Aerobic Membrane Bioreactor Research Articles

Electro-Fenton enhanced MBR for fouling alleviation based on MIL-88B-Fe derived carbon membrane with in-situ generated [rad]OH

Porous carbon membrane (PCM) derived from MIL-88B-Fe with the ability of in-situ generation of hydroxyl radical was introduced to electro-enhanced aerobic membrane bioreactor (EMBR) for membrane fouling mitigation and wastewater quality improvement. The resultant PCM obtained with the calcination temperature of 1000 °C owned significant enhancement on hydrophilic and conductive properties, which helped PCM under −1.2 V could completely remove 10 mg/L bovine serum albumin with 2.5 % membrane flux loss rate. During the 76-day operation of EMBR, the extracellular polymeric substances could be suppressed for depositing on the −1.2 V enhanced PCM due to the combined effect of electrostatic barrier and OH oxidation. The pollutant intensity of total cells, polysaccharides and proteins were all reduced on PCM with −1.2 V. After operation, 36.0 % of cake layer pores was blocked in EMBR by total cells, polysaccharides and proteins. However, it was accounted for 69.8 % of the control group. Above results explained why the EMBR owned an always lower transmembrane pressure. Meanwhile, the pollutants removal rates of COD and NH4+-N were as high as 95 % and 98 % with electro-enhanced filtration, respectively, which is attributed to the collaborated effect from electrochemical effect and significantly increased microbial species related to organic pollutants removal, such as Azohydromonas, Thermomonas.

Treatment of Synthetic Wastewater Containing Polystyrene (PS) Nanoplastics by Membrane Bioreactor (MBR): Study of the Effects on Microbial Community and Membrane Fouling.

The persistent presence of micro- and nanoplastics (MNPs) in aquatic environments, particularly via effluents from wastewater treatment plants (WWTPs), poses significant ecological risks. This study investigated the removal efficiency of polystyrene nanoplastics (PS-NPs) using a lab-scale aerobic membrane bioreactor (aMBR) equipped with different membrane types: microfiltration (MF), commercial ultrafiltration (c-UF), and recycled ultrafiltration (r-UF) membranes. Performance was assessed using synthetic urban wastewater spiked with PS-NPs, focusing on membrane efficiency, fouling behavior, and microbial community shifts. All aMBR systems achieved high organic matter removal, exceeding a 97% COD reduction in both the control and PS-exposed reactors. While low concentrations of PS-NPs did not significantly impact the sludge settleability or soluble microbial products initially, a higher accumulation increased the carbohydrate concentrations, indicating a protective bacterial response. The microbial community composition also adapted over time under polystyrene stress. All membrane types exhibited substantial NP removal; however, the presence of nano-sized PS particles negatively affected the membrane performance, enhancing the fouling phenomena and increasing transmembrane pressure. Despite this, the r-UF membrane demonstrated comparable efficiency to c-UF, suggesting its potential for sustainable applications. Advanced characterization techniques including pyrolysis gas chromatography/mass spectrometry (Py-GC/MS) were employed for NP detection and quantification.

Application of Recycled Ultrafiltration Membranes in an Aerobic Membrane Bioreactor (aMBR): A Validation Study.

A validation study using recycled ultrafiltration membranes (r-UF) on an aerobic membrane bioreactor (aMBR) was conducted for the first time. Four different polyethersulfone (PES) membranes were tested using synthetic urban wastewater (COD 0.4-0.5 g/L) during two experimental periods: (i) recycled ultrafiltration membrane (r-UF) and commercial UF membrane (molecular weight cut-off (MWCO) 150 kDa) (c-150 kDa); (ii) r-UF membrane modified by dip-coating using catechol (CA) and polyethyleneimine (PEI) (mr-UF) and c-20 kDa membrane. Permeability, fouling behavior, and permeate quality were evaluated. Extensive membrane characterization was conducted using scanning electron microscopy (SEM), atomic force microscopy (AFM), energy-dispersive X-ray (EDX), and confocal laser scanning microscopy (CLSM). Permeate quality for r-UF and mr-UF membranes was excellent and comparable to that obtained using commercial membranes under similar conditions. Additionally, r-UF and mr-UF membranes presented a steadier performance time. Additionally, r-UF membrane demonstrated less tendency to be fouled (Rf, m-1) r-UF 7.92 ± 0.57 × 1012; mr-UF 9.90 ± 0.14 × 1012, c-150 kDa 1.56 ± 0.07 × 1013 and c-20 kDa 1.25 ± 0.50 × 1013. The r-UF membrane showed an excellent antibiofouling character. Therefore, r-UF membranes can be successfully implemented for wastewater treatment in aMBR, being a sustainable and cost-effective alternative to commercial membranes that can contribute to overcome membrane fouling and membrane replacement issues.

Phage phylogeny, molecular signaling, and auxiliary antimicrobial resistance in aerobic and anaerobic membrane bioreactors

Phage emit communication signals that inform their lytic and lysogenic life cycles. However, little is known regarding the abundance and diversity of the genes associated with phage communication systems in wastewater treatment microbial communities. This study focused on phage communities within two distinct biochemical wastewater environments, specifically aerobic membrane bioreactors (AeMBRs) and anaerobic membrane bioreactors (AnMBRs) exposed to varying antibiotic concentrations. Metagenomic data from the bench-scale systems were analyzed to explore phage phylogeny, life cycles, and genetic capacity for antimicrobial resistance and quorum sensing. Two dominant phage families, Schitoviridae and Peduoviridae, exhibited redox-dependent dynamics. Schitoviridae prevailed in anaerobic conditions, while Peduoviridae dominated in aerobic conditions. Notably, the abundance of lytic and lysogenic proteins varied across conditions, suggesting the coexistence of both life cycles. Furthermore, the presence of antibiotic resistance genes (ARGs) within viral contigs highlighted the potential for phage to transfer ARGs in AeMBRs. Finally, quorum sensing genes in the virome of AeMBRs indicated possible molecular signaling between phage and bacteria. Overall, this study provides insights into the dynamics of viral communities across varied redox conditions in MBRs. These findings shed light on phage life cycles, and auxiliary genetic capacity such as antibiotic resistance and bacterial quorum sensing within wastewater treatment microbial communities.

Evaluation of autotrophic process influencing extracellular polymeric substances in aerobic membrane bioreactor with expanded ASM model

A mathematical model was developed to predict the formation of both the autotrophic and heterotrophic extracellular polymeric substances (EPS) in the aerobic membrane bioreactor (MBR). Batch experimental results and 45-day operation data on a pilot MBR at a sludge retention time (SRT) of 20 d were used to calibrate and validate the model. Simulated MBR setup results demonstrated the key role of the influent COD and NH4+-N in governing the composition of heterotrophic and autotrophic EPS in the MBR. These results also revealed that the autotrophic EPS process was non-ignorable in the system. According to the autotrophic EPS simulation in the MBR, the EPS yield increased with increasing influent COD/NH4+-N ratio towards a constant level. The EPS yield was significantly influenced by the SRT, attributed to the autotrophic process's impact on EPS. Simulation results revealed a slight increase in EPS yield with an SRT of up to 5 days, followed by a rapid decrease beyond that threshold.

UV/TiO2 photocatalysis as post-treatment of anaerobic membrane bioreactor effluent for reuse

Advanced oxidation processes have been widely applied as a post-treatment solution to remove residual organic compounds in water reuse schemes. However, UV/TiO2 photocatalysis, which provides a sustainable option with no continuous chemical addition, has very rarely been studied to treat anaerobically treated effluents. In the current study, the removal of organics and nutrients from an anaerobic membrane bioreactor (AnMBR) effluent is evaluated during adsorption and photocatalysis processes under various conditions of TiO2 dose and UV intensity and compared to the effluent from an aerobic membrane bioreactor (AeMBR). The sequence for preferential adsorption on TiO2 was found to be phosphorus, inorganic carbon and then ammonia/organic carbon were found. The competing effect between the organics and nutrients, along with the low UV transmission efficiency caused by the need for high doses of TiO2, ultimately compromise the organic removal efficiency in the AnMBR permeate. TiO2 dosage was found to have a greater impact than UV intensity on improving the overall removal performance as nutrients are competing for the adsorption site but are not photodegraded. Under the same operational condition, the UV/TiO2 photocatalysis displayed a higher removal efficiency of organic matter and phosphorus in the AeMBR effluent due to a lower initial organics concentration and absence of ammonia as compared to the AnMBR effluent.

Comparison of Trace Organic Chemical Removal Efficiencies between Aerobic and Anaerobic Membrane Bioreactors Treating Municipal Wastewater.

Evaluating persistent trace organic chemicals (TOrCs) and transformation products (TPs) in membrane bioreactors (MBRs) is essential, given that MBRs are now widely implemented for wastewater treatment and water reuse. This research applied comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC/TOF-MS)-based nontargeted analysis to compare the effectiveness of parallel aerobic and anaerobic MBRs (AeMBRs and AnMBRs, respectively), treating the same municipal wastewater. The average total chromatographic feature peak area abundances were significantly reduced by 84% and 72% from influent to membrane permeate in both the AeMBR and AnMBR (p < 0.05), respectively. However, the reduction of the average number of chromatographic features was significant for only AeMBR treatment (p = 0.006). A similar number of TPs were generated during both AeMBR and AnMBR treatments (165 vs 171 compounds, respectively). The overall results suggest that the AeMBR was more effective for reducing the diversity of TOrCs than the AnMBR, but both aerobic and anaerobic processes had a similar reduction of TOrC abundance. Suspect screening analysis using GC×GC/TOF-MS, which resulted in the tentative identification of 351 TOrCs, proved to be a powerful approach for uncovering compounds previously unreported in wastewater, including many fragrances and personal care products.

Performance of a Double-Filter-Medium Tandem Membrane Bioreactor with Low Operating Costs in Domestic Wastewater Treatment

To reduce the operating costs of conventional membrane bioreactors (MBRs) and improve the stability and quality of the dynamic membrane bioreactor (DMBR) effluent, a homemade inexpensive filter cloth assembly was connected to an up-flow ultra-lightweight-medium filter (UUF) in lieu of expensive membrane modules to form a double-filter-medium tandem (DT)-MBR. DT-MBR was used to treat domestic wastewater, and its removal efficiencies for chemical oxygen demand, ammonia nitrogen, total nitrogen, and total phosphorus were similar to those of aerobic MBR, with average removal rates of 91.1%, 98.4%, 15.1%, and 50.7%, respectively. The average suspended solid (SS) of the final effluent was 5.6 mg∙L−1, and the filter cloth assembly played a leading role in SS removal, with an average removal rate of 86.0% and a relatively stable removal effect with little impact via backwashing. The activated sludge zeta potential, flocculation and sedimentation properties, particle size distribution, microbial compositions, extracellular polymeric substances (EPS), and filtration resistance of the cake layer were analyzed; it was found that the cake layer, which can also be called the dynamic membrane (DM), had an excellent filtration performance. However, the DM theory could not reasonably explain why the effluent quality of the filter cloth assembly maintained good stability even after backwashing. The real reason must be related to the sieving of cloth pores. Therefore, the concept of an in situ autogenous static membrane (ISASM) was proposed. With low operating costs and good and stable effluent quality, DT-MBR is a desirable alternative to the traditional MBR.

Isolation and characterization of nitroguanidine-degrading microorganisms

Nitroguanidine (NQ) is a component of newly developed insensitive munition (IM) formulations which are more resistant to impact, friction, heat, or sparks than conventional explosives. NQ is also used to synthesize various organic compounds and herbicides, and has both human and environmental health impacts. Despite the wide application and associated health concerns, limited information is known regarding NQ biodegradation, and only one NQ-degrading pure culture identified as Variovorax strain VC1 has been characterized. Here, we present results for three new NQ-degrading bacterial strains isolated from soil, sediment, and a lab-scale aerobic membrane bioreactor (MBR), respectively. Each of these strains -utilizes NQ as a nitrogen (N) source rather than as a source of carbon or energy. The MBR strain, identified as Pseudomonas extremaustralis strain NQ5, is capable of degrading NQ at a rate of approximately 150 μmole L−1 h−1 under aerobic conditions with glucose as a sole carbon source - and NQ as a sole N source. The addition of NH4+ to strain NQ5 during active growth with NQ as a sole N source slowed the growth rate for several hours, and the strain released NH4+, presumably from NQ. When NO3− was added as an alternate N source under similar conditions, the NO3− was not consumed, but NH4+ release into the culture medium was again observed. Strain NQ5 was also able to utilize guanylurea, guanidine, and ethyl allophanate as N sources, and - tolerate salt concentrations as high as 4 % (as NaCl). The other two stains, NQ4 and NQ7, both identified as Arthrobacter spp., grew significantly slower than strain NQ5 under similar culture conditions and tolerated only ∼1 % NaCl. In addition, neither strain NQ4 nor strain NQ7 was able to degrade guanlyurea or ethyl allophanate, but each degraded guanidine. These strains, particularly strain NQ5, may have practical applications for in-situ and ex-situ NQ bioremediation.

Wastewater Remediation by Aerobic Membrane Bioreactor: Effect of Sludge Retention Time on Treatment Performance and Filtration Process

Wastewater Remediation by Aerobic Membrane Bioreactor: Effect of Sludge Retention Time on Treatment Performance and Filtration Process

Assessment of denitrification efficiency and membrane fouling potential in a sulfur-driven membrane bioreactor treating effluent from biological treatment

In this study, any remaining nitrate not eliminated during a biological treatment process with a low C/N ratio was effectively removed using sulfur powder in an autotrophic denitrification membrane bioreactor. Moreover, particular attention was given to investigating the potential for membrane fouling in a sulfur-based denitrification reactor, with a comparative analysis to conventional activated sludge in an aerobic membrane bioreactor. At an influent nitrate concentration of 320 mg/L, the removal efficiency reached 94–98 % within a 4-hour hydraulic retention time and at a reactor temperature of 30 °C. The sulfur-based denitrification reactor exhibited soluble microbial products concentration and specific cake resistance values of 38.3 mg/L and 1.4 × 1013 m/kg, respectively, which were 5.47 and 2.26 times higher than those of conventional activated sludge. Furthermore, it was observed that the supernatant from the sulfur-based denitrification reactor resulted in more significant fouling within the membrane surface.

Advancing aerobic digestion efficiency using ultrafine bubbles in wastewater treatment

The application of ultrafine/nanobubbles (NBs) was tested as an aeration mechanism in a laboratory scale, semi-batch, biological wastewater treatment unit and compared with a similar scale, conventional bubbling supported aerobic digestion unit. The results showed that the oxygen utilization rate (OUR) and volumetric oxygen mass transfer coefficient (kla) were doubled from 0.075 to 0.159 mg O2/min and 0.07 to 0.13 respectively, through the application of NBs compared to the use of conventional bubbles (CBs). This was achieved by exploiting the sufficient residence time NBs can have in the aqueous system along with its capacity of high mass transfer surface area to volume ratio. The twofold increment in the OUR and kla due to the application NBs improved the biodegradation rate of the organic matter from 5.83 to 17.5 mg/l.hr compared to the application of CBs. Thus, 60 % of the hydraulic residence time reduction was achieved by the application NBs compared to CBs to achieve a similar amount of organic waste degradation. Moreover, the membrane filtration results also showed a reduction in the sludge load and fouling rate for aerobic membrane bioreactors supported by NB systems. A possible mechanism for sludge reduction was also proposed based on the results achieved.

The Design and Performance Prediction Model of an Integrated Scheme of a Membrane Bioreactor and Anaerobic Digester for the Treatment of Domestic Wastewater and Biowaste

An innovative and integrated scheme that encompasses two well-established waste treatment technologies, the aerobic biological degradation of organic matter bioprocess via membranes and anaerobic digestion, was demonstrated as a zero-waste approach that may effectively treat wastewater and biowaste in an integrated and symbiotic manner. Aiming to create a tool for the design, monitoring, and control of the scheme, prediction models were developed, validated, and implemented for the process simulation of the integrated scheme. The minimization of selected objective functions led to the estimation of the models’ parameters. The activated sludge model no. 1 (ASM1) was adopted for the simulation of the aerobic membrane bioreactor. The kinetic parameters were calibrated using volatile suspended solids and total nitrogen as the objective functions permitting the model to simulate the bioprocess satisfactorily (Nash–Sutcliffe efficiency &gt; 0.86) and to calculate the concentration of the active biomass. The predominance of heterotrophic bacteria (4300 to 9770 mg COD/L) over autotrophic biomass (508 to 1422 mg COD/L) was showcased. For the anaerobic process unit, a simplified anaerobic digestion model 1 ADM1-R4 was used, and the first-order hydrolysis constants (kch 0.41 d−1, kpr 0.25 d−1, kli 0.09 d−1) and microbial decay rate (kdec 0.02 d−1) were evaluated, enabling an accurate prediction of biogas production rates. A full-scale implementation of the integrated scheme was conducted for a decentralized waste treatment plant in a small community. Preliminary design calculations were performed in order to estimate the values related to certain process and technical parameters. The performance of this full-scale plant was simulated by the developed model, presenting clear benefits for practical applications in waste treatment plants.

Performance Evaluation of a Pilot-Scale Aerobic Granular Sludge Integrated with Gravity-Driven Membrane System Treating Domestic Wastewater

This study describes a novel integration of aerobic granular sludge (AGS) with a gravity-driven membrane (GDM) system at a pilot scale with a treatment capacity of approximately 150 L per day to treat raw domestic wastewater. The treatment performance and energy consumption of the AGS-GDM system were compared to the neighboring full-scale aerobic membrane bioreactor (AeMBR), treating the same wastewater at about 4000(±500) m3 per day. The AGS-GDM system demonstrated superior nutrient (nitrogen and phosphorus) removal as compared to the AeMBR. The GDM unit was continuously supplied with AGS-treated effluent. The GDM unit started with high [ >20 L per m2 per h (LMH) ] flux, which gradually declined. The flux remained quite stable after 15 days reaching 3 LMH after 35 days without any physical or chemical cleaning. Our results suggest that AGS-GDM is a viable technology for decentralized wastewater treatment and reuse in water-scarce regions. The AGS-GDM could easily replace conventional AeMBR technology in the wastewater treatment and reclamation market.

A combined process of chemical precipitation and aerobic membrane bioreactor for treatment of citric acid wastewater

The wastewater generated from citric acid production has a high organic loading content. The treatment and reuse of citric acid wastewater with high organic loading become extremely important. In this study, the performance of calcium hydroxide (Ca(OH)2) precipitation as a low-cost and environmentally friendly pre-treatment method and aerobic membrane bioreactor (MBR) combined treatment system was investigated for the treatment of citric acid (CA) wastewater. At the first step, optimization parameters such as agitation speed (100, 150, 200 rpm), temperature (30, 50, 70 °C), and reaction time (2, 4, 6 h) for Ca(OH)2 precipitation as a pre-treatment method were investigated using response surface methodology (RSM) to achieve maximum chemical oxygen demand (COD) removal. Experimental sets were designed using Box-Behnken Design. As a result of pre-treatment with Ca(OH)2 precipitation, a COD removal efficiency of 97.3% was obtained. Then, pre-treated CA wastewater was fed continuously to the MBR process for 10 days, which was the second stage of the combined process. As a result of the MBR process, 92.0% COD removal efficiency was obtained for 24 h HRT and 10 days SRT. In total, 99.8% COD removal efficiency was obtained when combined process was used and COD concentration decreased from 52,000–114 mg/L. For the treatment and reuse of wastewater from citric acid production, Ca(OH)2 precipitation and MBR combined treatment systems demonstrated an effective strategy.

Combined use of strictly anaerobic MBBR and aerobic MBR for municipal wastewater treatment and removal of pharmaceuticals

An integrated lab-scale wastewater treatment system consisting of an anaerobic Moving Bed Biofilm Reactor (AnMBBR) and an aerobic Membrane Bioreactor (AeMBR) in series was used to study the removal and fate of pharmaceuticals during wastewater treatment. Continuous-flow experiments were conducted applying different temperatures to the AnMBBR (Phase A: 35 °C; Phase B: 20 °C), while batch experiments were performed for calculating sorption and biotransformation kinetics. The total removal of major pollutants and target pharmaceuticals was not affected by the temperature of the AnMBBR. In Phase A, the average removal of dissolved chemical oxygen demand (COD), biological oxygen demand (BOD), and ammonium nitrogen (NH4–N) was 86%, 91% and 96% while in Phase B, 91%, 96% and 96%, respectively. Removal efficiencies ranging between 65% and 100% were observed for metronidazole (MTZ), trimethoprim (TMP), sulfamethoxazole (SMX), and valsartan (VAL), while slight (<30%) or no removal was observed for carbamazepine (CBZ) and diclofenac (DCF), respectively. Application of a mass balance model showed that the predominant mechanism for the removal of pharmaceuticals was biotransformation, while the role of sorption was of minor importance. The AeMBR was critical for VAL, SMX and TMP biodegradation; the elimination of MTZ was strongly enhanced by the AnMBBR. In both bioreactors, Bacteroidetes was the dominant phylum in both bioreactors over time. In the AnMBBR, Cloacibacterium and Bacteroides had a higher abundance in the biocarriers compared to the suspended biomass.

Mechanistic insights into simultaneous reversible and irreversible membrane fouling control in a vibrating anaerobic membrane bioreactor for sustainable municipal wastewater treatment

Vibrating membrane (VM) technology has shown low energy demands for in-situ antifouling enhancement in aerobic membrane bioreactors, and is expected to have greater potential for sustainable wastewater treatment applied in anaerobic membrane bioreactors (AnMBRs). However, it remains unclear how VM improves antifouling performance in AnMBRs and how the membrane fouling orignates, develops and diminishes in comparison to the conventional in-situ biogas scouring. This study reported the successful adoption of VM as a effective antifouling strategy for the vibrating AnMBR (V-AnMBR) in long-term (514 days) municipal wastewater treatment. The V-AnMBR showed superior performance, achieving 61.8%–89.4% longer filtration time, 0.68%–1.04% more organics removal and 10.7%–30.6% higher methane yields compared to the conventional biogas-scouring AnMBR (C-AnMBR). Both AnMBRs showed that membrane foulant layer (FL) was dominated in the order of colloid(FL) > EPS(FL) > SMP(FL), which could be reduced by VM to lower 10.7%–11.5% of the reversible fouling and 21.4%–26.9% of the irreversible fouling compared to biogas scouring. Furthermore, VM minimized the breakdowns of biomass typically caused by biogas scouring and reduced the release of fouling contributors from the mixed liquor, including the half of reductions of biopolymers and aromatic proteins. This work offers in-depth explanations of how membrane fouling develops in AnMBRs treating municipal wastewater, and elucidates the mechanisms of how VM achieves dual benefits on preventing foulant self-development and reducing membrane fouling contributors. Such mechanistic insights into fouling development and membrane fouling contributors would advance the understandings of antifouling mechanisms and guide next-generation sustainable AnMBR technology for mainstream wastewater treatment.

Superhydrophilic micro/nano hierarchical functionalized-CuO/PVDF nanocomposite membranes with ultra-low fouling/biofouling performance for acetate wastewater treatment: MBR application

In membrane bioreactor (MBR) application, there are considerably influencing factors on membrane performance over time making serious problems, including reduced permeation flux and rejection percentage as well as formed thick fouling/biofouling layer. This study provided a new preparation strategy to fabricate extraordinary superhydrophilic CuO/PVDF nanocomposite membranes with micro/nano hierarchical structure, using a wet micro-pattern casting knife with simultaneous bombardment of hydrophilic CuO nanoparticles/non-solvent solution via cold spray coating (s-NIPs method). When compared to the neat membrane, the main characteristics of the superhydrophilic membrane enhanced such as surface area (70%) and pure water flux (PWF) (400%). Protein rejection (PR) and chemical oxygen demand (COD) removal were also obtained as about 96.7% and 97.8% at constant mixed liquor suspended solids (MLSS = 6000 mg/l) in a submerged aerobic MBR, fed by the synthesized sodium acetate wastewater (compared to the neat case: 78% and 91%), respectively. Furthermore, its excellent antifouling/biofouling properties were proved via significantly less formation of biofilm and adherence of extracellular polymeric substances (EPSs) and soluble microbial products (SMPs) on the membrane surface. Low variation of sludge flux and COD removal by increasing MLSS from 6000 (348 LMH and 96.7%) to 12000 mg/L (200 LMH and 94.2%) proved the significant impact of the preparation method on the membrane performance. Stability of the F–CuO coated layer caused superhydrophilicity and antibacterial properties to be maintained under long-period. The obtained results demonstrated potential of the fast, facile, simple, and one-step preparation method without compromising the membrane separation ability, while simultaneously providing superhydrophilicity, antibacterial activity, and ultra-low fouling/biofouling formation.

Granular activated carbon stimulates biogas production in pilot-scale anaerobic digester treating agro-industrial wastewater

This work examines the continuous addition (5 g/L) of conductive granular activated carbon (GAC) in an integrated pilot-scale unit containing an anaerobic digester (180 L) and an aerobic submerged membrane bioreactor (1600 L) connected in series for the treatment of agro-industrial wastewater. Biogas production increased by 32 % after the addition of GAC. Methanosaeta was the dominant methanogen in the digester, and its relative abundance increased after the addition of GAC. The final effluent after post-treatment with the aerobic membrane bioreactor had a total solids content <0.01 g/L and a chemical oxygen demand between 120 and 150 mg/L. A simple cost analysis showed that GAC addition is potentially profitable, but alternatives ways of retaining the GAC in the system need to be found. Overall, this study provides useful scientific data for the possible application of GAC in full-scale biogas projects.

Aerobic treatment of fish canning wastewater using a pilot-scale external membrane bioreactor

Fish canning wastewater is characterized by high salinity and organic matter, which makes its treatment particularly difficult. To this purpose, the use of an aerobic membrane bioreactor (AeMBR) process could be a perfect option for the treatment of this wastewater. The aim of this study was to evaluate the effect of different operational conditions on the performance of the biological process and ceramic ultrafiltration (UF) membrane in AeMBR pilot plant for fish canning wastewater treatment. The AeMBR pilot was operated under ambient conditions (21.5 °C), 12 days of sludge retention time (SRT) and for a hydraulic retention time (HRT) of 24 h. The effect of operational parameters including organic loading rate (OLR) (3–5 kg COD/m3.day); total dissolved solids (TDS) (2.5–5 g/L), oxygenation rate (700 and 1300 NL/h) and transmembrane pressure (TMP) (0.05–1.5 bar) affected the quality of the effluent. The main performance results were the removal of approximately 97% of COD, 98% of BOD, 90% of nitrate and over 97% of total Kjeldahl nitrogen (TKN) and total phosphorus (TP). The treated effluent at the output of the AeMBR meets the quality standards according to the Food and Agriculture Organization (FAO) directive and the Moroccan standards for the discharge and reuse of water for irrigation and watering.