The substitution of sand filtration by immersed-UF for surface water treatment: pilot-scale studies

2009 ◽  
Vol 60 (9) ◽  
pp. 2337-2343
Author(s):  
Sun Lihua ◽  
Li Xing ◽  
Zhang Guoyu ◽  
Chen Jie ◽  
Xu Zhe ◽  
...  
Keyword(s):  
Membrane Fouling ◽  
Operating Cost ◽  
Pilot Scale ◽  
Permeate Flux ◽  
Sand Filtration ◽  
Chemical Cleaning ◽  
Aeration Intensity ◽  
Drinking Water Standard ◽  
Average Operating ◽  
Operational Processes

The newly issued National Drinking Water Standard required that turbidity should be lower than 1 NTU, and the substitution of sand filtration by immersed ultrafiltration (immersed-UF) is feasible to achieve the standard. This study aimed to optimise the operational processes (i.e. aeration, backwashing) through pilot scale studies, to control membrane fouling while treating the sedimentation effluent. Results indicated that the immersed-UF was promising to treat the sedimentation effluent. The turbidity was below 0.10 NTU, bacteria and E. coli were not detected in the permeate water. The intermittent filtration with aeration is beneficial to inhibit membrane fouling. The critical aeration intensity is observed to be 60.0 m3 m−2 h−1. At this aeration intensity, the decline rate of permeate flux in one period of backwashing was 1.94% and 7.03% for intermittent filtration and sustained filtration respectively. The different membrane backwashing methods (i.e. aeration 1.5 min, synchronous aeration and water backwashing 2 min, water backwashing 1.5 min; synchronous aeration and water backwashing 3 min, water backwashing 2 min; aeration 3 min, single water backwashing 2 min; synchronous aeration and water backwashing 5 min; single water backwashing 5 min) on the recovery of permeate flux were compared, indicating that the synchronous aeration and water backwashing exhibited best potential for permeate flux recovery. The optimal intensity of water backwashing is shown to be 90.0 L m−2 h−1. When the actual water intensity was below or exceeded the value, the recovery rate of permeate flux would be reduced. Additionally, the average operating cost for the immersed UF membrane, including the power, the chemical cleaning reagents, and membrane modules replacement, was about 0.31 RMB/m3.

scholarly journals Enhanced Removal of Organic Pollutants and Reactive Dye in Polyethersulfone Submerged Membrane Bioreactor (PES-SMBR) for Textile Wastewater

2021 ◽  
Vol 16 (1) ◽  
pp. 329-341
Author(s):  
Tukaram P. Chavan ◽  
Ganpat B. More ◽  
Sanjaykumar R. Thorat
Keyword(s):  
Membrane Fouling ◽  
Membrane Bioreactor ◽  
Textile Wastewater ◽  
Pilot Scale ◽  
Reactive Dye ◽  
Hollow Fibre ◽  
Flow Mode ◽  
Permeate Flux ◽  
Chemical Cleaning ◽  
Submerged Membrane Bioreactor

The present investigation was carried out to assess the operation of a pilot-scale submerged membrane bioreactor (SMBR) for the treatment of reactive dye and textile wastewater. The operation of SMBR model was conducted by using a polyethersulfone (PES) hollow fibre membrane with continuous flow mode at different HRTs at 8, 6 and 4 h, for 90 days. During the entire operation, the average permeate flux, TMP, F/M ratio and OLR was found to be 19 (L/m²/h), 2.6 (psi), 0.10 (g BOD/(g MLSS•d) and 0.89 (kg BOD/m³.d), respectively. The variations in the permeate flux, TMP, F/M ratio and OLR have not adversely effects on the operation of the SMBR model. Throughout the entire operation, despite the TP, TDS and conductivity, the high amount of COD (82%), BOD (86%), NO3-N (79%), TSS (98%), turbidity (97%) and colour (79%), removal was achieved. The permeate flux was declined by membrane fouling and it was recovered by chemical cleaning as well as regular backwashing during the entire operation. The results obtained from the study concluded that the hollow fibre ultrafiltration polyethersulfone (PES) membrane shows good performance while treating textile wastewater along with reactive dye solution.

scholarly journals Removal Characteristics of N-Nitrosamines and Their Precursors by Pilot-Scale Integrated Membrane Systems for Water Reuse

2018 ◽  
Vol 15 (9) ◽  
pp. 1960 ◽  
Author(s):  
Haruka Takeuchi ◽  
Naoyuki Yamashita ◽  
Norihide Nakada ◽  
Hiroaki Tanaka
Keyword(s):  
Membrane Fouling ◽  
Water Reuse ◽  
Pilot Scale ◽  
Feed Water ◽  
Water Reclamation ◽  
Size Distributions ◽  
Membrane Systems ◽  
Chemical Cleaning ◽  
Ro Membrane ◽  
Feed Water Temperature

This study investigated the removal characteristics of N-Nitrosamines and their precursors at three pilot-scale water reclamation plants. These plants applies different integrated membrane systems: (1) microfiltration (MF)/nanofiltration (NF)/reverse osmosis (RO) membrane; (2) sand filtration/three-stage RO; and (3) ultrafiltration (UF)/NF and UF/RO. Variable removal of N-Nitrosodimethylamine (NDMA) by the RO processes could be attributed to membrane fouling and the feed water temperature. The effect of membrane fouling on N-Nitrosamine removal was extensively evaluated at one of the plants by conducting one month of operation and chemical cleaning of the RO element. Membrane fouling enhanced N-Nitrosamine removal by the pilot-scale RO process. This finding contributes to better understanding of the variable removal of NDMA by RO processes. This study also investigated the removal characteristics of N-Nitrosamine precursors. The NF and RO processes greatly reduced NDMA formation potential (FP), but the UF process had little effect. The contributions of MF, NF, and RO processes for reducing FPs of NDMA, N-Nitrosopyrrolidine and N-Nitrosodiethylamine were different, suggesting different size distributions of their precursors.

Knowledge-based system for automatic MBR control

2010 ◽  
Vol 62 (12) ◽  
pp. 2829-2836 ◽  
Author(s):  
J. Comas ◽  
E. Meabe ◽  
L. Sancho ◽  
G. Ferrero ◽  
J. Sipma ◽  
...  
Keyword(s):  
Automatic Control ◽  
Flow Rate ◽  
Membrane Fouling ◽  
Deterministic Model ◽  
Permeate Flux ◽  
Chemical Cleaning ◽  
Control Module ◽  
Flow Rates ◽  
Knowledge Based ◽  
Operational Variables

MBR technology is currently challenging traditional wastewater treatment systems and is increasingly selected for WWTP upgrading. MBR systems typically are constructed on a smaller footprint, and provide superior treated water quality. However, the main drawback of MBR technology is that the permeability of membranes declines during filtration due to membrane fouling, which for a large part causes the high aeration requirements of an MBR to counteract this fouling phenomenon. Due to the complex and still unknown mechanisms of membrane fouling it is neither possible to describe clearly its development by means of a deterministic model, nor to control it with a purely mathematical law. Consequently the majority of MBR applications are controlled in an “open-loop” way i.e. with predefined and fixed air scour and filtration/relaxation or backwashing cycles, and scheduled inline or offline chemical cleaning as a preventive measure, without taking into account the real needs of membrane cleaning based on its filtration performance. However, existing theoretical and empirical knowledge about potential cause-effect relations between a number of factors (influent characteristics, biomass characteristics and operational conditions) and MBR operation can be used to build a knowledge-based decision support system (KB-DSS) for the automatic control of MBRs. This KB-DSS contains a knowledge-based control module, which, based on real time comparison of the current permeability trend with “reference trends”, aims at optimizing the operation and energy costs and decreasing fouling rates. In practice the automatic control system proposed regulates the set points of the key operational variables controlled in MBR systems (permeate flux, relaxation and backwash times, backwash flows and times, aeration flow rates, chemical cleaning frequency, waste sludge flow rate and recycle flow rates) and identifies its optimal value. This paper describes the concepts and the 3-level architecture of the knowledge-based DSS and details the knowledge-based control module. Preliminary results of the application of the control module to regulate the air flow rate of an MBR working with variable flux demonstrates the usefulness of this approach.

Comparative investigation on the impact of polymeric substances on membrane fouling during sub-critical and critical flux operation of a municipal membrane bioreactor

2008 ◽  
Vol 58 (9) ◽  
pp. 1849-1855 ◽  
Author(s):  
S. Lyko ◽  
T. Wintgens ◽  
T. Melin
Keyword(s):  
Membrane Fouling ◽  
Pilot Scale ◽  
Comparative Investigation ◽  
Hollow Fibre ◽  
Size Exclusion ◽  
Dominant Factor ◽  
Permeate Flux ◽  
Critical Flux ◽  
Operational Conditions ◽  
The Impact

Soluble organic macromolecules are ubiquitous in activated sludge supernatant. For the operation of membrane bioreactors (MBR) this group of substances is considered as the dominant factor causing severe membrane fouling due to the concentration polarisation phenomenon. The well established critical flux concept for the characterisation of membrane bioreactor's operation limits is based on filtration data only. As there is an cause-and-effect relation between the partial retention of organic compounds and the limited flux according the critical flux concept the aim of this study was to draw a comparison between different permeate fluxes on the retention of organic macromolecules. Thus, a municipal pilot-scale MBR with three capillary hollow fibre membrane modules was operated in sub critical, critical and supercritical flux mode, respectively and the retention of macromolecules was quantified by size exclusion chromatography. Three permeate extraction pumps allow a simultaneous operation with different operational conditions for each membrane module and proved the crucial impact of permeate flux on the fouling rate. The interchange of these conditions gave evidence of an optimised start-up procedure for MBRs characterised by higher permeate fluxes. An increased flux causes both a higher retention of soluble macromolecules and subsequent a higher fouling rate.

Pilot trial study of a compact macro-filtration membrane bioreactor process for saline wastewater treatment

2014 ◽  
Vol 70 (1) ◽  
pp. 120-126 ◽  
Author(s):  
Dao Guan ◽  
W. C. Fung ◽  
Frankie Lau ◽  
Chao Deng ◽  
Anthony Leung ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Membrane Fouling ◽  
Membrane Bioreactor ◽  
Treatment Process ◽  
Pilot Trial ◽  
Operating Cost ◽  
Oxygen Demand ◽  
Laser Scanning Microscopy ◽  
Permeate Flux ◽  
Saline Wastewater

Conventional membrane bioreactor (MBR) systems have increasingly been studied in recent decades. However, their applications have been limited due to their drawbacks such as low flux, membrane fouling, and high operating cost. In this study, a compact macro-filtration MBR (MfMBR) process was developed by using a large pore size membrane to mitigate the membrane fouling problem. A pilot trial of MfMBR process was set up and operated to treat 10 m3/day of saline wastewater within 4 h. The system was operated under an average permeate flux of 13.1 m3/(m2·day) for 74 days. The average total suspended solids, total chemical oxygen demand, biological oxygen demand, total Kjeldahl nitrogen, and total nitrogen removal efficiencies achieved were 94.3, 83.1, 98.0, 93.1, and 63.3%, respectively, during steady-state operation. The confocal laser scanning microscopy image indicated that the backwash could effectively remove the bio-cake and dead bacteria. Thus, the results showed that the MfMBR process, which is essentially a primary wastewater treatment process, had the potential to yield the same high quality effluent standards as the secondary treatment process; thereby suggesting that it could be used as an option when the economic budget and/or land space is limited.

Understanding membrane fouling: a review of over a decade of research

2003 ◽  
Vol 3 (5-6) ◽  
pp. 155-164 ◽  
Author(s):  
J.-M. Laîné ◽  
C. Campos ◽  
I. Baudin ◽  
M.-L. Janex
Keyword(s):  
Organic Matter ◽  
Natural Organic Matter ◽  
Membrane Fouling ◽  
Inorganic Compounds ◽  
Operating Cost ◽  
Hydraulic Performance ◽  
Polymeric Membranes ◽  
Permeate Flux ◽  
Competitive Price

Since the first membrane applications at the end of the 1980s, the water treatment engineering community has been able to develop reliable low pressure membrane systems that are capable of producing high quality drinking water at a competitive price, making membrane technology an attractive solution to both upgrade existing plants and design new ones. A competitive price means low capital and operating cost, which are inversely proportional to membrane hydraulic performance (permeate flux). Porous membranes lose their hydraulic performance as materials accumulate on their surfaces and/or within their pores, a process called membrane fouling. Although a significant effort has been devoted to elucidating the fouling mechanisms of polymeric membranes by natural organic matter (NOM), no single model has yet been accepted. In fact, most of the existing literature is contradictory, showing that membrane fouling is far from being fully understood. This article reviews over a decade of Ondeo's experience on characterizing and preventing fouling of polymeric membranes by natural organic matter and inorganic compounds. The review focuses on the role of NOM size and hydrophobicity, of membrane chemistry, and of solution pretreatment (coagulation and/or adsorption). In addition, the efficacy of some currently used strategies to minimize membrane fouling is also discussed.

scholarly journals Membrane surface properties and their effects on real waste oil-in-water emulsion ultrafiltration

Water SA ◽  
2019 ◽  
Vol 45 (3 July) ◽  
Author(s):  
Marjana Simonič
Keyword(s):  
Surface Properties ◽  
Membrane Fouling ◽  
Membrane Surface ◽  
Cross Flow ◽  
Influential Factors ◽  
Permeate Flux ◽  
Chemical Cleaning ◽  
Water Emulsion ◽  
Oil In Water ◽  
Oil In Water Emulsion

Membrane surface properties and their effect on the efficiency of ultrafiltration (UF) of real waste oily emulsions was studied. Experiments were performed in cross-flow operation at total recycle condition in a lab-scale system. The ceramic UF membrane in the tubular type module was employed. During the experiments permeate flux was measured. The most important influential factors, such as temperature, TMP, and pH, were considered during the experiments. Zeta potential was measured in order to explain the phenomena on the membrane surface. The isoelectric point of the fouled membrane was shifted to the alkaline range. COD removal efficiency reached 89%. Gas chromatography measurements were performed in order to determine the composition of waste emulsions. SEM micrographs showed the formation of calcite on the membrane, which contributed to membrane fouling. Chemical cleaning was examined using alkaline and acid solutions, and a cleaning strategy was determined.

Pilot-plant study of a high recovery membrane filtration process for drinking water treatment

2000 ◽  
Vol 41 (10-11) ◽  
pp. 77-84 ◽  
Author(s):  
J.Y. Huang ◽  
S. Takizawa ◽  
K. Fujita
Keyword(s):  
Membrane Fouling ◽  
Membrane Filtration ◽  
Cross Flow ◽  
Drinking Water Treatment ◽  
Pilot Scale ◽  
Raw Water ◽  
Circulation Flow ◽  
High Recovery ◽  
Chemical Cleaning ◽  
Cross Flow Filtration

Successful application of energy efficient dead-end micro-filtration (MF), which does not require recirculation like cross-flow filtration, depends on achieving high recovery rates. In this study, two different types of pilot scale membrane systems (horizontally and vertically stretched membrane filters) were evaluated based on the effects of pre-chlorination, intermittent chlorination and circulation flow by air-scrubbing. Additionally, the effects of operating factors including physical cleaning and chemical cleaning on membrane fouling were examined. The vertically stretched membranes showed better performance than horizontally stretched membranes at filtration fluxes of either 0.55 m/day or 0.78 m/day even under 2.6 to 27.5°C and raw water turbidity higher than 300 units, as long as intermittent chlorination (10 mg/l once a week) along with the circulation flow by air-scrubbing (once in 30 minutes) in the housing were employed. It was demonstrated that the vertically stretched membranes have been operated for one year without chemical cleaning of the membranes, wherein the recovery of raw water as a filtrate was 97.0% or 98.9%.

scholarly journals Textile Wastewater Treatment for Water Reuse: A Case Study

Processes ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 34 ◽  
Author(s):  
Hua Yin ◽  
Peiwen Qiu ◽  
Yuange Qian ◽  
Zhuwen Kong ◽  
Xiaolong Zheng ◽  
...  
Keyword(s):  
Textile Industry ◽  
Water Reuse ◽  
Natural Waters ◽  
Removal Rate ◽  
Operating Cost ◽  
Textile Wastewater ◽  
Color Removal ◽  
Combined Processes ◽  
Sand Filtration ◽  
Drinking Water Standard

The reduced natural waters and the large amount of wastewater produced by textile industry necessitate an effective water reuse treatment. In this study, a combined two-stage water reuse treatment was established to enhance the quality and recovery rate of reused water. The primary treatment incorporated a flocculation and sedimentation system, two sand filtration units, an ozonation unit, an ultrafiltration (UF) system, and a reverse osmosis (RO) system. The second treatment included an ozonation unit, a sand filtration unit, and UF and RO systems. The color removal rate increased with the increasing ozone dosage, and the relational expression between the ozone dosage and color removal rate was fitted. Ozonation greatly reduced the color by 92.59 and 97.27 times during the primary and second ozonation stages, respectively. RO had the highest removal rate. The combined processes showed good performance in water reuse treatment. The treated, reused water satisfied the reuse standard and surpassed the drinking water standard rates for chemical oxygen consumption (CODcr), color, NH3-N, hardness, Cl−, SO42−, turbidity, Fe3+, and Cu2+. The operating cost of reuse water treatment was approximately 0.44 USD·m−3.

scholarly journals Membrane cleaning in membrane distillation of reverse osmosis concentrate generated in landfill leachate treatment

2021 ◽  
Author(s):  
Xiaolin Jia ◽  
Kuiling Li ◽  
Baoqiang Wang ◽  
ZhiChao Zhao ◽  
Deyin Hou ◽  
...  
Keyword(s):  
Reverse Osmosis ◽  
Landfill Leachate ◽  
Membrane Fouling ◽  
Membrane Distillation ◽  
Water Recovery ◽  
Permeate Flux ◽  
Chemical Cleaning ◽  
Leachate Treatment ◽  
Membrane Cleaning ◽  
Cleaning Methods

Abstract As a thermally induced membrane separation process, membrane distillation (MD) has drawn more and more attention for the advantages of treating hypersaline wastewaters, especially the concentrate from reverse osmosis (RO) process. One of the major obstacles in widespread MD application is the membrane fouling. We investigated the feasibility of direct contact membrane distillation (DCMD) for landfill leachate reverse osmosis concentrate (LFLRO) brine treatment and systematically assessed the efficiency of chemical cleaning for DCMD after processing LFLRO brine. The results showed that 80% water recovery rate was achieved when processing the LFLRO brine by DCMD, but the membrane fouling occurred during the DCMD process, and manifested as the decreasing of permeate flux and the increasing of permeate conductivity. Analysis revealed that the serious flux reduction was primarily caused by the fouling layer that consist of organic matters and inorganic salts. Five cleaning methods were investigated for membrane cleaning, including hydrogen chloride (HCl)-sodium hydroxide (NaOH), ethylene diamine tetraacetic acid (EDTA)-NaOH, critic acid, sodium hypochlorite (NaClO) and sodium dodecyl sulphate (SDS) cleaning. Among the chemical cleaning methods investigated, the 3 wt.% SDS cleaning showed the best efficiency at recovering the performance of fouled membranes.

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