Porous Structure of Polydimethylsiloxine Membranes and Solvent Recovery by Low–Pressure Membrane Filtration

The City of Baltimore, Maryland is one of many US cities faced with challenges related to increasing potable water demands, diminishing fresh water supplies, and aging infrastructure. To address these challenges, the City recently undertook a $7M study to evaluate water supply and treatment alternatives and develop the conceptual design for a new 120 million gallon per day (MGD) water treatment plant. As part of this study, an innovative raw water management tool was constructed to help model source water availability and predicted water quality based on integration of a new and more challenging surface water supply. A rigorous decision-making approach was then used to screen and select appropriate treatment processes. Short-listed treatment strategies were demonstrated through a year-long pilot study, and process design criteria were collected in order to assess capital and operational costs for the full-scale plant. Ultimately the City chose a treatment scheme that includes low-pressure membrane filtration and post-filter GAC adsorption, allowing for consistent finished water quality irrespective of which raw water supply is being used. The conceptual design includes several progressive concepts, which will: 1) alleviate treatment limitations at the City's existing plants by providing additional pre-clarification facilities at the new plant; and 2) take advantage of site conditions to design and operate the submerged membrane system by gravity-induced siphon, saving the City significant capital and operations and maintenance (O&M) costs. Once completed, the new Fullerton Water Filtration Plant (WFP) will be the largest low-pressure membrane plant in North America, and the largest gravity-siphon design in the world.

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Organic colloids and their influence on low-pressure membrane filtration

Water Science & Technology ◽

10.2166/wst.2004.0728 ◽

2004 ◽

Vol 50 (12) ◽

pp. 311-316 ◽

Cited By ~ 9

Author(s):

C. Laabs ◽

G. Amy ◽

M. Jekel

Keyword(s):

Wastewater Treatment ◽

Glass Fiber ◽

Membrane Filtration ◽

Membrane Surface ◽

Treatment Plant ◽

Low Pressure ◽

Colloidal Solutions ◽

Cake Layer ◽

Stirred Cell ◽

Macromolecular Component

Wastewater treatment by low-pressure membrane filtration (MF and UF) is affected to a large extent by macromolecules and colloids. In order to investigate the influence of organic colloids on the membrane filtration process, colloids were isolated from a wastewater treatment plant effluent using a rotaryevaporation pre-concentration step followed by dialysis. Stirred cell tests were carried out using redissolved colloids, with and without additional glass fiber filtration. After constant pressure membrane filtration of 190 L/m2, the initial flux had declined by 50% for colloids > 6-8 kD (glass fiber filtered) with a hydrophilic MF membrane and for colloids >12-14 kD (glass fiber filtered) with a hydrophobic MF membrane. For the non-filtered colloidal solutions, the flux decline was even steeper with the flux being below 10% of the initial flux after 190 L/m2 were passed through the membranes. As with larger particles, colloids form a filtration cake layer on top of the membrane surface when used as isolates without prior filtration. This filtration cake is easily removed during backwashing. However, polysaccharides as a macromolecular component of the colloid isolate cause severe fouling by the formation of a gel layer on the membrane surface that is difficult to remove completely.

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Low-pressure submerged membrane filtration for potential reuse of detergent and water from laundry wastewater

Journal of Water Process Engineering ◽

10.1016/j.jwpe.2020.101264 ◽

2020 ◽

Vol 36 ◽

pp. 101264 ◽

Cited By ~ 6

Author(s):

Muhammad Roil Bilad ◽

Normi Izati Mat Nawi ◽

Divvya Dharshini Subramaniam ◽

Norazanita Shamsuddin ◽

Asim Laeeq Khan ◽

...

Keyword(s):

Membrane Filtration ◽

Low Pressure

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Irregular Surface and Porous Structure of SiO2 Films Deposited at Low Temperature and Low Pressure

Journal of The Electrochemical Society ◽

10.1149/1.1838681 ◽

1998 ◽

Vol 145 (7) ◽

pp. 2569-2572 ◽

Cited By ~ 9

Author(s):

F. N. Dultsev ◽

L. A. Nenasheva ◽

L. L. Vasilyeva

Keyword(s):

Low Temperature ◽

Porous Structure ◽

Low Pressure ◽

Irregular Surface ◽

Sio2 Films

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Trends for Low-Pressure Membrane Filtration

IDA Journal of Desalination and Water Reuse ◽

10.1179/ida.2011.3.2.12 ◽

2011 ◽

Vol 3 (2) ◽

pp. 12-13

Author(s):

Robert Huehmer

Keyword(s):

Membrane Filtration ◽

Low Pressure

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Simultaneous removal of phosphorus and EfOM using MIEX, coagulation, and low-pressure membrane filtration

Environmental Technology ◽

10.1080/09593330.2015.1055819 ◽

2015 ◽

Vol 36 (24) ◽

pp. 3167-3175 ◽

Cited By ~ 1

Author(s):

Hyun-Chul Kim ◽

Thomas C. Timmes ◽

Brian A. Dempsey

Keyword(s):

Membrane Filtration ◽

Low Pressure ◽

Simultaneous Removal

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Risk management approach for monitoring UF membrane integrity and experimental validation using MS2-phages

Water Science & Technology Water Supply ◽

10.2166/ws.2008.051 ◽

2008 ◽

Vol 8 (2) ◽

pp. 239-244 ◽

Cited By ~ 1

Author(s):

Anne Brehant ◽

Karl Glucina ◽

Isabelle Lemoigne ◽

Jean-Michel Laine

Keyword(s):

Removal Efficiency ◽

Membrane Filtration ◽

Membrane Integrity ◽

Drinking Water Treatment ◽

Low Pressure ◽

Full Scale ◽

Microbial Pathogens ◽

Management Approach ◽

Pathogen Removal ◽

Bench Scale

Low-pressure membrane filtration systems, such as microfiltration (MF) and ultrafiltration (UF), have received a great deal of attention in the past 15 years due to their ability to remove microbial pathogens, especially Cryptosporidium and Giardia. The major concern for the application of membrane technology is, however, how to ensure integrity of these barriers, since small defects in membranes could result in a significant reduction in pathogen removal efficiency. In order to ensure safe drinking water treatment, a number of environmental agencies request the membrane operators to conduct regular direct integrity tests to control the microbial log removal values (LRV) of the plants. Typically, test conditions must be selected to provide information on defects larger than 3 μm to ensure Cryptosporidium removal. In that context, the objective of this project was to develop and validate, both at bench-scale and full-scale, a model based on the equations proposed by USEPA and ASTM that uses the air flow rate throughout a defect during the air pressure test for predicting the microbial LRV. The project was conducted on a pressurised low-pressure membrane module. MS2-phages were used at bench-scale to validate the model and the selected assumptions with various calibrated defects carried out on the membrane fibres. The validity of the model was then evaluated at full-scale. A user-friendly tool using the Hagen Poiseuille Model proposed by the ASTM was developed to assist membrane operators in the integrity monitoring. The calibration of the model with full-scale tests resulted in adjusting some key-parameters representing air diffusion, flow regime and particles deposition. The numerical applications provide a very reliable result in predicting the pathogen removal efficiency and the equivalent number of broken fibres. This model could detect one complete broken fibre out of more than 700,000 fibres, which guaranteed more than 4 log of microorganism removal efficiency.

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Modeling NOM fouling of low pressure membranes: impact of membrane properties and NOM characteristics

Water Science & Technology Water Supply ◽

10.2166/ws.2008.003 ◽

2008 ◽

Vol 8 (1) ◽

pp. 75-83

Author(s):

NoHwa Lee ◽

John Pellegrino ◽

Gary Amy

Keyword(s):

Membrane Fouling ◽

Membrane Filtration ◽

Principal Component ◽

Low Pressure ◽

Time Frame ◽

Membrane Properties ◽

Flux Decline ◽

Cake Layer ◽

Highly Correlated ◽

Significant Flux

This research attempted to identify characteristic coordinates responsible for significant flux decline in low pressure membrane filtration, and to explain relationships among those coordinates with a modeling approach. A Pearson's correlation matrix supported that significant flux decline over a short time frame (low delivered DOC) is highly correlated with high molecular weight (MW) components of NOM. Simulations of flux decline by model equations were close to the experimental results revealing that low pressure membrane fouling is dominantly affected by NOM characteristics and membrane properties. One source water, exhibiting the highest flux decline, showed mostly cake formation as a fouling mechanism. The results indicate that significant flux decline is caused by high MW components leading to formation of a cake layer. Principal component analysis (PCA) revealed that high MW polysaccharides are the most important NOM component affecting significant membrane fouling.

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