Sequencing Batch Reactor System Research Articles

Shock load response in an SBR-activated sludge process treating high load wastewater

In this study, the production of storage polymers is made when cheese production wastewater is treated. Cheese plants typically produce high-strength wastewaters on an intermittent basis and are particularly suitable for treatment in Sequencing Batch Reactor (SBR) systems. The SBRs were operated in triplicate under two filling scenarios: 'React Fill' (RF) with mixing/aeration; 'Static Fill' (SF) with no mixing/aeration. The results suggest that an 'SF' approach outperforms an 'RF' with respect to storage products production (50% more PHB, 15% more glycogen). Additionally, the famine phase duration will vary depending on wastewater strength, suggesting optimisation per waste stream.

Effect of chloride concentration on nitrogen removal from landfill leachate in sequencing batch reactor after MAP pretreatment

Leachate generated from landfill is becoming a great environmental challenge to China as it contains high concentration of COD, ammonium and some other substances. Nitrogen removal through the conventional nitrification-denitrification process is hampered by the low C/N ratio especially for the old age landfill sites and the high energy consumption for aeration. In this study, the combination of magnesium ammonium phosphate (MAP) precipitation and Sequencing batch reactor (SBR) was suggested as a new process for the treatment of high strength ammonium, and the effect of high concentration of Cl⁻ after MAP precipitation because of the use of MgCl₂ was investigated on SBR performance. The practical upper limit of Cl⁻ for nitrification was found to be 12,000 mg/L, above which resulted in significant accumulation of ammonium in SBR system. It is suggested that an ammonium removal of 70% was suitable for the MAP treatment to achieve a balance between increasing the C/N ratio and avoiding detrimental effect from high concentration of Cl⁻ in the succeeding SBR system. DGGE analysis indicated that high diversity of Ammonium oxidizing bacteria (AOB) could be maintained at a Cl⁻ concentration of 12,000 mg/L.

Optimization of phosphorus removal in uniFed SBR system for domestic wastewater treatment

The characteristic of phosphorus removal and appropriate change of the traditional operation modes were investigated in UniFed sequencing batch reactor (SBR) laboratory-scale apparatus (40 L), treating actual domestic wastewater with low ratios of C/N (2.57) and C/P (30.18), providing theoretical basis for actual application of wastewater treatment plant. UniFed SBR system with its unique operation mode had the distinct superiority of phosphorus removal. On this occasion, the effect of volumetric exchange ratio (VER) and the method of influent introduction for phosphorus removal were studied. When the carbon source became the limiting factor to phosphorus release, the higher the VER, the lower the phosphorus concentration in the effluent. Three different influent patterns, including one-time filling, four-time filling, and continuous filling with the same quantity of wastewater could increase the release rate of anaerobic phosphorus from 0.082 to 0.143 mg·P·(L·min)−1. Appropriate change of the traditional operation modes could optimize the efficiency of phosphorus removal. When the feed/ decant time was extended from 2 h to 4 h, the phosphorous removal efficiency increased from 59.93% to 88.45% without any external carbon source. In the mode of alternation of anoxic-aerobic (A/O) condition, phosphorous removal efficiency increased from 55.07% to 72.27% clearly. The carbon source in the influent can be used adequately, and denitrifying phosphorus removal was carried out in anoxic stage 2 (A2). This mode was optimal for the treatment of actual domestic wastewater with low C/N and C/P ratios.

Effects of Cr(VI) on the performance and kinetics of the activated sludge process

The substrates removal performance, removal kinetics and the electron transport system (ETS) of sludge were investigated by sequencing batch reactors (SBR) and batch assays, respectively. Compared to the control system, significant decreases were observed in substrate removal efficiency with the Cr(VI)-feeding concentration up to 5 mg L(-1) in SBR system. And the recovery for NH4+-N removal were more difficult than that of COD after the termination of Cr(VI)-feeding. Significant inhibitory effects of Cr(VI) on the ETS activity and substrate removal kinetics were observed in the batch assays. The inhibitory effects of Cr(VI) would be overestimated on COD removal and underestimated on NH4+-N removal by the short-term batch assay as compared to the long-term operations. Additionally, significant correlations between the ETS activity and the inhibitory rates of Cr(VI) on substrate removal indicated the ETS activity can provide effective predictions on the potential performance of substrate removal in activated sludge.

Sequencing batch reactor technology for biological wastewater treatment: a review

AbstractWastewater treatment has been a challenge throughout the years due to varying influent characteristics and stringent effluent regulations. In response to this dilemma, a reliable, cost‐effective and high‐efficiency sequencing batch reactor (SBR) technology has been recently developed. SBRs are variations of the activated sludge process that operates on a fill‐and‐draw basis. It combines both aerobic–anaerobic phases in one unit and saves up to 25% of the aeration costs concomitant with low sludge production. Consequently, simultaneous nitrogen and phosphorus removal from the wastewater could be achieved by adjusting the actual operating cycle. This review paper discusses the technical description and operational flexibility of SBR for the treatment of wide range of effluent under different operational conditions, together with its modifications that could increase the effectiveness of SBR systems in the future. Copyright © 2010 Curtin University of Technology and John Wiley & Sons, Ltd.

Progress in the Development of Control Strategies for the SBR Process

AbstractThe sequencing batch reactor (SBR) process has shown great success in the treatment of industrial wastewater from intermittent discharge factories and for the treatment of domestic wastewater from medium or small towns. As automation technology has developed, many studies have been conducted to determine the optimal conditions for the SBR process. This review outlines the progress and application of control strategies that have been developed for the SBR process and provides a summary and comparison of the advantages and disadvantages of various control strategies, especially fixed‐time control strategies and various real‐time control strategies. Moreover, an analysis and discussion of novel optimal control methods for biologic nutrient removal are provided. Although previous studies in this field have greatly enriched our understanding of SBR systems, it is clear that many unsolved problems remain. Therefore, a summary of unanswered questions regarding control strategies for the SBR process is provided and future research directions are suggested.

Toward Polyhydroxyalkanoate Production Concurrent with Municipal Wastewater Treatment in a Sequencing Batch Reactor System

Bacteria can synthesize cytoplasmic granules known as polyhydroxyalkanoates (PHAs), which are carbon and energy storage reserves, from organic carbon when subject to stressful environmental conditions. PHAs are also biodegradable thermoplastics with many potential commercial applications. The purpose of the research reported herein was to evaluate the feasibility of integrating PHA production within a municipal wastewater treatment (WWT) configured as a sequencing batch reactor (SBR). Four bench-scale WWT SBRs were tested at decreasing organic loading rates to assess the potential to enrich for microbes capable of feast/famine PHA synthesis. For each treatment SBR, sidestream batch reactors receiving higher quantities of primary solids fermenter liquor were operated to produce PHA. Results from this study demonstrate that a treatment SBR supplied moderate strength wastewater can enrich for the target microorganisms, with PHA yields of 0.23–0.31-mg PHA per mg chemical oxygen demand, and produce high quality effluent. In sidestream batch reactors, microorganisms that fed excess quantities of substrate can rapidly synthesize significant quantities of PHA. Based on the results of this study, we estimate that a 1 million gallon per day SBR WWT-PHA production system could generate 11–36 t (12–40 t) of PHA annually.

MSBR을 이용한 크루즈선 오·폐수 처리 장치

본 연구는 크루즈선에 적합한 생물학적 오 폐수처리장치 개발을 위하여 SBR, MBR, MSBR 공정을 Lab scale 실험을 수행하여 오염물 처리 효율과 크루즈선이라는 특수 환경과의 접목성을 검토한 결과 MSBR공정이 처리효율과 장치 운영 면에서 가장 적합한 공정으로 평가되었다. MSBR 공정은 처리 대상 물질이 특정 성분에 국한 되지 않고 유기물, 영양염류, 병원성 미생물 처리에 있어 모두 안정적인 효율을 나타내었으며, 소요용적 및 장치의 운영 면에서도 우수한 결과를 나타내어 선박이라는 특수한 현장 적용에 매우 유리한 공정으로 확인되었다. MSBR 공정의 BOD, COD 및 SS 제거 효율은 99%, 98%, 99%로 나타나 IMO의 규제 기준을 모두 만족하였으며, 총질소와 인의 제거 효율도 76%, 59%로 강화되어 가는 해양오염기준을 충만족시킬 수 있는 공정으로 판단되었다. Lab scale experiment study was carried out for biological process development on cruise. SBR(Sequence Batch Reactor), MBR(Membrane Bioreactor), and MSBR(Membrane Sequence Batch Reactor) system were investigated for practical application on shipboard sewage treatment. From the results it was suggested that MSBR system might be suitable process for cruise in terms of pollutant removal efficiency, maintenance and special environmental conditions of cruise. About 99% of BOD, 98% of COD and 99% of SS were removed in MSBR system. In addition, about 76% of total nitrogen was reduced and the total phosphorus reduction averaged 59%.

Evaluation on the impacts of predators on biomass components and oxygen uptake in sequencing batch reactor and continuous systems

An expanded unified model for the biomass fractions, soluble-organic fractions, and oxygen-uptake rates considering extracellular polymeric substances (EPS), intracellular storage products ( X STO), and predators for activated sludge is used to study the impacts of predators on biomass components and oxygen uptake. The new model is applied to evaluate how predation affects the oxygen-uptake rate (OUR) and the different forms of biomass: active bacteria ( X H), X EPS, and X STO, under dynamic feast-and-famine and continuous conditions. For the dynamic conditions of a sequencing batch reactor (SBR), eliminating predators from the model increases X H and X EPS fractions significantly, and this causes the substantial increases in OUR and MLVSS once the famine period begins. An analysis of how the OUR is distributed among the several respiration processes shows that the predation of X H is the most significant oxygen utilization rate process in the system under famine conditions of an SBR. Application of the model to simulate the long-term operation of an SBR indicates that predators reach their maximum fraction in the MLVSS (∼4% of MLVSS) at a solids retention time of about 13 days, but they are washed out at a solids retention time less than ∼3 days. Simulation for a continuous system indicates that predators take more time (about 800 h) to reach steady state and reach their maximum fraction (∼5.5%) at an SRT of ∼14 days. Comparison of SBR and continuous systems reveals that the predators have greater impact in the continuous system because the permanent near-famine condition accentuates predation processes.

Performance and fouling characteristics in a membrane sequence batch reactor (MSBR) system coupled with aerobic granular sludge

The treatment performances and membrane fouling parameters of a membrane sequencing batch reactor (MSBR) used to treat synthetic wastewater were studied over 300 days. Aerobic granular sludge ranging from 500 to 1000 µm in particle diameter was cultivated after a period of regulation in operating conditions. The MSBR with aerobic granules achieved a high removal efficiency of pollutants. The emergence of aerobic granules in the MSBR system improved the membrane performance, as indicated by the fouling rate being maintained below 0.1 kPa d − 1 when the MLSS concentration was greater than 18 g L − 1 . The change in granule size and improved sludge settleability played an important role in sustaining the membrane permeability. Specifically, the reduced SVI led to a decrease in the supernatant TOC concentration that corresponded to a slower rise in TMP and less membrane fouling. Proteins were the primary components of EPS, while polysaccharides constituted a higher portion in SMP. In addition, the relative hydrophobicity (RH) and zeta potential increased in the sludge, while the protein to carbohydrate ratio (P/C) of both EPS and SMP increased after the formation of aerobic granules. These changes also enhanced the filterability of the mixed liquor.

Development of granular sludge for textile wastewater treatment

Microbial granular sludge that is capable to treat textile wastewater in a single reactor under intermittent anaerobic and aerobic conditions was developed in this study. The granules were cultivated using mixed sewage and textile mill sludge in combination with anaerobic granules collected from an anaerobic sludge blanket reactor as seed. The granules were developed in a single sequential batch reactor (SBR) system under alternating anaerobic and aerobic condition fed with synthetic textile wastewater. The characteristics of the microbial granular sludge were monitored throughout the study period. During this period, the average size of the granules increased from 0.02 ± 0.01 mm to 2.3 ± 1.0 mm and the average settling velocity increased from 9.9 ± 0.7 m h −1 to 80 ± 8 m h −1. This resulted in an increased biomass concentration (from 2.9 ± 0.8 g L −1 to 7.3 ± 0.9 g L −1) and mean cell residence time (from 1.4 days to 8.3 days). The strength of the granules, expressed as the integrity coefficient also improved. The sequential batch reactor system demonstrated good removal of COD and ammonia of 94% and 95%, respectively, at the end of the study. However, only 62% of color removal was observed. The findings of this study show that granular sludge could be developed in a single reactor with an intermittent anaerobic–aerobic reaction phase and is capable in treating the textile wastewater.

Effect of pH on continuous biohydrogen production from liquid swine manure with glucose supplement using an anaerobic sequencing batch reactor

pH is considered as one of the most important factors governing the hydrogen fermentation process. In this project, five pH levels, ranging from 4.4 to 5.6 at 0.3 increments, were tested to evaluate the pH effect on hydrogen production from swine manure supplemented with glucose in an anaerobic sequencing batch reactor system with 16 h of hydraulic retention time (HRT). The optimal hydrogen yield (1.50 mol H 2/mol glucose) was achieved at pH 5.0 when the maximum production rate of 2.25 L/d/L was obtained. Continuous hydrogen production was achieved for over 3 weeks for pH 5.0, 4.7, and 4.4, with no significant methane produced. However, as pH increased to 5.3 and 5.6, methane production was observed in the biogas with concurrent reductions in hydrogen production, indicating that methanogens could become increasingly activated for pH 5.3 or higher. Acetate, propionate, butyrate, valerate, and ethanol were the main aqueous products whose distribution was significantly affected by pH as well.

Model‐Based Design of Sequencing Batch Reactor for Removal of Biodegradable Organics and Nitrogen

The process design of sequencing batch reactors (SBR) based on mathematical modeling is complex because of the unsteady nature of the process and the large number of kinetic and stoichiometric parameters involved. This paper proposes a model-based design methodology that uses a mathematical model with fewer parameters for removal of organic and nitrogen substrates in the SBR. The resulting mathematical model has been calibrated and validated before its use in model-based design. The data for model calibration and validation were obtained from the operation of a full-scale 836 m3/h (5.3 mgd) SBR system at the City of Tahlequah, Oklahoma. A calibration methodology also was presented to determine unknown kinetic and stoichiometric parameters using an optimization technique called simulated annealing. Model-based design reduced the total volume of the reactor by approximately 11% from the existing design. It also eliminated 0.92 hours of cycle time and 1.07 hours of aeration time per cycle, which would result in a total energy savings of $11,640 per year for the 836 m3/h (5.3 mgd) SBR system.

Achieving the nitrite pathway using FA inhibition and process control in UASB-SBR system removing nitrogen from landfill leachate

An up-flow sludge blanket (UASB) and sequencing batch reactor (SBR) system was introduced to remove organics and nitrogen from landfill leachate. The synergetic effect of free ammonia (FA) inhibition and process control was used to achieve the nitrite pathway in the SBR. In previous research, inhibition of FA on nitrite oxidizing bacteria (NOB) activity has been revealed and the process control parameters (DO, ORP and pH) exactly indicate the end-point of nitritation. The method was implemented in the SBR achieving stable nitrogen removal via the nitrite pathway from landfill leachate. The degree of nitrite accumulation during the nitritation was monitored along with the simultaneous and advanced removal of organics and nitrogen in the UASB-SBR system. The nitrifying bacteria community was quantitatively analyzed by fluorescence in situ hybridization (FISH) techniques. Batch tests were carried out to investigate the denitritation kinetics of microbial bacteria in the SBR. Experimental results showed that the nitrite pathway could be repeatedly and reliably achieved by synergetic effect of FA inhibition and process control. FISH analysis showed the dominant nitrifying bacteria were ammonia-oxidizing -Proteobacteria. Relationship between nitrite concentration and nitrite reduction rate followed the Monod-type equation. The maximum specific nitrite utilization rate (k) and half-velocity constant (Ks) were calculated as 0.44 gN gVSS 1 d 1 and 15.8 mg L 1 , respectively.

Biological treatment of anaerobically digested palm oil mill effluent (POME) using a Lab-Scale Sequencing Batch Reactor (SBR)

The production of highly polluting palm oil mill effluent (POME) has resulted in serious environmental hazards. While anaerobic digestion is widely accepted as an effective method for the treatment of POME, anaerobic treatment of POME alone has difficulty meeting discharge limits due to the high organic strength of POME. Hence, subsequent post-treatment following aerobic treatment is vital to meet the discharge limits. The objective of the present study is to investigate the aerobic treatment of anaerobically digested POME by using a sequencing batch reactor (SBR). The SBR performance was assessed by measuring Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD) and Total Suspended Solids (TSS) removal as well as Sludge Volume Index (SVI). The operating pH and dissolved oxygen concentrations were found to be 8.25–9.14 and 1.5–6.4 mg/L, respectively, throughout the experiment. The experimental results demonstrate that MLVSS, OLR and sludge loading rate (SLR) play a significant role in the organic removal efficiency of SBR systems and therefore, further investigation on these parameters was conducted to attain optimum SBR performance. Maximum COD (95–96%), BOD (97–98%) and TSS (98–99%) removal efficiencies were achieved at optimum OLR, SLR and MLVSS concentration ranges of 1.8–4.2 kg COD/m 3 day, 2.5–4.6 kg TSS/m 3 day and 22,000–25,000 mg/L, respectively. The effluent quality remained stable and complied with the discharge limit. At the same time, the sludge showed good settling properties with average SVI of 65. It is envisaged that the SBR process could complement the anaerobic treatment to produce final treated effluent which meets the discharge limit.

Reduction of oxidative stress by bioaugmented strain Pseudomonas sp. HF-1 and selection of potential biomarkers in sequencing batch reactor treating tobacco wastewater

Oxidative stress induced by toxic pollutants is generally responsible for the poor performance of many sequencing batch reactors (SBRs) treating organic wastewater. In this study, the oxidative stress in two SBR systems that dealt with tobacco wastewater was monitored by measuring four popular biomarkers (superoxide dismutase, SOD; catalase, CAT; glutathione, GSH; and malondialdehyde, MDA). In the non-BA (non-bio-augmented) system, more intense oxidative stress was induced by a higher concentration of nicotine in tobacco wastewater, and excessive oxidative stress was induced by 250 mg/l of nicotine at the final stage. However, when a nicotine-degrading bacterial strain Pseudomonas sp. HF-1 was added to the BA (bio-augmented) system, the oxidative stress was significantly reduced compared to the non-BA system (p < 0.01).These results suggested that the oxidative stress was mainly induced by nicotine in the SBR treatment of tobacco wastewater, and that bioaugmentation with strain HF-1 would be a potential strategy to reduce the oxidative stress and thereby improve the performance in SBRs. Additionally, the positive correlation between the nicotine content and CAT, GSH and MDA activity in both systems implied that these parameters can be used as biomarkers for reflecting the performance of SBR treatment of tobacco wastewater, and in monitoring nicotine environmental pollution.

Experimental evaluation of decrease in the activities of polyphosphate/glycogen‐accumulating organisms due to cell death and activity decay in activated sludge

Decrease in bacterial activity (biomass decay) in activated sludge can result from cell death (reduction in the amount of active bacteria) and activity decay (reduction in the specific activity of active bacteria). The goal of this study was to experimentally differentiate between cell death and activity decay as the cause of decrease in bacterial activity. By means of measuring maximal anaerobic phosphate release rates, verifying membrane integrity by live/dead staining and verifying presence of 16S rRNA with fluorescence in situ hybridization (FISH), the decay rates and death rates of polyphosphate-accumulating organisms (PAOs) in a biological nutrient removal (BNR) system and a laboratory phosphate removing sequencing batch reactor (SBR) system were determined, respectively, under famine conditions. In addition, the decay rate and death rate of glycogen-accumulating organisms (GAOs) in a SBR system with an enrichment culture of GAOs were also measured under famine conditions. Hereto the maximal anaerobic volatile fatty acid uptake rates, live/dead staining, and FISH were used. The experiments revealed that in the BNR and enriched PAO-SBR systems, activity decay contributed 58% and 80% to the decreased activities of PAOs, and that cell death was responsible for 42% and 20% of decreases in their respective activities. In the enriched GAOs system, activity decay constituted a proportion of 74% of the decreased activity of GAOs, and cell death only accounted for 26% of the decrease of their activity.

Evaluation of two types of bioflocs derived from biological treatment of fish effluent as feed ingredients for Pacific white shrimp, Litopenaeus vannamei

Under laboratory-scale conditions, two types of bioflocs were used as a feed ingredient for Pacific white shrimp ( Litopenaeus vannamei). This feeding trial was conducted indoors in recirculating aquaculture systems with seawater renewal. Bioflocs were produced in sequencing batch reactors (SBR) using carbon supplementation (sucrose) and in a membrane biological reactor (MBR) without carbon supplementation. Both types of bioflocs were produced using tilapia farm effluent as a feed for the SBR and MBR systems. The bioflocs were dried and were used in shrimp feed as a replacement for fishmeal and/or soybean protein. A control diet (without bioflocs) was compared against four diets with MBR bioflocs (at 10, 15, 21, and 30% inclusion levels) and SBR bioflocs (at 10, 15, and 21% inclusion levels). At these biofloc inclusion rates, soy protein was replaced completely and fishmeal by as much as 67%. The control and biofloc diets were formulated to be equivalent for levels of crude protein, total fat, crude fiber, calcium, magnesium, phosphorus, potassium, and sodium. Seven juvenile shrimp were stocked per tank and each dietary treatment was tested using 8 replicates over a 35 day feeding trial. Dietary treatments had some impact on shrimp performance. Even though no differences ( P > 0.05) were observed between means for final survival (92.9 to 100%) or harvest biomass (536 to 574 g/m 2), some evidence ( P < 0.05) of faster growth rates was observed for diets with bioflocs inclusion compared to the control diet. Growth rates ranged from 1.44 to 1.66 g/week. Therefore, data indicate that bioflocs produced using either SBR or MBR systems could replace fishmeal and soybean protein. Furthermore, the SBR and MBR systems can be used to treat effluent from a tilapia farm thus reducing effluent waste into the environment.

Shortcut Nitrification and Denitrification of Swine Wastewater in a Sequencing Batch Reactor System

Wastewater generated by confined swine production is characterized by high ammonium nitrogen (NH4 +-N) content, the elimination of which would require significant amounts of air in nitrification and organic carbon, serving as the electron donor, in denitrification. Shortcut nitrification and denitrification (SND) is a novel nitrogen removal process that has drawn researchers' attention lately. In this study, the application of SND in swine wastewater treatment was investigated using two sequencing batch reactors (SBRs) connected in series in order to reduce the needs for energy and carbon dosage. The first SBR produced a nitrite-rich effluent that was fed to the second SBR, where both nitrogen and phosphorus removal were achieved. Three COD/NOx-N ratios (3.6, 4.8, and 6) were selected to test the influence of carbon availability on the total inorganic nitrogen (TIN) reduction and phosphorus removal efficiencies for the second SBR. It was observed that COD/NOx-N ratios of 4.8 and 6 could achieve 97% and 98% TIN removals with effluents containing less than 20 mg L-1 TIN, while the 3.6 ratio resulted in only 84% removal, with a significant amount of nitrate accumulated in the system. The COD/NOx-N ratio had no significant influence on dissolved phosphorus (DP) removal, and the mean value of DP removal was about 52%. Two solid retention times (SRTs) were selected to test the effect of SRT on nitrogen and phosphorus removal. No significant difference in TIN removal was observed under SRT of 16 and 23 days, but DP removal was much better under SRT of 23 days than 16 days (around 67% vs. 38%). In conclusion, the introduction of SND to swine wastewater treatment obtained a satisfactory result for nitrogen removal but not for phosphorus under the current operational settings. Chemical precipitation may have to be used to further reduce phosphorus in the SBR effluent.

Advanced landfill leachate treatment using a two-stage UASB-SBR system at low temperature

A two-stage upflow anaerobic sludge blanket (UASB) and sequencing batch reactor (SBR) system was introduced to treat landfill leachate for advanced removal of COD and nitrogen at low temperature. In order to improve the total nitrogen (TN) removal efficiency and to reduce the COD requirement for denitrification, the raw leachate with recycled SBR nitrification supernatant was pumped into the first-stage UASB (UASB1) to achieve simultaneous denitrification and methanogenesis. The results showed that UASB1 played an important role in COD removal and UASB2 and SBR further enhanced the nutrient removal efficiency. When the organic loading rates of UASB1, UASB2 and SBR were 11.95, 1.63 and 1.29 kg COD/(m 3·day), respectively, the total COD removal efficiency of the whole system reached 96.7%. The SBR acted as the real undertaker for NH 4 +-N removal due to aerobic nitrification. The system obtained about 99.7% of NH 4 +-N removal efficiency at relatively low temperature (14.9–10.9°C). More than 98.3% TN was removed through complete denitrification in UASB1 and SBR. In addition, temperature had a significant effect on the rates of nitrification and denitrification rather than the removal of TN and NH 4 +-N once the complete nitrification and denitrification were achieved.