Ultrafiltration: The Water Purification Process

INTRODUCTION
Ultrafiltration is a water purification process that can be used for the removal of particulates and macromolecules from raw water to produce potable and drinking water. They have been used to either replace existing secondary (coagulation, flocculation, sedimentation) and tertiary filtration (sand filtration and chlorination) systems employed in water treatment plants. When treating water with high suspended solids, UF is often integrated into the process, utilizing primary (screening, flocculation and filtration) and some secondary treatments as pre-treatment stages. Ultrafiltration processes are currently preferred over traditional treatment methods for the following reasons:
• No chemicals required (aside from cleaning)
• Constant product quality regardless of feed quality
• Compact plant size
• Capable of exceeding regulatory standards of water quality, achieving 90-100% pathogen removal
CASE STUDY
The use of Ultra Filtration process is currently used in the Twin Oaks Valley Water Treatment Plant in San Diego County.
San Diego County’s has three million residents currently receive drinking water from the Metropolitan Water District of Southern California (MWD), which treats the water at one of its Water Treatment Plants. But growth in the area has exceeded the water district’s ability to deliver sufficient quantities of water during the summer season. The Twin Oaks Valley water treatment plant helps to mitigate any water shortages and also provide a self-sufficient, affordable, high quality supply that will meet the area’s demands.
The Zee Weed ultrafiltration system does not require the need for heavy and area consuming pretreatment systems such as coagulation and flocculation that are specified in the convent...

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...untreated water entering leaves as high-quality drinking water and hence ensures the elimination of waste and by products.
Disadvantages of Ultra Filtration
Ultra Filtration processes are limited by the high cost incurred due to membrane fouling and replacement. Additional pretreatment of feed water is required to prevent excessive damage to the membrane units. The water treatment plant is not yet affected by this problem but, pretreatment might be necessary in the near future considering the ultrafiltration membrane durability.
Conclusion
The use of ultrafiltration unit in the water treatment plant of San Diego County helped the county in various ways as discussed above. The water flowing in the river had a certain amount of solid substances and required amount of microbiological particles in it which also helped in encouraging the use of Ultrafiltration process.