MBR System Research Articles

Mixed and membrane-separated culturing of synthetic cyanobacteria-yeast consortia reveals metabolic cross-talk mimicking natural cyanolichens

Metabolite exchange mediates crucial interactions in microbial communities, significantly impacting global carbon and nitrogen cycling. Understanding these chemically-mediated interactions is essential for elucidating natural community functions and developing engineered synthetic communities. This study investigated membrane-separated bioreactors (mBRs) as a novel tool to identify transient metabolites and their producers/consumers in mixed microbial communities. We compared three co-culture methods (direct mixed, 2-chamber mBR, and 3-chamber mBR) to grow a synthetic binary community of the cyanobacterium Synechococcus elongatus PCC 7942 and the fungus Rhodotorula toruloides NBRC 0880, as well as axenic S. elongatus. Despite not being natural lichen constituents, these organisms exhibited interactions resembling those in cyanolichens. S. elongatus fixed CO2 into sugars as the primary shared metabolite, while R. toruloides secreted various biochemicals, predominantly sugar alcohols, mirroring the metabolite exchange observed in natural lichens. The mBR systems successfully captured metabolite gradients and revealed rapidly consumed compounds, including TCA cycle intermediates and amino acids. Our approach demonstrated that the 2-chamber mBR optimally balanced metabolite exchange and growth dynamics. This study provides insights into cross-species metabolic interactions and presents a valuable tool for investigating and engineering synthetic microbial communities with potential applications in biotechnology and environmental science.

Influence of the oxidative phosphorylation uncoupler m-chlorophenol on activated sludge production, nutrients removal efficiency and bacterial community structure of a membrane reactor system

In this work, the effects of the metabolic uncoupler meta-chlorophenol (m-CP) on excess sludge production and performance of an MBR system, as well as on activated sludge communities, were investigated. MLVSS were significantly reduced from 8410 mg/L to 5175 mg/L during the first week of the addition of 125 mg/L m-CP, while, thereafter, biosolids were restored to the level prior to uncoupler’s addition. Adding m-CP resulted in more severe effects on nitrifiers rather than organoheterotrophs. Both alkalinity, dissolved oxygen (DO), electrical conductivity (EC) and pH data evidenced the adverse effect of m-CP on the nitrification process. PO43--P concentration drastically raised immediately after m-CP addition from 2.48 ± 0.35 mg/L to 11.84 mg/L, possibly due to the uncoupling of P-release and the hydrolysis of phosphorus reserves. Diversity was highly affected by the addition of m-CP, resulting in the significant decrease of Chao1, Shannon and Fisher indices. By establishing stable operating conditions after m-CP addition, Pseudomonas, Arcanobacterium, Trichococcus, Kocuria and Actinobaculum raised from almost undetectable levels (0.12 % of the total relative abundance) to 35.9 %, 17.8 %, 15.1 %, 11.5 % and 5.7 %, respectively, indicating a massive shift in bacterial community structure, while no nitrifying taxa were detected after m-CP addition.

Enhancing Rubber Industry Wastewater Treatment through an Integrated AnMBR and A/O MBR System: Performance, Membrane Fouling Analysis, and Microbial Community Evolution.

This study explores the effectiveness of an integrated anaerobic membrane bioreactor (AnMBR) coupled with an anoxic/oxic membrane bioreactor (A/O MBR) for the treatment of natural rubber industry wastewater with high sulfate, ammonia, and complex organic contents. This study was conducted at the lab-scale over a duration of 225 days to thoroughly investigate the efficiency and sustainability of the proposed treatment method. With a hydraulic retention time of 6 days for the total system, COD reductions were over 98%, which reduced the influent from 22,158 ± 2859 mg/L to 118 ± 74 mg/L of the effluent. The system demonstrates average NH3-N, TN, and total phosphorus (TP) removal efficiencies of 72.9 ± 5.7, 72.8 ± 5.6, and 71.3 ± 9.9, respectively. Despite an average whole biological system removal of 50.6%, the anaerobic reactor eliminated 44.9% of the raw WW sulfate. Analyses of membrane fouling revealed that organic fouling was more pronounced in the anaerobic membrane, whereas aerobic membrane fouling displayed varied profiles due to differential microbial and oxidative activities. Key bacterial genera, such as Desulfobacterota in the anaerobic stage and nitrifiers in the aerobic stage, are identified as instrumental in the biological processes. The microbial profile reveals a shift from methanogenesis to sulfide-driven autotrophic denitrification and sulfammox, with evidence of an active denitrification pathway in anaerobic/anoxic conditions. The system showcases its potential for industrial application, underpinning environmental sustainability through improved wastewater management.

Collaborative Misbehaviour Response System for Improving Road Safety

This paper advocates for a proactive approach to traffic safety by introducing a collaborative Misbehaviour Response System (MBR) designed to preemptively address hazardous driving behaviours such as wrong-way driving and distracted driving. The system integrates with electric vehicles (EVs), leveraging advanced technologies like ADAS, edge computing, and cloud services to enhance road safety. Upon detection of misbehaviour, the MBR system utilizes data from interconnected parking facilities to identify the nearest safe location and provides navigation guidance to authorities and nearby vehicles. The paper presents a prototype of the MBR system, demonstrating its efficiency in detecting misbehaviours and coordinating swift responses. It also discusses the system’s limitations and societal implications, outlining future research directions, including integration with autonomous vehicle systems and variable speed limit technologies, to further improve road safety through proactive and context-aware response mechanisms.

Combination of membrane bioreactor with chemical coagulation for the treatment of real pharmaceutical wastewater: Comparison of simultaneous and consecutive pre-treatment of coagulation on MBR performance

In this work, the combination of the coagulation process with the MBR system to reclaim effluent in pharmaceutical industries was investigated. In this research, comparison/concentration optimization of two modes of integrations, including simultaneous; one-step one pot, and consecutive coagulation MBR were investigated. Results showed that COD removal in simultaneous and consecutive modes at optimum values were 85 % and 95.8 %, respectively, which were considerably higher than that of control MBR; 53.89 %. The total fouling ratio for control MBR, simultaneous, and consecutive modes at optimum conditions were 70.69 %, 37.3 %, and 42.5 %, respectively, confirming that the integrated coagulation process and MBR system were considerably effective. Analyzing the secreted metabolite, e.g. protein, carbohydrate, and LB/TB-EPS ratio in the MBR tank as well as on the membrane surface showed that the charge-neutralization and entrapment of bio-foulants by aggregated clots during the coagulation hinder the adhesion of the biofouling agents on the membrane surface, therefore in-line with the flux attenuation trend, lower metabolite concentration results in less membrane fouling. It was found that simultaneous coagulative MBR with 100 mg/L FeCl3 concentration demonstrates better fouling mitigation in comparison with consecutive (even with poly aluminum chloride; PACl as coagulant aid) MBR, while the latter mode shows better performance in terms of wastewater treatment. These findings open avenues for future techno-economic assessments of a coagulation-assisted MBR, providing a cost-effective solution for treating high-strength wastewater on a larger scale.

Feasibility study of powdered activated carbon membrane bioreactor (PAC-MBR) for source-separated urine treatment: A comparison with MBR

Micropollutants (MPs) such as pharmaceuticals and personal care products are a group of emerging environmental contaminants, which are structurally complex and can cause adverse physiological effects on human health at low concentration. This study demonstrated that a hybrid process of powdered activated carbon and microfiltration membrane bioreactor (PAC-MBR) could be utilized for efficient removal of metronidazole, acetaminophen, naproxen, ibuprofen, carbamazepine, estriol (> 99 %) from source-separated urine via physical adsorption and biodegradation in a single step, without compromising the operating system stability. PAC addition to MBR improved 5 % of nitrification performance in terms of ammonia to nitrate conversion rate. Further, it improved organic removal efficiency from 88.6 ± 2.9 % to 96.0 ± 1.2 %, promoted rapid biomass growth, increased sludge floc size growth by 17 % and reduced membrane fouling propensities. This study showed the production of a micropollutant-free fertiliser from source-separated urine achieving a complete nutrient recovery in a single stage MBR system.

Nitrogen Removal Mechanism and Microbial Community Changes of the MBR Bioaugmented with Two Novel Fungi Pichia kudriavzevii N7 and Candida tropicalis N9

Ammonia nitrogen wastewater causes dissolved oxygen concentrations to decrease and the content of harmful substances to increase. To characterize the application properties of two novel strains of highly efficient ammonium transforming fungi—Pichia kudriavzevii N7 and Candida tropicalis N9—this study used both as compound microbial agents to treat nitrogenous wastewater. Here, we investigated the bioaugmentation effect of compound fungi N7 and N9 in the MBR bioreactor and the effect of N7 and N9 on the fungal and bacterial microbial communities in the system. The results revealed that in the first week after inoculation of N7 and N9, the average removal rate of ammonium in the experimental and control groups were 89.43% and 82.86%, respectively, and the NO3−-N accumulation concentrations were 12.56 mg·L−1 and 17.73 mg·L−1, respectively. The average transformation rate of total nitrogen in the experimental and control groups were 46.32% and 30.6%, respectively. ITS sequencing results indicated that N9 could be a dominant fungus in the complex MBR system. The results of 16S rRNA sequencing showed that the dominant bacterial communities in the system were changed by the inoculation of compound fungi. Therefore, the compound fungi can be applied to strengthen the treatment of nitrogenous wastewater due to its compatibility.

Optimizing slug bubble size for application of the ultra-thin flat sheet membranes in MBR: a comprehensive study combining CFD simulation and experiment.

Optimizing the slug bubble size specifically for ultra-thin flat sheet membranes in MBR systems can effectively enhance the scouring force and improve fouling control efficiency, thereby further advancing their targeted and widespread application. In this study, a three-dimensional model was developed based on the practical application to investigate the impact of slug bubbles on scouring performance in ultra-thin flat sheet MBR systems, encompassing their evolution, disturbance level, and shear stress. A membrane fouling probability index for quantifying the distribution of membrane fouling, along with a turbulence intensity index have been proposed. The findings revealed that the 20-mL slug bubble induced the highest disturbance level in the surrounding fluid, characterized by an instantaneous peak velocity of 0.63m/s at the local system level, conducive to bubble scouring. And exerted the greatest shear stress effect, achieving the most effective reduction in membrane contamination, with a maximum shear stress of 1.82Pa. The experimental validation conducted during the operational cycles confirmed that the scouring effect of 20-mL slug flow yielded in a maximum proportion of 48.16% within the low fouling probability region. The results provided evidence supporting the assertion that specific aeration conditions producing 20mL of bubbles resulted in minimal membrane fouling, ensuring a more pronounced scouring effect. The combination anythsis of slug bubble characteristics and behaviors, integrating theoretical and experimental approaches, implied that 20mL was the optimal bubble size in ultra-thin flat sheet MBR, which fulfilled the optimal air scouring effect.

Mitigation of fouling problem and optimization of treatment effect in the polyvinylidene fluoride (PVDF) based electrochemical membrane bioreactor (EMBR)

The hydrophobic polyvinylidene fluoride (PVDF) membrane is one of the most widely used membrane material in the treatment of domestic sewage, while it still endures the fouling problem. Many studies have focused on the fouling control, among which the electrochemical membrane bioreactor (EMBR) is promising because of its chemical-free nature, but the specific influence of applied electric field on the mitigation of membrane fouling and the treatment effect are unclear and need further exploration. In this work, the influence and interaction of operation parameters (operation voltage, electrode spacing, power-on mode, and hydraulic retention time) on fouling development and pollutants removals in a PVDF based EMBR were carefully explored for the optimal operating conditions. Results showed that the run time of EMBR system under optimal conditions was 23.4 % longer than that of the MBR system without a weak electric field, indicating that the membrane fouling problem was well alleviated. In addition, the effluent quality of EMBR was also improved than that treated by the MBR system. The removal rates of chemical oxygen demand, ammonia nitrogen, total phosphorus, and total nitrogen were increased by 2.25 %, 2.64 %, 9.02 %, and 12.1 %, respectively, revealing the improvement of this EMBR system in sewage treatment. This work shows that introduction of a weak electric field in MBR system not only effectively controls membrane fouling, but also increases the effluent quality, and thus endows EMBR as a candidate for sustainable and green technique in sewage treatment.

Advancements and Challenges in Membrane Bioreactor Technology for Industrial Wastewater Treatment

Due to its success in achieving the majority of wastewater treatment objectives, Membrane Bioreactor Technology (MBR) has replaced the Conventional Activated Sludge Process (CAS) as the leading method for treating wastewater. Nowadays, the treatment of industrial wastewater become one of the world’s major concerns, MBR technologies are used more frequently. This technology has a bright future in wastewater treatment (especially industrial wastewater). In general, this article is designed to give a general view of various aspects of an MBR, with the aim of addressing and overcoming any potential drawbacks or limitations. In this work, the fouling in MBR technology its variations and mechanisms, influencing factors are also discussed in detail. However, membrane fouling is thought to be the biggest challenge this technology faces. One of the main agents that causes the fouling of the membrane is Extracellular Polymeric Substances (EPS), which results in a decrease in filterability and a decline in membrane flux, which affects the membrane lifespan. Furthermore, it looks into how to minimize membrane fouling in MBR systems and offers biological tactics to lessen the likelihood of membrane fouling in MBR technology. Finally, this work quoted also how artificial technology might help to increase removal effectiveness and prevent filtering membrane obstruction.

Treatment of printing and dyeing wastewater using Fenton combined with ceramic microfiltration membrane bioreactor

The release of printing and dyeing wastewater (PDW) into the environment is a concern attributed to its acute, chronic and cytotoxic effects to aquatic life. Two anaerobic/aerobic-membrane bioreactors (A/O–MBRs) were operated continuously to treat raw (untreated) and Fenton oxidized PDW. After about 70 days acclimatization, 67% of the chemical oxygen demand (COD) and 35% of adsorbable organic halogens (AOX) were removed by direct biodegradation in A/O–MBR without Fenton pre-treatment, while 90% of the COD and 79% of AOX were removed in Fenton + A/O–MBR system. Fenton oxidation play a dominate role on the COD and AOX removal of PDW in the combination system. The Fenton pre–treatment of PDW could remarkably reduce membrane fouling. The Shannon indices showed that the microbial diversity in anaerobic flocs were significantly higher than the microbial diversity in aerobic flocs in both two A/O–MBR systems. The metagenomics analysis found that the key functional genes responsible for the AOX biodegradation were EC3.1.1.45, pcaI, and pcpD. The transcript per million (TPM) abundance of EC3.1.1.45 and pcaI significantly up-regulated in both anaerobic and aerobic flocs after 70 days acclimatization. Based on the pilot applications study, the total operation cost of Fenton + A/O–MBR processes for PDW remediation was approximately 1.263–1.384 USD/t. This study provides a promising technique for removing AOX and other organic contaminants from PDW.

A CFD simulation and experimental study: The impact of aerator design on the bubble flow pattern, foulant removal and scouring capability of flat sheet membrane bioreactor (FSMBR)

Membrane fouling is a main drawback of membrane bioreactor systems. Moreover, optimization of influential parameters via practical analyses is tedious and time-consuming. Therefore, the CFD-RSM approach accompanied by experimental results was employed to propose the optimal aerator design. In comparison with the linear nozzles, simulation results proposed that at equal air flow rate, the angular nozzle aerators with 30° toward the surface of the membrane could provide higher amounts of surface tension, air scouring capabilities as well as air volume fraction at a similar air flow. Simulation findings were experimentally validated using a bench-scale MBR system. Obtained results showed that the irreversible fouling ratio to the total fouling ratio for neat membrane was decreased from 62.99 % to 43.97 % for linear and angular nozzles, respectively. This improvement in the nozzle performance was more pronounced for nanocomposite membranes, in which the abovementioned ratio was decreased from 43.44 % to 24.57 %. It is confirmed that the impact of nozzle design on the nanocomposite membrane was 30.48 % higher than that of the neat membrane. Specific aeration demand (SADm) value was decreased from 0.77 to the 0.49 [Nm3/(m2h)] at an equal amount of shear stress and lower inlet velocity, when linear nozzles were replaced by the angular nozzles. The lower SADm and better foulant capability leads to the optimal operation condition and lower energy as well as operating costs.

A Mechanistic Model for Hydrogen Production in an AnMBR Treating High Strength Wastewater.

In the global race to produce green hydrogen, wastewater-to-H2 is a sustainable alternative that remains unexploited. Efficient technologies for wastewater-to-H2 are still in their developmental stages, and urgent process intensification is required. In our study, a mechanistic model was developed to characterize hydrogen production in an AnMBR treating high-strength wastewater (COD > 1000 mg/L). Two aspects differentiate our model from existing literature: First, the model input is a multi-substrate wastewater that includes fractions of proteins, carbohydrates, and lipids. Second, the model integrates the ADM1 model with physical/biochemical processes that affect membrane performance (e.g., membrane fouling). The model includes mass balances of 27 variables in a transient state, where metabolites, extracellular polymeric substances, soluble microbial products, and surface membrane density were included. Model results showed the hydrogen production rate was higher when treating amino acids and sugar-rich influents, which is strongly related to higher EPS generation during the digestion of these metabolites. The highest H2 production rate for amino acid-rich influents was 6.1 LH2/L-d; for sugar-rich influents was 5.9 LH2/L-d; and for lipid-rich influents was 0.7 LH2/L-d. Modeled membrane fouling and backwashing cycles showed extreme behaviors for amino- and fatty-acid-rich substrates. Our model helps to identify operational constraints for H2 production in AnMBRs, providing a valuable tool for the design of fermentative/anaerobic MBR systems toward energy recovery.

Long-term performance of ZVI-stimulating anaerobic/aerobic system - PEI modified ceramic membrane SMBR in reusing food wastewater for irrigation: An industrial project and microbial community shift

A large-scale project was carried out using an integrated treatment system composed of anaerobic and aerobic unit followed by ceramic membrane SMBR for reclaiming 200 m3/d of food wastewater for the purpose of irrigation. Utilization of ZVI technology to facilitate the organic contaminants degradation in UASB and aerobic unit in the operation of successive 240 days was investigated. A membrane flux of around 30 LMH was stably attained in a novel PEI-modified flat sheet ceramic membrane SMBR equipped with in situ intensive mechanical cleaning bush system. The ceramic MBR system investigated had significantly alleviated membrane fouling and no severe membrane fouling occurred throughout the whole filtration process. Overall, the combined treatment system can produce high quality reusable water for irrigation and the final effluent had a COD of around 120 mg/L and BOD5 of around 32 mg/L, respectively. Finally, variations in dominant species in both initial sludge Day-1 and sludge Day-240 in ZVI assisting UASB and aerobic unit was further unraveled by the high throughput sequencing analysis.

Exploring the application of the hybrid nano-bioreactor technology based on the developed polyethersulfone mixed-matrix membrane for industrial effluent treatment

Due to the high concentration of various contaminants in the paper mill effluent, it must undergo an efficient treatment process before being discharged to the environment or being reused in the production cycle. In the present study, the submerged membrane adsorption bioreactor (SMABR) system was used for the treatment of the paper mill effluent. The modified polyethersulfone PES/MoS2 membrane was fabricated by incorporating exfoliated MoS2 nanosheets prepared in the laboratory, into the PES matrix. This membrane along with the powdered activated carbon (PAC) were utilized in the SMABR system for the paper mill effluent treatment. After the acclimation of the sludge with the target effluent, the optimum values of food to microorganism (F/M), hydraulic retention time (HRT), and adsorbent dosage were determined separately to be 0.451, 18 h, and 3 g/L by considering the maximum values of chemical oxygen demand (COD) removal and mixed liquor suspended solid MLSS concentration in each stage. In the final stage, the MBR and SMABR systems (using the pristine and modified membranes, separately) were prepared to separately investigate the effect of the presence of the PAC adsorbent and modified membrane, on the output parameters. In all systems, the values of pH and dissolved oxygen (DO) were maintained in the normal range (pH: 6.2–6.7, DO>2) to provide favorable conditions for the growth of microorganisms. Most importantly, best performance in this study was related to the SMABR system consisting the PES/MoS2 membrane and PAC adsorbent, with the highest values of COD removal (96%), MLSS concentration (15620 mg/L), and membrane permeation flux (110 L/m2.h). It is worth mentioning that the functionalized membrane exhibited better hydrophilicity compared with the pristine membrane, resulting in high water permeation flux, which is in accordance with the performance results.

Mediation of Bacterial Interactions via a Novel Membrane-Based Segregator to Enhance Biological Nitrogen Removal.

The regulation of microbial subpopulations in wastewater treatment plants (WWTPs) with desired functions can guarantee nutrient removal. In nature, "good fences make good neighbors," which can be applied to engineering microbial consortia. Herein, a membrane-based segregator (MBSR) was proposed, where porous membranes not only promote the diffusion of metabolic products but also isolate incompatible microbes. The MBSR was integrated with an anoxic/aerobic membrane bioreactor (i.e., an experimental MBR). The long-term operation showed that the experimental MBR exhibited higher nitrogen removal (10.45 ± 2.73 mg/L total nitrogen) than the control MBR (21.68 ± 4.23 mg/L) in the effluent. The MBSR resulted in much lower oxygen reduction potential in the anoxic tank of the experimental MBR (-82.00 mV) compared to that of the control MBR (83.25 mV). The lower oxygen reduction potential can inevitably aid in the occurrence of denitrification. The 16S rRNA sequencing showed that the MBSR significantly enriched acidogenic consortia, which yielded considerable volatile fatty acids by fermenting the added carbon sources and allowed efficient transfer of these small molecules to the denitrifying community. Moreover, the sludge communities of the experimental MBR harbored a higher abundance of denitrifying bacteria than those of the control MBR. Metagenomic analysis further corroborated these sequencing results. The spatially structured microbial communities in the experimental MBR system demonstrate the practicability of the MBSR, achieving nitrogen removal efficiency superior to that of mixed populations. Our study provides an engineering method for modulating the assembly and metabolic division of labor of subpopulations in WWTPs. IMPORTANCE This study provides an innovative and applicable method for regulating subpopulations (activated sludge and acidogenic consortia), which contributes to the precise control of the metabolic division of labor in biological wastewater treatment processes.

Influence of shear stress on the intracellular bis-(3′-5′)-cyclic dimeric guanosine monophosphate (c-di-GMP) level within an MBR biofilm

Biofilms are inevitable and typically adhere on solid surfaces such as the membrane surfaces in membrane bioreactors. Aeration has been widely used in the aerobic stage of water treatment to hydrodynamically generate shear stress to disrupt biofilm formation. The current study quantified the influence of shear stress on mature biofilms by examining its influence on bacteria Quorum Sensing behaviour which involves c-di-GMP molecules. The level of external shear stress was determined via validated Computational Fluid Dynamics simulation and the level of c-di-GMP was measured directly. It was found that bacteria are very sensitive to environmental shear stress; a small change of 0.05 Pa can lead to an intracellular c-di-GMP fluctuation of 5.6 pmol/mg protein. The mediating effect of shear stress on c-di-GMP level is nonlinear. In MBR systems, a time-averaged shear stress exceeding 0.72 Pa is indicated as it generates lower c-di-GMP and a looser biofilm that has low biodiversity.

Microbial Electrochemical Systems and Membrane Bioreactor Technology for Wastewater Treatment

AbstractMembrane bioreactors (MBRs) and microbial electrochemical systems (MESs) are promising technologies for wastewater treatment and generation of electricity from organic matter. The application of MBRs is limited due to membrane fouling and high energy consumption. The novel design of the coupling system of microbial fuel cell and membrane bioreactor (MFC‐MBR), which efficiently combines microbial degradation in MFCs and uses the microelectric field to reduce and mitigate membrane fouling in MBR. The fundamentals of extracellular electron transport, the performance of MFCs, different types of MBR systems, and the novelty of the MFC‐MBR coupling system for wastewater treatment are reviewed.

Effect of Antiscalant Usage and Air Diffuser Perforation Diameter on Filtration Performance of Submerged Flat Sheet MBR for Treatment of High Salinity and Scaling Propensity Wastewater

Membrane fouling and mineral scaling remain major drawbacks for MBR technology. Membrane fouling reduces the filtration ability in MBR systems by increasing transmembrane pressure (TMP) and thus increases the operational cost. This study focused on the application of commercially available antiscalant in a pilot MBR system and the effect of diffuser perforation diameter for the treatment of high mineral scaling propensity wastewater. Submerged flat sheet membranes (Kubota, nominal pore size: 0.4 µm) were used in the pilot-scale test unit operated in the wastewater treatment plant of ITOB Organized Industrial Zone, Izmir, Turkey. The commercially available antiscalants employed were coded AS-1 and AS-2 for antiscalant study. Long term effect of the two antiscalants employed was investigated under high mixed liquor suspended solid (MLSS) concentration (17–21 g/L) for two months of MBR operation. The effect of low MLSS concentration (10–13 g/L) was also studied without changing the concentration of antiscalant type and concentration. AS-1 was found to be more effective in terms of mineral scale control. The effect of diffuser perforation diameter (1, 3 and 5 mm) on mineral scaling minimization in MBR pilot system was also studied. The best performance with respect to membrane fouling control was found with an air diffuser having 3 mm of diffuser perforated diameter. Some quality analyses of the product water were also carried out to assess the effect of antiscalant addition on microbial activities in the MBR unit. The findings in this study reveal that the use of antiscalants has not affected biological treatment performance of MBR pilot system. The removal ranges obtained during all MBR studies were 98.47–99.9%, 84.62–99.4%, 89.5–98.5%, 86.90–99.9%, 67.01–99.2%, 75.03–93.9%, and 20.36–71.5% for total suspended solid (TSS), color, chemical oxygen demand (COD), NH4-N, PO4-P, NO2-N, and total nitrogen (TN) respectively.

The potential of microalgae Dunaliella salina to treat shrimp pond wastewater in a PAN/GO membrane bioreactor

Graphene has attracted a significant amount of attention because to its excellent mechanical, electrical, thermal, and optical characteristics. In this work, a membrane bioreactor with hollow fibre PAN/GO nanocomposite was studied for the treatment of Persian Gulf shrimp pond wastewater. Dunaliella salina microalgae have been used for better treatment and the formation of sludge mass in a shorter period of treatment in the MBR system. Additionally, GO nanoparticles were used in order to improve the hydrophilicity of the membranes. Various tests, such as Pure water permeate (PWP), X-ray diffraction spectroscopy (XRD), Atomic force microscopy (AFM), Dynamic light scattering (DLS), Contact angle (CA), Scanning electronic microscopy (SEM), Fourier transform infrared substances (FTIR) were used to characterize the synthesized membranes. To evaluate the treated wastewater, several factors were evaluated, including: TP, TN, TSS, NTU, BOD, COD, EC. The contact angle was reduced by the inclusion of GO nanoparticles from 53.8° for PAN-0 to 45.4° for PAN-3. The results of FTIR analysis confirmed the synthesis of GO and showed the formation of different deposits as fouling on the surface of the prepared membranes after MBR process. Also, the removal percentage of COD and BOD5 was over 90% for membranes with graphene oxide nanoparticles. The turbidity for all fabricated membranes were removed ∼98%. Also, very little fouling occurred in the membranes constructed with GO membranes and the maximum concentration of GO let to maximum performance regarding to the high potential of fouling control. In addition, the growth of Microalgae Dunaliella salina with shrimp wastewater was observed successfully. In conclusion, the finding of this work not only proposed a promising solution for controlling fouling in an MBR but also resulted in a benefit product, i.e. microalgae Dunaliella salina.