Removal of silica from brackish water by electrocoagulation pretreatment to prevent fouling of reverse osmosis membranes

Den, Walter; Wang, Chia-Jung

doi:10.1016/j.seppur.2007.07.025

Cited by 140 publications

(70 citation statements)

References 22 publications

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“…Peiris et al (Peiris et al, 2013) found that polyaluminum chloride as a chemical coagulant could reduce hydraulically irreversible fouling caused by humic substances and protein-like matters. EC has been intensively studied recently as an unconventional pretreatment method (Den and Wang, 2008;Millar et al, 2014;Zhao et al, 2014). Hakizimana et al (Hakizimana et al, 2015) concluded that EC is highly potential in mitigating organic fouling as well as biofouling due to its capacity to reduce dissolved organic matter and microorganisms from water.…”

Section: Pretreatment Technologiesmentioning

confidence: 99%

A review of reverse osmosis membrane fouling and control strategies

Jiang

Li²

2017

Science of The Total Environment

710

362

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Reverse osmosis (RO) membrane technology is one of the most important technologies for water treatment. However, membrane fouling is an inevitable issue. Membrane fouling leads to higher operating pressure, flux decline, frequent chemical cleaning and shorter membrane life. This paper reviews membrane fouling types and fouling control strategies, with a focus on the latest developments. The fundamentals of fouling are discussed in detail, including biofouling, organic fouling, inorganic fouling and colloidal fouling. Furthermore, fouling mitigation technologies are also discussed comprehensively. Pretreatment is widely used in practice to reduce the burden for the following RO operation while real time monitoring of RO has the advantage and potential of providing support for effective and efficient cleaning. Surface modification could slow down membrane fouling by changing surface properties such as surface smoothness and hydrophilicity, while novel membrane materials and synthesis processes build a promising future for the next generation of RO membranes with big advancements in fouling resistance. Especially in this review paper, statistical analysis is conducted where appropriate to reveal the research interests in RO fouling and control.Graphic Abstract

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Section: Pretreatment Technologiesmentioning

confidence: 99%

A review of reverse osmosis membrane fouling and control strategies

Jiang

Li²

2017

Science of The Total Environment

710

362

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“…From a more general perspective, Ning has written a review on reactive silica in natural waters 3 . There have also been several reports dealing with the issue of silica in geothermal waters [4][5][6] and in fouling of membranes 2,3,[6][7][8][9][10][11][12][13][14][15] . It is unfortunately beyond the scope of this report to make an economic comparison between some of these different approaches to silica removal.…”

Section: Figure 1 Proposed Ge Solution For the Use Of Impaired Watermentioning

confidence: 99%

Technology to Facilitate the Use of Impaired Waters in Cooling Towers

Colborn

2012

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Executive Summary:The project goal was to develop an effective silica removal technology and couple that with existing electro-dialysis reversal (EDR) technology to achieve a cost effective treatment for impaired waters to allow for their use in the cooling towers of coal fired power plants. A quantitative target of the program was a 50% reduction in the fresh water withdrawal at a levelized cost of water of $3.90/Kgal.Over the course of the program, a new molybdenum-modified alumina was developed that significantly outperforms existing alumina materials in silica removal both kinetically and thermodynamically. The Langmuir capacity is 0.11g silica/g adsorbent. Moreover, a low cost recycle/regeneration process was discovered to allow for multiple recycles with minimal loss in activity. On the lab scale, five runs were carried out with no drop in performance between the second and fifth run in ability to absorb the silica from water. The Mo-modified alumina was successfully prepared on a multiple kilogram scale and a bench scale model column was used to remove 100 ppm of silica from 400 liters of simulated impaired water. Significant water savings would result from such a process and the regeneration process could be further optimized to reduce water requirements.Current barriers to implementation are the base cost of the adsorbent material and the fine powder form that would lead to back pressure on a large column. If mesoporous materials become more commonly used in other areas and the price drops from volume and process improvements, then our material would also lower in price because the amount of molybdenum needed is low and no additional processing is required. There may well be engineering solutions to the fine powder issue; in a simple concept experiment, we were able to pelletize our material with Boehmite, but lost performance due to a dramatic decrease in surface area.

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“…Few studies have investigated treatment of potentially scale-forming species, such as silica, calcium and magnesium, especially at the concentrations present in industrial process waters. Two studies have investigated EC for dissolved silica removal, one as part of a dewatering process (Bayat et al, 2006) and one as a pretreatment for reverse osmosis (Den and Huang, 2008). However, neither of these studies investigated the relationship between coagulant dose and silica removal.…”

Section: Introductionmentioning

confidence: 99%

Laboratory and pilot testing of electrocoagulation for removing scale-forming species from industrial process waters

Schulz

Baygents

Farrell

2009

Int. J. Environ. Sci. Technol.

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This study investigated the performance of electrocoagulation using iron and aluminum electrodes for removing silica, calcium and magnesium from cooling tower blowdown and reverse osmosis reject waters. Experiments were conducted at both the bench and pilot scales to determine the levels of target species removal as a function of the coagulant dose. At the bench scale, aluminum removed the target compounds from both cooling tower blowdown and reverse osmosis reject more efficiently than iron. A 2 mM aluminum dose removed 80 % of the silica and 20 to 40 % of the calcium and magnesium. The same iron dose removed only 60 % of the silica and 10 to 20 % of the calcium and magnesium. When operated with iron electrodes, pilot unit performance was comparable to that of the bench unit, which suggests that such systems can be scaled-up on the basis of coagulant dose. However, when operated with aluminum electrodes the pilot unit underperformed the bench unit due to fouling of the electrode surfaces after a few hours of operation. This result was completely unexpected based on the short-term experiments performed using the bench unit.

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Removal of silica from brackish water by electrocoagulation pretreatment to prevent fouling of reverse osmosis membranes

Cited by 140 publications

References 22 publications

A review of reverse osmosis membrane fouling and control strategies

A review of reverse osmosis membrane fouling and control strategies

Technology to Facilitate the Use of Impaired Waters in Cooling Towers

Laboratory and pilot testing of electrocoagulation for removing scale-forming species from industrial process waters

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