Performance Of Anaerobic Membrane Bioreactor Research Articles

Role of biochar addition to improve anaerobic membrane bioreactors to resist oil stress in synthetic food wastewater treatment

This study investigated biochar addition to improve the performance and stability of anaerobic membrane bioreactor (AnMBR) to resist different oil contents in food wastewater treatment. Results show that an increase in oil content in synthetic food wastewater from 2 to 4 g/L of oleate-Na aggravated AnMBR performance in terms of methane (CH4) production and membrane fouling as showed by an obvious increase in transmembrane pressure (TMP). The reduced performance was caused by the accumulation of volatile fatty acids (VFAs) to inhibit the growth and activity of Methanobacterium in response to increased oil content. Nevertheless, biochar addition improved AnMBR resistance to against oil increase. The dominance of Methanobacterium and their potential mutualism with genus T78 were enhanced by biochar to sustain CH4 yield. Moreover, biochar reduced the production of extracellular polymeric substance (EPS) to alleviate membrane fouling.

Predicting Anaerobic Membrane Bioreactor Performance Using Flow-Cytometry-Derived High and Low Nucleic Acid Content Cells.

Having a tool to monitor the microbial abundances rapidly and to utilize the data to predict the reactor performance would facilitate the operation of an anaerobic membrane bioreactor (AnMBR). This study aims to achieve the aforementioned scenario by developing a linear regression model that incorporates a time-lagging mode. The model uses low nucleic acid (LNA) cell numbers and the ratio of high nucleic acid (HNA) to LNA cells as an input data set. First, the model was trained using data sets obtained from a 35 L pilot-scale AnMBR. The model was able to predict the chemical oxygen demand (COD) removal efficiency and methane production 3.5 days in advance. Subsequent validation of the model using flow cytometry (FCM)-derived data (at time t - 3.5 days) obtained from another biologically independent reactor did not exhibit any substantial difference between predicted and actual measurements of reactor performance at time t. Further cell sorting, 16S rRNA gene sequencing, and correlation analysis partly attributed this accurate prediction to HNA genera (e.g., Anaerovibrio and unclassified Bacteroidales) and LNA genera (e.g., Achromobacter, Ochrobactrum, and unclassified Anaerolineae). In summary, our findings suggest that HNA and LNA cell routine enumeration, along with the trained model, can derive a fast approach to predict the AnMBR performance.

Primary evaluation of COF-based mixed matrix membranes to antifouling property

Nowadays, anaerobic membrane bioreactors (AnMBRs) are one of the considerable wastewater treatment technologies. However, the performance of AnMBRs in wastewater treatment is faded due to the membrane fouling issue. Due to that concern, it gives a reason to find a material with high quality properties to prepare an antifouling membrane for the application in AnMBRs. In this present study, a new ultrafiltration (UF) membrane incorporated covalent organic framework (COF) was successfully constructed by interfacial polymerization method. A mixed-matrix membranes (MMMs) in various concentrations of COF range of 0 to 1 wt% was prepared and characterized by SEM, XRD, FTIR and AFM analysis. The analysis has confirmed the incorporation of the COF to the UF membrane. The effect of various COF concentration towards the antifouling property of the prepared membranes were evaluated. The results show, the increasing of COF concentration from 0 to 1 wt% has led to the increasing in the rejection rate from 26.11% to 95.87%. Besides, the membrane hydrophilicity significantly improved by 30.53%, when the water contact angle decreased from 66.94° to 46.50°. These results suggested that the PES/COF MMMs has great potential to offer an efficient separation with superior antifouling membrane for AnMBRs.

Life cycle assessment of AnMBR technology for urban wastewater treatment: A case study based on a demo-scale AnMBR system

This study aims at assessing the environmental performance of a projected full-scale anaerobic membrane bioreactor (AnMBR) treating urban wastewater (UWW) at ambient temperature. To this aim, data from an AnMBR demonstration plant equipped with commercially available equipment, including industrial hollow fiber and degassing membranes, was used for projecting a full-scale facility. The use of real operation data allows to obtain robust results that contribute to improve the knowledge of the environmental performance of this technology, pointing out its strengths and the challenges that still need to be addressed. Life cycle assessment (LCA) was applied by means of Ecoinvent data base and ReCiPe2016 methodology considering 1 kg of removed COD as functional unit. Additionally, sensitivity and uncertainty analysis were conducted. Energy balance showed AnMBR performing as energy producer (net energy surplus up to −0.688 kWh·kg CODrem−1) and carbon sink (emissions credit up to 0.223 kgCO2eq·kgCODrem−1). Results also showed energy recovery, heavy metals in sludge, dissolved methane in the effluent, and effluent nutrient content as the most important aspects affecting LCA outcome. Construction phase affected some impact categories significantly (e.g., 51–71% in mineral resource scarcity, 18–27% in fossil resource scarcity, 21–28% in water consumption), therefore its exclusion should be carefully evaluated. CHP efficiency, dissolved methane recovery, filtration productivity, membrane scouring, reactor mixing, HRT and SRT appeared most influencing parameters. Finally, actions leading to increase the recovery and valorization of dissolved methane and/or of nutrients through, for instance, fertigation, improve the environmental performance of AnMBR for UWW treatment.

Anaerobic Membrane Bioreactor for Microalgae and Primary Sludge Co-Digestion at Pilot Scale: Instrumentation, Control and Automation Implementation, and Performance Assessment

Anaerobic membrane bioreactor (AnMBR) technology is gaining interest for circular economy integration in the water sector. However, its complexity, arising from the integration of anaerobic processes with membrane technology, poses a key challenge. Developing an appropriate instrumentation, control, and automation (ICA) system is essential for its reliable long-term operation. In this study, an ICA system was developed to successfully manage an AnMBR pilot plant co-digesting two waste streams (microalgae and primary sludge). The ICA implementation enabled its stable long-term operation for 576 days, ensuring the proper performance of biological and filtration processes and yielding 215 NmLCH4·gCODinf−1 at 35 °C. Variables such as temperature, oxidation-reduction potential, permeate flux and biogas flow were identified as key parameters and controlled. This included a 23% reduction in the integral of absolute error compared to a PID controller for permeate flow and the maintenance of a 0.5% standard deviation for digester temperature. These controls enabled AnMBR performance optimization, the rapid detection of process issues, and early corrective actions. As a start-up strategy to ensure proper filtration performance in the long term, critical flux tests were conducted, guaranteeing a competitive total annualized equivalent cost of 0.0016 EUR/m3 for optimal conditions. The study also calculated greenhouse gas emissions in different scenarios, proposing optimal and more sustainable pilot plant operations, mesophilic conditions, biogas upgrading through microalgae cultivation, and grid injection, reducing emissions by 423 kgCO2e·tCOD−1. To ensure the viability of emerging technologies such as AnMBR, proper start-up protocols are crucial, including favorable filtration and biological process operating conditions, ICA implementation, and key parameter control for technical, economic and environmental success.

Effect of hydraulic retention time on biological nutrients removal in an anaerobic membrane bioreactor treating low-strength drain wastewater

This work compares the nutrients removal efficiency of an anaerobic membrane bioreactor (AnMBR) treating low-strength drain wastewater (total chemical oxygen demand CODt of 157.09 ± 34.83 mg/L) at two different hydraulic retention times (HRTs). Because nutrients removal is poor in anaerobic systems, longer HRTs of 4 days and 3 days were opted for in this study. AnMBR performance was superior at 3 day HRT with removal efficiencies of 53.32 ± 4.83 % (CODt), 88.60 ± 19.04 % (ammonia-nitrogen, NH4+-N), and 63.65 ± 4.90 % (phosphate, PO43−) with higher permeate flux of around 6.6 L/m2 h. The possible reason for achieving better nutrients removal at 3 day HRT could be enough food and adequate contact time experienced by the microorganisms. Therefore, longer yet sufficient HRT can be an approach for improved nutrients removal in an AnMBR treating low-strength wastewater.

Anaerobic membrane bioreactor for hygiene wastewater treatment in controlled ecological life support systems: Degradation of surfactants and microbial community succession

The treatment and reuse of hygiene wastewater is crucial to “close the loop” in the controlled ecological life support system (CELSS), and to guarantee longer space missions or planetary habitation. In this work, anaerobic membrane bioreactor (AnMBR) was applied for hygiene wastewater treatment, focused on surfactant degradation and microbial community succession. The removal efficiency of COD and surfactants was 90%∼97% and 80% with a urine source-separation strategy. The microbial community gradually shifted from methanogens to sulfur-metabolizing and surfactant-degradation bacteria, such as Aeromonas. Sulfate was a surfactant degradation product, which triggered sulfate reduction and methane inhibition. The activated carbohydrate and sulfur metabolism were the key mechanism of the microbial process for the excellent performance of AnMBR. This study analyzed the degradation mechanism from the perspective of microbial mechanism, offers a solution for CELSS hygiene wastewater treatment, and supports the future improvement and refinement of AnMBR technology.

Effect of Hydraulic retention time on performance of anaerobic membrane bioreactor treating slaughterhouse wastewater

Slaughterhouse wastewater is a major environmental concern in many Vietnamese cities due to its high organic content and unpleasant odor. This study aimed to evaluate performance of a submerged flat sheet Anaerobic membrane bioreactor (AnMBR) system at different hydraulic retention time (HRT, 8–48 h) treating wastewater from a slaughterhouse in Hanoi City (Vietnam) at ambient temperature. The wastewater characteristics were as follows: chemical oxygen demand (COD) of 910 ± 171 mg/L; suspended solids (SS) of 273 ± 139 mg/L; and total nitrogen (T-N) of 115 ± 31 mg/L. The AnMBR system achieved high removal efficiencies for SS (99%) and COD (>90%) at an optimum HRT of 24 h. The biomethane yield reached 0.29 NL CH4/g CODinf. Importantly, the system maintained stable operation without flux decay and membrane fouling. HRT longer than 24 h could offer the better effluent quality without an increase in transmembrane pressure (TMP); however, it led to a lower methane production rate. Shorter HRT of 8–12 h caused a high TMP over −10 kPa, posing a risk for membrane fouling and biomass loss during cleaning, thus resulting in a low methane production. Our results suggest that AnMBR can be a reliable technology for wastewater treatment, reuse and energy recover from slaughterhouse wastewater in Vietnam and other similar climate countries.

Enhancing the Performance of AnMBR Treating Municipal Wastewater at a High Organic Loading Rate with Iron Addition

The performance of a laboratory-scale 40 L anaerobic membrane bioreactor (AnMBR) treating municipal wastewater with and without iron supplementation was evaluated at ambient temperatures at a hydraulic retention time (HRT) of 6 h and sludge retention time (SRT) of 50 days. The system exhibited satisfactory performance during the summer and winter periods with average COD removal efficiencies of 73 ± 4% and 60 ± 4%, respectively. Moreover, two different FeCl3 dosages were studied for optimizing operation in terms of organic load removal, phosphorus removal, biogas production, membrane fouling, and emerging contaminant removal. The addition of 25 mg FeCl3 L−1 improved the performance of the AnMBR. More specifically, average effluent COD concentrations without FeCl3 addition were 177 ± 21 mg/L, while after the addition of 25 mg FeCl3 L−1 and 30 mg FeCl3 L−1, COD decreased to 147 ± 8 mg/L and 149 ± 11 mg/L, respectively. Moreover, effluent TP decreased by 75% with the dosage of 25 mg FeCl3 L−1 and was almost completely removed with 30 mg FeCl3 L−1. The membrane performance was slightly improved by FeCl3 dosing while biogas production was not affected by iron addition. AnMBR appeared inadequate for the removal of almost all the selected micropollutants, and the effect of iron addition on micropollutant removal was very limited.

Decreasing hydraulic retention time of anaerobic membrane bioreactor: Effect on core genera and microbial contaminants removal

A pilot-scale (35 L) anaerobic membrane bioreactor (AnMBR) treating municipal wastewater was operated under decreasing hydraulic retention times (HRT) of 12 h, 10 h and 8 h, and evaluated for its performance and removal of bacterial cells. There was an increased variability in COD and bacterial cells removal when HRT was 8 h, and a positive net growth rate of potential pathogen-containing genera Mycobacterium sp. was reported when AnMBR was operated at HRT of 8 h. Specifically, metagenomic assembled genomes of opportunistic pathogenic Mycobacterium franklinii were reconstructed uniquely in the 8 h HRT effluent. In contrast, co-occurrence network results showed when the HRT was 10 h, the microbial interactions were higher and bacterial syntrophs and methanogens had a more prevalent role in the microbial network. Our findings suggest that an optimal HRT (10 h) is required to achieve stable AnMBR performance and removal of microbial contaminants from untreated municipal wastewater, and can facilitate proper sizing of AnMBR.

Performance of Anaerobic Membrane Bioreactor (AnMBR) with Sugarcane Bagasse Ash-based Ceramic Membrane treating Simulated Low-strength Municipal Wastewater: Effect of Operation Conditions.

The online version contains supplementary material available at 10.1007/s11270-023-06173-3.

Performance evaluation and energy potential analysis of anaerobic membrane bioreactor (AnMBR) in the treatment of simulated milk wastewater

An anaerobic membrane bioreactor (AnMBR) was employed as primary treatment unit for anaerobic treatment of simulated wastewater to produce high effluent quality. A lab scale hollow fiber membrane was used to scrutinize the performance of AnMBR as a potential treatment system for simulated milk wastewater and analyze its energy recovery potential. The 15 L bioreactor was operated continuously at mesophilic conditions (35 °C) with a pH constant of 7.0. The membrane flux was in the range of 9.6–12.6 L/m2. h. The different organic loading rates (OLRs) of 1.61, 3.28, 5.01, and 8.38 g-COD/L/d, of simulated milk wastewater, were fed to the reactor and the biogas production rate was analyzed, respectively. The results revealed that the COD removal efficiencies of 99.54 ± 0.001% were achieved at the OLR of 5.01 gCOD/L/d. The highest methane yield was found to be at OLR of 1.61 gCOD/L/d at HRT of 30 d with the value of 0.33 ± 0.01 L-CH4/gCOD. Moreover, based on the analysis of energy balance in the AnMBR system, it was found that energy is positive at all the given HRTs. The net energy production (NEP) ranged from 2.594 to 3.268 kJ/gCOD, with a maximum NEP value of 3.268 kJ/gCOD at HRT 10 d HRT. Bioenergy recovery with the maximum energy ratio, of 4.237, was achieved with an HRT of 5 d. The study suggests a sizable energy saving with the anaerobic membrane process.

Effect of sludge retention time on the performance and sludge filtration characteristics of an aerobic membrane bioreactor treating textile wastewater

In this study, the impact of different sludge retention times (SRTs) on the wastewater treatment performance of an aerobic membrane bioreactor (MBR) was investigated using real textile industry wastewater. For this purpose, two laboratory-scale membrane bioreactors were operated in parallel. Under the same conditions, one of the systems was operated at an SRT of 30 d and, the other at SRTs of 20 d, and 10 d, respectively. The total chemical oxygen demand (COD), color and soluble total nitrogen (TN) of the wastewater averaged 927 ± 277 mg/L, 910 ± 287 PtCo and 39 ± 10 mg/L, respectively. COD removal efficiency remained above 90 % in all the tested SRTs. While the color removal efficiency was 55 % and 60 % at SRTs of 30 d and 20 d, respectively, it decreased to 50 % at SRT of 10 d. In addition, the impact of different SRTs on membrane filtration performance was studied. With the reduction of SRT to 10 d, an increase was observed in specific resistance to filtration (SRF) and supernatant filterability (SF) values, while viscosity decreased due to lower suspended solid (SS) concentration. According to gel permeation chromatography (GPC) analysis, the molecular weights of organic substances in the permeate distributed over a wide spectrum as SRT decreased. Also, signals given by the low molecular weight organic compounds were higher.

Effect of salinity on removal performance of anaerobic membrane bioreactor treating azo dye wastewater.

Membrane bioreactor (MBR) is an attractive option method for treating azo dye wastewater under extreme conditions. The present study assessed the effect of salinity on the performance of anaerobic MBR in treating azo dye wastewater. Increased salinity showed adverse effects on the decolorization efficiency and chemical oxygen demand (COD) removal efficiency. The decolorization efficiency decreased from 95.8% to 82.3% and 73.1% with a stepwise increasing of salinity from 0 to 3% and 5%, respectively. The COD removal efficiency decreased from 80.7% to 71.3% when the salinity increased from 0 to 3% and then decreased to 58.6% at 5% salinity. The volatile fatty acids (VFAs) concentration also increased as the salinity increased. Furthermore, increased salinity led to the elevated production of soluble microbial products (SMP) and extracellular polymeric substances (EPS), which can provide a protective barrier against harsh environments. More serious membrane fouling was observed as the SMP and EPS concentrations increased. The concentration of loosely bound EPS (LB-EPS), tightly bound EPS (TB-EPS), and the polysaccharide/protein (PS/PN) ratios in LB-EPS and TB-EPS all increased when the salinity was elevated. The production of SMP and EPS was caused by the generation of PS in response to the saline environment. Lactobacillus, Lactococcus, Anaerosporobacter, and Pectinatus were the dominant bacteria, and Lactobacillus and Lactococcus were the decolorization bacteria in the MBR. The lack of halophilic bacteria was the main reason for the decreased decolorization efficiency in the salinity environment.

Impacts of lipids on the performance of anaerobic membrane bioreactors for food wastewater treatment

This study investigated the resistance of anaerobic membrane bioreactor (AnMBR) to lipid gradients during food wastewater treatment. Sodium oleate (oleate-Na) was added to synthetic food wastewater to simulate lipids. Results show that AnMBR could adapt to a certain content of lipids by stimulate biomass growth and activity. As the dosage of oleate-Na increased from 0 to 2 g/L, the removal of total organic carbon (TOC) decreased for several days and then recovered back to above 90%. Such a decrease and increase profile was also observed for biogas production and methane yield, which stabilized at 0.61 and 0.41 L/gCOD, respectively, after oleate-Na addition was maintained at 2 g/L for 13 days. Nevertheless, further addition of 4 g/L oleate-Na led to system failure with a reduction of TOC removal and biogas production from 92% to 62% and from 0.61 L/gCOD to 0.083 L/gCOD, respectively, given a significant accumulation of volatile fatty acids to 2940 mg/L. Further microbial analysis showed that the genus Methanosaeta enriched to 50% with 2 g/L oleate-Na addition and thus contributed to the recovery of methane production. By contrast, adding 4 g/L oleate-Na inhibited the proliferation of the genus Methanosarcina to reduce organic biodegradation and then methane production.

Experimental investigation of the performance of anaerobic membrane bioreactor with electrolytic regeneration (AMBER) for challenges and options in wastewater treatment

Significant changes in wastewater services are necessary for achieving the sustainable development goals (SDGs), by utilizing resource recovery, recycle, and reuse in urban wastewater-treatment plants. Based on recent experiences, to improve the filtration behavior of a membrane bioreactor, a hybrid system including an upgraded anaerobic baffled reactor coupled with an electrolysis process and a nanocomposite-membrane was developed. The system, called an anaerobic membrane bioreactor with electrolytic regeneration (AMBER), is a bio-electrochemical process that is expected to be simultaneously efficient in both biogas augmentation and fouling mitigation. The goals were to enhance the stability and efficiency of the anaerobic membrane bioreactor. The integration of the electrolytic process with the ABR (EABR) using a pair of iron electrodes enhanced the removal of contaminants in the ABR while successfully maintained pH in the optimum range for anaerobic digestion (6.8 to 7.2). Then, the performance of AMBER in pollutant removal, including organic load, suspended solids, and microbial load, were investigated over 240 days. The results showed that configuration considerably enhanced permeate flux, as it reduced the deposition of extracellular polymeric substances (EPS) on the surface of the nanocomposite membrane, leading to a reduction in membrane fouling. EPS was extracted and quantified to compare the effect of biogas backwash on the function of the membrane reactor. After 7 d of operation with a daily biogas backwash, the flux reduction was approximately 13 % for the conventional combination of the anaerobic baffled reactor and the membrane bioreactor (AMBR), while it was limited to 4 % in AMBER. After cleaning by the biogas, EPS formation decreased 63 % in AMBER when compared to the AMBR. The results revealed that AMBER can be considered an environmentally competitive bioenergy technology for wastewater treatment with the purpose of water recovery and reuse, employing optimized operational conditions, application of antifouling membranes, and electrically-based strategies.

Impacts of nano-zero-valent iron on antibiotic removal by anaerobic membrane bioreactor for swine wastewater treatment

This study investigated the impact of nano-zero-valent iron (nZVI) on the removal of veterinary antibiotics by an anaerobic membrane bioreactor (AnMBR) for swine wastewater treatment. Ten veterinary antibiotics belonged to three commonly used groups, namely tetracyclines, fluoroquinolones, and sulfonamides, were evaluated. Results show that nZVI addition could improve AnMBR performance for the removal of both phosphorus and ammonium. Moreover, nZVI addition to AnMBR could improve the biodegradation of antibiotics to enhance their overall removal. Of the three groups of antibiotics, the enhancement was most obvious for sulfonamides with an increase in the removal rate from 32 – 62% to 64–97% when 2.6 g L−1 nZVI was added to AnMBR. Further microbial and redundancy analyses indicate that the removal of sulfonamides was closely and positively correlated to the relative abundance of the genera Lentimicrobium and Methanomethylovorans. By contrast, nZVI reduced the removal of tetracycline, ciprofloxacin, and norfloxacin by AnMBR. Microbial analysis showed that nZVI dosage slightly reduced methane yield by promoting the growth of Mesotoga but reducing the proliferation of Methanomassiliicoccus to potentially disrupt the hydrogenotrophic pathway. In addition, adding nZVI reduced the ratios of protein to polysaccharide in both extracellular polymeric substances and soluble microbial products, thereby mitigating membrane fouling.

Techno-economic analysis of forward osmosis pre-concentration before an anaerobic membrane bioreactor: Impact of draw solute and membrane material

This research investigated the impact of draw solute and membrane material on the economic balance of a forward osmosis (FO) system pre-concentrating municipal sewage prior to an anaerobic membrane bioreactor (AnMBR). Eight and three different draw solutes were evaluated for cellulose triacetate (CTA) and polyamide thin film composite (TFC) membranes, respectively. The material of the FO membrane was a key economic driver since the net cost of TFC membrane was substantially lower than the CTA membrane. The draw solute had a moderate impact on the economic balance. The most economically favourable draw solutes were sodium acetate and calcium chloride for the CTA membrane and magnesium chloride for the TFC membrane. The FO + AnMBR performance was modelled for both FO membrane materials and each draw solute considering three FO recoveries (50, 80 and 90%). The estimated COD removal efficiency of the AnMBR was similar regardless of the draw solute and FO membrane material. However, the COD and draw solute concentrations in the permeate and digestate increased as the FO recovery increased. These results highlight that FO membranes with high permselectivity are needed to improve the economic balance of mainstream AnMBR and to ensure the quality of the permeate and digestate.

Anaerobic membrane bioreactors for wastewater treatment: mechanisms, fouling control, novel configurations, and future perspectives

As the world focuses on reducing greenhouse gas emissions and recovering energy from sewage, technologies that can recover energy and reuse wastewater are becoming increasingly important. Anaerobic membrane bioreactor (AnMBR) technology has recently attracted attention, as it can achieve energy recovery and yields high-quality effluent. However, the large-scale commercial application of AnMBRs requires that certain barriers be overcome, including membrane pollution and dissolved methane recovery. In this review article, we summarize the basic principles of anaerobic wastewater digestion and discuss the excellent performance of AnMBRs for wastewater treatment. Various factors, membrane types, and pollution are discussed, and control strategies for dealing with membrane pollution are put forward. In addition, a variety of new AnMBRs are described that may better control membrane pollution. Finally, future research directions for AnMBRs are presented to promote the large-scale integrated application of AnMBRs for industrial wastewater treatment.

Experimental Investigation of the Performance of Anaerobic Membrane Bioreactor with Electrolytic Regeneration (Amber) for Challenges and Options in Wastewater Treatment

Experimental Investigation of the Performance of Anaerobic Membrane Bioreactor with Electrolytic Regeneration (Amber) for Challenges and Options in Wastewater Treatment