Side-stream Membrane Bioreactor Research Articles

Phytoremediation capability of Anabaena sp. for high organic and chromium-loaded wastewater in membrane bioreactors.

The efficiency of Anabaena sp. was analyzed for the phytoremediation of wastewater loaded with organic matter and heavy metals like chromium. Simulated wastewater was contaminated with chromium. A side-stream membrane bioreactor was used for the treatment of wastewater. A feed tank of 20 L capacity was used with a stirring arrangement. A ceramic microfiltration membrane composed of clay and alumina was obtained from Johnson & Johnson. The removal efficiency of chemical oxygen demand, biochemical oxygen demand, and chromium was evaluated. The process was used for algae harvesting and wastewater treatment. About 92% of chemical oxygen demand (COD), 98% chromium, and oil and grease were completely removed. Membrane fouling was explained by the pore blocking and cake resistance model. Stress in algal cells was determined from the superoxide dismutase (SOD) and catalase (CAT) analysis. The lipid content of algal cells was measured.

Comparative analysis of membrane fouling mechanisms induced by operation modes of membrane bioreactors with aerobic granular sludge

This experimental work investigated fouling characteristics induced by two different configurations of membrane bioreactor (MBR), which are submerged MBR and sidestream MBR with aerobic granular sludge. Submerged membrane bioreactor with granular sludge (Sub-MGSBR) ran the longest operation time 61 days with a steady overall TMP increase rate; Sidestream membrane bioreactor with granular sludge (SS-MGSBR) performed only 39 days, which exhibited Sub-MGSBR had more efficiently retarding membrane fouling. In both membrane bioreactors with flocculent sludge (MFSBRs) as a control, membrane foulants were compact, and cake resistance was the dominant fouling factor. In MGSBRs, however, pore blocking resistance turned out the key fouling factor. Especially in Sub-MGSBR, it went beyond 75%, and there was the most conglomeration of microorganisms of foulants with the highest porosity. Extracellular polymeric substances (EPS) content of foulants proved membrane fouling was hardly just for granules accumulation into cake but microorganisms’ growth in MGSBRs.

The Advancement in Membrane Bioreactor (MBR) Technology toward Sustainable Industrial Wastewater Management.

The advancement in water treatment technology has revolutionized the progress of membrane bioreactor (MBR) technology in the modern era. The large space requirement, low efficiency, and high cost of the traditional activated sludge process have given the necessary space for the MBR system to come into action. The conventional activated sludge (CAS) process and tertiary filtration can be replaced by immersed and side-stream MBR. This article outlines the historical advancement of the MBR process in the treatment of industrial and municipal wastewaters. The structural features and design parameters of MBR, e.g., membrane surface properties, permeate flux, retention time, pH, alkalinity, temperature, cleaning frequency, etc., highly influence the efficiency of the MBR process. The submerged MBR can handle lower permeate flux (requires less power), whereas the side-stream MBR can handle higher permeate flux (requires more power). However, MBR has some operational issues with conventional water treatment technologies. The quality of sludge, equipment requirements, and fouling are major drawbacks of the MBR process. This review paper also deals with the approach to address these constraints. However, given the energy limitations, climatic changes, and resource depletion, conventional wastewater treatment systems face significant obstacles. When compared with CAS, MBR has better permeate quality, simpler operational management, and a reduced footprint requirement. Thus, for sustainable water treatment, MBR can be an efficient tool.

Evaluating Laboratory Side-stream Membrane Bioreactor and Nanofiltration System for Treating Domestic Wastewater and Reuse

This paper presents Membrane Bioreactor (MBR) and Nanofiltration (NF) systems as alternative and effective approaches for treatment and reusing domestic sewage. The goal is to investigate the general performance of a membrane bioreactor and nanofilteration membrane ability to satisfy water reuse requirements using water quality index such as total suspended solids (TSS), chemical oxygen demand (COD), and ammonia (NH3). The findings show that the MBR system produces high-quality permeating water. TSS, COD and NH3 rejection rates were 99%, 90.3%, and 82.5% (on average). In addition, MBR technology is quite successful as a pre-NF treatment. We also evaluated how pressure and temperature affect the effectiveness of the NF membrane removal of TDS, COD, ammonia, and permeating flux. The results showed that the applied pressure has a favorable impact on the total removal rate; however, the feeding temperature has a negative impact. The feeding temperature, in addition to pressure, has a good influence on the flux of the NF system.

Performance assessment of the indigenous ceramic UF membrane in bioreactor process for highly polluted tannery wastewater treatment

The present study evaluates the performance of an indigenously developed ceramic ultrafiltration (UF) membrane in a lab-scale membrane bioreactor (MBR) process to treat real tannery effluent with varying organic loading (1500-6000mg/L). UF membrane was prepared by the coating of bentonite clay on tubular clay-alumina macroporous support. The membrane surface was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, BET adsorption-desorption, contact angle measurement, and atomic force microscopy. In the side-stream MBR process, sewage sludge from a local sewage treatment plant was used as an activated sludge source with a constant sludge retention time of 30days. Membrane filtration was performed in cross-flow mode using a single-channel membrane module. Artificial neural network (ANN) modeling tool was used to analyze the influence of various independent input variables, namely, the hydraulic retention time (4-10h), mixed liquor suspended solid (MLSS) concentration (2-8g/L), and influent COD concentration (1500-6000mg/L) on COD removal (%) with feed-forward backpropagation method. Membrane study was done at a transmembrane pressure of 4.3bar and feed flow rate of 7.5 L/min to observe the flux declination and fouling of the UF membrane with time. Average COD and BOD concentrations obtained in the treated effluent were 147.56 and 31mg/L, respectively, and chromium concentration was < 0.1mg/L; thus, treated effluent quality was found to be suitable for industrial recycling purposes apart from the safe environmental discharge. An in-depth study was undertaken to understand the removal mechanism in the MBR process, nature and extent of membrane fouling, changes in the morphology of the UF membrane, surface wettability, and surface topology by detailed surface characterization of the membrane pre- and post-filtration.

Performance assessment of a side-stream membrane bioreactor for the treatment of kitchen wastewater

Wastewater recovery from different sources is a prominent solution to the present water crisis. Membrane bioreactor (MBR) is one of the eminent separation processes to enable reusable water. Hence, the significance of the present study is to treat kitchen wastewater (KWW) by bioreactor integrated membrane processes. The in-situ microbial consortium prepared from the KWW was used in the bioreactor, which helped in degradation of the pollutants under continuous aeration. The indigenously synthesized nanofiltration (NF) membrane made of hydrophilized polyamide (HPA) was characterized by scanning electron microscopy (SEM), X-Ray Diffraction (XRD), and contact angle measurement to study crystalline nature, morphology, and hydrophilicity, respectively. From the experimental results, maximum water recovery and permeate flux of 82%, and 79 L/m2h were obtained through MBR at an optimum pressure of 10 kg/cm2 for 733 s, respectively. Significant reduction in impurities was observed, by removal of 97.6% chemical oxygen demand (COD), 93.7% total dissolved solids (TDS), 94.6% total suspended solids (TSS), and 98.5% turbidity, along with complete removal of color by integration of the bioreactor with NF process on the 12th day of operation. Further, the process was scaled-up to a pilot plant level, and a cost estimate for the production of reusable water is presented. The obtained water was found fit for reuse in various domestic applications, facilitating freshwater consumption and, therefore water conservation.

Fouling control of submerged and side-stream membrane bioreactors based on the statistical analysis of mid-term assays

The response surface methodology has been applied to study reversible and irreversible fouling rates caused by anaerobic sludge in membrane bioreactors, with the aim of controlling membrane fouling by adjusting filtration conditions. The challenge of obtaining statistically significant results of long-term fouling by means of mid-term assays has been addressed. The individual and combined effects of the filtration flux, backwashing intensity, gas sparging and crossflow velocity on membrane fouling, were analyzed in two types of membranes: an external tubular membrane and a submerged hollow fiber membrane. In the external membrane, the reversible fouling rate was as low as 0.27 ± 0.10 mbar/min, depending mainly on the filtration flux and gas sparging. However, the principal control parameter of the irreversible fouling rate was the crossflow velocity, reaching 2.12 ± 1.75 1012 m−2 in terms of increase of resistance per cubic meter filtered by square meter of membrane. In the submerged membrane, the irreversible fouling rate was quite lower, 0.78 ± 0.40 mbar/d, despite the reversible fouling rate was higher, 1.26 ± 0.42 mbar/min. In this case, the irreversible fouling depended mainly on the backwashing frequency despite the reversible fouling was more affected by the filtration flux and gas sparging. Hence, the approach used to control the reversible fouling rate does not involve mitigating irreversible fouling on both submerged and external membranes. This study provides a methodological basis for the selection of site-specific operating conditions, under which sustainable operation of membrane bioreactors could be achieved.

Research of operation efficiency of side-stream membrane bioreactors

Membrane bioreactors nowadays are intensively applied in wastewater treatment worldwide. Such type of treatment systems have a large scope of implementation at facilities of different capacity. A detailed study required to analyze how to implement reconstruction of WWTP by means of membrane equipment that can be located close to existing facilities of biological treatment in small containers without the installation of new capital containers is required. Following that goal there is a certain interest to investigate the operation of side-stream membrane bioreactors under various pressure conditions and to compare its corresponding efficiency and costs (capital and operation). The paper is focused on estimation of operation parameters (backwash frequency, power consumption and specific energy consumption) for three values (1,6 g/L, 2,5 g/L and 7 g/L) of mixed liquor suspended solids (MLSS) if the filtration goes under pressure of 0,5 bar.

Research of filtration and energy parameters of membrane bioreactors

Membrane bioreactors nowadays are intensively applied in wastewater treatment worldwide. The paper refers to a research, which goal was to evaluate the optimal parameters of membrane bioreactor performance. A focus was given to a part of the research that considered operation of side-stream membrane bioreactor under pressure of 0.2 MPa and variable amount of backwashes. There were three types of feed water investigated with mixed liquor suspended solids concentrations of 1.6, 2.5 and 7 g/L, respectively. The article provides results of permeate production and their processing to obtain specific energy consumption for each combination of operation parameters.

Human Adenovirus 40 Removal in Sidestream Membrane Bioreactor

AbstractThis preliminary study investigates how the removal of human adenovirus in a membrane bioreactor (MBR) depends on the MBR configuration. Results from a sidestream MBR (ssMBR) are compared w...

Development of graphene oxide/chitosan composite membrane on ceramic support for atrazine remediation by MBR process.

Graphene oxide (GO)-based composite ultrafiltration (UF) membranes were prepared on macroporous ceramic support tubes following a new way. Chitosan was used as an intermediate matrix between the substrate and GO coating. It has hydroxyl and amine groups, which enhances its film forming capacity with hydrophilic GO. This led us to use them as precursors for membrane development. Process efficiency of the prepared UF membrane was assessed in terms of the removal of toxic pesticide atrazine in side-stream membrane bioreactor (MBR) processes. Response surface methodology (RSM) was used to optimize the atrazine biodegradation efficiency. Enhanced atrazine removal of > 95% was obtained in the MBR treatment at the optimized conditions. Hermia's model equations were applied to analyze the mechanism of membrane fouling in the UF-MBR system. The influencing parameters were studied in details and pneumatic backpulsing was applied to minimize fouling in the UF-MBR system by statistical analysis. Mixed liquor suspended solids (MLSS) was found to affect both atrazine biodegradation and membrane fouling; hence, its effect was thoroughly analyzed. The developed process hence proved to be highly proficient in terms of such organic pesticides removal for long-term operations.

Organic Foulants Characteristics in Membrane Bioreactor

A laboratory scale side stream membrane bioreactor system with flat sheet membrane was operated for 5–days run at three different aeration rates (100, 200 and 300 L/h). The organic foulants deposited on the membrane surface was studied after extraction with 5% NaOH solution using three spectroscopic techniques. The IR spectra showed no distinct similarity in peaks among the three. The fluorescence spectra showed increase of soluble microbial products in foulant with decrease of aeration rate. This was supported by the size exclusion chromatography in which biopolymers concentration in fouling decreased with increasing aeration rate.

Application of compact sewage treatment technologies in Hong Kong

With the outcry for compact sewage treatment technologies in recent years, the Drainage Services Department of the HKSAR Government set up a pilot compact sewage treatment plant comprising a mechanical filter mesh and membrane bioreactors (MBRs) at the Shatin Sewage Treatment Works (STSTW) from July 2014 to September 2015 to acquire a better understanding of their performances with respect to the treatment capacity, ease of operation as well as maintenance and effluent quality. With calculations based on these well-informed assumptions, the footprint required for a mechanical filter mesh is about 1/8th of that of a conventional primary sedimentation tank. The pilot trial showed that the total suspended solid removal of the mechanical filter mesh installed was comparable to that of a primary sedimentation tank, and it could handle the diurnal peak loads and shock loads of the STSTW. With a deodorisation unit in place, the impact of odour nuisance was eliminated. As the mechanical filter mesh could effectively filter out hair and fibres, it could protect the downstream MBRs from fouling as well. For the two piloting MBRs, the immersed MBR was less sensitive to the operating mixed liquor suspended solids and had less downtime than the sidestream MBR. Meanwhile, less E.coli was detected in the permeate from the immersed MBR.

Comparison between mixed liquors of two side-stream membrane bioreactors treating wastewaters from waste management plants with high and low solids anaerobic digestion

In the last years, biological treatment plants for the previously separated organic fraction from municipal solid wastes (OFMSW) have gained importance. In these processes a liquid effluent (liquid fraction from the digestate and leachate from composting piles), which has to be treated previously to its discharge, is produced. In this paper, the characteristics of the mixed liquor from two full-scale membrane bioreactors treating the effluents of two OFMSW treatment plants have been evaluated in view to study their influence on membrane fouling in terms of filterability. For that, the mixed liquor samples have been ultrafiltrated in an UF laboratory plant. Besides, the effect of the influent characteristics to MBRs and the values of the chemical and physical parameters of the mixed liquors on the filterability have been studied. Results showed that the filterability of the mixed liquor was strongly influenced by the soluble microbial products in the mixed liquors and the influent characteristics to MBR. Permeate flux of MBR mixed liquor treating the most polluted wastewater was considerable the lowest (around 20 L/m2 h for some samples), what was explained by viscosity and soluble microbial products concentration higher than those measured in other MBR mixed liquor.

Performance evaluation of an side-stream anaerobic membrane bioreactor: Synthetic and alcoholic beverage industry wastewater

Performance evaluation of an side-stream anaerobic membrane bioreactor: Synthetic and alcoholic beverage industry wastewater

Nitrifying biomass characterization and monitoring during bioaugmentation in a membrane bioreactor

A membrane bioreactor (MBR), fed with domestic wastewater, was bioaugmented with nitrifying biomass selected in a side-stream MBR fed with a synthetic high nitrogen-loaded influent. Microbial communities evolution was monitored and comparatively analysed through an extensive bio-molecular investigation (16S rRNA gene library construction and terminal-restriction fragment length polymorphism techniques) followed by statistical analyses. As expected, a highly specialized nitrifying biomass was selected in the side-stream reactor fed with high-strength ammonia synthetic wastewater. The bioaugmentation process caused an increase of nitrifying bacteria of the genera Nitrosomonas (up to more than 30%) and Nitrobacter in the inoculated MBR reactor. The overall structure of the microbial community changed in the mainstream MBR as a result of bioaugmentation. The effect of bioaugmentation in the shift of the microbial community was also verified through statistical analysis.

Performance of commercial membranes in a side-stream and submerged membrane bioreactor for model textile wastewater treatment

Membrane bioreactor (MBR) is one of the last techniques that allow a high quality of treated industrial effluents, which can be perfectly integrated into industrial processes, not only for the quasi-total reuse of water but also for the reduction of the manufacturing cost. The main objective of this work was to make a study, comparing the performance of commercial membranes in a side stream membrane bioreactor (SSMBR) and submerged membrane bioreactor (SMBR), at laboratory scale, for the treatment of the same Model Textile Dye Wastewater (MTDW). In order to reach the target, we kept the same operating conditions for both of the units SSMBR and SMBR, namely pH, temperature, conductivity, and MLSS, whereas the hydraulic retention time (HRT) was different. This is due to the reactors capacities and the membrane module surface being different (20 L/0.00856 m2 and 57 L/0.33 m2) for side-stream and submerged MBR, respectively. The COD removal efficiency was varied between 90 and 97%, respectively, and color rejection was found in the range of 20–40% for red dye and 50–90% for blue dye in both units. In order to improve the wastewater quality, a nanofiltration membrane (NF) was tested in the SSMBR unit and still has to be tested in the SMBR.

Proteins causing membrane fouling in membrane bioreactors.

In this study, the details of proteins causing membrane fouling in membrane bioreactors (MBRs) treating real municipal wastewater were investigated. Two separate pilot-scale MBRs were continuously operated under significantly different operating conditions; one MBR was a submerged type whereas the other was a side-stream type. The submerged and side-stream MBRs were operated for 20 and 10 days, respectively. At the end of continuous operation, the foulants were extracted from the fouled membranes. The proteins contained in the extracted foulants were enriched by using the combination of crude concentration with an ultrafiltration membrane and trichloroacetic acid precipitation, and then separated by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). The N-terminal amino acid sequencing analysis of the proteins which formed intensive spots on the 2D-PAGE gels allowed us to partially identify one protein (OmpA family protein originated from genus Brevundimonas or Riemerella anatipestifer) from the foulant obtained from the submerged MBR, and two proteins (OprD and OprF originated from genus Pseudomonas) from that obtained from the side-stream MBR. Despite the significant difference in operating conditions of the two MBRs, all proteins identified in this study belong to β-barrel protein. These findings strongly suggest the importance of β-barrel proteins in developing membrane fouling in MBRs.

Development of a Comprehensive Fouling Model for a Rotating Membrane Bioreactor System Treating Wastewater

Membrane bioreactors (MBRs) are now main stream wastewater treatment technologies. In recent times, novel pressure driven rotating membrane disc modules have been specially developed that induce high shear on the membrane surface, thereby reducing fouling. Previous research has produced dead-end filtration fouling model which combines all three classical mechanisms that was later used by another researcher as a starting point for a greatly refined model of a cross flow side-stream MBR that incorporated both hydrodynamics and soluble microbial products’ (SMP) effects. In this study, a comprehensive fouling model was created based on this earlier work that incorporated all three classical fouling mechanisms for a rotating MBR system. It was tested and validated for best fit using appropriate data sets. The initial model fit appeared good for all simulations, although it still needs to be calibrated using further appropriate data sets.

Treatment of cosmetic wastewater by a full-scale membrane bioreactor (MBR).

This work evaluates the treatment of wastewater from a personal care products factory by a full-scale side-stream membrane bioreactor (MBR) intermittently fed. The wastewater contained particulate and soluble chemical oxygen demand (COD) which is partially removed by physicochemical pretreatment. Steady removal efficiencies above 98 % were achieved for BOD5, COD and suspended solids. Fats, oils and grease present in the raw wastewater were also successfully removed. The MBR was operated at an average permeate flux of 12 L/m2 · h (LMH) working at a transmembrane pressure of 272 ± 97 mbar. The soluble microbial products concentration remained fairly stable at 175 ± 25 and 85 ± 15 mg/L for proteins and carbohydrates, respectively. This maintained the filtration characteristics of the mixed liquor unaltered over a long-term basis, which was evidenced by a constant permeability of 43 ± 19 LMH/bar. Most of the trace organics detected in the wastewater were completely removed and only some fragrances were detected in the permeate at trace concentrations.