scholarly journals Forward osmosis membrane fouling and cleaning for wastewater reuse

2016 ◽  
Vol 7 (2) ◽  
pp. 111-120 ◽  
Author(s):  
Youngbeom Yu ◽  
Seockheon Lee ◽  
Sung Kyu Maeng
Keyword(s):  
Activated Sludge ◽  
Flow Velocity ◽  
Membrane Fouling ◽  
Suspended Solids ◽  
Wastewater Reuse ◽  
Forward Osmosis ◽  
Cross Flow ◽  
Short Period ◽  
Cross Flow Velocity ◽  
Cleaning Methods

Membrane fouling properties and different physical cleaning methods for forward osmosis (FO) and reverse osmosis (RO) laboratory-scale filtration systems were investigated. The membrane fouling, with respect to flux reduction, was lower in FO than in RO when testing an activated sludge effluent. Cross-flow velocity, air-scouring, osmotic backwashing and effect of a spacer were compared to determine the most effective cleaning method for FO. After a long period of fouling with activated sludge, the flux was fully recovered in a short period of osmotic backwashing compared with cleaning by changing cross-flow velocity and air-scouring. In this study, the osmotic backwashing was found to be the most efficient way to clean the FO membrane. The amount of RNA recovered from FO membranes was about twice that for RO membranes; biofouling could be more significant in FO than in RO. However, the membrane fouling in FO was lower than that in RO. The spacer increased the flux in FO with activated sludge liquor suspended solids of 2,500 mg/L, and there were effects of spacer on performance of FO–MBR membrane fouling. However, further studies are required to determine how the spacer geometry influences on the performance of the FO membrane.

Parametric Study of Ultrafiltration

2009 ◽  
Author(s):  
Nina Zhou ◽  
A. G. Agwu Nnanna
Keyword(s):  
Flow Velocity ◽  
Suspended Solids ◽  
Cross Flow ◽  
Transmembrane Pressure ◽  
High Flux ◽  
Permeate Flux ◽  
Membrane Performance ◽  
Cross Flow Velocity ◽  
High Concentrations ◽  
Cleaning Methods

The performance of cross flow hollow fiber ultrafiltration (UF) membrane with molecular weight cut off (MWCO) 100 kDaltons was studied in order to effectively remove suspended solids in wastewater. Experiments were carried out to investigate the influence of the several factors such as cross flow velocity, transmembrane pressure (TMP), water temperature, and concentration of suspended solids on the membrane performance. Several cleaning methods were applied to remove the fouling. The experimental results showed that increasing TMP, temperature and cross flow velocity all resulted in increasing permeate flux. It is observed that high TMP aggravated the fouling while high cross flow velocity alleviated the fouling. High concentrations of suspended solids led to the reduction of permeate flux. It is also found that both combination of chemical, back- and forward-washing as well as soaking cleaning methods effectively removed fouling and achieved high flux recovery. The suspended solids were effectively removed by our UF system, and the water quality is significantly improved after ultrafiltration.

scholarly journals Biofouling Mitigation Approaches during Water Recovery from Fermented Broth via Forward Osmosis

Membranes ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 307
Author(s):  
Stavros Kalafatakis ◽  
Agata Zarebska ◽  
Lene Lange ◽  
Claus Hélix-Nielsen ◽  
Ioannis V. Skiadas ◽  
...  
Keyword(s):  
Flow Velocity ◽  
Forward Osmosis ◽  
Cross Flow ◽  
Feed Solution ◽  
Mitigation Strategies ◽  
Water Recovery ◽  
Operational Parameters ◽  
Solution Ph ◽  
Sustainable Solutions ◽  
Cross Flow Velocity

Forward Osmosis (FO) is a promising technology that can offer sustainable solutions in the biorefinery wastewater and desalination fields, via low energy water recovery. However, microbial biomass and organic matter accumulation on membrane surfaces can hinder the water recovery and potentially lead to total membrane blockage. Biofouling development is a rather complex process and can be affected by several factors such as nutrient availability, chemical composition of the solutions, and hydrodynamic conditions. Therefore, operational parameters like cross-flow velocity and pH of the filtration solution have been proposed as effective biofouling mitigation strategies. Nevertheless, most of the studies have been conducted with the use of rather simple solutions. As a result, biofouling mitigation practices based on such studies might not be as effective when applying complex industrial mixtures. In the present study, the effect of cross-flow velocity, pH, and cell concentration of the feed solution was investigated, with the use of complex solutions during FO separation. Specifically, fermentation effluent and crude glycerol were used as a feed and draw solution, respectively, with the purpose of recirculating water by using FO alone. The effect of the abovementioned parameters on (i) ATP accumulation, (ii) organic foulant deposition, (iii) total water recovery, (iv) reverse glycerol flux, and (v) process butanol rejection has been studied. The main findings of the present study suggest that significant reduction of biofouling can be achieved as a combined effect of high-cross flow velocity and low feed solution pH. Furthermore, cell removal from the feed solution prior filtration may further assist the reduction of membrane blockage. These results may shed light on the challenging, but promising field of FO process dealing with complex industrial solutions.

scholarly journals Behaviour of Aquaporin Forward Osmosis Flat Sheet Membranes during the Concentration of Calcium-Containing Liquids

Membranes ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 108
Author(s):  
Alibek Omir ◽  
Aliya Satayeva ◽  
Aigerim Chinakulova ◽  
Arailym Kamal ◽  
Jong Kim ◽  
...  
Keyword(s):  
Flow Velocity ◽  
Saturation Index ◽  
Membrane Surface ◽  
Water Flux ◽  
Forward Osmosis ◽  
Cross Flow ◽  
Calcium Sulphate ◽  
Attenuated Total Reflection ◽  
Flat Sheet ◽  
Cross Flow Velocity

This study aims to examine the scaling and performance of flat sheet aquaporin FO membranes in the presence of calcium salts. Experiments showed that the application of calcium sulphate (CaSO4) resulted in an 8–78% decline in the water flux. An increase in the cross-flow velocity from 3 to 12 cm/s reduced the decline in the flux by 16%. The deposition of salt crystals on the membrane surface led to the alteration in the membrane’s intrinsic properties. Microscopy, attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy, and X-Ray fluorescence (XRF) analyses confirmed measurements of the zeta potential and contact angle. The use of a three-salt mixture yielded severe scaling as compared with the application of calcium sulphate dehydrate (CaSO4 × 2H2O), i.e., a result of two different crystallisation mechanisms. We found that the amount of sodium chloride (NaCl), saturation index, cross-flow velocity, and flow regime all play an important role in the scaling of aquaporin FO flat sheet membranes.

Optimal Fiber Spacing in Externally Pressurized Hollow Fiber Module for Solid Liquid Separation

1992 ◽  
Vol 26 (5-6) ◽  
pp. 1245-1254 ◽  
Author(s):  
W. Y. Kiat ◽  
K. Yamamoto ◽  
S. Ohgaki
Keyword(s):  
Activated Sludge ◽  
Flow Velocity ◽  
Hollow Fiber ◽  
Packing Density ◽  
Cross Flow ◽  
Kaolin Clay ◽  
Flux Decline ◽  
Fiber Packing Density ◽  
Cross Flow Velocity ◽  
Clay Suspensions

Flux decline and clogging mechanism in hollow fiber bundle by activated sludge and kaolin clay suspensions were investigated experimentally. Filtration characteristics of hollow fiber bundles consisting of 10 fiber threads but different in packing density were observed. The main reason for severe flux decline was due to the accumulation of particles at the space in between fibers. The results showed that there was no particle accumulation when fiber packing density β was lower than a critical value βa. Maximum filtration flux and maximum membrane productivity Q/Vr,which is defined as the filtration rate per unit volume of bundle, were obtained below and at this point, respectively. When fiber packing density β was increased, accumulation of particles happened and flux declined rapidly to a minimum, then increased to a maximum and then decreased when surface clogging predominated in the case of activated sludge filtration, but remained almost constant for the case of kaolin clay suspensions. The critical point where accumulation of particles started was related to cross flow velocity. The higher the cross flow velocity, the higher the value of βa obtained.

scholarly journals DETERMINATION OF FOULING MECHANISM IN ULTRAFILTRATION OF ELECTROPLATING WASTEWATER

2018 ◽  
Vol 80 (3-2) ◽  
Author(s):  
Danu Ariono ◽  
Anita Kusuma Wardani ◽  
Putu Teta Prihartini Aryanti ◽  
Ahmad Nurul Hakim ◽  
I Gede Wenten
Keyword(s):  
Flow Velocity ◽  
Membrane Fouling ◽  
Membrane Surface ◽  
Cross Flow ◽  
Permeate Flux ◽  
High Concentration ◽  
Filtration Time ◽  
Electroplating Wastewater ◽  
Fouling Mechanism ◽  
Cross Flow Velocity

Wastewater from electroplating industries is usually contaminated with high concentration of hazardous materials, such as nickel, copper, and chromium. Therefore, the electroplating wastewater is one of the environmental problems that require a novel solution to reduce risks for human and environment. Ultrafiltration is a promising technology to overcome this problem due to its ability to reject all suspended solids. However, membrane fouling still becomes a major obstacle in ultrafiltration processes. Fouling reduces the permeate flux and increases membrane operational costs due to membrane cleaning. In this work, fouling mechanism that occurred in polyacrylonitrile based ultrafiltration for electroplating wastewater treatment was investigated. The effects of trans-membrane pressure (TMP) and cross flow velocity on fouling mechanism were also studied. The results showed that in the first 20 minutes, intermediate blocking was occurred on the membrane surface, while cake formation was happened for the rest of filtration time. These results were applied for all TMP and cross flow velocity.

Fouling and long-term durability of an integrated forward osmosis and membrane distillation system

2015 ◽  
Vol 72 (11) ◽  
pp. 2000-2005 ◽  
Author(s):  
T. Husnain ◽  
B. Mi ◽  
R. Riffat
Keyword(s):  
Membrane Fouling ◽  
Tap Water ◽  
Membrane Surface ◽  
Wastewater Reuse ◽  
Forward Osmosis ◽  
Cross Flow ◽  
Domestic Wastewater ◽  
Membrane Distillation ◽  
Hydrophobic Membrane

An integrated forward osmosis (FO) and membrane distillation (MD) system has great potential for sustainable wastewater reuse. However, the fouling and long-term durability of the system remains largely unknown. This study investigates the fouling behaviour and efficiency of cleaning procedures of FO and MD membranes used for treating domestic wastewater. Results showed that a significant decline in flux of both FO and MD membranes were observed during treatment of wastewater with organic foulants. However, shear force generated by the increased cross-flow physically removed the loosely attached foulants from the FO membrane surface and resulted in 86–88% recovery of flux by cleaning with tap water. For the MD membrane, almost no flux recovery was achieved due to adsorption of organic foulants on the hydrophobic membrane surface, thus indicating significant irreversible fouling/wetting, which may not be effectively cleaned even with chemical reagents. Long-term (10 d) tests showed consistent performance of the FO membrane by rejecting the contaminants. However, organic foulants reduced the hydrophobicity of the MD membrane, caused wetting problems and allowed contaminants to pass through. The results demonstrate that combination of the FO and MD processes can effectively reduce irreversible membrane fouling and solve the wetting problem of the MD membrane.

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