solids and total Kjeldahl nitrogen due to the increase in temperature. Their corresponding average removal values were 90, 91, 97, and 54%, respectively, compared with 88, 90, 91, and 46% in winter. Nitrogen removal was related to nitrification/denitrification and bacterial assimilation, where its activity increased in the summer. The quality of the treated effluent during the whole seasons complies with the National Regulatory Standards for reuse in irrigation. [ABSTRACT FROM PUBLISHER]

Glucaric acid, a promising bio-based chemical for the production of adipic acid, is produced on a commercial Pt/C catalyst via aerobic oxidation of glucose in water. Facile oxidation of gluconic acid, an intermediate oxidation product of glucose, under optimal conditions of an initial pH of 7.2, 80 °C, 13.8 bar O2 and a glucose/Pt molar ratio of 54, enabled a maximum glucaric acid yield of 74%, the highest yield reported to date. It is found that in an acidic solution, gluconic acid is the major product while in a highly basic solution, selectivity to glucaric acid is poor due to its C–C bond cleavage to low carbon chain carboxylic acids. High temperatures and high Pt loadings result in lower selectivity to glucaric acid. Recyclability and characterization studies reveal that the catalyst is stable after five cycles with no sign of Pt leaching into the solution. [ABSTRACT FROM AUTHOR]

Microbubble aeration is supposed to be highly efficient for oxygen supply in aerobic wastewater treatment. In the present study, the performance of a fixed-bed biofilm reactor microbubble-aerated using a Shirasu porous glass (SPG) membrane system was investigated when treating synthetic municipal wastewater. The biofilm formation on the carriers was enhanced with microbubble aeration due to the strong adhesion of microbubbles to the solid surface. The dissolved oxygen concentration, the removals of chemical oxygen demand (COD) and nitrogen, and the oxygen utilization efficiency were influenced by the organic loading rate at a certain oxygen supply capacity. The relatively optimal organic loading rate was determined as 0.82 kgCOD/(m3 d) when the oxygen supply capacity was 0.93 kgO2/(m3 d), where COD and ammonia removal efficiencies were 91.7% and 53.9%, respectively. The corresponding SPG membrane area-based COD removal capacity was 6.88 kgCOD/(m2 d). The oxygen utilization efficiency of microbubble aeration was obviously higher compared to conventional bubble aeration. The simultaneous nitrification and denitrification occurred in the biofilm reactor and the total nitrogen removal efficiency of 50.4% was achieved under these conditions. In addition, the increase in air supply capacity of the SPG membrane system was suggested to improve its energy utilization efficiency. [ABSTRACT FROM AUTHOR]

In this work, a new model was developed to quantitatively evaluate and compare anaerobic/anoxic/aerobic (A 2 O) and reversed A 2 O processes for municipal wastewater treatment using projection pursuit method based on particle swarm optimization (PSO). The optimal projection direction was obtained by optimizing the projection index function using the PSO algorithm. By fitting the logistic equation, the evaluation model was established. Then, the calculated ranks of the evaluation samples were computed. The overall performance of both A 2 O and reversed A 2 O processes were evaluated using the established model as a case study. The results show that the mean rank of the A 2 O process (1.79 ± 0.39) was lower than that of the reversed A 2 O process (1.97 ± 0.41), indicating that the former was better than the later under the same operating conditions. Through resolving multi-factor evaluation problems, such a PSO-based model is demonstrated to be effective to quantitatively assess wastewater treatment processes. [ABSTRACT FROM AUTHOR]

The increased use of ZnO nanoparticles (NPs) in everyday products indicates the importance of studying NPs release to the wastewater and its possible effect on biological process for wastewater treatment. Therefore, the aim of this work was to study the effect of the presence of ZnO NPs in aerobic wastewater treatment. The results indicated that the oxygen uptake rate of microorganisms is inhibited for concentrations higher than 473 mg L of ZnO NPs. The diversity of microorganisms involved in wastewater treatment was reduced in presence of ZnO NPs. Related to morphological interaction between ZnO NPs and suspended biomass, physical damage in flocs structure were observed in presence of ZnO NPs. However, the internalization of Zn compounds in microorganisms not presented mechanical damage in the membrane cell. These findings suggest that inhibition in oxygen uptake was caused for negative effect that ZnO NPs induces in aerobic microorganisms involved in wastewater treatment. [ABSTRACT FROM AUTHOR]

A membrane bioreactor (MBR p ), a hybrid moving bed biofilm reactor-membrane bioreactor containing carriers in the anaerobic, anoxic and aerobic zones (hybrid MBBR-MBR ap ) and a hybrid moving bed biofilm reactor-membrane bioreactor which contained carriers only in the anaerobic and anoxic compartments (hybrid MBBR-MBR bp ) were used in parallel and compared regarding the nutrient and organic matter removal from municipal wastewater. The hydraulic retention time (HRT) was 18 h. A kinetic study for the heterotrophic and autotrophic bacteria, mainly nitrite-oxidizing bacteria (NOB), was carried out and related to the nutrient and organic matter removal. The hybrid MBBR-MBR ap performed best regarding chemical oxygen demand (COD) and total phosphorus (TP) removals, with values of 85.82 ± 2.12% and 81.42 ± 3.85%, respectively. This system had a higher phosphorus release under anaerobic conditions and a higher phosphorus uptake under aerobic conditions. The highest TN removal efficiency was obtained for the hybrid MBBR-MBR bp , with a value of 61.39 ± 10.71%. [ABSTRACT FROM AUTHOR]

Industrial wastewater with a high Na2SO4 concentration is characterized by high osmotic pressure and salinity, and requires pretreatment before discharging into central treatment facilities. To date, few studies have addressed the chemical oxygen demand (COD) removal in biotreatment of Na2SO4 wastewater. Here, a novel aerobic system for treating Na2SO4 wastewater was developed based on screening halotolerant bacterial strains. The system maintained a stable COD removal at >90% in saturated concentration (varying from 5 to 40% depending on the temperature) of Na2SO4 for 5 years. Activated sludge was initially constructed by cultured strains of Hyphomicrobium sp. CB03, Dietzia sp. XM15, Staphylococcus sp. T211, Flavobacterium sp. AXY1, Ochrobactrum sp. BY4, Bacillus sp. BYXT, Sphingobacterium sp.YY1, Rhodococcus sp. NH7-4, Stappia sp. HM4, Microbacterium sp. PY3-1, and Pseudomonas sp. MN3-2. Uncultured phylum TM7 was detected in the sludge after acclimatization. The present aerobic cultivable halotolerant bacterial community was successfully applied to large scale removal of organic pollutants in saline wastewater. [ABSTRACT FROM AUTHOR]

The effect of air flow rate (AFR), pretreatment time, and temperature on a microaerobic pretreatment were determined, including its effect on CH 4 generation. For this, four AFR (0.1, 0.3, 0.5 and 1 vvm), three temperatures (20, 25 and 35 °C) and three aeration times (24, 48 and 60 h) were evaluated in 1-L and 5-L bioreactors. The effect on CH 4 production was evaluated in 280-mL bioreactors, using previously aerated sewage sludge. It was found that the micro-aerobic pretreatment improves the hydrolytic process, with an increase of proteins, total sugars, soluble chemical oxygen demand (COD), and a greater removal of volatile suspended solids (VSS) compared to a system without aeration. It was determined that an AFR = 0.3 vvm, 48 h of aeration time, and a temperature of 35 °C were the best operational conditions for increasing hydrolysis rate. VSS removal under the aerobic pretreatment follows first order kinetics. Finally, the aeration pretreatment allows a 211% increase of methane generation compared to a process without pretreatment, improving also total COD and VSS removal. [ABSTRACT FROM AUTHOR]

Aerobic granular sludge (AGS) is widely used in domestic sewage treatment, but high ammonia nitrogen removal by AGS is difficult because nitrifiers cannot work effectively at low temperatures. This study investigated the AGS performance on treating high ammonia nitrogen wastewater with the aid of an isolated pure nitrifier at low temperatures. Five isolated and identified strains possessed high ammonia nitrogen or nitrite degradation ability and good adaptability to varying temperature and pH values. AGS was formed in 33 days with a smooth surface and compact structure. However, the ammonia nitrogen removal capability was remarkably low because of the excessive influent ammonia nitrogen. With a higher hydrophobicity and better adhesion ratios, the bioaugmentation of the five strains with AGS was obvious. The chemical oxygen demand and ammonia nitrogen removal efficiencies were 90.7 and 86.3%, respectively, and the total nitrogen removal improved by a factor of 3.1. The dissolved oxygen consumption did not change after the inoculation of the five strains. However, the free ammonia concentration significantly decreased, which can facilitate a high ammonia nitrogen removal at low temperature. [ABSTRACT FROM AUTHOR]

BACKGROUND The environmental and health effects caused by oxytetracycline ( OTC) contamination of aquatic systems are a serious problem throughout the world. The OTC-contaminated wastewater cannot be treated effectively by conventional anaerobic and aerobic biological treatments. Few studies have investigated the systematic treatment of OTC-contaminated wastewater. RESULTS A system including micro-electrolysis ( ME), an expanded granular sludge bed ( EGSB) and an anoxic/oxic activated sludge process (A/O) could treat OTC production wastewater effectively. First, a ME reactor packed with new ceramic-corrosion-cell fillers, serving as a pretreatment step, was effective in removing residual OTC and enhancing biodegradability of the wastewater. Second, EGSB and A/O reactors played the main role in removing chemical oxygen demand ( COD), ammonium nitrogen ( NH3-N) and chroma (color of the wastewater). After reaching steady state, the coupled ME-EGSB-A/O system removed more than 95.0% of COD, 90.0% of NH3-N and 80.0% of color, and the final effluent met the requirements of the national discharge standard ( COD ≤ 500 mg L−1, NH3-N ≤ 45 mg L−1 and chroma ≤ 70; CJ 343-2010, China). CONCLUSION The coupled ME-EGSB-A/O system could treat the OTC production wastewater effectively. These findings have significant implications for a cost-efficient system in OTC production systematic treatment. © 2015 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

This study investigated the formation of aerobic granular sludge with the main objective of Acid Red 18 (AR18) biodegradation in an altering anaerobic-aerobic sequencing batch reactor. According to the obtained results, the cultivated granules showed a stable structure in the treatment of synthetic wastewater containing 50 mg/L AR18, while no considerable variety in their characteristics and no granule break up were observed. As reported by many researchers, decolourization of AR18 is due to the anaerobic biodegradation of the azo bond; however, monitoring of the dye biodegradation through UV-Vis spectroscopy showed that the contribution of the aerobic phase in dye removal was significant. This indicates the penetration of AR18 into the inner layers of granules and the ability of anaerobic microorganisms within the granules to degrade the dye through the consumption of tightly bound extracellular polymeric substances (EPS) as a carbon and energy source. The aerobic granules were not able to decompose anaerobically formed AR18 intermediates under aerobic conditions. The increase of the initial dye concentration from 50 to 100 mg/L caused the production of excess loosely bound EPS, which led to instability of the granules and hampered the dye removal efficiency. [ABSTRACT FROM AUTHOR]

The effects of different chromium (Cr(VI)) concentrations (0, 5, 10, 25, and 50 mg/L) on pollutant removal, nitrification ability, and microbial activity of aerobic granular sludge in sequencing batch reactors were analyzed. When compared with the control system, Cr(VI) decreased the average chemical oxygen demand (COD) and ammonia nitrogen removal rates. Significant correlations between the inhibitory rate of specific ammonia utilization rate (sAUR) and Cr(VI) concentration suggested that sAUR inhibition rate could be an effective indicator to predict the biological nitrification process in the aerobic granular sludge system. Although appropriate Cr(VI) concentration stimulated electron transport system activity of the granules, more than 25 mg/L Cr(VI) obviously inhibited the activity. The total polysaccharide and protein contents of the extracellular polymeric substances (EPS) linearly increased with increasing Cr(VI) concentrations of up to 25 mg/L. Furthermore, Cr(VI) exhibited greater inhibitory effects on the nitrification process than on the organic substrate removal process. This may be owing to the lower tolerance of nitrifying bacteria to Cr(VI), when compared with that of organics-degrading heterotrophic bacteria; distribution of nitrifying and heterotrophic bacteria, which occurred at the outer and inner layers of the granular sludge, respectively; and improvement in the COD removal rate of the micro-organisms as a result of EPS secretion. [ABSTRACT FROM AUTHOR]

Aerobic granular sludge (AGS) was cultivated in a bench scale sequencing batch reactor within 21 days. Strategy of the rapid startup was inoculated with part of mature AGS during cultivation, while aerobic biological selector was implemented for the inhibiting outgrowth of filamentous bacteria and fast selection of zoogloea bacteria. Then, the cultivated AGS was employed for the treatment of solvent recovery raffinate. Stable AGS was successfully domesticated after 55 days under strategy of gradually increase the proportion of real wastewater in influent. The domesticated AGS was orange, irregular shape, smooth and compact. SVI, SV 30 /SV 5 , MLVSS/MLSS, EPS, PN/PS, average particle size, granulation rate, (SOUR) H and (SOUR) N of AGS were 19.06 mL/g, 0.97, 0.55, 30.05 mg/g MLVSS, 1.10, 1.28 mm, 98.87%, 32.47 and 7.97 mg O 2 /h g VSS respectively. Finally, COD, TIN, NH 4 + –N and TP of the effluent were lower than 25.9 mg/L, 1.64 mg/L, 1.13 mg/L and 0.21 mg/L, and their removal rate was more than 98.43%, 97.12%, 98.02% and 98.09% respectively. Thus, COD, TP removal, nitrification and denitrification were realized in a single bioreactor. The result indicated that the feasibility of AGS for high C/N ratio industrial wastewater treatment. [ABSTRACT FROM AUTHOR]

Winery industries generate large volumes of high-strength wastewater whose characteristics greatly vary depending on either seasons, production technologies or scale of the wineries. Winery wastewater (WW) is persistent to degrade by means of the conventional activated sludge process because of the high organic loading and polyphenolic content especially during vintage. To face this situation, a number of processes have recently been attempted as alternatives or integrative to biological treatments. However, there is still no agreement on the best practice to treat WW. Despite even more stringent standards, untreated or partially treated effluents continue to be improperly discharged into aquatic or soil matrixes, influencing microbial communities and physicochemical soil properties. This work presents a review on the state-of-the-art of management of wastewater originated from winery industries. Advantages and drawbacks of the treatment technologies at bench-, pilot-, and full-scale applications in the scientific literature have been considered to draw out a sustainable management scheme. [ABSTRACT FROM PUBLISHER]

We present a non-linear programming formulation for the computation of optimal aeration policies in a sequencing batch reactor for wastewater streams treatment. We assume that organic matter and nitrogen are the main pollutants to be removed to meet water quality targets. The novelty of the work lies in the fact that no binary variables are required to compute the switching time between the aerobic and anoxic stages of the water treatment process leading to a simpler, robust and easier to compute optimization formulation. Moreover, because the control valve, through which air is fed to the reactor, can take either its minimum or maximum bounds as well as any fractional values between such bounds, improved optimal aeration profiles are reported. Such improved profiles mean that shorter processing times are required, compared to previous solutions, leading also to a reduction in the operation cost of the wastewater treatment process. Although the optimal operation policies were computed for a typical home wastewater stream, the optimization formulation can also be extended for the treatment of other polluted streams. [ABSTRACT FROM AUTHOR]

A pilot-scale aerated lagoon was used for the aerobic treatment of pulp and paper mill effluent from September 1 to December 1, 2014. The aerated lagoon was installed at the chemistry laboratory in the Chemical Engineering Department at the Durango Institute of Technology and was fed with real pulp and paper mill effluent. The experimental work was run under various operating conditions. The operating parameters (total and volatile suspended solids (VSS) and dissolved oxygen concentration (DO)) and environmental variables (temperature, pH, COD, and BOD5 of influent water) were monitored daily. In all the experiments conducted, the aerated lagoon generated an effluent of optimal quality complying with the requirements of SEMARNAT (2003) and CONAGUA (2003). A model that explains the behavior of the system under realistic operating conditions was obtained. The model indicated an optimal DO of approximately 4 mg/L for concentrations up to 1000 mg/L, showing variations in concentrations above this value. This data indicate that the flexibility of the bacterial formulation and its ability to adapt to environmental changes play an important role in the stability of an aerated lagoon. [ABSTRACT FROM AUTHOR]

[Display omitted] • The alpha factor increases over the aeration phase length of a batch reactor. • Alpha dynamics follow a first-order relation. • Alpha was related to the removal of soluble biodegradable organic carbon (bCODs) • Adsorption of bCODs was described by Langmuir isotherm. • Exchange ratio and temperature influences alpha as well. In the pursuit of reducing carbon footprint and in view of increasing energy prices, energy efficiency is more important than ever before. Batch-wise operated aerobic granular sludge reactors consume up to 50% less energy compared to conventional activated sludge systems because pumping energy is reduced and mixing equipment is not needed. Further energy reduction efforts should therefore target aeration energy requirements. The alpha factor is an important factor influencing the oxygen transfer efficiency, however the dynamic behaviour of alpha has hardly been investigated in general and never for an aerobic granular sludge reactor. This study showed that alpha increases during the aeration phase of a cycle due to the influence of different process parameters. Through a data analysis study of 175 batch cycles of the Prototype Nereda® installation in Utrecht over the summer and winter period of 2020–2021, the exchange ratio and temperature were identified as the main influencing factors on the rate of increase of alpha in a batch cycle. A higher exchange ratio was related to a slower increase in alpha over the aeration phase, while a higher temperature was related to a faster increase in alpha. Moreover, alpha was characterized by a same minimal value at the beginning of every aeration phase, which could be explained by the adsorption of soluble biodegradable organic carbon described by a Langmuir adsorption model. Two mathematical models, a decreasing exponential and a first order model, were set up to unravel the dynamic behaviour of alpha. Both models were discussed in view of their practical implications for the design and performance optimization of aerobic granular sludge reactors and other batch-wise operated aerobic wastewater treatment systems. [ABSTRACT FROM AUTHOR]

Multivariate analysis was used to identify the variables affecting the performance of pilot-scale activated sludge (AS) reactors treating old leachate from a landfill and from domestic wastewater. Raw leachate was pre-treated using air stripping to partially remove the total ammoniacal nitrogen (TAN). The control AS reactor (AS-0%) was loaded only with domestic wastewater, whereas the other reactor was loaded with mixtures containing leachate at volumetric ratios of 2 and 5%. The best removal efficiencies were obtained for a ratio of 2%, as follows: 70 ± 4% for total suspended solids (TSS), 70 ± 3% for soluble chemical oxygen demand (SCOD), 70 ± 4% for dissolved organic carbon (DOC), and 51 ± 9% for the leachate slowly biodegradable organic matter (SBOM). Fourier transform infrared (FTIR) spectroscopic analysis confirmed that most of the SBOM was removed by partial biodegradation rather than dilution or adsorption of organics in the sludge. Nitrification was approximately 80% in the AS-0% and AS-2% reactors. No significant accumulation of heavy metals was observed for any of the tested volumetric ratios. Principal component analysis (PCA) and partial least squares (PLS) indicated that the data dimension could be reduced and that TAN, SCOD, DOC and nitrification efficiency were the main variables that affected the performance of the AS reactors. [ABSTRACT FROM AUTHOR]

An anoxic sewage treatment process, an upflow anaerobic sludge blanket (UASB) followed by an aerated bio-filter (ABF), was investigated for the reduction of oxygen demand and the separation efficiency of the organic matter. After recycling the nitrified effluent, complete denitrification occurred in the UASB, with an enhancement in both turbidity characteristics and TCOD removal rates. Low turbidity and COD in the effluent of the UASB reduced the oxygen demand and improved the nitrification efficiency in the subsequent ABF. Both with and without the recycling of the nitrified effluent in the UASB, 95 and 63% of the TCOD values, respectively, were removed. Compared with a conventional activated sludge system, approximately 11.74% of the TCOD was converted to CO2in both the UASB and the ABF, generating an approximately 60% reduction in the amount of CO2. After accumulation in the UASB, 84% of the influent TCOD could be sequestered for use as a marginal energy source in a subsequent anaerobic digester. [ABSTRACT FROM PUBLISHER]

The effect of a two-step process on the concentration of pathogens and indicator microorganisms in black water (0.9-1% total solids) was studied. The treatment combined auto-thermal aerobic digestion (ATAD) and ammonia sanitisation. First, the temperature of the black water was increased through ATAD and when a targeted temperature was reached (33, 41 and 45.5 WC studied), urea was added to a 0.5% concentration (total ammonia nitrogen >2.9 g L-1). Escherichia coli and Salmonella spp. were reduced to non-detectable levels within 3 days following urea addition at temperatures above 40 °C, whereas when urea was added at 33 °C E. coli was still present after 8 days. By adding urea at temperatures of 40 °C and above, a 5 log10 reduction in Enterococcus spp. and a 3 log10 reduction in Ascaris suum eggs was achieved 1 week after the addition. With combined ATAD and ammonia treatment using 0.5% ww urea added at an aerobic digestion temperature >40 °C, black water was sanitised regarding the pathogens studied in 2 weeks of total treatment time. [ABSTRACT FROM AUTHOR]

This work aims at optimizing performance of the multimode anaerobic/anoxic/aerobic (AAO) system, which could be flexibly operated under AAO, reversed AAO (RAAO) and anoxic/aerobic (AO) modes, based on effluent quality and operating costs at low temperature of 12.5 °C. Influences of sludge retention time (SRT) on effluent quality, functional biomass and operating cost were evaluated for each mode. The AAO has a better performance than RAAO and AO at SRT of 5–25 d under the same operating cost for its higher pollutant removal efficiency and concentration of phosphorus-accumulating organisms. Furthermore, an operating region conforming to required discharge standards was established for the AAO mode by regulating returned activated sludge (RAS) and mixed liquor recirculation (MLR). Optimal condition was obtained using MLR ratio of 100%, RAS ratio of 50%, and SRT of 16 d. Dynamic simulation results showed that multi-criteria modeling was a useful tool in process optimization. [ABSTRACT FROM AUTHOR]

This work studied the removal effect of pollutants and the components in extracellular polymeric substances (EPS) extracts obtained from aerobic granular sludge (AGS) with high concentration of ammonia nitrogen and analyzed EPS using Fourier-transformed IR (FTIR) spectrometer. The AGS demonstrated perfect performance in simultaneous removal of organic matter and ammonia nitrogen, and the removal rates were both maintained above 90%, the stable nitrite accumulation was achieved as well. The main particle size was more than 1.4 mm and the higher electrical conductivity was caused by the existences of organic and mineral fractions in EPS. Ca, K, Fe, Mg, Zn, and Cu were the main mineral elements contained in EPS extracts. Mineral fractions of EPS improve the stabilization of the AGS. [ABSTRACT FROM AUTHOR]

Dye wastewater is one of typically non-biodegradable industrial effluents. A new process linking Fenton's oxidation with biological oxidation proposed in this study was investigated to degrade the organic substances from real dye wastewater. During the combination process, the Fenton's oxidation process can reduce the organic load and enhance biodegradability of dye wastewater, which is followed by biological aerated filter (BAF) system to further remove organic substances in terms of discharge requirement. The results showed that 97.6% of chemical oxygen demand (COD) removal by the combination process was achieved at the optimum process parameters: pH of 3.5, H2O2 of 2.0 mL/L, Fe(II) of 500 mg/L, 2.0 h treatment time in the Fenton's oxidation process and hydraulic retention time (HRT) of 5 h in the BAF system. Under these conditions, COD concentration of effluent was 72.6 mg/L whereas 3020 mg/L in the influent, thus meeting the requirement of treated dye wastewater discharge performed by Chinese government (less than 100 mg/L). These results obtained here suggest that the new process combining Fenton's oxidation with biological oxidation may provide an economical and effective alternative for treatment of non-biodegradable industrial wastewater. [ABSTRACT FROM AUTHOR]

Nitrification kinetics of a full-scale anaerobic/anoxic/aerobic wastewater treatment plant were investigated by considering the anaerobic (ηA) and anoxic reduction factors (ηN) on decay rate of nitrifying biomass (bAUT) for estimating minimum sludge age (θmc). Ammonium nitrogen in the effluent was fluctuating seasonally with low nitrification efficiency from December to June. The measuredbAUTvalues were 0.175, 0.092, and 0.077 d−1under aerobic, anoxic, and anaerobic conditions, respectively. A low maximum specific growth rate at 20°C (0.48 d−1) and high temperature correction factor (1.208) were yielded in the range of 10–25°C, indicating that the activity of nitrifying biomass was low and depended more sensitively on lower temperatures. At temperature below 12.1°C, the decay rate of nitrifying biomass exceeded growth rate, and a negativeθmcwas obtained. The extremely high (12.1–15.0°C) or negative (<12.1°C)θmcindicated that prolonging sludge age was probably malfunctioned at cold temperature. [ABSTRACT FROM PUBLISHER]

In the rural area of the Tibetan Plateau (RATP), the characteristics of domestic waste, people’s environmental awareness, people’s willingness to pay and their influence factors were firstly studied by questionnaires, field samplings and laboratory tests. The results showed that, in the RATP, the generation of domestic waste was 85 g•d-1 per capita and it was mainly composed of plastics, inert waste, kitchen waste, glass and paper. The waste bulk density, moisture content, ash, combustible and low calorific value were 65 kg•m-3, 19.25%, 44.90%, 35.85% and 10,520 kJ•kg-1 respectively. These characteristics are influenced by income sources and geographical position to some extent. Classified collection should be promoted widely on the household and the village basis. Compost, fermentation, landfill, bioreactor landfill and semi-aerobic landfill have been approved as effective techniques to treat domestic waste, except incineration. The distance of 50–800 m between each collection facility and the disposal fee of around $0.8 per month per household are suggested. For suburbs or large population villages, it’s better to treat domestic waste by the centralized way. But for the remote rural areas, a decentralized way is proposed. Significantly, the educational and economic influence should be considered into an effective domestic waste management program. Implications: The current situatio n of the environment in the rural areas of the Tibetan Plateau (RATP) was surveyed. There, the generation of organics and moisture of domestic waste were low but ash, recyclables, and combustibles were high. People’s knowledge of domestic waste was absent but their participation in management was strong. Based on the current situation, compost, fermentation, and landfill were effective but incineration was inappropriate. Also, a localized mini landfill for a cluster of villages and or settlements was the best method there. [ABSTRACT FROM PUBLISHER]

This paper presents the results of a study of a sludge subjected to the (ATAD) process - Autothermal Thermophilic Aerobic Digestion occurring in a two-stage installation operated in a municipal wastewater treatment plant in Olecko, Poland. The study of the sludge and the analysis of obtained results were conducted over 2011 and 2014. The subject of the study was a thickened sludge in an intermediate tank from which it was next transferred to facility reactors. The stabilization of processed sludge was evaluated analyzing the change in the dry mass (DS) content in the sludge. Measurements were carried out in thickened sludge samples and after the ATAD process. Collected results were then subjected to a statistical analysis and it was determined to which extent as resulted from the subject process the dry mass and the dry organic mass (VS) content was changing in the sludge. Also, it was analyzed how the oxygen chemical demand (COD) was changing. The dry mass content in the thickened sludge was from 60 g/1 to 160 g/1. After the process, this amount was from 35 to 76 g/1. Similarly, the organic mass content in a dry sludge mass changed from initial values within a range of 44-135 g/1 to 23-60 g/1 after the ATAD process. Also, the organic substance content expressed as COD decreased from 80 to 467 g O2/I in a thickened sludge to 51-261 g O2/I in the sludge after the process. The article presents conclusions from the result of the conducted study as well as personal experience. [ABSTRACT FROM AUTHOR]

The objective of this paper is to investigate the COD removal efficiency of the Kermanshah landfill leachate by applying the aerobic sequencing batch reactor (ASBR). The ASBR was operated to investigate the COD removal efficiency at the various hydraulic retention time (HRT) and COD concentrations. In order to study the effects of COD concentration and HRT based on response surface methodology at three-level, two-variable central composite design of experiments were used. The results showed that the leachate could be effectively treated with 90% of COD removal at the lowest COD concentration (16,000 mg/L) in influent. The removal efficiency decreased gradually down to 30.9% when COD increased to 48,000 mg/L. The system has strong tolerance to organic shock loading in this experiment. The five suggested models based on the mentioned variables were applied to predict the response values. The value of the HRT, as important variables, showed that efficiency of reactor decreased from 70 to 50%, when the HRT decreased from 6 to 2 d. This study contributed to a better understanding of the function of HRT and COD concentration in the system. [ABSTRACT FROM PUBLISHER]

This review of literature published in 2014 focuses on waste related to chemical and allied products. The topics cover the waste management practices, hospital waste, pesticide waste, chemical wastewater, pesticide wastewater and pharmaceutical wastewater. The other topics include aerobic treatment, anaerobic treatment, sorption and ozonation. [ABSTRACT FROM AUTHOR]

The application of microaerobic conditions during sludge digestion has been proven to be an efficient method for H 2 S removal from biogas. In this study, three microaerobic treatments were considered as an alternative to the technique of biogas desulfurization applied (FeCl 3 dosing to the digesters) in a WWTP comprising three full-scale anaerobic reactors treating sewage sludge, depending on the reactant: pure O 2 from cryogenic tanks, concentrated O 2 from PSA generators, and air. These alternatives were compared in terms of net present value ( NPV ) with a fourth scenario consisting in the utilization of iron-sponge-bed filter inoculated with thiobacteria. The analysis revealed that the most profitable alternative to FeCl 3 addition was the injection of concentrated O 2 (0.0019 €/m 3 biogas), and this scenario presented the highest robustness towards variations in the price of FeCl 3 , electricity, and in the H 2 S concentration. [ABSTRACT FROM AUTHOR]

A novel Reverse Flow Baffled Reactor (RFBR) was constructed to achieve aerobic granulation in continuous-flow process in order to treat the high quantity of influent wastewater. Municipal wastewater was fed to a 120 L reactor and successfully produced aerobic granules revealing a sludge volume index (SVI) of 33 mL/g. Aerobic granules possessed higher extracellular polymeric substances (EPS) content than seed sludge. The protein/polysaccharide (PN/PS) ratio in the EPS was determined to be about 10:1. Bacterial community analysis revealed that most of the species ( Bacteroidetes , Nitrospira and Proteobacteria ) found in the seed sludge were preserved in the reactor, except Pedobacter species that was washed out from the reactor. Moreover, different bacterial species were identified in RFBR and SBR (sequencing batch reactor) granules due to different process and operational parameters. Presence of Fe, Ca, Al, Si and P in wastewater were aggregated in granules (acted as a core) and enhanced the granulation. However, the RFBR was operated in periodic feast-famine condition, short settling time, high height/diameter ( H / D ) ratio, and without sludge return pump, which led to successful granulation in continuous-flow mode. [ABSTRACT FROM AUTHOR]

Coastal Zone Act Reauthorization Amendments (CZARA, Section 6217) necessitate the requirement that onsite wastewater disposal units located near impaired surface waters or groundwater to provide at least 50% nitrogen removal. Approximately 38% of Hawaii households use onsite systems including septic tanks and cesspools that cannot meet this requirement. Upgrades to aerobic treatment units (ATUs) are a possible compliance solution. In Hawaii, ATUs must meet National Sanitation Foundation Standard 40 (NSF40) Class I effluent criteria. Previously, a multi-chamber, flowthrough, combined attached/suspended growth type ATU (OESIS-750) and presently, a sequencing batch type ATU (CBT 0.8KF-210) were evaluated for NSF40 compliance, nutrient removal capability (NSF245), and adaptability for water reuse (NSF350). Both units easily achieved the NSF40 Class I effluent criteria. While the OESIS-750 achieved only 19% nitrogen removal, the CBT unit achieved 81% nitrogen removal, meeting the NSF245 criteria and CZARA requirements for applications in critical wastewater disposal areas. In addition, the CBT consistently produced effluent with turbidity less than 2 NTU (NSF350) and UVT254 greater than 70%, facilitating the production of unrestricted-use recycled water. [ABSTRACT FROM AUTHOR]

Central composite design and response surface methodology (RSM)were implemented to optimize the operational parameters for a cross-flow aerobic sludge reactor (CFASR) in remedying mixed printing and dyeing wastewater (MPDW). The individual and interactive effects of three variables, hydraulic retention time (HRT), pH and sludge loading rate (SLR), on chemical oxygen demand (COD) and terephthalic acid (TA) removal rates were evaluated. For HRT of 15.3–19.8 hours, pH of 7.2–8.1 and SLR of 0.4–0.6 kg chemical oxygendemand (COD) per kg mixed liquor suspended solids per day, COD and TA removal rates of the CFASR exceeded 85% and 90%, respectively. The check experiment revealed that the effluent from the optimized CFASR was stable below the limitation of 100 mg COD/L and the TA concentration decreased by 6.0% compared to the usual CFASR. The results verified that the RSM was useful for optimizing the operation parameters of the CFASR in remedying MPDW. [ABSTRACT FROM AUTHOR]

In this study, the role of extracellular polymeric substances (EPS) in biosorption of dye wastewater was evaluated using aerobic granular sludge as biosorbent. Based on the experimental data, the removal efficiencies of methylene blue (MB) by EPS and Sludge were 9.38 and 80.72%, respectively, implying that EPS made a certain contribution for MB removal. The adsorption rates of EPS, Sludge, and total Sludge + EPS for MB were better fitted with pseudo-second order kinetic model, and the equilibrium adsorption isotherm data agreed well with Langmuir model. The interaction between EPS and MB was explored by a combined three-dimensional excitation–emission matrix (3D-EEM) and synchronous fluorescence spectra. 3D-EEM indicated that protein- and humic acid-like substances were the main peaks of EPS, and gradually quenched with increased MB concentrations. According to synchronous fluorescence spectra, the main fluorescence quenching was caused by tryptophan residues, and the type belonged to a combined dynamic and static quenching. [ABSTRACT FROM AUTHOR]

Short initial settling time and rapidly increased ammonium nitrogen loading were employed to cultivate nitrifying granular sludge treating inorganic wastewater with 1000 mg/L ammonium nitrogen. It was found that the nitrifying granule-dominant sludge was formed in a sequencing batch reactor (SBR) with influent ammonium concentration increased from 200 to 1000 mg N/L within 55 days. During the following 155-day operation period, nitrifying granules exhibited good performance with an ammonium removal efficiency of 99 %. In the meantime, sludge volume index (SVI) decreased from 92 to 15 mL/g and the mean size of the nitrifying granules increased from 106 to 369 μm. Mixed liquor suspended solids (MLSS) decreased from the initial 6.4 to around 3 g/L during the granulation period and increased to over 10 g/L at the end of the operation. The long-term stability of nitrifying granules and the reactor performance were not negatively affected by inhibition from free ammonia (FA) and free nitrous acid (FNA) in this study. This makes the granule sludge technology promising in treating high-strength ammonium wastewater in practice. [ABSTRACT FROM AUTHOR]

Two sequencing batch reactors were operated to investigate the effect of influent alkalinity and reactor pH on aerobic granulation. In the first reactor R1 with high influent alkalinity the pH was adjusted in the neutral range, and in the second reactor R2 with low alkalinity the pH was held within the acidic range. The R1-dominating species were bacteria and the appearance time of granules was three weeks after reactor start-up. On the other hand, the acidic environment of R2 provided favorable conditions for fungal growth, and rapid granule formation occurred within the first week of operation. The varying microbial structure of granules resulted in different reactor performance in terms of evolution time and morphology of granules, suspended solids in the reactors, settling ability of granules, effluent quality of treated wastewater, and physical strength of the granules. [ABSTRACT FROM AUTHOR]

In the last years the treatment of the organic fraction of municipal solid waste has been carried out using combined anaerobic/aerobic processes, where anaerobic digestion is followed by the aerobic stabilization of the digestate. Such a treatment provides a positive net energy balance associated with the methane energy recovery as well as the production of a soil conditioner. However the high complexity of the treatment requires an accurate management of all the treatment units. To this end, mass balances represent a useful tool, allowing both the control and maximization of process yields as well as the minimization of the treatment costs. This work aims at evaluating the performances of a combined anaerobic/aerobic source-sorted OFMSW plant by means of mass balances, elaborated with reference to both conventional and non-conventional operational parameters. Results pointed out the key role of organic waste pretreatment as well as the effectiveness of both anaerobic and aerobic processes in providing an adequate biostabilization level of the treated waste. [ABSTRACT FROM AUTHOR]

On-site wastewater treatment systems (OWTS) are widely used in Western Australia (WA) to treat and dispose of household wastewater in areas where centralized sewerage systems are unavailable. Septic tanks, aerobic treatment units (ATUs), and composting toilets with greywater systems are among the most well established and commonly used OWTS. However, there are concerns that some OWTS installed in WA are either performing below expected standards or failing. Poorly performing OWTS are often attributed to inadequate installation, inadequate maintenance, poor public awareness, insufficient local authority resources, ongoing wastewater management issues, or inadequate adoption of standards, procedures, and guidelines. This paper is to review the installations and failures of OWTS in WA. Recommendations to the Department of Health Western Australia (DOHWA) and Local Government (LG) in regard to management strategies and institutional arrangements of OWTS are also highlighted. [ABSTRACT FROM AUTHOR]

Sodium acetate as carbon source, tolerance to organic loading rate (OLR) by aerobic granular sludge in a cyclic aerobic granular reactor (CAGR) was investigated by gradually increasing the influent COD. AGS could maintain stability in the continuous flow reactor under OLR ⩽ 15 kg/m 3 d in the former 65 days, and SVI, granulation rate, average particle size and water content was 21 ml/g, 98%, 1.8 mm and 97.2% on the 65th day. However, AGS gradually disintegrated after the 66th day when OLR increased to 18 kg/m 3 d, and granules’ properties deteriorated rapidly in a short time. High removal rates to pollutants were achieved by CAGR in the former 65 days, but the removal rates of pollutants dropped sharply from the 66th day. With the increase of OLR and particle size, anaerobic cores inside the granules were formed by massive dead cells, while instability of anaerobic core eventually led to the collapse of the system. [ABSTRACT FROM AUTHOR]

Phosphate accumulating bacterium Pseudomonas stutzeri YG-24 exhibited efficient heterotrophic nitrification and aerobic denitrification ability. Single factor experiments showed that both heterotrophic nitrification and aerobic denitrification occurred with sodium citrate as carbon source and lower C/N ratio of 8. High average NH 4 + -N, NO 2 − -N and NO 3 − -N removal rates of 8.75, 7.51 and 7.73 mg L −1 h −1 were achieved. The application of strain YG-24 in wastewater samples resulted in TN, NH 4 + -N, NO 2 − -N, NO 3 − -N and P removal efficiencies of 85.28%, 88.13%, 86.15%, 70.83% and 51.21%. Sequencing and quantitative amplification by real-time PCR of napA , nirS and ppk showed that nitrogen removal pathway of strain YG-24 was achieved through heterotrophic ammonium nitrification coupled with fast nitrite denitrification (NH 4 + -N to NO 2 − -N and then to gaseous nitrogen) directly. These results demonstrated the strain as a suitable candidate to simultaneously remove both nitrogen and phosphate in wastewater treatment. [ABSTRACT FROM AUTHOR]

The use of saline water in urban areas for non-potable purposes to cope with fresh water scarcity, intrusion of saline water, and disposal of industrial saline wastewater into the sewerage lead to elevated salinity levels in wastewaters. Consequently, saline wastewater is generated, which needs to be treated before its discharge into surface water bodies. The objective of this research was to study the effects of salinity on the aerobic metabolism of phosphate-accumulating organisms (PAO), which belong to the microbial populations responsible for enhanced biological phosphorus removal (EBPR) in activated sludge systems. In this study, the short-term impact (hours) of salinity (as NaCl) was assessed on the aerobic metabolism of a PAO culture, enriched in a sequencing batch reactor (SBR). All aerobic PAO metabolic processes were drastically affected by elevated salinity concentrations. The aerobic maintenance energy requirement increased, when the salinity concentration rose up to a threshold concentration of 2 % salinity (on a W/ V basis as NaCl), while above this concentration, the maintenance energy requirements seemed to decrease. All initial rates were affected by salinity, with the NH- and PO-uptake rates being the most sensitive. A salinity increase from 0 to 0.18 % caused a 25, 46, and 63 % inhibition of the O, PO, and NH-uptake rates. The stoichiometric ratios of the aerobic conversions confirmed that growth was the process with the highest inhibition, followed by poly-P and glycogen formation. The study indicates that shock loads of 0.18 % salt, which corresponds to the use or intrusion of about 5 % seawater may severely affect the EBPR process already in wastewater treatment plants not exposed regularly to high salinity concentrations. [ABSTRACT FROM AUTHOR]

Aerobic granule, a form of microbial aggregate, exhibits good potential in degrading toxic and recalcitrant substances. In this study, the inhibitory and toxic effects of trichloroethylene (TCE), a model compound for aerobic co-metabolism, on phenol-grown aerobic granules were systematically studied, using respiratory activities after exposure to TCE as indicators. High TCE concentration did not exert positive or negative effects on the subsequent endogenous respiration rate or phenol dependent specific oxygen utilization rate (SOUR), indicating the absence of solvent stress and induction effect on phenol-hydroxylase. Phenol-grown aerobic granules exhibited a unique response to TCE transformation product toxicity, that small amount of TCE transformation enhanced the subsequent phenol SOUR. Granules that had transformed between 1.3 and 3.7 mg TCE g SS −1 showed at most 53% increase in the subsequent phenol SOUR, and only when the transformation exceeded 6.6 mg TCE g SS −1 did the SOUR dropped below that of the control. This enhancing effect was found to sustain throughout several phenol dosages, and TCE transformation below the toxicity threshold also lessened the granules' sensitivity to higher phenol concentration. The unique toxic effect was possibly caused by the granule's compact structure as a protection barrier against the diffusive transformation product(s) of TCE co-metabolism. [ABSTRACT FROM AUTHOR]

The extracellular polymeric substances (EPS) are important macromolecular components in microbial aggregates. The three EPS extraction methods - ultrasound + cation exchange resins (CER) + sulfide, ultrasound+ formamide+ NaOH, and ultrasound + heat - were investigated in the study, and the component differences of extracted EPS from the loose flocs and dense aerobic granules were compared using chemical analysis and three-dimensional excitation-emission matrix (3D-EEM). Results showed that the contents of EPS were extracted effectively by ultrasound+ formamide + NaOH and ultrasound + heat methods, and the ultrasound+ CER+ sulfide method did not extract the polysaccharides (PS) or protein (PN) contents from the sludge samples. The 3D-EEM analysis indicated that the nature of peak B/D, peak C/E/F, and peak A/G were attributed to PN-like, humic acid-like and fulvic acid-like fluorophores. All fluorophores can be detected from the EPS extracted through the ultrasound+ heat method. Hopefully this will provide more information about the EPS interaction mechanism of microbial aggregates. [ABSTRACT FROM AUTHOR]