Effluent Chemical Oxygen Demand Research Articles

Modeling of an activated sludge process for effluent prediction-a comparative study using ANFIS and GLM regression.

In this paper, nonlinear system identification of the activated sludge process in an industrial wastewater treatment plant was completed using adaptive neuro-fuzzy inference system (ANFIS) and generalized linear model (GLM) regression. Predictive models of the effluent chemical and 5-day biochemical oxygen demands were developed from measured past inputs and outputs. From a set of candidates, least absolute shrinkage and selection operator (LASSO), and a fuzzy brute-force search were utilized in selecting the best combination of regressors for the GLMs and ANFIS models respectively. Root mean square error (RMSE) and Pearson's correlation coefficient (R-value) served as metrics in assessing the predicting performance of the models. Contrasted with the GLM predictions, the obtained modeling results show that the ANFIS models provide better predictions of the studied effluent variables. The results of the empirical search for the dominant regressors indicate the models have an enormous potential in the estimation of the time lag before a desired effluent quality can be realized, and preempting process disturbances. Hence, the models can be used in developing a software tool that will facilitate the effective management of the treatment operation.

Evaluation of Pre-Chlorinated Wastewater Effluent for Microalgal Cultivation and Biodiesel Production

Microalgae are promising feedstock to produce biodiesel and other value added products. However, the water footprint for producing microalgal biodiesel is enormous and would put a strain on the water resources of water stressed countries like South Africa if freshwater is used without recycling. This study evaluates the utilization of pre-chlorinated wastewater as a cheap growth media for microalgal biomass propagation with the aim of producing biodiesel whilst simultaneously remediating the wastewater. Wastewater was collected from two wastewater treatment plants (WWTPs) in Durban, inoculated with Neochloris aquatica and Asterarcys quadricellulare and the growth kinetics monitored for a period of 8 days. The physicochemical parameters; including chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) were determined before microalgal cultivation and after harvesting. Total lipids were quantified gravimetrically after extraction by hexane/isopropanol (3:2 v/v). Biodiesel was produced by transesterification and characterised by gas chromatography. The total carbohydrate was extracted by acid hydrolysis and quantified by spectrophotometric method based on aldehyde functional group derivatization. Asterarcys quadricellulare utilized the wastewater for growth and reduced the COD of the wastewater effluent from the Umbilo WWTP by 12.4%. Total nitrogen (TN) and phosphorus (TP) were reduced by 48% and 50% respectively by Asterarcys quadricellulare cultivated in sterile wastewater while, Neochloris reduced the TP by 37% and TN by 29%. Although the highest biomass yield (460 mg dry weight) was obtained for Asterarcys, the highest amount of lipid (14.85 ± 1.63 mg L−1) and carbohydrate (14.84 ± 0.1 mg L−1) content were recorded in Neochloris aquatica. The dominant fatty acids in the microalgae were palmitic acid (C16:0), stearic acid (C18:0) and oleic acid (C18:1). The biodiesel produced was determined to be of good quality with high oxidation stability and low viscosity, and conformed to the American society for testing and materials (ASTM) guidelines.

Optimization of sensing performance in an integrated dual sensors system combining microbial fuel cells and upflow anaerobic sludge bed reactor

Two bio-cathode microbial fuel cells (MFCs) with Upflow anaerobic sludge blanket (UASB) are integrated to construct a UASB-MFC dual sensors system, developed to solve the problems of low accuracy and less information about the single sensor system. The bio-cathode MFC is developed as the biosensor for UASB operation performance and online monitoring. Owing to the biosorption of anaerobic microbes, the MFC in the suspended layer is more suitable for effluent chemical oxygen demand (COD) real-time monitoring, and the MFC in the sludge layer is more suitable for total volatile fatty acid (TVFA) real-time monitoring. Electrochemical analysis discovers that the lower electron transfer resistance determines the higher sensitivity of MFC in the suspended layer. The difference in species abundance indicates that TVFA has a stronger inhibitory effect on MFC in the sludge layer. The novel UASB-MFC dual sensors system shows promising potential for COD and TVFA simultaneous online monitoring, which can enhance the reliability of anaerobic reaction.

Enhanced electricity generation and effective water filtration using graphene-based membrane air-cathodes in microbial fuel cells

Air-cathodes in microbial fuel cells that can also filter wastewater provide the dual benefits of electricity production and reduction of the effluent chemical oxygen demand. Air-cathodes prepared using a novel activated carbon/graphene membrane (2, 5 or 10% graphene by weight) prepared by phase inversion have good conductivities (5.6 ± 0.5 to 7.3 ± 0.6 mS cm−1) compared to control (3.0 ± 0.4 mS cm−1, activated carbon, no graphene). The cathode with 5 wt% graphene produces the highest maximum power density of 1460 ± 10 mW m−2, which is 58% higher than that the control (928 ± 8 mW m−2). The increased power is due to an 88% reduction in charge transfer resistance of 6.0 ± 0.3 Ω (cathode with 5 wt% graphene) compared to the control. Following a cycle of treatment and current generation, 60 ± 1% of the chemical oxygen demand is removed from the remaining chemical oxygen demand, producing an effluent chemical oxygen demand concentration of 20 ± 1 mg L−1. Biomass (4.99 ± 0.02 mg-protein cm−2) is decreased by 33% compared to the control. These results demonstrate that cathodes made with graphene can produce electricity and a high quality effluent with low cathode biofouling.

Biological treatment and ultrafiltration of woodchip pre-hydrolysis liquor from dissolving pulp mills

Abstract Dissolving pulps could be considered as the future biorefineries, which normally generate liquor during the wood chip pre-hydrolysis (PHL). PHL has high chemical oxygen demand (COD) and biochemical oxygen demand (BOD). Mills do not have efficient means for disposal of PHL, being in general burned in the recovery boiler with a high cost due to its low consistency. The objectives of this work were to evaluate i) the biotreatability of PHL and the effects it would have on a kraft mill effluent biological treatment plant and ii) the use of ultrafiltration (UF) membrane to treat the PHL prior to biological treatment. PHL was generated into lab with a hydrothermal process and was mixed with kraft pulp mill effluent in different proportions and added to sequencing batch reactors (SBRs). The SBRs achieved high rates of COD removal (>75 %). However, treated effluent COD increased with the increase in PHL dose. This treatment using UF membranes reduced the COD load. Biotreatability of the UF permeate was higher than that of PHL. UF retentate, with 28 % of the volume and a much higher solids content than the initial PHL, would have a significantly lower evaporation energy demand if sent to the black liquor evaporators.

Evaluation of different structures of moving bed biofilm reactors (MBBR) for synthetic wastewater treatment

Performance of three different structures of moving bed biofilm reactors (MBBR) treating synthetic wastewater was evaluated. The three systems were operated under the same conditions of dissolved oxygen (DO) 3 mg/L at 26 °C. The effluent of chemical oxygen demand (COD) decreased from 111.6 mg/L in reactor 1 (R1), 128.8 mg/L in reactor 2 (R2), and 154.5 mg/L in reactor 3 (R3), to less than 100 mg/L, respectively, with concentration of influent NH4+-N rising from 30 mg/L to 50 mg/L. The concentration of effluent NH4+-N for R1, R2 and R3 were close to 2 mg/L, 4 mg/L and 5 mg/L, respectively. The highest TN removal rate in R1 achieved average 84.4 %, which was 6.0 % and 9.7 % higher than those of R2 and R3, respectively. R1 with two baffles in it exhibited well fluidization and abundant microbes growing on carrier.

Biological treatment of real petrochemical wastewater containing styrene using submerged membrane bioreactor: effects of HRT

In this study, real petrochemical wastewater treatment was investigated at four hydraulic retention times (HRTs) of 30, 18, 12 and 6 h, using membrane bioreactor. Initial evaluation confirmed the presence of styrene and more than 30 different types of compounds in petrochemical wastewater. Laboratory tests and gas chromatography–mass spectrometry (GC–MS) studies indicated that at all HRTs, styrene and chemical oxygen demand (COD) removal efficiencies are higher than 99 and 95%, respectively. Further investigations also revealed that HRT decreasing, not only does not reduce the COD removal efficiency, but also improves the effluent COD by increasing mixed liquor suspended solids. Also GC–MS analysis indicated that styrene as the major pollutant was removed over 99%. Transmembrane pressure was monitored for determining membrane fouling. Data showed severe membrane fouling occurred at HRT of 6 h which was attributed to increase in soluble microbial products.

Physicochemical assessment of industrial textile effluents of Punjab (India)

Urbanization and industrialization are generating huge quantities of untreated wastewater leading to increased water pollution and human diseases in India. The textile industry is one of the leading polluters of surface water and consumes about 200–270 tons of water to produce 1 ton of textile product. The primary objective of the present study was to investigate the pollution potential of textile industry effluent draining into Buddha Nallah stream located in Ludhiana, Punjab (India), and determine the seasonal variation in physicochemical parameters (pH, water temperature, total dissolved solids, total suspended solids, biochemical oxygen demand (BOD) and chemical oxygen demand (COD) of Buddha Nallah water. During summer months, for Site 1 and Site 2, the value of pH was in the alkaline range of 8.78 ± 0.47 and 8.51 ± 0.41, respectively. The values of pH in the rainy season were found to be in the range of 7.38 ± 0.58 and 7.11 ± 0.59 for Site 1 and Site 2, respectively. In the autumn and winter seasons, the average pH values were found to be in the range of 8.58 ± 1.40 and 8.33 ± 0.970, respectively. The maximum mean temperature in summer was recorded as 41.16 ± 4.99 °C, and lowest mean temperature in winter was recorded as 39.25 ± 2.25 °C at Site 2. The suspended solids were found to be highest (143.5 ± 75.01 and 139.66 ± 71.87 mg/L) in autumn for both the sites and lowest (86.50 + 15.10 mg/L) in the rainy season for Site 1. The values of BOD and COD of the textile effluent of both sites during all the seasons ranged from 121–580 to 240–990 mg/L, respectively, much higher than WHO water quality standard of 30 mg/L for BOD and 250 mg/L for COD. The present study deals with the collection of textile industry effluent and its characterization to find out the physicochemical load being drained by the effluent generated from textile industries, on the natural wastewater streams.

FeS2 Nanoparticles Decorated Graphene as Microbial-Fuel-Cell Anode Achieving High Power Density.

Microbial fuel cells (MFCs) have received great attention worldwide due to their potential in recovering electrical energy from waste and inexhaustible biomass. Unfortunately, the difficulty of achieving the high power, especially in real samples, remains a bottleneck for their practical applications. Herein, FeS2 nanoparticles decorated graphene is fabricated via a simple hydrothermal reaction. The FeS2 nanoparticles decorated graphene anode not only benefits bacterial adhesion and enrichment of electrochemically active Geobacter species on the electrode surface but also promotes efficient extracellular electron transfer, thus giving rise to a fast start-up time of 2 d, an unprecedented power density of 3220 mW m-2 and a remarkable current density of 3.06 A m-2 in the acetate-feeding and mixed bacteria-based MFCs. Most importantly, the FeS2 nanoparticles decorated graphene anode successfully achieves a power density of 310 mW m-2 with simultaneous removal of 1319 ± 28 mg L-1 chemical oxygen demand in effluents from a beer factory wastewater. The characteristics of improved power generation and enhanced pollutant removal efficiency opens the door toward development of high-performance MFCs via rational anode design for practical application.

Research on the enhancement of biological nitrogen removal at low temperatures from ammonium-rich wastewater by the bio-electrocoagulation technology in lab-scale systems, pilot-scale systems and a full-scale industrial wastewater treatment plant

In cold areas, nitrogen removal performance of wastewater treatment plants (WWTP) declines greatly in winter. This paper systematically describes the enhancement effect of a periodic reverse electrocoagulation technology on biological nitrogen removal at low temperatures. The study showed that in the lab-scale systems, the electrocoagulation technology improved the biomass amount, enzyme activity and the amount of nitrogen removal bacteria (Nitrosomonas, Nitrobacter, Paracoccus, Thauera and Enterobacter). This enhanced nitrification and denitrification of activated sludge at low temperatures. In the pilot-scale systems, the electrocoagulation technology increased the relative abundance of cold-adapted microorganisms (Luteimonas and Trueperaceae) at low temperatures. In a full-scale industrial WWTP, comparison of data from winter 2015 and winter 2016 showed that effluent chemical oxygen demand (COD), NH4+-N, and NO3−-N reduced by 10.37, 3.84, and 136.43 t, respectively, throughout the winter, after installation of electrocoagulation devices. These results suggest that the electrocoagulation technology is able to improve the performance of activated sludge under low-temperature conditions. This technology provides a new way for upgrading of the performance of WWTPs in cold areas.

Investigation on the Influence of Bio-catalytic Enzyme Produced from Fruit and Vegetable Waste on Palm Oil Mill Effluent

Pre-consumer waste from supermarkets, such as vegetables and fruits dreg are always discarded as solid waste and disposed to landfill. Implementing waste recovery method as a form of waste management strategy will reduce the amount of waste disposed. One of the ways to achieve this goal is through fermentation of the pre-consumer supermarket waste to produce a solution known as garbage enzyme. This study has been conducted to produce and characterize biocatalytic garbage enzyme and to evaluate its influence on palm oil mill effluent as a pre-treatment process before further biological process takes place. Garbage enzyme was produced by three-month long fermentation of a mixture of molasses, pre-consumer supermarket residues, and water in the ratio of 1:3:10. Subsequently, the characterization of enzyme was conducted based on pH, total solids (TS), total suspended solids (TSS), total dissolved solids (TDS), chemical oxygen demand (COD), and enzyme activities. The influence of produced enzyme was evaluated on oil & grease (O&G), TSS and COD of palm oil mill effluent (POME). Different levels of dilution of garbage enzyme to POME samples (5%, 10%, 15%) were explored as pre-treatment (duration of six days) and the results showed that the garbage enzyme contained bio-catalytic enzyme such as amylase, protease, and lipase. The pre-treatment showed removal of 90% of O&G in 15% dilution of garbage enzyme. Meanwhile, reduction of TSS and COD in dilution of 10% garbage enzyme were measured at 50% and 25% respectively. The findings of this study are important to analyse the effectiveness of pre-treatment for further improvement of anaerobic treatment process of POME, especially during hydrolysis stage.

Dynamic Simulation of Petrochemical Wastewater Treatment Using Wastewater Plant Simulation Software

A dynamic simulation model was developed, calibrated and validated for a petrochemical plant in Terengganu, Malaysia. Calibration and validation of the model was conducted based on plant monitoring data spanning 3 years resulting in a model accuracy (RMSD) for effluent chemical oxygen demand (COD), ammoniacal nitrogen (NH3-N) and total suspended solids (TSS) of ±11.7 mg/L, ±0.52 mg/L and ± 3.27 mg/L respectively. The simulation model has since been used for troubleshooting during plant upsets, planning of plant turnarounds and developing upgrade options. A case study is presented where the simulation model was used to assist in troubleshooting and rectification of a plant upset where ingress of a surfactant compound resulted in high effluent TSS and COD. The model was successfully used in the incident troubleshooting activities and provided critical insights that assisted the plant operators to quickly respond and bring back the system to normal, stable condition.

Modeling of extracellular polymeric substances production at different Carbon/Nitrogen ratio and solid retention time by artificial neural network

Aims: The ability of extracellular polymeric substances (EPS) production was observed in many species of heterotrophic microorganisms through the biological wastewater treatment systems. Materials and Methods: The batch experiments at different carbon/nitrogen and solid retention time (SRT) were carried out to investigate the effects of initial nitrogen concentration and SRT on EPS production and chemical oxygen demand (COD) removal efficiency. The artificial neural network (ANN) was developed to modeling of obtained data. Results: The results showed that: (i) with increasing SRT, the COD removal improves; (ii) initially, the amount of carbohydrate increases as SRT increases; however, with further increase of SRT, it declines; (iii) the protein/carbohydrate ratio improves as SRT decreases; (iv) the carbohydrate and protein concentration of soluble EPS increased with increasing initial nitrogen concentration from 0 to 10 mg/L; and (v) further increase of initial nitrogen concentration lead to depletion of carbohydrate production. Conclusion: The highest yield (Y) value was calculated at low sludge age and deficient initial nitrogen concentration, which may be due to the application of EPS production mechanism. The ANN model moderately predicted effluent COD concentration, carbohydrate, and protein production.

Energy-saving optimization of coking wastewater treated by aerobic bio-treatment integrating two-stage activated carbon adsorption

Contaminants removal efficiency and energy consumption are of practical importance in wastewater treatment. Herein, an energy saving system including aerobic bio-treatment combined with a two-stage adsorption (AB-2A) was proposed and applied to the treatment of coking wastewater. The adsorption before bio-treatment partially extracts energy and organic constituents from the wastewater, making the subsequent bio-treatment more effective. The adsorption after bio-treatment brings the effluent to the discharge requirements. In comparison with the biological treatment combined with subsequent ozonation (M0 mode), the proposed system rationalizes the material flows in the wastewater treatment by optimized activated carbon utilization targeting higher adsorption and energy extraction efficiencies. The combined system AB-2A aimed at reducing the chemical oxygen demand (COD) to the national discharge standard at maximized net energy benefit (NEB) and benefit cost ratio (BCR). The modified cost benefit analysis was applied to energy balance evaluation of the system. Two combustible adsorbents, a commercial activated carbon (CAC) and a sludge-derived activated carbon (SAC), were used for pollutants adsorption. The results showed that the average effluent COD of the combined system AB-2A reached 78.8 mg/L when subjected to the activated carbon adsorption after biodegradation, with 7.0 g/L CAC added sequentially to the biologically treated and then to the raw coking wastewater (M2(CAC) mode). COD removal efficiency of M2(CAC) mode exceeded 96% being equal to the reference result of M0 mode. Additionally, the NEB and BCR reached −11.81 kWh/m3 and 0.80 in M2(CAC) mode, respectively. Moreover, the M2 mode applying SAC (M2(SAC) mode) in amount of 7.0 g/L demonstrated the highest energy recovery compared to M0 and the separate adsorbent application to the raw influent and the bio-treated effluent (M1 mode). The difference values of NEB and BCR in M2(SAC) compared to M0 were shown as big as 28.87 kWh/m3 and 0.07, respectively. The excess sludge recycling in the wastewater treatment resulted in the positive benefit in energy saving. Summarizing, the AB-2A system using SAC appears to be high COD removal efficiency and energy saving in the future sustainable wastewater treatment.

Treatment of high-strength purified terephthalic acid (PTA) wastewater using a magnetic porous ceramic support in laboratory-scale anaerobic-aerobic fluidized bed reactors

Laboratory-scale anaerobic-aerobic fluidized-bed bioreactors (FBR) with porous magnetic ceramics as support were successfully applied to treat purified terephthalic acid (PTA) wastewater. After a short 14-day start-up period, the system was stably operating. During the 40 d stable period, the system organic loading rate (OLR) increased from 6.68 to 23.87 kg chemical oxygen demand (COD)/(m3d), the effluent COD and PTA were below 90 and 30 mg/L, respectively. The FBR presented excellent COD and PTA removal efficiency with a low hydraulic retention time (HRT) value of six hours. The growth kinetic parameters suggested that the biomass in FBR possess high maximum specific growth rate (μmax = 2.22 d−1) and good tolerance to varied OLR (Ks = 258.67 mg COD/L).

Methane Cycle Anaerobic Membrane Bioreactor with Desulfurization for Treating High Sulfate Organic Wastewater at Normal Temperature

The operational performance of a methane cycle anaerobic membrane bioreactor (MCAnMBR) with desulfurization for the treatment of high sulfate organic wastewater was investigated. Within 63 days, the MCAnMBR with desulfurization was started successfully at a normal temperature of 26-34℃. The two main problems at the beginning of debugging, sludge loss and increased pH, were effectively solved by adjusting the gas path system and adding methanol to the inflow for acclimation. The results show that the inflow concentration of SO42- from 650 mg·L-1to 5800 mg·L-1can be treated well with the conditions of hydraulic retention time (HRT)=120 h, a volume loading of 3.61-4.36 kg·(m3·d)-1, pH of 7.18-7.61, and temperature of 23.3-25.4℃. The effluent chemical oxygen demand (COD) concentration could be lowered to 23 mg·L-1. The total removal rate of COD could remain stable at 96.23%-99.77%, and the SO42- conversion rate was about 83.83%-95.51%. These results indicated that the MCAnMBR reactor with desulfurization could effectively solve the problem of secondary sulfide inhibition. A gradient experiment revealed that the high Na2SO4 inflow could be treated when the influent COD ranged from 18000 mg·L-1to 21000 mg·L-1, the concentration of SO42- ranged between 9082 mg·L-1 and 9600 mg·L-1, and the COD/SO42-=2.

Water and wastewater minimization in a petrochemical industry through mathematical programming

Petrochemical industries have large water demands in their operations, such as distillation, extraction, washing processes and cooling systems. The present work discusses water and wastewater minimization in the production process of a Brazilian petrochemical industry, applying mass integration via mathematical programming. This research is a case study applied in industrial scale, using data from a petrochemical plant. Alternatives for water reuse were evaluated by analyzing water consumption and wastewater generation processes by using a superstructure and a nonlinear mathematical programming model. The concentration of chemical oxygen demand in effluents was considered as a limiting factor. The alternatives found in this study could lead to total economy of 280,320 m3/y of water, and 236,520 m3/y of wastewater that would no longer be generated. This volume would sufficiently supply 4626 inhabitants for one year, considering the average water consumption per capita in Brazil, which is of 166 L per capita per day. Using this process, potential benefits could be achieved with water reuse.

Anaerobic treatment of raw domestic wastewater in a UASB-digester at 10 °C and microbial community dynamics

Direct anaerobic treatment of domestic wastewater is becoming attractive as it can change a wastewater treatment plant from energy consuming to energy producing. A pilot scale UASB-digester was studied to treat domestic wastewater at temperatures of 10–20 °C and an HRT of 6 h. The results show a stable chemical oxygen demand (COD) removal efficiency of 60 ± 4.6% during the operation at 12.5–20 °C. COD removal efficiency decreased to 51.5 ± 5.5% at 10 °C as a result of insufficient methanogenic capacity caused by low temperature and increased influent COD load (from 2.0 g/(L·d) to 3.0 g/(L·d)). Suspended COD removal was 76.0 ± 9.1% at 10–20 °C. Soluble COD removal fluctuated due to variation of the influent COD concentration, but the effluent COD concentration remained 90 ± 23 mg/L at temperatures between 12.5 and 20 °C. The methane production was 39.7 ± 4.4% of the influent COD, which was 80% of influent biological methane potential. The specific methanogenic activity of the UASB sludge and the digester sludge was 0.26 ± 0.03 and 0.29 ± 0.03 g CH4 COD/(g VSS d), respectively. The methanogenic community analysis revealed an overall dominance of the acetoclastic Methanosaetaceae and the hydrogenotrophic Methanomicrobiales during the operation between 10–20 °C. The results of the UASB-digester treating domestic wastewater at 10–20 °C as reported in this paper provide support for application of anaerobic domestic wastewater treatment in moderate climate zones.

Recalcitrant Compounds Removal in Raw Leachate and Synthetic Effluents Using the White-Rot Fungus Bjerkandera adusta

Recalcitrant compounds limit the efficiency of conventional biological processes for wastewater treatment, representing one of the major issues in the field. This study focused on the treatment of three effluents with White-Rot-Fungus (WRF) Bjerkandera adusta MUT 2295 in batch tests, with biomass cultivated in attached form on polyurethane foam cubes (PUFs) to test its efficiency in the removal of the target effluents’ recalcitrant fraction. Treatment efficiency of B. adusta was evaluated on landfill leachate (Canada) and two solutions containing synthetic recalcitrant compounds, which were prepared with tannic and humic acid. Chemical Oxygen Demand (COD) and color removal, the production of manganese peroxidases, and the consumption of a co-substrate (glucose) were monitored during the experiment. Biological Oxygen Demand (BOD5) and fungal dry weight were measured at the beginning and at the end of the experiment. After co-substrate addition, effluent COD was 2300 ± 85, 2545 ± 84, and 2580 ± 95 (mg/L) in raw leachate and tannic and humic acids, respectively. COD removal of 48%, 61%, and 48% was obtained in raw leachate and in the synthetic effluents containing tannic and humic acids, respectively. Color removal of 49%, 25%, and 42% was detected in raw leachate and in tannic and humic acid solutions, respectively. COD and color removals were associated with the increase of fungal dry weight, which was observed in all the trials. These results encourage the use of the selected fungal strain to remove tannic acid, while further investigations are required to optimize leachate and humic acid bioremediation.

Bacterial community analysis of anoxic/aeration (A/O) system in a combined process for gibberellin wastewater treatment.

Gibberellin wastewater cannot be directly discharged without treatment due to its high concentrations of sulfate and organic compounds and strong acidity. Therefore, multi-stage anaerobic bioreactor + micro-aerobic+ anoxic/aeration (A/O) + biological contact oxidation combined processes are used to treat gibberellin wastewater. However, knowledge of the treatment effects of the A/O process and bacterial community structure in the aeration tank reactors of such systems is sparse. Therefore, this study was conducted to investigate the treatment effects and operation of the A/O process on gibberellin wastewater, as well as changes in the bacterial community structure of activated sludge in the aeration tank during treatment. Moreover, removal was examined based on evaluation of effluent after A/O treatment. Although influent chemical oxygen demand (COD), NH3-N and total phosphorus (TP) fluctuated, effluent COD, NH3-N and TP remained stable. Moreover, average COD, NH3-N and TP removal efficiency were 68.41%, 93.67% and 45.82%, respectively, during the A/O process. At the phylum level, Proteobacteria was the dominant phylum in all samples, followed by Chloroflexi, Bacteroidetes and Actinobacteria. Proteobacteria played an important role in the removal of organic matter. Chloroflexi was found to be responsible for the degradation of carbohydrates and Bacteroidetes also had been found to be responsible for the degradation of complex organic matters. Actinobacteria are able to degrade a variety of environmental chemicals. Additionally, Anaerolineaceae_uncultured was the major genus in samples collected on May 25, 2015, while Novosphingobium and Nitrospira were dominant in most samples. Nitrosomonas are regarded as the dominant ammonia-oxidizing bacteria, while Nitrospira are the main nitrite-oxidizing bacteria. Bacterial community structure varied considerably with time, and a partial Mantel test showed a highly significant positive correlation between bacterial community structure and DO. The bacterial community structure was also positively correlated with temperature and SO42-.