scholarly journals Characterization of the Fouling Layer on the Membrane Surface in a Membrane Bioreactor: Evolution of the Foulants’ Composition and Aggregation Ability

Membranes ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 85 ◽  
Author(s):  
Linlin Yan ◽  
Ruixue Li ◽  
Yu Song ◽  
Yanping Jia ◽  
Zheng Li ◽  
...  
Keyword(s):  
Membrane Fouling ◽  
Membrane Bioreactor ◽  
Extracellular Polymeric Substances ◽  
Membrane Surface ◽  
Extracellular Dna ◽  
Transmembrane Pressure ◽  
Average Roughness ◽  
Three Stages ◽  
Fast Rise

In this study, the characteristics of membrane foulants were analyzed with regard to morphology, composition, and aggregation ability during the three stages of transmembrane pressure (TMP) development (fast–slow–fast rise in TMP) in a steady operational membrane bioreactor (MBR). The results obtained show that the fouling layer at the slow TMP-increase stage possessed a higher average roughness (71.27 nm) and increased fractal dimension (2.33), which resulted in a low membrane fouling rate (0.87 kPa/d). A higher extracellular DNA (eDNA) proportion (26.12%) in the extracellular polymeric substances (EPS) resulted in both higher zeta potential (-23.3 mV) and higher hydrophobicity (82.3%) for initial foulants, which induced and increased the protein proportion in the subsequent fouling layer (74.11%). Furthermore, the main composition of the EPS shifted from protein toward polysaccharide dominance in the final fouling layer. The aggregation test confirmed that eDNA was essential for foulant aggregation in the initial fouling layer, whereas ion interaction significantly affected foulant aggregation in the final fouling layer.

scholarly journals Biomass Characteristics and Their Effect on Membrane Bioreactor Fouling

Molecules ◽  
2019 ◽  
Vol 24 (16) ◽  
pp. 2867 ◽  
Author(s):  
Petros K. Gkotsis ◽  
Anastasios I. Zouboulis
Keyword(s):  
Membrane Fouling ◽  
Membrane Bioreactor ◽  
Suspended Solids ◽  
Extracellular Polymeric Substances ◽  
Membrane Surface ◽  
Membrane Resistance ◽  
Soluble Microbial Products ◽  
Gelling Properties ◽  
Microbial Products ◽  
Soluble Part

Biomass characteristics are regarded as particularly influential for fouling in Membrane Bio-Reactors (MBRs). They primarily include the Mixed Liquor Suspended Solids (MLSS), the colloids and the Extracellular Polymeric Substances (EPS). Among them, the soluble part of EPS, which is also known as Soluble Microbial Products (SMP), is the most significant foulant, i.e., it is principally responsible for membrane fouling and affects all fundamental fouling indices, such as the Trans-Membrane Pressure (TMP) and the membrane resistance and permeability. Recent research in the field of MBRs, tends to consider the carbohydrate fraction of SMP (SMPc) the most important characteristic for fouling, mainly due to the hydrophilic and gelling properties, which are exhibited by polysaccharides and allow them to be easily attached on the membrane surface. Other wastewater and biomass characteristics, which affect indirectly membrane fouling, include temperature, viscosity, dissolved oxygen (DO), foaming, hydrophobicity and surface charge. The main methods employed for the characterization and assessment of biomass quality, in terms of filterability and fouling potential, can be divided into direct (such as FDT, SFI, TTF100, MFI, DFCM) or indirect (such as CST, TOC, PSA, RH) methods, and they are shortly presented in this review.

Electrically enhanced MBR system for total nutrient removal in remote northern applications

2012 ◽  
Vol 65 (4) ◽  
pp. 737-742 ◽  
Author(s):  
V. Wei ◽  
M. Elektorowicz ◽  
J. A. Oleszkiewicz
Keyword(s):  
Wastewater Treatment ◽  
Nutrient Removal ◽  
Membrane Fouling ◽  
Membrane Bioreactor ◽  
Extracellular Polymeric Substances ◽  
Climatic Conditions ◽  
Transmembrane Pressure ◽  
Treatment Technology ◽  
Electrically Enhanced ◽  
P Removal

Thousands of sparsely populated communities scatter in the remote areas of northern Canada. It is economically preferable to adopt the decentralized systems to treat the domestic wastewater because of the vast human inhabitant distribution and cold climatic conditions. Electro-technologies such as electrofiltration, elctrofloatation, electrocoagulation and electrokinetic separation have been applied in water and conventional wastewater treatment for decades due to the minimum requirements of chemicals as well as ease of operation. The membrane bioreactor (MBR) is gaining popularity in recent years as an alternative water/wastewater treatment technology. However, few studies have been conducted to hyphenate these two technologies. The purpose of this work is to design a novel electrically enhanced membrane bioreactor (EMBR) as an alternative decentralized wastewater treatment system with improved nutrient removal and reduced membrane fouling. Two identical submerged membranes (GE ZW-1 hollow fiber module) were used for the experiment, with one as a control. The EMBR and control MBR were operated for 4 months at room temperature (20 ± 2 °C) with synthetic feed and 2 months at 10 °C with real sewage. The following results were observed: (1) the transmembrane pressure (TMP) increased significantly more slowly in the EMBR and the interval between the cleaning cycles of the EMBR increased at least twice; (2) the dissolved chemical oxygen demand (COD) or total organic carbon (TOC) in the EMBR biomass was reduced from 30 to 51%, correspondingly, concentrations of the extracellular polymeric substances (EPS), the major suspicious membrane foulants, decreased by 26–46% in the EMBR; (3) both control and EMBR removed >99% of ammonium-N and >95% of dissolved COD, in addition, ortho-P removal in the EMBR was >90%, compared with 47–61% of ortho-P removal in the MBR; and (4) the advantage of the EMBR over the conventional MBR in terms of membrane fouling retardation and phosphorus removal was further demonstrated at an operating temperature of 10 °C when fed with real sewage. The EMBR system has the potential for highly automated control and minimal maintenance, which is particularly suitable for remote northern applications.

scholarly journals Mechanism of Membrane Fouling Control by HMBR: Effect of Microbial Community on EPS

2020 ◽  
Vol 17 (5) ◽  
pp. 1681
Author(s):  
Qiang Liu ◽  
Ying Yao ◽  
Delan Xu
Keyword(s):  
Microbial Community ◽  
Membrane Fouling ◽  
Membrane Bioreactor ◽  
Extracellular Polymeric Substances ◽  
Microbial Community Composition ◽  
Domestic Wastewater ◽  
Control Group ◽  
Transmembrane Pressure ◽  
Fouling Control ◽  
Cake Layer

A hybrid membrane bioreactor (HMBR) employing activated sludge and biofilm simultaneously is proved to represent a good performance on membrane fouling control compared to conventional membrane bioreactor (CMBR) by reducing extracellular polymeric substances (EPS), especially bound EPS (B-EPS). In order to better understand the mechanism of membrane fouling control by the HMBR in regard of microbial community composition, a pilot scale HMBR operated to treat domestic wastewater for six months, and a CMBR operated at the same time as control group. Results showed that HMBR can effectively control membrane fouling. When transmembrane pressure reached 0.1 MPa, the membrane module in the HMBR operated for about 26.7% longer than that in the CMBR. In the HMBR, the quantity of EPS was significantly lower than that in the CMBR. In this paper, soluble EPS was also found to have a close relationship with cake layer resistance. The species richness and diversity in the HMBR were higher than those in the CMBR, and a certain difference between the compositions of microbial communities in the two reactors was confirmed. Therefore, the difference in microbial community compositions may be the direct reason why EPS in the HMBR was lower than that in the CMBR.

A venturi device reduces membrane fouling in a submerged membrane bioreactor

2016 ◽  
Vol 74 (1) ◽  
pp. 147-156 ◽  
Author(s):  
Necati Kayaalp ◽  
Gokmen Ozturkmen
Keyword(s):  
Membrane Fouling ◽  
Membrane Bioreactor ◽  
Membrane Surface ◽  
Oxygen Transfer Rate ◽  
Surface Cleaning ◽  
Aeration Rate ◽  
Transmembrane Pressure ◽  
Submerged Membrane Bioreactor ◽  
System A ◽  
Do Concentration

In this study, for the first time, a venturi device was integrated into a submerged membrane bioreactor (MBR) to improve membrane surface cleaning and bioreactor oxygenation. The performances of a blower and the venturi device were compared in terms of membrane fouling and bioreactor oxygenation. Upon comparing membrane fouling, the performances were similar for a low operation flux (18 L/m2.h); however, at a medium flux (32 L/m2.h), the venturi system operated 3.4 times longer than the blower system, and the final transmembrane pressure was one-third that of the blower system. At the highest flux studied (50 L/m2.h), the venturi system operated 5.4 times longer than the blower system. The most notable advantage of using a venturi device was that the dissolved oxygen (DO) concentration of the MBR was in the range of 7 to 8 mg/L at a 3 L/min aeration rate, while the DO concentration of the MBR was inadequate (a maximum of 0.29 mg/L) in the blower system. A clean water oxygenation test at a 3 L/min aeration rate indicated that the standard oxygen transfer rate for the venturi system was 9.5 times higher than that of the blower system.

scholarly journals Nutrients Enrichment and Process Repercussions in Hybrid Microfiltration Osmotic Membrane Bioreactor: A Guideline for Forward Osmosis Development Based on Lab-Scale Experience

Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 1098
Author(s):  
Khum Gurung ◽  
Morten Lykkegaard Christensen ◽  
Mika Sillanpää ◽  
Mohamed Chaker Ncibi ◽  
Mads Koustrup Jørgensen
Keyword(s):  
Water Permeability ◽  
Membrane Fouling ◽  
Membrane Bioreactor ◽  
Extracellular Polymeric Substances ◽  
Forward Osmosis ◽  
Microbial Inactivation ◽  
Transmembrane Pressure ◽  
Pressure Step ◽  
Draw Solution ◽  
Osmotic Membrane Bioreactor

The effects of reverse salt diffusion through a forward osmosis membrane were studied in a microfiltration osmotic membrane bioreactor. The reactor was used to treat and simultaneously concentrate nutrients from wastewater. The system was operated at different draw solution concentrations, leading to varying salinity conditions. A relatively low, yet stable forward osmosis flux was observed regardless of increasing draw solution conductivities from 10 to 50 mS cm−1. A substantial increase in sludge conductivity from 5.7 to 19.8 mS cm−1 was observed during the operation. Batch transmembrane pressure-step experiments showed a decline in sludge filtration properties with increasing salinity buildup in sludge due to increasing deflocculation and associated release of protein and carbohydrate fractions of extracellular polymeric substances. Mathematical simulations showed that accumulation of total dissolved solids could mainly be attributed to reverse flux of salts from the draw solution rather than by the enrichment of incoming nutrients when forward osmosis membrane’s salt permeability was high and water permeability low. Ideally, salt permeability below 0.010 L m−2 h−1 and effective water permeability above 0.13 L m−2 h−1 bar−1 are crucial to ensure enhanced nutrient enrichment and reduce sludge osmotic pressure, microbial inactivation, sludge deflocculation and membrane fouling.

Identification of the effect of extracellular polymeric substances on bacterial adhesion to the membrane surface in a membrane bioreactor using Pseudomonas fluorescens

2007 ◽  
Vol 55 (1-2) ◽  
pp. 35-42 ◽  
Author(s):  
Y. Yeo ◽  
N. Jang ◽  
J. Cho ◽  
K.-S. Kim ◽  
I.S. Kim
Keyword(s):  
Pseudomonas Fluorescens ◽  
Membrane Fouling ◽  
Bacterial Adhesion ◽  
Membrane Bioreactor ◽  
Extracellular Polymeric Substances ◽  
Municipal Wastewater ◽  
Membrane Surface ◽  
Municipal Wastewater Treatment ◽  
Wastewater Treatment Process ◽  
Specific Cake Resistance

In a membrane bioreactor (MBR) process containing a variety of bacteria, the bacterial adhesion to the membrane surface, prior to cake formation, causes an increased filtration resistance. In this study, Pseudomonas fluorescens, commonly found in the municipal wastewater treatment process with activated sludge, was used to show the effects of extracellular polymeric substances (EPS) on bacterial adhesion to the membrane surface in the MBR. Of the various roles of EPS in promoting membrane fouling, the adhesion of bacteria to the membrane surface was calculated using the specific cake resistance (α, m/kg). Although the amount of EPS binding with bacteria was increased by the addition of Ca2 + , there was no significant effect on the bacterial growth. The results of the particle size distribution showed that the addition of Ca2 +  increased flocculation, allowing the formation of a complex with the bacteria and EPS. In order to identify the effects of the addition of Ca2 +  on the hydrophobicity, the contact angle was also measured. The result showed that the addition of Ca2 +  showed no significant differences in the hydrophobicity, even though there was an increase in flocculation. With the bacteria containing a higher EPS concentration, a higher specific cake resistance was observed. From the results of the adhesion experiment, which was conducted with various EPS levels, displayed as the COD and TOC concentration, an increased EPS concentration was shown to promote bacterial adhesion to the membrane surface.

Effect of a suspended carrier on membrane fouling in a submerged membrane bioreactor

2006 ◽  
Vol 53 (6) ◽  
pp. 211-220 ◽  
Author(s):  
Chun-Hai Wei ◽  
Xia Huang ◽  
Cheng-Wen Wang ◽  
Xiang-Hua Wen
Keyword(s):  
Membrane Fouling ◽  
Membrane Bioreactor ◽  
Membrane Surface ◽  
Transmembrane Pressure ◽  
Fouling Control ◽  
Submerged Membrane Bioreactor ◽  
Negative Effect ◽  
Sludge Particle ◽  
Carrier Volume ◽  
Suspended Carrier

In an attempt at membrane fouling control, a kind of cylindrical plastic suspended carrier was added in a submerged membrane bioreactor (SMBR) and its effect was investigated in this study. According to the transmembrane pressure (TMP) profiles and the sludge characteristics in comparative runs with and without suspended carriers, it was found that the suspended carriers added in SMBR had two effects on membrane fouling: one was the positive effect of mechanically scouring the membrane surface and the other was the negative effect of breaking up sludge flocs. Sludge particle size distribution change was mainly responsible. It was suggested to apply the suspended carrier at higher MLSS concentration and lower carrier dose based on the consideration for retarding sludge breakage caused by the carrier. The experiment was conducted under higher MLSS (8 g L−1) and lower carrier dose (carrier volume/total volume = 1%). The TMP increase was effectively retarded by added suspended carriers compared to the system without addition of the carriers. The effect of suspended carriers on membrane fouling at high MLSS concentration was verified.

scholarly journals Pilot Study on the Combination of Different Pre-Treatments with Nanofiltration for Efficiently Restraining Membrane Fouling While Providing High-Quality Drinking Water

Membranes ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 380
Author(s):  
Yan Chen ◽  
Huiping Li ◽  
Weihai Pang ◽  
Baiqin Zhou ◽  
Tian Li ◽  
...  
Keyword(s):  
Drinking Water ◽  
Activated Carbon ◽  
Membrane Fouling ◽  
Membrane Surface ◽  
Post Treatment ◽  
Size Exclusion ◽  
Transmembrane Pressure ◽  
Feed Water ◽  
High Quality ◽  
Treated Water

Nanofiltration (NF) is a promising post-treatment technology for providing high-quality drinking water. However, membrane fouling remains a challenge to long-term NF in providing high-quality drinking water. Herein, we found that coupling pre-treatments (sand filtration (SF) and ozone–biological activated carbon (O3-BAC)) and NF is a potent tactic against membrane fouling while achieving high-quality drinking water. The pilot results showed that using SF+O3-BAC pre-treated water as the feed water resulted in a lower but a slowly rising transmembrane pressure (TMP) in NF post-treatment, whereas an opposite observation was found when using SF pre-treated water as the feed water. High-performance size-exclusion chromatography (HPSEC) and three-dimensional excitation–emission matrix (3D-EEM) fluorescence spectroscopy determined that the O3-BAC process changed the characteristic of dissolved organic matter (DOM), probably by removing the DOM of lower apparent molecular weight (LMW) and decreasing the biodegradability of water. Moreover, amino acids and tyrosine-like substances which were significantly related to medium and small molecule organics were found as the key foulants to membrane fouling. In addition, the accumulation of powdered activated carbon in O3-BAC pre-treated water on the membrane surface could be the key reason protecting the NF membrane from fouling.

Investigation of long-term operation and biomass activity in a membrane bioreactor system

2011 ◽  
Vol 63 (9) ◽  
pp. 1906-1912 ◽  
Author(s):  
Simos Malamis ◽  
Andreas Andreadakis ◽  
Daniel Mamais ◽  
Constantinos Noutsopoulos
Keyword(s):  
Membrane Fouling ◽  
Membrane Bioreactor ◽  
Extracellular Polymeric Substances ◽  
Operating Conditions ◽  
Term Operation ◽  
Solids Retention ◽  
Biomass Activity ◽  
Long Term Performance ◽  
Term Performance

The aim of this work was to evaluate the long-term performance of a Membrane Bioreactor (MBR) that operated continuously for 2.5 years and to assess membrane fouling and biomass activity under various operating conditions. Furthermore, a method for the characterisation of influent wastewater was developed based on its separation into various fractions. The MBR system operated at the solids retention times (SRT) of 10, 15, 20 and 33 days. The increase of SRT resulted in a decrease of the fouling rate associated with the reduction of extracellular polymeric substances. Moreover, the SRT increase resulted in a significant reduction of the Oxygen Uptake Rate (OUR) due to the lower availability of substrate and in a notable decrease of the maximum OUR since high SRT allowed the development of slower growing microorganisms. Biomass consisted of small flocs due to extensive deflocculation caused by intense aeration. Finally, the method developed for wastewater characterisation is straightforward and less time consuming than the usual method that is employed.

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