Membrane filtration processes for removing arsenic from drinking water (second place)

Document Type

Conference Proceeding

Publication Title

World Water Congress 2005: Impacts of Global Climate Change - Proceedings of the 2005 World Water and Environmental Resources Congress

Publication Date



In recent years, arsenic has increasingly become a concern in water quality, especially in drinking water quality. Concerns have risen due to the alarming health effects associated with long term arsenic exposure. This paper reports on the concerns and the methods that are being used to effectively reduce arsenic levels in drinking water. Since arsenic is considered a carcinogen, the EPA has taken action. The Safe Drinking Water Act set the standards for contaminants found in drinking water. Arsenic, one of the contaminants, had a standard of 50 parts per billion (ppb) under the Act. However, in 2001, the EPA established more stringent water quality standards. By 2006, all water supplies must comply with the new 10 ppb standard for arsenic. A very efficient method for removing arsenic from drinking water is a membrane process. Compared to methods used in the past, membrane processes offer a higher and more efficient removal rate. There are four types of membrane processes: reverse osmosis, microfiltration, ultrafiltration, and nanofiltration. Each of these processes offer similar results but have different benefits in their uses. A membrane process is a filtering method driven by a force. That force is usually pressure. Each of the processes is greatly affected by the pore size of the filter. The membrane holds back any contaminant that is bigger than the pore size of the filter. Arsenic is a contaminant that with the correct filter pore size can be stopped at the membrane. Nanofiltration is ideal for arsenic removal. It, along with the other membrane processes, significantly depends on the temperature of the water, the pH, the presence of any other contaminants, the initial concentration of arsenic present in the water, and the operation pressure. Nanofiltration is a high pressure method that produces high removal efficiencies. Furthermore, a study in Bangladesh is highlighted that illustrates the effectiveness of nanofiltration and different methods of applying that process. However, it does require an extensive pretreatment process to initially get the arsenic concentration down to efficient operating levels. With that pretreatment, nanofiltration can then be used to get the arsenic level in the water to measures that meet the more stringent standards set by the EPA. If all water sources and point sources agree to the best available technology, this new level of water pollution control can be achieved. Copyright ASCE 2005.

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