Anaerobic Tank Research Articles

Study on the effectiveness of an independent biological phosphorus removal system based on immobilized biological fillers nitrogen removal system in municipal wastewater

This study focused on the problem that simultaneous nitrogen and phosphorus removal cannot be achieved in current urban sewage treatment systems. To address this, a pilot system was developed to first use immobilized biologically active fillers to remove nitrogen, and then use activated sludge to independently remove phosphorus. The goal was to maximize the effectiveness of biological phosphorus removal. This study mainly aimed at analyzing the post-independent phosphorus removal characteristics and mechanisms; the composition of the phosphorus removing bacteria; and the contribution rate of the system. The effluent PO43--P of the system remained stable at 0.15–0.2 mgL−1, with the phosphorus removal anaerobic tank maintaining a "micro-release" state. When the hydraulic retention time (HRT) of the aerobic phosphorus removal tank was reduced to 1 h, the contribution rate of the aerobic phosphorus removal bacteria decreased from 28.42% to 16.68%; the contribution rate of the denitrifying phosphorus removal bacteria increased from 72.58% to 83.32%; and the abundance of the dominant bacteria Dechloromonas and Thaurea significantly increased. The phosphorus removal system provides a new approach for deep phosphorus removal in main municipal wastewater systems.

Optimization of nutrient rich solution for direct fertigation using novel side stream anaerobic forward osmosis process to treat textile wastewater

The current study focused on the performance of a lab scale side stream anaerobic fertilizer drawn forward osmosis (An-FDFO) setup and optimization of nutrient rich solution to achieve sustainable water reuse from high strength synthetic textile wastewater. Three fertilizer draw solutes including Mono Ammonium Phosphate (MAP), Ammonium Sulphate (SOA) and Mono Potassium Phosphate (MKP) were blended in six different ratios with total molar concentration not exceeding 1 M. Among six blended draw solutions (DS), combination with high concentration of SOA have shown highest flux and combination with high concentration of MKP have shown highest reverse solute flux, while those with high concentration of MAP remain moderate both in flux and RSF. During long term runs, SOA: MKP (0.75: 0.25 M) showed longest filtration duration of 217 h in Run 1, with highest initial flux of 8.29 LMH and minimum dilution factor to achieve final nutrients concentration fit for direct fertigation, followed by Run 3 MAP: SOA: MKP (0.2: 0.6: 0.2 M) and then Run 2 MAP: MKP (0.75: 0.25). Moreover, deterioration of mixed liquor characteristics occurs in membrane tank due to high RSF. Similarly, the same inhibitory effect of reverse salt on biogas production was also assessed through Bio-Methane Potential experiments. However, Anaerobic Continuous Stirring Tank Reactor exhibited high performance efficacy, highlighting the importance of side stream submerged configuration in forward osmosis (FO) process.

Mutual Influence Between Microbial Community, Wastewater Characteristics, and Antibiotic Resistance Genes During Spiramycin Production Wastewater Treatment

Wastewater from antibiotic production usually contains a huge amount of antibiotic resistance genes (ARG). Therefore, it is essential to study the dissemination and control of antibiotic resistance during the treatment of antibiotic production wastewater. The mutual influence between microbial community evolution, wastewater characteristics, and ARG was investigated using high-throughput sequencing and a variety of statistical analysis methods. Results showed that the influent characteristics had only a marginal influence on the microbial community of each treatment section. Methanogenic bacteria and sulfate-reducing bacteria were the dominant microbes in the anaerobic and anoxic tank. Chemical oxygen demand (COD), NO2--N, and PO43--P exhibited an intimate relationship with the microbial community, whereas biomass, NH4+-N, and COD showed a strong correlation with ARG and mobile genetic elements (MGE). In the sludge, more genera (including pathogenic bacteria) were significantly correlated with ARG and MGE than that in the wastewater, indicating that bacteria in the sludge had a greater chance of acquiring pathogenicity and resistance. Therefore, more attnetion should be given to waste sludge from the treatment plants of antibiotic production wastewater. This research could provide further understanding of antibiotic resistance dissemination and control during wastewater treatment, especially for antibiotic production wastewater.

Change the original microbial community structure in the hydrolysis acidification tank to enhance the COD removal performance of oily wastewater.

The hydrolysis acidification tank mainly relies on microorganisms to treat oily sewage, but in many cases the chemical oxygen demand (COD) of the effluent from the hydrolysis acidification tank does not decrease or even increase. In this work, about 50 L of oily wastewater is treated in a facultative anaerobic hydrolysis acidification tank with a temperature of 29 °C, pH 6, high-throughput sequencing technology analyzes found that after long-term operation of the hydrolysis and acidification tank, the dominant bacterial Pseudomonas accounted for only 2.87%, at this time, the effluent COD of the hydrolysis and acidification tank was 450 mg/L. Pseudomonas stutzeri LH-42 a strain screened in the laboratory, was domesticated and colonized in the hydrolysis acidification tank. High-throughput sequencing and bioinformatics analysis showed that the proportion of Pseudomonas in the hydrolysis acidification tank reached 5.89%, the effluent COD of the hydrolysis and acidification tank was 200 mg/L. The above results indicate the importance of the proportion of Pseudomonas in the hydrolysis and acidification tank for the COD degradation of oily wastewater.

Performance evaluation and kinetic modeling of an upflow anaerobic sludge blanket septic tank for domestic wastewater treatment.

This work evaluated the UASB-septic tank performance using different kinetic models that correlated process efficiency and methane production with hydraulic and organic loading rates through experiments with five different HRT (48 h, 36 h, 24 h, 18 h, and 12 h) using synthetic domestic wastewater. The modified Stover-Kincannon model provided the best fitting to calculate kinetics constants, with an R2 above 98% for linear regression, and predicted the effluent COD more accurately than the other models. Methane yield was 0.3294 L CH4/g COD removed, being closer to the theoretical value, and the Van der Meer and Heertjes model had the highest R2 for methane production. Organic matter and solids removal were 45% for TS, 70% and 68% for total and soluble COD, and 85% for TSS. Pollutant removal markedly decreased when the reactor operated HRT below 24 h; thus, it is recommended to operate the UASB-septic tank at this HRT.

Perencanaan Instalasi Pengolahan Limbah Cair Rumah Sakit Aliyah 3 Kota Kendari

The purpose of this study was to determine the amount of liquid waste discharge at the hospital. Data from the number of hospital patient beds is 54 beds, so the activities taking place in Aliyah Hospital 3 in Kendari city produces a maximum discharge of liquid waste of 3.78/day. The form and design of processing liquid waste which is a rectangle with anaerobic- aerobic bio filter treatment system. Liquid waste processing with anaerobic-aerobic bio filter process consists of several parts namely the oil separator tank, equalization tank, early settling tank, anaerobic bio filter tank, aerobic bio filter tank, final settling tank and equipped with a chlorinated contractor tub. As for the size of each tank, which is like an oil separator tank (0,9 m × 0,5 m × 0,7 m), equalization tank (2,6 m × 1,3 m × 1,1 m), early settling tank (1,6 m × 0,8 m × 0,9 m), anaerobic bio filter tank (2,5 m × 1,3 m × 1,4 m), aerobic bio filter tank (1,8 m × 1 m × 1 m), final settling tank (1,8 m × 0,7 m × 0,7 m) and chlorinated tank (0,6 m × 0,3 m × 0,4 m). This process system was chosen because it is in accordance with the amount of liquid waste treatment system is safe, inexpensive and easy to operate.

MBR공정의 운전조건의 변화에 따른 여과성능 개선연구

Membrane bioreactor (MBR) combining an activated sludge process and membrane filtration could achieve high nutrient removal efficiency and complete biomass retention without a secondary clarifier. Membrane fouling remains the most challenging issue in MBR operation and attracts considerable attention in MBR studies. The objective of this study is to investigate the influence of permeate flux, aeration mode and strength, and mixed liquor suspended solid (MLSS) on membrane filtration of small-scale MBR (the capacity 100㎥/d), which consisted of anaerobic, anoxic, and aeration tank coupled with membrane. Experiments were conducted with real MBR using real wastewater (BOD <250 mg/L, COD <220 mg/L, T-N <65 mg/L, T-P <8 mg/L, E-coli <100,000 no/mL). As a result, the increase of both permeate flux and MLSS increased TMP of MBR while the increase of aeration strength decreased the TMP. Compared to the existing operation conditions of MBR, the operation conditions of shorter filtration time (8 min on/ 2 min off) for a cycle and lower MLSS (<3000 mg/L) in MBR resulted in longer filtration duration time (about two times) as well as the reduction of cleaning chemical.

Role of air scouring in anaerobic/anoxic tanks providing nitrogen removal by mainstream anammox conversion in a hybrid biofilm/suspended growth full-scale WWTP in China.

A full-scale wastewater treatment plant in China experienced unintentional anammox bacterial enrichment on biofilm carriers placed in the anaerobic and anoxic zones of an anaerobic/anoxic/oxic process under ambient temperatures and without bioaugmentation. Here, we show that microaerophilic conditions resulting from air scouring needed for biofilm carrier suspension in the anaerobic/anoxic zones can support a robust nitritation/anammox process. Results from an in situ on/off air scouring test showed that air scouring strongly induced both ammonia and total inorganic nitrogen removal in the anaerobic/anoxic zones. Ammonium concentration in the anaerobic and anoxic tanks remained constant or even slightly increased when air scouring was off, indicating that air scouring made a noticeable difference in nitrogen profiles in the anaerobic/anoxic zones. Various batch tests further indicated that partial denitrification is not likely to generate nitrite for anammox bacteria. Robust nitritation, and anammox on the carriers, can occur at low dissolved oxygen conditions, as measured in the full-scale facility. The observations show that mainstream deammonification without sidestream bioaugmentation at moderate temperature is feasible and further optimization by a more dedicated design can result in improved nitrogen removal in cases when chemical oxygen demand is limited in mainstream wastewater treatment. PRACTITIONER POINTS: Microaerophilic conditions in a full-scale IFAS reactor caused mainstream anammox in moderate temperate area. Robust nitritation, and anammox on the carriers, can occur at low dissolved oxygen conditions in anaerobic/anoxic tanks with air scouring. Anammox can function well with conventional nitrification and denitrification process at mainstream conditions for stable nitrogen removal.

Data on Biogas Production Quality: Evidence from the Wastewater Treatment Plant of Durrës

The wastewater treatment plant (WWTPD) located in Durrës, responsible for a treatment area of 205,000 inhabitants, employs the tertiary advanced wasterwater treatment to generate biogas from activated sludge for self use. The biogas collected from the anaerobic digestion tank feed the boiler and the co-generation unit which is then transformed to power its own energy grid. In order to evaluate the quality of biogas produced by anaerobic digestion of WWTPD’s sludge, is measured the percentage of CH4 and CO2 from the biogas production during a three years period (2016 – 2018).&#x0D; From the performed analyses has resulted a percentage of CH4 up to 75% and 25% CO2 in 2016. While the lowest percentage of CH4 in 2018 with respectively 70% CH4 and 30% CO2.&#x0D; Based on the value measurements, qualitative results of biogas parameters show that physicochemical and biochemical processes are performed under strict conditions and anaerobic digestion is performed according to standards.

Data on Biogas Production Quality: Evidence from the Wastewater Treatment Plant of Durrës

The wastewater treatment plant (WWTPD) located in Durrës, responsible for a treatment area of 205,000 inhabitants, employs the tertiary advanced wasterwater treatment to generate biogas from activated sludge for self use. The biogas collected from the anaerobic digestion tank feed the boiler and the co-generation unit which is then transformed to power its own energy grid. In order to evaluate the quality of biogas produced by anaerobic digestion of WWTPD’s sludge, is measured the percentage of CH4 and CO2 from the biogas production during a three years period (2016 – 2018).&#x0D; From the performed analyses has resulted a percentage of CH4 up to 75% and 25% CO2 in 2016. While the lowest percentage of CH4 in 2018 with respectively 70% CH4 and 30% CO2.&#x0D; Based on the value measurements, qualitative results of biogas parameters show that physicochemical and biochemical processes are performed under strict conditions and anaerobic digestion is performed according to standards.

Perencanaan Instalasi Pengolahan Limbah Cair Rumah Sakit Aliyah 3 Kota Kendari

The purpose of this study was to determine the amount of liquid waste discharge at the hospital. Data from the number of hospital patient beds is 54 beds, so the activities taking place in Aliyah Hospital 3 in Kendari city produces a maximum discharge of liquid waste of 3.78/day. The form and design of processing liquid waste which is a rectangle with anaerobic- aerobic bio filter treatment system. Liquid waste processing with anaerobic-aerobic bio filter process consists of several parts namely the oil separator tank, equalization tank, early settling tank, anaerobic bio filter tank, aerobic bio filter tank, final settling tank and equipped with a chlorinated contractor tub. As for the size of each tank, which is like an oil separator tank (0,9 m × 0,5 m × 0,7 m), equalization tank (2,6 m × 1,3 m × 1,1 m), early settling tank (1,6 m × 0,8 m × 0,9 m), anaerobic bio filter tank (2,5 m × 1,3 m × 1,4 m), aerobic bio filter tank (1,8 m × 1 m × 1 m), final settling tank (1,8 m × 0,7 m × 0,7 m) and chlorinated tank (0,6 m × 0,3 m × 0,4 m). This process system was chosen because it is in accordance with the amount of liquid waste treatment system is safe, inexpensive and easy to operate.

CFD Modeling of a Stirred Anaerobic Digestion Tank for Evaluating Energy Consumption through Mixing

The anaerobic digestion process is an effective means to eliminate the detrimental impacts of cattle manure discharge into the environment, i.e., biochemical contamination and substantial methane emissions, the latter leading to global warming. For proper operation of anaerobic digesters, an efficient mixing provides a relatively homogenous mixture of the feedstock within the tank. This study aims to investigate the mixing process and the total energy consumption needed for stirring by using an asymmetrical mixer. A further objective is to analyze the formation of stagnant volume and the velocity gradient in the digester in order to assure the mixing efficiency of the mixer type. The computational model is implemented as the finite volume method, and the rheological properties of the feedstock are considered. The results are validated by comparing the on-site power consumption of the mixer with the values obtained by the numerical torque. At various mixer speeds, the dead volume does not exceed 0.5% of the digester tank; however, with the increase of the mixer rotation speed, the energy consumption of the mixer increases drastically.

Characterization of the biodegradation of synthetic and organic wastewater in an anaerobic tank reactor using microalgae

AbstractThe anaerobic digestion is a well-known method in waste management of biodegradable wastes to transform waste to energy. Proper digestion requires optimal fermentation conditions to improve the quality and yield of biogas.The objective of this study was to characterize the biodegradation process of synthetic and organic wastewater. Microalgae (Chlorella vulgaris) were utilized as a bioindicator for anaerobic digestion and monitoring of the fermentation process. Besides bioindication, the viability of the microalgae and the chlorophyll concentration were also assessed in such fermentation processes, since microalgae can be a potential source for biofuel production and a plant nutrient.The biodegradation process was studied for a month in an anaerobic tank reactor. The fermentation processes and lengths of the fermentation stages were successfully monitored and separately identified based on the pH and gas development. Furthermore, the amount and dynamics of the biogas yield also revealed that the fermentation process was about 510 hours in both cases. In contrast, increased temperature in thermophilic range (45°C) accelerates the degradation processes and resulted in shorter hydrolysis (60 hours), acetogenesis (24 hours) and longer methanogenesis (81 hours) stages, where higher biogas yield was also achieved (59.3%). During the process, the concentration of nutrients showed logarithmical tendencies and COD showed power tendency in time. The extent and the direction of the changes were in correspondence with microalgae activity. In thermophilic circumstances, living microalgae biomass dropped significantly without recovery therefore such an environment is not a viable option for microalgae growth. Moreover, dead microalgae biomass seems to act as a substrate for fermentation slightly increasing the concentration of some nutrients in the wastewater.

Rancang Bangun Biofilter untuk Pengolahan Limbah Cair Kegiatan Sentra Wisata Kuliner di Kecamatan Tambaksari, Kota Surabaya

The development of culinary business at Culinary Tourism Centre (CTC) has produced domestic wastewater from dish washing activities and food residues. One CTC in Tambaksari District, Surabaya City has not had Wastewater Treatment Plant (WWTP) yet. The CTC only has equalization tank for accommodating wastewater before discharged into the water body. This research aimed to determine the characteristics of domestic wastewater from the CTC and to design the appropriate WWTP in the CTC. The standard was based on the Regulation of the East Java Governor Number 72 Year 2013. The result showed that the concentrations of TSS, grease and oil, BOD, COD were 14 mg/L, 1.59 mg/L, 1154.8 mg/L, and 2054.8 mg/L, respectively. The WWTP units consisted of a grease trap, an equalization tank, primary sedimentation tank, anaerobic tank, aerobic tank, and secondary sedimentation tank. The estimated cost to build the WWTP was IDR 278,093,774.

Aerobic Granular Sludge Operation and Nutrient Removal Mechanism from Domestic Sewage in an Anaerobic/Aerobic Alternating Continuous Flow System

Mature aerobic granular sludge was inoculated at room temperature in an anaerobic/aerobic alternating continuous flow system. The system consisted of two independent anaerobic and aerobic tanks. Actual domestic sewage was used as the influent to explore the influence of the gas intensity and hydraulic residence time on the continuous flow system. The results revealed that the conditions of a reflux ratio of 2, lower aeration intensity (0.6 mL·min-1), and proper hydraulic residence time (9 h) were more conducive to the removal of pollutants. Under such conditions, the average removal rate of TP was 80.43%, the average removal rate of TN was 83.6%, the average removal rate of COD was 90.39%, the sludge concentration was approximately 2100 mg·L-1, the sludge volume index was maintained below 50 mL·g-1, and the particle size was 700-800 nm. The EEM-PARAFAC model was used to characterize and analyze the EPS at different stages. The results revealed that changing the parameters could change the composition of EPS. The hydraulic residence time had a greater impact on the continuous flow system than the aeration intensity. In addition, a preliminary conceptual reaction process model in the anaerobic/aerobic alternating continuous flow system was built using high-throughput pyrosequencing and phylogenetic assignment. Eleven major functional bacteria related to nitrogen and phosphorus removal were found in the system.

A COMPREHENSIVE ASSESSMENT OF SEPTAGE MANAGEMENT IN BANTUL, YOGYAKARTA

Aim: This study aims to assess the entire process of septage management comprising regulation, operational procedures, finance, community involvement, and water quality analysis to maximize the initial and hugest human fecal sludge treatment called Faecal Sludge Treatment Plant (IPLT) in Yogyakarta. Methodology and Results: The Modified EHRA (Environmental Health Risk Assessment) method was applied which focused only on wastewater treatment aspect. Several regulations including standard quality methods (SNI) were utilized and made a comparison between baseline rules and obtained results. Furthermore, quality assessment was accomplished by observation and interview. The results showed that the human sector needs to improve not only the amount of operators but also urgently put up protective personal equipment during the suction process. The dissemination of attractive information about sludge suction service done by PUPKP as a representation of the local government among the dwellers ought to upgrade a lot. Technologies employed which are carriage transportation and vacuum machine, are good enough. Contrarily, septage treatment plants require extra-effort to enhance it as most water quality parameters barely meet the standard quality. BOD, COD, ammonia, total coliform, oil and grease do not meet the third class of water quality (Government Regulation of Republic of Indonesia No. 82/2001). Subsequently, the effectiveness of each unit i.e. anaerobic tank and stabilization ponds are under 50% and the loading rate has a maximum capacity of 87.5m3/day, and 60m3/day minimum capacity. Conclusion, significance and impact of study: Therefore, almost all aspects of septage management in Bantul Yogyakarta are required to improve

Biodeterioration kinetics and microbial community organization on surface of cementitious materials exposed to anaerobic digestion conditions

Anaerobic digestion is a process that can produce renewable energy through the fermentation of biodegradable biomass. Industrial anaerobic digestion tanks are usually made of concrete but the production of various aggressive compounds (CO2, NH4+ and volatile fatty acids) during the microbial fermentation leads to deterioration of the concrete structure. In addition, the formation of a microbial biofilm on the cementitious material surface could generate even more intense biodeterioration. The objective of this study is to gain a better understanding of the involvement of biofilm in the biodeterioration of cementitious materials during an anaerobic digestion process. More specifically, the study focuses on the heterogeneity of microbial populations within the biofilm and the reactive medium in anaerobic digestion. Laboratory scale anaerobic bioreactors mimicking the industrial anaerobic digestion medium were constructed and CEM I cement pastes were immersed in this medium for 2, 3, 4, 5, 10 and 15 weeks. The biodeterioration of the cement pastes was evaluated by determining the deteriorated thickness. The aggressive compounds in the medium were quantified. The biofilm attached to the surface of the cement pastes was analyzed using 16 s rRNA gene sequencing. To evaluate the heterogeneity of the biofilm, the growth of biofilm layers was successively caused to stall by using two distinct biofilm removal techniques. Three microbial fractions were defined: planktonic microorganisms, and the microorganisms within the biofilm that were loosely and strongly attached. The results showed that the planktonic lifestyle was more associated with microorganisms producing methane and consuming volatile fatty acids, while the biofilm was more associated with bacteria producing acids, mainly members of the Clostridium genus. A microbial community shift due to a reversible propionic acid accumulation during the first 5 weeks was also observed. In addition, no major differences were spotted between the loosely and strongly attached biomass, indicating homogeneity in the two layers of the biofilm. These results suggest that the biofilm could increase the biodeterioration of concrete since volatile fatty acids could be produced in massive quantities near the surface of the cement samples by the acidogenic microbial population more present within the biofilm.

Microbial Community Structure of Waste Water Treatment Plants in Different Seasons

Wastewater treatment plants (WWTPs) have different treatment effects during different seasons due to changes in water quality and temperature. To understand bacterial community structure and diversity dynamics in the WWTPs, this study employed high-throughput sequencing technology during winter and summer. A total of 60 activated sludge samples were collected in five WWTPs in Beijing with different treatment processes in summer (temperature=28℃±2℃, water temperature=24.9℃±1.1℃) and winter (temperature=0℃±3℃, water temperature=16.8℃±1.3℃). The relative abundances of dominant bacterial genera in activated sludge varied significantly between the WWTPs but microbial community structure was typically similar between different treatment units (i.e., the anaerobic tank, anoxic tank, and aerobic tank) at each WWTP. At the same time, different bacteria dominated in winter and summer, when the relative abundance of SJA-15, Ferruginibacter, and Blasocatellaceae was 6.07%, 4.50%, and 4.44% respectively, when the relative abundance of Nitrospira, Methylotenera, and RBG-13-54-9 in winter was 10.17%, 3.96%, and 3.28%, respectively. Correlation analysis showed that temperature, total nitrogen (TN), NH4+-N, total phosphorus (TP), and chemical oxygen demand (COD) were the main environmental factors affecting microbial community structure, of which temperature had the greatest effect on species composition followed by TN. Furthermore, a predictive analysis of functional enzymes indicated that the abundance of key enzymes involved in the nitrogen cycle in the activated sludge of WWTPs is higher in winter than that in summer. These results show that temperature, water quality, and treatment process affect bacterial community structure (i.e., dominance and abundance) in WWTP activated sludge.

Development of a method for calculating a anaerobic digester with bubbling mixing

Currently, there is a development of biogas technologies designed to obtain an alternative source of biogas energy and utilize organic waste. When developing and designing biogas plants, an important task is to determine the design and technological parameters of the anaerobic digester in order to obtain the maximum biogas yield. For the research, an anaerobic digester equipped with a bubbling mixing system was used. The bubble tube is made in the form of a spiral and forms a cone with the base downward. A calculation method has been developed that makes it possible to determine the physical and chemical properties of the biomass, the geometric parameters of the digester, the specific and total volume of biogas produced, the design parameters of the digester heating system, the design and technological parameters of the bubbling-type mixing system. With the help of the developed methodology, the design and technological parameters of the anaerobic digester of the biogas station for the disposal of organic waste from a pig breeding enterprise and a meat processing plant were determined. As a result of calculations, it was established that the station contains 3 anaerobic digester tanks with a volume of 200 m3 each, utilizes 40 m3 of waste per day and produces 1600 m3 of biogas per day.

Characteristics of the community-structure of A2O processes under different dissolved oxygen conditions in plateau areas

This study conducted a Pilot-Scale Anaerobic-Anoxic-Aerobic Process (A2O) experiment in a highland city of Linzhi. Four Dissolved oxygen (DO) working conditions of 2.0, 1.5, 1.0, and 0.5 mg/L was designed in this experiment. The 16SrRNA gene sequencing was performed on sludge from the anaerobic, anoxic and aerobic tanks. Through the composition analysis of sludge on Phylum, Class and Genus level, it can be found that the number of bacterial community at each level of the bacterial community was relatively low. Indicators of community richness, community evenness and community diversity were relatively low compared to other regions. The bacterial communities at different levels are significantly different from the reported dominant community and abundance. Correlation analysis between environmental factors and bacterial community structure proved that DO had significant correlation with bacterial community structure (P<0.05). The removal rates of the total phosphorous (TP), Total nitrogen (TN), Ammonia nitrogen (NH3-N) and Chemical Oxygen Demand (COD) were all affected by the sample communities structure. The composition of the bacterial community structure included nitrifying bacteria, denitrifying bacteria and polyphosphate-accumulating organisms, but the abundance was relatively low. The results also showed that the dominant community in different DO conditions and different reactors has large differences.