Membrane-aerated Biofilm Reactor System Research Articles

Enhanced degradation of methanethiol via operational pH regulation in biofilm reactor: Insight of sulfur metabolism pathways and microbial adaptation mechanism

Methanethiol (CH3SH), a typical organic sulfur pollutant, poses significant risks to both human health and ecological stability due to its high toxicity and corrosive properties. Membrane aerated biofilm reactor (MABR) has been regarded as a promising and eco-friendly solution for removing organic sulfur from wastewater. However, the oxidation of CH3SH might lead to spontaneous acidification, which might affect microbial metabolic activities to influence the CH3SH biotransformation in MABR system. This work demonstrated that operational pH regulation could effectively promote the complete conversion of CH3SH to SO42- in MABR, while the transformation efficiency was only 40.6% under uncontrolled pH condition. Meanwhile, operational pH regulation resulted in 35.2% reduction in the excessive secretion of extracellular polymeric substances, thereby building a stable biofilm structure with sufficient oxygen mass transfer to enhance the CH3SH transformation. Additionally, operational pH regulation favored the enrichment of sulfur-oxidizing microorganisms (e.g., Rhodanobacter and Rhodobacter), while the uncontrolled pH favored the proliferation of microorganisms in harsh environment (e.g., Chitinophagaceae sp. and Sphingobacteriales sp.). Moreover, operational pH regulation enhanced the expression of critical genes involved in sulfur metabolism (e.g., SELENBP1 and SoxA), accompanied with glycolysis (e.g., ppgK and pfkB) and pyruvate metabolism (e.g., ackA and aceE), which could provide sufficient energy and electron. Conversely, these gene expressions were down-regulated in pH unregulation reactor, while the microbial adaptation mechanism was activated through the enhancement of DNA replication, quorum sensing, and two-component system, enabling resistance to extreme acidic conditions. This study would provide the in-depth understanding of operational pH regulation on organic sulfur degradation and transformation in MABR system and offer novel guidance for organic sulfur removal.

The C/N Ratio’s Effect on a Membrane-Aerated Biofilm Reactor (MABR): COD and Nitrogen Removal, Biofilm Characteristics, and Microbial Community Structure

In this study, a laboratory-scale membrane aerated biofilm reactor system was operated successively through four phases with different C/N ratios (7, 5, 3, and 1) for 15 days each to investigate the C/N ratio’s effect on the COD and nitrogen removal. The COD and NH4+-N removal efficiencies were slightly affected; however, NO3−-N accumulated in the C/N = 1 phase, and slight NO2−-N accumulation was observed in the C/N = 7 phase, leading to lower total nitrogen (TN) removal in the two phases. The TN removal efficiency reached the highest in the C/N = 5 phase at around 70%, and the TN concentration was reduced to 12.3 mg/L on average. Biomass and biofilm thickness had a positive correlation with C/N ratios. The C/N ratio affected not only the generation of extracellular polymeric substances but also their chemical composition. Microbial analysis revealed that a C/N ratio of 5 was the most suitable for both nitrifying and denitrifying bacteria, and a higher C/N ratio favored aerobic denitrifying microbes.

Membrane aerated biofilm reactor system driven by pure oxygen for wastewater treatment

Pure oxygen is proposed for wastewater treatment due to its advantages over conventional air aeration. This study investigates a Pure Oxygen-based Membrane Aerated Biofilm Reactor (PO-MABR) for the first time under various operating conditions. The PO-MABR employs a gas-permeable membrane for direct diffusion of low-pressurized pure oxygen to the biofilm, ensuring exceptional carbon and nitrogen removal. The effectiveness of PO-MABR was investigated by varying operational conditions, including temperature, carbon-to-nitrogen ratio, gas pressure, and flow rate. Results indicate superior performance, with a 97% chemical oxygen demand removal and 19% higher total nitrogen removal than Air-Ventilated MABR (A-MABR) due to thicker biofilm and unique microbial structures in PO-MABR. Also, PO-MABR demonstrated resilience to low temperatures and effectively treated both high and low-strength wastewater. The findings emphasize the efficiency of PO-MABR in wastewater treatment, advocating for its adoption due to superior carbon and nitrogen removal across diverse operational conditions.

Performance and mechanism of the synergistic hexavalent chromium and nitrogen removal in a MABR system

Co-contaminant of hexavalent chromium [Cr(Ⅵ)] and nitrogen in wastewaters produce serious environmental problems. However, it remains little in the way of continuous flow biological reactor to concurrently eliminated Cr(Ⅵ) and nitrogen in wastewater. Here, a single membrane aerated biofilm reactor (MABR) system was employed to achieve synergistic Cr(Ⅵ) and nitrogen removal. Cr(Ⅵ) and nitrogen removal performances, Cr(VI) reduction products, and microorganism functional groups characteristics, as well as microbial community structure and functional genes were investigated. Moreover, we revealed the role of “secretion”, potentially secreted by the biofilm, in nitrogen and Cr(Ⅵ) degradation. Results indicated that the Cr(Ⅵ) removal efficiency and simultaneous nitrification and denitrification (SND) rate reached 90.60 ± 1.45 % and 96.03 ± 1.47 %, respectively, when the influent Cr(Ⅵ) concentration reached 50 mg/L. Cr(Ⅵ) was mainly reduced to Cr(Ⅲ), which was attached to biofilm and secretion surfaces. Microorganism functional groups, including carbonyl (C = O), carboxyl (O-C = O) and hydroxyl (OH–) played an essential role in the adsorption and chelation of Cr(III). Acinetobacter, Lentimicrobium, NS11-12 marine group and Hydrogenophaga were identified as the main Cr(Ⅵ) reducers and denitrifiers. The abundance of genes related to Cr(VI) reduction and nitrogen transformation increased notably in both the biofilm (NasA, ChrR) and secretion (NemA, NfsAB, AzoR) systems under high Cr(VI) stress. The “secretion” played an “secondary system” to enhance nitrogen and Cr(Ⅵ) removal. This study provides new insights into the concurrent Cr(Ⅵ) and nitrogen removal from MABR system by the integrated biofilm and secretion.

Temperature dependence of nitrification in a membrane-aerated biofilm reactor.

The membrane-aerated biofilm reactor (MABR) is a novel method for the biological treatment of wastewaters and has been successfully applied for nitrification. To improve the design and adaptation of MABR processes for colder climates and varying temperatures, the temperature dependence of a counter-diffusional biofilm's nitrification performance was investigated. A lab-scale MABR system with silicone hollow fibre membranes was operated at various temperatures between 8 and 30°C, and batch tests were performed to determine the ammonia oxidation kinetics. Biofilm samples were taken at 8 and 24°C and analysed with 16S rRNA sequencing to monitor changes in the microbial community composition, and a mathematical model was used to study the temperature dependence of mass transfer. A high nitrification rate (3.08 g N m-2 d-1) was achieved at 8°C, and temperature dependence was found to be low (θ = 1.024-1.026) compared to suspended growth processes. Changes in the community composition were moderate, Nitrospira defluvii remaining the most dominant species. Mass transfer limitations were shown to be largely responsible for the observed trends, consistent with other biofilm processes. The results show that the MABR is a promising technology for low temperature nitrification, and appropriate management of the mass transfer resistance can optimise the process for both low and high temperature operation.

Metagenomic analysis revealed the mechanism of extracellular polymeric substances on enhanced nitrogen removal in coupled MABR systems with low C/N ratio containing salinity

A combined membrane-aerated biofilm reactor (MABR) was conducted to treat various C/N ratios with saline wastewater. The influence of C/N on nitrogen removal property, extracellular polymeric substances (EPS) features, bacterial community and relevant functional genes were investigated. Fourier-transform infrared spectrum (FTIR), three-dimensional exaction and emission matrix (3D-EEM) fluorescence spectra and metagenomics analysis were conducted to study the mechanism of EPS for enhanced nitrogen removal at low C/N ratio. The results showed that TN removal rate of the whole MABR system were 73.21%, 69.51% and 67.04%, respectively, with the C/N ratio of 6, 4.5 and 3. MABR-2 biofilms secreted more EPS under low C/N and high-salinity conditions to maintain intracellular and extracellular osmotic pressure balance and to participate in cellular metabolic processes. Meanwhile, under the stimulation of low C/N, MABR-2 system with low influent loading was in a “starvation state”, thus EPS could be utilized by the biofilm of MABR-2 system as carbon source to enhance nitrogen removal. Besides, metagenomics analysis showed that aerobic denitrification and dissimilatory nitrite reduction to ammonia (DNRA) were dominant nitrogen removal pathways in MABR-2 system at low C/N ratio. EPS might participate in related metabolic processes in the electron donors and energy production processes as well as the electron transfer pathways in denitrification system. This work provided a feasible practical application scheme for the enhanced TN removal of low C/N ratio containing salinity.

Development and Application of Membrane Aerated Biofilm Reactor (MABR)—A Review

As a new type of biological treatment process, membrane aerated biofilm reactors (MABRs), which have received extensive attention and research in recent years, could reduce energy consumption by 70% compared to the traditional activated sludge process. The MABR system uses bubble-free aeration membrane material as the carrier, the counter-diffusion mechanism of oxygen and pollutants enables ammonium oxidizing bacteria (AOB) and nitrate oxidizing bacteria (NOB) to adhere to the membrane surface so that simultaneous nitrification and denitrification (SND) can occur to achieve simultaneous nitrogen and carbon removal. Currently, MABR technology has been successfully applied to the treatment of municipal sewage, various industrial wastewater, pharmaceutical, high salinity, high ammonia, aquaculture wastewater, landfill leachate and black and odorous water bodies in rivers. Many laboratory experiments and pilot-scale MABR reactors have been used to study the performance of membrane materials, the mechanism of pollutant removal and the effects of different factors on the system. However, the performance of MABR is affected by factors such as dissolved oxygen (DO), pH, C/N, biofilm thickness, hydraulic retention time (HRT), temperature, etc., which limits large-scale promotion. Therefore, membrane materials, membrane modules, biofilm, application of MABR technology, influencing factors of MABR system performance, and limitations and perspectives of MABR are reviewed in this paper, and we expect to provide valuable information.

Assessing the performance and microbial structure of biofilms in membrane aerated biofilm reactor for high p-nitrophenol concentration treatment

P-nitrophenol (PNP) is a mono-nitrophenol compound that is highly toxic and difficult to degrade, causing great harm to the ecological environment and human health. In this study, a membrane aerated biofilm reactor (MABR) was used to degrade high PNP concentration without external carbon sources. This experiment mainly presented the process performance of MABR under high-load shock of PNP and variations in the community biodiversity and compositions of MABR biofilm. The experimental results showed that as the concentration of PNP in the influent gradually increased from 100 mg/L to 400 mg/L, the MABR exhibited a strong shockproof ability. The performance of the MABR peaked at an influent PNP concentration of 200 ± 50 mg/L, the removal efficiencies of PNP and chemical oxygen demand (COD) were 94.40% and 79.57%, respectively, and the removal loads were 3.644 g·m−2·d−1 and 4.975 g·m−2·d−1, respectively. The results of high-throughput sequencing revealed that MABR biofilms had high microbial richness and diversity, in which the microbial activity was not influenced by high-load shock. PNP, as a selective pressure, was used by microorganisms as the sole carbon source. The relative abundance of dominant phyla (Patescibacteria, Firmicutes, Actinobacteriota, Proteobacteria, and Bacteroidota), classes (Saccharimonadia, Clostridia, Actinobacteria, Bacilli, Gammaproteobacteria, Bacteroidia, and CPR2), and genera (TM7a, unclassified_o_Saccharimonadales, Proteiniclasticum, and norank_f_norank_o_Saccharimonadales) were different between the evaluated samples. Numerous candidate phyla radiation (CPR) bacteria were enriched in the MABR, indicating that CPR was the functional bacteria responsible for the degradation of high concentrations of PNP. The findings of this study demonstrated that the MABR system possesses great feasibility and potential for the advanced treatment of phenolic compounds.

Enhanced removal of sulfur-containing organic pollutants from actual wastewater by biofilm reactor: Insights of sulfur transformation and bacterial metabolic traits

Sulfur-containing organic pollutants in wastewater could threaten human health due to their high malodor and toxicity, and their conversion processes are more complex than inorganic sulfur compounds. Membrane aerated biofilm reactor (MABR), as a novel and environmentally-friendly biofilm-based technology, is able to remove inorganic sulfur in synthetic wastewater. However, it is unknown how sulfur-containing organic pollutants in actual wastewater are transformed in MABR system. This work demonstrated the feasibility of MABR to eliminate sulfur-containing organic pollutants in actual wastewater, and the removal efficiency could be reached at approximately 100%. Meanwhile, over 70% of sulfur-containing organic contaminants were transformed to SO42− during the long-term operation. Further analysis indicated that the functional bacteria that participated in sulfur transformation and carbohydrates degradation (e.g., Chujaibacter, Microscillaceaesp., and Thiobacillus) were evidently enriched when treating actual wastewater. Moreover, the critical metabolic pathways (e.g., sulfur metabolism, glycolysis metabolism, and pyruvate metabolism), and the corresponding genetic expressions (e.g., nrrA, tauA, tauC, sorA, and SUOX) were evidently up-regulated during long-term operation, which was beneficial for the transformation of sulfur-containing organic pollutants in actual wastewater by MABR. This work would expand the application of MABR for treating the actual sulfur-containing organic wastewater and provide an in-depth understanding of the organic sulfur transformation in MABR.

Factors impacting simultaneous nitrification and denitrification in a membrane aerated biofilm reactor (MABR) system treating municipal wastewater

Simultaneous nitrification and denitrification (SND) was achieved in an MABR (membrane aerated biofilm reactor) system treating primary settled municipal sewage. Under ideal conditions, the total nitrogen (TN) concentration was reduced from approximately 50 mg/L to less than 5 mg/L. TN removal was highly variable ranging between 15% and 92% due to varying amounts of denitrification observed during the four seasons. One factor identified as impacting denitrification was the soluble biodegradable COD (sbCOD) to TN ratio. When the sbCOD/N ratio was reduced from 1.8 to 1.3, denitrification was limited as there was insufficient electron donor available to reduce nitrate to nitrogen gas. The availability of sbCOD was not the only factor that negatively impacted denitrification, also the ratio between the amount of oxygen supplied versus the oxygen demand (theoretical oxygen required for oxidation of all COD and TN) of the feed (O2/F ratio) played a role. When the O2/F ratio was high (4.9) (indicating an oversupply of oxygen) denitrification was limited in the MABR system, even when the sbCOD/N was in a good range (1.6–1.8). The results from this study demonstrate that simultaneous nitrification and denitrification can be realised using a pure standalone MABR system (i.e., no mixed liquor) and that the sbCOD availability and the O2 load supplied to the system versus the oxygen demand are critical to obtain effective simultaneous nitrification and denitrification (SND).

Biological Nitrogen Removal by A Membrane-Aerated Biofilm Reactor: An Attempt to Treat Urine Wastewater with High Sustainability

Human urine contains the majority of nutrients in domestic wastewater, therefore treatment of source-separated urine by sustainable methods would become a low-cost and eco-friendly alternative to conventional urban wastewater treatment system. In this work, a waste stream composed of real urine and hygiene wastewater was prepared, which had characteristic of high nitrogen content and low available C/N ratio. Membrane-aerated biofilm reactor (MABR) is an emerging technology utilizing microporous or nonporous aeration membranes as the substrate for biofilm attachment, and this configuration could promote the growth of autotrophic nitrifying bacteria and the efficiency of nitrogen removal process. The waste stream was treated with a home-made MABR system to remove the organic carbon and nitrogen pollutants. Over a four-month operation period with the incoming waste stream concentration progressively elevated, the system achieved 90-95% removal of TOC, 50-73% oxidation of ammonium-nitrogen, and 24-63% removal of total nitrogen from the influent, without external carbon source input. The results indicated that MABR has the potential for urine wastewater treatment with low consumption in energy and materials.

Steel pickling rinse wastewater treatment by two-stage MABR system: Reactor performance, extracellular polymeric substances (EPS) and microbial community

A bench-scale two-stage membrane-aerated biofilm reactor (MABR) system was applied to treat steel pickling rinse wastewater with high salinity and refractory organic. The effects of salinity and aeration pressure on the treatment efficiency, extracellular polymeric substances (EPS) characteristics and microbial community structure were studied. The optimal removal efficiencies of COD, NH+ 4-N and TN reached to 62.84%, 99.57% and 51.65%, respectively. Shortcut nitrification was achieved at low aeration, and the salinity less than 4% did not remarkable affect system performance. Colorimetric determination, three-dimensional exaction-emission matrix (3D-EEM) and Fourier transform infrared spectrum (FTIR) were employed to characterize the content and composition of proteins (PN) and polysaccharides (PS) in EPS of the biofilm. The results indicated that PN, not PS, response to changes of environmental conditions played a key role. Moreover, EPS might alleviate intracellular and extracellular osmotic pressure imbalance induced by high salinity, which imparted the biofilm in MABR with prominent salt-tolerant. High-throughput sequencing displayed that nitrifiers (Nitrosomonas, Nitrospira), denitrifiers (Dechloromonas, Hyphomicrobium, Denitromonas, Denitratisoma, Candidatus_Competibacter) and aerobic denitrifiers (Pseudomonas, Thauera) were predominant salt-tolerant bacteria.

Organic matter and total nitrogen removal from wastewater using a pilot-scale membrane-aerated biofilm reactor

A pilot-scale membrane-aerated biofilm reactor (MABR) modified with Polyvinyl Alcohol (PVA) gel bio-carriers containing denitrifying bacteria was operated with the purpose of enhancing total nitrogen removal efficiency from actual domestic wastewater. MABR system was operated under 6, 9 and 12 h of hydraulic retention times (HRT) in different time periods. Addition of the bio-carriers increased nitrification and total nitrogen removal efficiencies by maximum of 11% and 18% at 12 h of HRT respectively. Maximum of 88% of nitrification and 79% of total nitrogen removal efficiencies were reported in the PVA gel modified MABR. Organic matter removal performance was mostly maintained above 90% with insignificant improvements. In addition to this, natural pH increase observed after PVA gel addition paves a new way for potential cost reduction in industrial scale MABR applications. Low sludge volume index around 80 mL/g indicated rapid settling characteristics of produced sludge.

Modelling melamine biodegradation in a membrane aerated biofilm reactor

Membrane aerated biofilm reactor (MABR) system is excellent in developing slow growing microorganisms and treating micropollutants prior to entering the aquatic environment. In this work, a mathematical biofilm model was developed to assess melamine biodegradation under different conditions and to predict the profiles of melamine, nitrogen species and microbial biomass in the MABR system. Comtabolism linked to growth of ammonia oxidizing bacteria (AOB) or heterotrophic bacteria (HB) and their respective metabolism were involved in the model to contribute to melamine biodegradation. Results demonstrated the good predictive performance of the developed model in describing dynamic profiles of melamine, COD and nitrogen species in the MABR system. The relative contribution by AOB-induced cometabolism and metabolism by AOB and HB varied depending on the stratification of the biofilm system with AOB prevalent in the inner layer of the biofilm. Metabolism by AOB and HB played more important roles than AOB-induced cometabolism in melamine removal. Controlling optimal biofilm thickness in the suitable range (e.g., more than 750 μm) might realize better simultaneous removal of melamine and nitrogen. This work might provide further insight on efficient removal of melamine from wastewater.

Advanced treatment of coal chemical reverse osmosis concentrate with three-stage MABR.

The issue of reverse osmosis concentrate (ROC) has attracted significant attention due to its complex and toxic constituents under high salinity conditions. In this work, a three-stage membrane-aerated biofilm reactor (MABR) system was constructed to treat such wastewater without an external carbon source. The effects of operating conditions including aeration pressure, reflux ratio, temperature and hydraulic retention time on the removal performance of the integrated system were evaluated and optimized. Under the optimal operating parameters, the removal efficiencies of COD, NH4+–N, NO3−–N, and TN reached 69.36%, 80.95%, 54.55%, and 54.36%, respectively. Three-dimensional fluorescence analysis indicated that humic acid was mostly removed from raw water. Moreover, microbial diversity analysis indicated that the microbial community structure of each reactor could be individually modulated to exert different functions and enhance the system performance. The integrated MABR system exhibits great feasibility and potential for the advanced treatment of coal chemical ROC.

Coal chemical reverse osmosis concentrate treatment by membrane-aerated biofilm reactor system

Coal chemical reverse osmosis concentrate (ROC), which is characterized by high salinity and high organics, remains as a serious environmental problem. In this study, a lab-scale three-stage membrane-aerated biofilm reactor (MABR) system was designed to treat such a ROC. The effects of influent salinity and operating parameters (pH, DO and HRT) on the treatment efficiency were discussed. The removal efficiencies of COD, NH4-N and TN under the optimal operating parameters reached to 81.01%, 92.31% and 70.72%, respectively. Simultaneous nitrification and denitrification (SND) as well as shortcut nitrogen removal were achieved. The salinity less than 3% did not induce significant decrease in treatment efficiency and microbial communities. Moreover, the dominant phyla in biofilms were Proteobacteria and Bacteroidetes. This work demonstrated MABR had great potential in ROC treatment.

Pilot scale treatment of polluted surface waters using membrane-aerated biofilm reactor (MABR)

ABSTRACTThe increasing threat to human health and aquatic life caused by nitrogen pollution in surface waters requires critical attention. The membrane-aerated biofilm reactor (MABR) is a promising alternative compared to conventional technologies. In this work, a pilot-scale MABR system was employed to treat polluted surface water in continuous-flow mode. The nitrogen removal performances with the variations of the aeration parameters, hydraulic loading and C/N ratio were explored. The results showed that intra-membrane pressure plays a dominant role in improving the denitrification rate. The nitrification dynamics of the MABR system were favoured in conditions of low influent C/N ratios and hydraulic loading, but limit the denitrification process due to insufficient carbon source. A counter optimal hydraulic loading of 0.016 m3/(m2 day) (hydraulic retention time of 36 h), and a corresponding increase in the influent C/N ratio was beneficial for nitrogen removal. When the influent C/N ratio was raised to a factor of 8, the total organic carbon (TOC), ammonium and total nitrogen (TN) removal efficiency could reach 80.0%, 92.2% and 60.3%, respectively. This indicated that the MABR has a potential to remove TN by simultaneous nitrification and denitrification (SND) in polluted surface water treatment.

Autotrophic nitrogen removal in membrane-aerated biofilms: Archaeal ammonia oxidation versus bacterial ammonia oxidation

Recent discovery of ammonia-oxidizing archaea (AOA) not only substantially improved our understanding of the global nitrogen cycle, but also provided new possibilities for nitrogen removal from wastewater. In particular, compared to ammonia-oxidizing bacteria (AOB), the high ammonia oxidation under oxygen-limited conditions driven by AOA is potentially more suitable for autotrophic nitrogen removal in a single-stage membrane aerated biofilm reactor (MABR) through coupling with anaerobic ammonia oxidation (Anammox). In this work, mathematical modeling is applied to assess the system performance and associated microbial community structure of an AOA–Anammox MABR under low- (30mgNL−1) and high-strength (500mgNL−1) ammonium conditions, with a side-by-side comparison to an AOB–Anammox MABR system under the same conditions. Results demonstrate that both ammonium surface loading (or hydraulic retention time) and oxygen surface loading significantly affect the system performance. In contrast to AOB–Anammox system, the AOA–Anammox MABR shows higher total nitrogen (TN) removal and lower oxygen supply, with much better repression of NOB and substantially wider operating window for high-level TN removal (>80%) in terms of varied oxygen and ammonium loadings. These results provide first insights and useful information for design and operation of this novel AOA–Anammox MABR system in its potential future applications.

Nitrogen removal performances of a polyvinylidene fluoride membrane-aerated biofilm reactor

A membrane-aerated biofilm reactor (MABR) with polyvinylidene fluoride (PVDF) hollow fiber membranes was developed, and the nitrogen removal performances with the increase of influent NH4+−N concentration from 30 mg/L to 120 mg/L were investigated. The results indicated that simultaneous nitrification and denitrification (SND) process was realized in this MABR system, and the nitrogen removal performances were affected by the influent NH4+−N concentration. The limitation of influent NH4+−N concentration for this MABR system was 70 mg/L with a maximum specific NH4+−N conversion rate and specific total nitrogen removal rate of 55.67 and 52.87 kg/m3 d, showing better performances compared with other studies. The nitrogen removal was realized through nitrification, denitrification and possible anaerobic ammonium oxidation (ANAMMOX) with partial nitrification. The polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) was used to analyze the microbial community of biofilm in this MABR system, revealing the bacteria community diversity of biofilm. Besides various ammonia-oxidizing bacteria and nitrite-oxidizing bacteria, Nitrosomonas sp. and Planctomycetes sp. were found to conduct ANAMMOX with partial nitrification under oxygen limited condition.

Mixed pharmaceutical wastewater treatment by integrated membrane-aerated biofilm reactor (MABR) system – A pilot-scale study

A pilot-scale integrated membrane-aerated biofilm reactor (MABR) system, consisted of hydrolysis/acidification pretreatment, MABR process and activated carbon adsorption post-processing, was designed to treat the high-loading mixed pharmaceutical wastewater. A study of MABR process was conducted to investigate the effect of aeration condition, circulation flow rate and water quality on performance over 260days. The performances of these processes were evaluated by the removal efficiency of COD, BOD5, turbidity, NH4+–N and TN. MABR process could effectively remove above 90% of COD and 98% of ammonia. The capacities per unit volume of MABR could reach up to 1311gCOD/m3d and 48.2gNH4+–N/m3d with single membrane aeration, and the oxygen utilization rate could be as high as 45%. After post-processing, the effluent of integrated treatment MABR system kept stable with COD below 200mg/L and NH4+–N below 3mg/L.