Membrane-aerated Biofilm Reactor Research Articles

Removal of sulfamethoxazole in an algal-bacterial membrane aerated biofilm reactor: Microbial responses and antibiotic resistance genes

Antibiotics are frequently detected in wastewater, but often are poorly removed in conventional wastewater treatment processes. Combining microalgal and nitrifying bacterial processes may provide synergistic removal of antibiotics and ammonium. In this research, we studied the removal of the antibiotic sulfamethoxazole (SMX) in two different reactors: a conventional nitrifying bacterial membrane aerated biofilm reactor (bMABR) and algal-bacterial membrane aerated biofilm reactor (abMABR) systems. We investigated the synergistic removal of antibiotics and ammonium, antioxidant activity, microbial communities, antibiotic resistance genes (ARGs), mobile genetic elements (MGEs), and their potential hosts. Our findings show that the abMABR maintained a high sulfamethoxazole (SMX) removal efficiency, with a minimum of 44.6 % and a maximum of 75.8 %, despite SMX inhibition, it maintained a consistent 25.0 % ammonium removal efficiency compared to the bMABR. Through a production of extracellular polymeric substances (EPS) with increased proteins/polysaccharides (PN/PS), the abMABR possibly allowed the microalgae-bacteria consortium to protect the bacteria from SMX inactivation. The activity of antioxidant enzymes caused by SMX was reduced by 62.1–98.5 % in the abMABR compared to the bMABR. Metagenomic analysis revealed that the relative abundance of Methylophilus, Pseudoxanthomonas, and Acidovorax in the abMABR exhibited a significant positive correlation with SMX exposure and reduced nitrate concentrations and SMX removal. Sulfonamide ARGs (sul1 and sul2) appeared to be primarily responsible for defense against SMX stress, and Hyphomicrobium and Nitrosomonas were the key carriers of ARGs. This study demonstrated that the abMABR system has great potential for removing SMX and reducing the environmental risks of ARGs.

Partitioned granular sludge coupling with membrane-aerated biofilm reactor for efficient autotrophic nitrogen removal

The partial nitritation-anammox process based on a membrane-aerated biofilm reactor (MABR) faces several challenges, such as difficulty in suppressing nitrite-oxidizing bacteria (NOB), excessive effluent nitrate, and ineffective synergy between denitrification and anammox bacteria. Therefore, a novel partitioned granular sludge coupling with MABR (G-MABR) was constructed. The chemical oxygen demand (COD) and nitrogen removal efficiency were 88.8 ± 1.8 %–92.6 ± 1.2 % and 88.8 ± 1.5 %–93.6 ± 0.7 %, respectively. The COD was mainly lowered in the lower granular sludge-zone, while nitrogen was removed in the upper MABR-zone. NOB was significantly suppressed in the MABR-zone due to competition for substrate with denitrifying bacteria and anammox bacteria. This partitioned configuration reduced the C/N ratio in the MABR-zone, thus facilitating autotrophic nitrogen removal. Both partial nitrification and denitrification provided nitrite for anammox bacteria in granular sludge, whereas partial nitrification mainly supplied nitrite to the anammox bacteria in membrane biofilms.

Efficient and sustainable removal of linear alkylbenzene sulfonate in a membrane biofilm: Oxygen supply dosage impacts mineralization pathway

Linear alkylbenzene sulfonate (LAS) can be thoroughly mineralized within sufficient oxygen (O2), but which is energy intensive and may causes serious foaming problem. Although cometabolism can achieve efficient LAS removal within a wide range of O2 dosages, how O2 dosage systematically affects LAS metabolic pathway is still unclear. Here, membrane aerated biofilm reactor (MABR) enabled accurate O2 delivery and bulk dissolved oxygen (DO) control. MABR achieved efficient removal of LAS (>96.4 %), nitrate (>97.8 %) and total nitrogen (>96.2 %) at the three target DO conditions. At high DO condition (0.6 mg/L), LAS was efficiently removed by aerobic mineralization (predominant) coupled with aerobic denitrification biodegradation with the related functional enzymes. Pseudomonas, Flavobacterium, Hydrogenophaga, and Pseudoxanthomonas were dominant genus contributing to four possible LAS aerobic metabolic pathways. As O2 dosage reduced to only 29.7 % of the demand for LAS mineralization, O2 facilitated LAS activation, benzene-ring cleavage and a portion of respiration. NO3--N respiration-induced anaerobic denitrification also contributed to ring-opening and organics mineralization. Desulfomicrobium and Desulfonema related two possible anaerobic metabolic pathways also contributed to LAS removal. The findings provide a promising strategy for achieving low-cost high LAS-containing greywater treatment.

Life Cycle Assessment of Hydrogenotrophic Denitrification in Membrane Aerated Biofilm Reactors for Sustainable Wastewater Treatment

The conventional anaerobic-anoxic-oxic (AAO) process for wastewater treatment is associated with high energy consumption and pollutant emissions due to its reliance on heterotrophic denitrification. In contrast, membrane aerated biofilm reactors (MABR) coupled with hydrogenotrophic denitrification (H2-MABR) offers a more promising alternative. This study conducts a life cycle assessment (LCA) to evaluate the environmental and economic benefits of H2-MABR compared to traditional AAO processes. Results indicate that even with a limited reactor life, the application of MABR in actual wastewater treatment plants can yield over 30% reduction in environmental and economic impacts. Using CO2 from biogas as a carbon source significantly reduces carbon emissions during the anaerobic stage, while the efficient nitrogen removal minimizes the need for wastewater recirculation and electricity consumption. The H2-driven denitrification process also avoids emissions and secondary pollution risks associated with organic electron donors. Furthermore, coupling H2-MABR with renewable energy source and Power-to-Gas technology further enhances sustainability by ensuring a stable hydrogen supply. Given the significant potential of H2-MABR for improving wastewater treatment, further research and large-scale implementation are highly encouraged.

Increased oxygen partial pressure enhances toxicity reduction by membrane aerated biofilm reactor treating oil and gas industrial wastewater

Wastewater produced during oil and gas extraction processes is one of the largest residual water streams. Also known as produced water (PW), it has a complex composition and is typically toxic to aquatic ecosystems. This study explores the use of membrane aerated biofilm reactors (MABR) for biological removal of dissolved organic compounds and associated toxicity. Three different oxygen partial pressures (0.2, 0.6 and 1 bar), the last two mimicking subsea pressures at 20 and 40 m below the sea level, respectively, were tested at three different hydraulic retention times (HRT of 24, 12 and 6 h). Reactors were fed both with onshore and offshore PW. Removal rates for organic carbon increased at decreasing HRT. Highest oxygen partial pressure led to best performance at 6 h HRT (30.1 ± 3.0 g-COD m−2 d−1) when treating onshore PW and at all HRT when treating offshore PW, with highest COD removal rate still at 6 h HRT (9.4 ± 1 g-COD m−2 d−1). Removal efficiencies ranged from 78 % when treating onshore PW at 24 h HRT to 36–49 % when treating offshore PW at 6 h HRT. All treatments led to a reduction in toxicity (>92 % reduction for offshore PW), with 0.2 bar oxygen partial pressure showing worst performance, while 0.6 and 1 bar did not show significant differences. The biofilms were dominated by hydrocarbonoclastic, responsible of hydrocarbons biodegradation, and sulfur cycling bacteria. Overall, MABR were effective treating PW and operating at higher oxygen partial pressures yield to better performance, especially at high volumetric loading rates.

Simultaneous removal of ammonia nitrogen, sulfamethoxazole, and antibiotic resistance genes in self-corrosion microelectrolysis-enhanced counter-diffusion biofilm system

A self-corrosion microelectrolysis (SME)-enhanced membrane-aerated biofilm reactor (eMABR) was developed for the removal of pollutants and reduction of antibiotic resistance genes (ARGs). Fe2+ and Fe3+ formed iron oxides on the biofilm, which enhanced the adsorption and redox process. SME can induce microorganisms to secrete more extracellular proteins and up-regulate the expression of ammonia monooxygenase (AMO) (0.92 log2). AMO exposed extra binding sites (ASP-69) for antibiotics, weakening the competition between NH4+-N and sulfamethoxazole (SMX). The NH4+-N removal efficiency in the S-eMABR (adding SMX and IC) increased by 44.87 % compared to the S-MABR (adding SMX). SME increased the removal performance of SMX by approximately 1.45 times, down-regulated the expressions of sul1 (−1.69 log2) and sul2 (−1.30 log2) genes, and controlled their transfer within the genus. This study provides a novel strategy for synergistic reduction of antibiotics and ARGs, and elucidates the corresponding mechanism based on metatranscriptomic and molecular docking analyses.

Insights into the azo dye decolourisation and denitrogenation in micro-electrolysis enhanced counter-diffusion biofilm system

In this study, electron transport pathways were activated and diversified by coupling counter-diffusion biofilms with micro-electrolysis for Alizarin yellow R (AYR) denitrogenation. Due to the binding of AYR to two residues of EC 4.1.3.36 with higher binding energy, the expression of EC 4.1.3.36 was down-regulated, causing the EC 3.1.2.28 and EC 2.5.1.74 for menaquinone synthesis (redox mediator) undetectable in Membrane aerated biofilm reactors (MABR). Spontaneous electron generation in the micro electrolysis-coupled MABR (ME-MABR) significantly activated two enzymes. Activated menaquinone up-regulated decolourisation related genes expression in ME-MABR, including azoR (2.12 log2), NQO1 (2.97 log2), wrbA (0.45 log2), and ndh (0.47 log2). The diversified electron flow pathways also promoted the nitrogen metabolism coding genes up-regulation, accelerating further inorganic nitrogen denitrogenation after AYR mineralisation. Compared to MABR, the decolourisation, mineralisation, and denitrogenation in ME-MABR increased by 25.80 %, 16.53 %, and 13.32 %, respectively. This study provides new insights into micro-electrolysis enhanced removal of AYR.

Exploring Aeration Strategies for Enhanced Simultaneous Nitrification and Denitrification in Membrane Aerated Bioreactors: A Computational Approach.

In this study we employ computational methods to investigate the influence of aeration strategies on simultaneous nitrification-denitrification processes. Specifically, we explore the impact of periodic and intermittent aeration on denitrification rates, which typically lag behind nitrification rates under identical environmental conditions. A two-dimensional deterministic multi-scale model is employed to elucidate the fundamental processes governing the behavior of membrane aerated biofilm reactors (MABRs). We aim to identify key factors that promote denitrification under varying aeration strategies. Our findings indicate that the concentration of oxygen during the off phase and the duration of the off interval play crucial roles in controlling denitrification. Complete discontinuation of oxygen is not advisable, as it inhibits the formation of anaerobic heterotrophic bacteria, thereby impeding denitrification. Extending the length of the off interval, however, enhances denitrification. Furthermore, we demonstrate that the initial inoculation of the substratum (membrane in this study) influences substrate degradation under periodic aeration, with implications for both nitrification and denitrification. Comparison between continuous and periodic/intermittent aeration scenarios reveals that the latter can extend the operational cycle of MABRs. This extension is attributed to relatively low biofilm growth rates associated with non-continuous aeration strategies. Consequently, our study provides a comprehensive understanding of the intricate interplay between aeration strategies and simultaneous nitrification-denitrification in MABRs. The insights presented herein can contribute significantly to the optimization of MABR performance in wastewater treatment applications.

Intensified partial nitrification and microbiome response in a membrane pulsing-aerated biofilm reactor

Membrane aerated biofilm reactor (MABR) has been developed as an energy-saving process for nitrogen removal in municipal sewage treatment, even in high ammonia wastewater. However, the impact of aeration pattern on biofilm microbiome assemblage and nitrification is not well understood. In this study, MABR and membrane pulsing-aerated biofilm reactor (MpABR) were established for partial nitrification under high ammonium loadings. The MABR and MpABR exhibited a 95 % nitrite accumulation rate (NAR), with over 60 % ammonium removal and nitrite conversion achieved after the start-up phase. The MABR and MpABR gradually adapted to the substantial increase in ammonium loading (350 mg NH4+-N·L-1), resulting in stable and high NAR (96 %), ammonium removal efficiency (70 %), and nitrite conversion efficiency (67 %). Orthogonal experiments revealed that ammonium loading rate (ALR) was the primary factor regulating nitrite conversion and oxygen levels. A moderate ALR was preferable to achieve ideal partial nitrification and energy saving. Furthermore, the integrated MpABR-anaerobic ammonium oxidation (Anammox) maintained high total nitrogen (TN) removal (> 90 %) under high ALR conditions. Microbiome analysis revealed that nitrifiers (Nitrosomonas) and denitrifiers (Stenotrophomonas and Arenimonas) alternately dominated the biofilms at different stages. These findings highlight the potential for achieving efficient partial nitrification effects using a MpABR. The excellent TN removal performance of the MpABR-Anammox suggests its wide applicability in energy-efficient wastewater treatment.

Simultaneous carbon, nitrogen and phosphorus removal in sequencing batch membrane aerated biofilm reactor with biofilm thickness control via air scouring aided by computational fluid dynamics

Membrane aerated biofilm reactor (MABR) is challenged by biofilm thickness control and phosphorus removal. Air scouring aided by computational fluid dynamics (CFD) was employed to detach outer biofilm in sequencing batch MABR treating low C/N wastewater. Biofilm with 177–285 µm thickness in cycle 5–15 achieved over 85 % chemical oxygen demand (COD) and total inorganic nitrogen (TIN) removals at loading rate of 13.2 gCOD/m2/d and 2.64 gNH4+-N/m2/d. Biofilm rheology measurements in cycle 10–25 showed yield stress against detachment of 2.8–7.4 Pa, which were equal to CFD calculated shear stresses under air scouring flowrate of 3–9 L/min. Air scouring reduced effluent NH4+-N by 10 % and biofilm thickness by 78 µm. Intermittent aeration (4h off, 19.5h on) and air scouring (3 L/min, 30 s before settling) in one cycle achieved COD removal over 90 %, TIN and PO43−-P removals over 80 %, showing great potential for simultaneous carbon, nitrogen and phosphorus removals.

Achieving Simultaneous Nitrification and Denitrification by a Membrane Aerated Biofilm Reactor at Moderate Lumen Pressure

Achieving Simultaneous Nitrification and Denitrification by a Membrane Aerated Biofilm Reactor at Moderate Lumen Pressure

Heated Aeration for Nitrite-Oxidizing Bacteria (NOB) Control in Anammox-Integrated Membrane-Aerated Biofilm Reactors (MABR)

Heated Aeration for Nitrite-Oxidizing Bacteria (NOB) Control in Anammox-Integrated Membrane-Aerated Biofilm Reactors (MABR)

Ammonia monooxygenase-mediated cometabolic biotransformation of volatile 4-chlorophenol in nitrifying counter-diffused biofilms: A combined molecular dynamics simulation, DFT calculation and experimental study

Ammonia monooxygenase (AMO)-mediated cometabolism of organic pollutants has been widely observed in biological nitrogen removal process. However, its molecular mechanism remains unclear, hindering its practical application. Furthermore, conventional nitrification systems encounter significant challenges such as air pollution and the loss of ammonia-oxidizing bacteria, when dealing with wastewater containing volatile organic pollutants. This study developed a nitrifying membrane-aerated biofilm reactor (MABR) to enhance the biodegradation of volatile 4-chlorophenol (4-CP). Results showed that 4-CP was primarily removed via Nitrosomonas nitrosa-mediated cometabolism in the presence of NH4+-N, supported by the increased nicotinamide adenine dinucleotide (NADH) and adenosine triphosphate (ATP) content, AMO activity and the related genes abundance. Hydroquinone, detected for the first time and produced via oxidative dechlorination, as well as 4-chlorocatechol was primary transformation products of 4-CP. Nitrosomonas nitrosa AMO structural model was constructed for the first time using homology modeling. Molecular dynamics simulation suggested that the ortho-carbon in the benzene ring of 4-CP was more prone to metabolismcompared to the ipso-carbon. Density functional theory calculation revealed that 4-CP was metabolized by AMO via H-abstraction-OH-rebound reaction, with a significantly higher rebound barrier at the ipso-carbon (16.37 kcal·mol-1) as compared to the ortho-carbon (6.7 kcal·mol-1). This study fills the knowledge gap on the molecular mechanism of AMO-mediated cometabolism of organic pollutants, providing practical and theoretical foundations for improving volatile organic pollutants removal through nitrifying MABR.

Increasing urine nitrification performance with sequential membrane aerated biofilm reactors

This study aimed to investigate whether separating organics depletion from nitrification increases the overall performance of urine nitrification. Separate organics depletion was facilitated with membrane aerated biofilm reactors (MABRs). The high pH and ammonia concentration in stored urine inhibited nitrification in the first stage and therewith allowed the separation of organics depletion from nitrification. An organics removal of 70 % was achieved at organic loading rates in the influent of 3.7 gCOD d−1 m−2. Organics depletion in a continuous flow stirred tank reactor (CSTR) for organics depletion led to ammonia stripping through diffused aeration of up to 13 %. Using an MABR, diffusion into the lumen amounted for 4 % ammonia loss only. In the MABR, headspace volume and therefore ammonia loss through the headspace was negligible. By aerating the downstream MABR for nitrification with the off-gas of the MABR for organics depletion, 96 % of the ammonia stripped in the first stage could be recovered in the second stage, so that the overall ammonia loss was negligibly low. Nitrification of the organics-depleted urine was studied in MABRs, CSTRs, and sequencing batch reactors in fed batch mode (FBRs), the latter two operated with suspended biomass. The experiments demonstrated that upstream organics depletion can double the nitrification rate. In a laboratory-scale MABR, nitrification rates were recorded of up to 830 mgNL−1 d−1 (3.1 gN m−2 d−1) with ambient air and over 1500 mgNL−1 d−1 (6.7 gN m−2 d−1) with oxygen-enriched air. Experiments with a laboratory-scale MABR showed that increasing operational parameters such as pH, recirculation flow, scouring frequency, and oxygen content increased the nitrification rate. The nitrification in the MABR was robust even at high pH setpoints of 6.9 and was robust against process failures arising from operational mistakes. The hydraulic retention time (HRT) required for nitrification was only 1 to 2 days. With the preceding organics depletion, the HRT for our system requires 2 to 3 days in total, whereas a combined activated sludge system requires 4 to 8 days. The N2O concentration in the off-gas increases with increasing nitrification rates; however, the N2O emission factor was 2.8 % on average and independent of nitrification rates. These results indicate that the MABR technology has a high potential for efficient and robust production of ammonium nitrate from source-separated urine.

Achieving Long-Term Stability of Partial Nitrification and Autotrophic Denitrification in an MABR via Sulfide Dosing.

While partial nitrification (PN) has the potential to reduce energy for aeration, it has proven to be unstable when treating low-strength wastewater. This study introduces an innovative combined strategy incorporating a low rate of oxygen supply, pH control, and sulfide addition to selectively inhibit nitrite-oxidizing bacteria (NOB). This strategy led to a stable PN in a laboratory-scale membrane aerated biofilm reactor (MABR). Over a period of 260 days, the nitrite accumulation ratio exceeded 60% when treating synthetic sewage containing 50 mg NH4+-N/L. Through in situ activity testing and high-throughput sequencing, the combined strategy led to low levels of nitrite-oxidation activity (<5.5 mg N/m2 h), Nitrospira species (relative abundance <1%), and transcription of nitrite-oxidation genes (undetectable). The addition of sulfide led to simultaneous PN and autotrophic denitrification in the single-stage MABR, resulting in over 60% total inorganic nitrogen removal. Sulfur-based autotrophic denitrification consumed nitrite and inhibited NOB conversion of nitrite to nitrate. The combined strategy has potential to be applied in large-scale sewage treatment and deserves further exploration.

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.

Establishing mainstream partial nitrification in the membrane aerated biofilm reactor by limiting the oxygen concentration in the biofilm

The proliferation of nitrite oxidizing bacteria (NOB) still remains as a major challenge for nitrogen removal in mainstream wastewater treatment process based on partial nitrification (PN). This study investigated different operational conditions to establish mainstream PN for the fast start-up of membrane aerated biofilm reactor (MABR) systems. Different oxygen controlling strategies were adopted by employing different influent NH4+-N loads and oxygen supply strategies to inhibit NOB. We indicated the essential for NOB suppression was to reduce the oxygen concentration of the inner biofilm and the thickness of aerobic biofilm. A higher NH4+-N load (7.4 g-N/(m2·d)) induced higher oxygen utilization rate (14.4 g-O2/(m2·d)) and steeper gradient of oxygen concentration, which reduced the thickness of aerobic biofilm. Employing closed-end oxygen supply mode exhibited the minimum concentration of oxygen to realize PN, which was over 46% reduction of the normal open-end oxygen mode. Under the conditions of high NH4+-N load and closed-end oxygen supply mode, the microbial community exhibited a comparative advantage of ammonium oxidizing bacteria over NOB in the aerobic biofilm, with a relative abundance of Nitrosomonas of 30–40% and no detection of Nitrospira. The optimal fast start-up strategy was proposed with open-end aeration mode in the first 10 days and closed-end mode subsequently under high NH4+-N load. The results revealed the mechanism of NOB inhibition on the biofilm and provided strategies for a quick start-up and stable mainstream PN simultaneously, which poses great significance for the future application of MABR.

Surface Modification of PVDF and PTFE Hollow Fiber Membranes for Enhanced Nitrogen Removal in a Membrane-Aerated Biofilm Reactor

Surface Modification of PVDF and PTFE Hollow Fiber Membranes for Enhanced Nitrogen Removal in a Membrane-Aerated Biofilm Reactor

A single-stage MABR reactor in the post-treatment of poultry slaughterhouse wastewater: nitrogen removal and microbial community

ABSTRACT The deammonification process is an efficient alternative to remove nitrogen from wastewater with a low carbon/nitrogen ratio. However, the reactor configuration and operational factors pose challenges for applications in treatment systems to remove nitrogen from municipal and industrial wastewater on a large scale. To address this gap, this study evaluated a new deammonification strategy using a single-stage membrane aerated biofilm reactor (MABR), operated with continuous flow, under different hydraulic retention times (HRT) in the post-treatment of poultry slaughterhouse wastewater with a low nitrogen load, similar to domestic wastewater. The performance of the MABR reactor and the microbial community was evaluated over a long period at HRTs of 12, 24, and 36 hours, corresponding to nitrogen volumetric loads of 181.0 g N.m−3.d−1, 87.4 g N.m−3.d−1 and 67.8 g N.m−3.d−1. The results show that total nitrogen (TN) removal and the microbial community in the MABR reactor were influenced by changes in HRT. The highest efficiency in TN removal was obtained with an HRT of 24 hours, in which the maximum TN removal efficiency was 77.04%. Candidatus Brocadia and Candidatus Jettenia were the two genera of bacteria with Anammox activity present in the reactor, with relative abundances of 7.27% and 0.74%, respectively. This study helps to deepen the understanding of the application of the single-stage MABR reactor in real wastewater treatment with a low nitrogen load.

Performance and microbial community evolution of toluene degradation in the presence of acetone vapors using hybrid membrane-aerated biofilm reactors (HMABRs)

Biological treatment methodologies offer cost-effective and eco-friendly solutions for volatile organic compounds (VOCs) removal, but they face limitations in effectively treating hydrophobic VOCs. Herein, this study introduces the Hybrid Membrane Aerated Biofilm Reactor (HMABR) for VOC treatment. The HMABR integrates a bio-trickling filter-like spraying function with MABR technology to construct a non-submerge system. What’s more, introducing hydrophilic gases enhances the degradation of hydrophobic VOCs in pollutant biotreatment. While hydrophilic VOCs are readily degraded by microorganisms, the mechanisms of their co-degradation remain understudied. Toluene and acetone, common industrial VOCs, were examined in the HMABR system. HMABR exhibits outstanding toluene removal, reaching a maximum capacity of 142.04 gm−3h−1. The addition of acetone boosts this capacity by 70.1 gm−3h−1, altering EPS composition, and notably increasing the PN/PS ratio from 0.35 to 2.76. It can be inferred that acetone’s presence enhances biofilm EPS hydrophobicity, aiding toluene breakdown. Besides, when adding acetone, the biofilm EPS sample exhibited a more compact secondary protein structure. Analysis of the microbial community in the HMABR system identified a dominance of Pseudomonadota, with an increased abundance of Rhodanobacter, which correlated strongly with toluene degradation in the presence of acetone. Gene analysis revealed an increase in toluene degradation genes in Rhodanobacter when acetone was added. Furthermore, acetone activation was found to enhance metabolic pathways related to xylene degradation and the tricarboxylic acid (TCA) cycle, thereby improving toluene removal efficiency. These findings provide insights into co-metabolism in treating hydrophobic pollutants in HMABR and contribute to designing more effective treatment systems for VOCs.