(156g) Coagulation and Ultrafiltration of High-Alkalinity Greywater

Water is perhaps the most essential natural resource. Unfortunately, fresh water is becoming increasingly scarce, and with the world population continuing to grow, the need for improved methods of water utilization, treatment and recycling is becoming ever more pressing. Greywater is produced by a number of household activities including dishwashing, showering, bathing and laundry. Water from these sources is characterized by the presence of a variety of organic and inorganic impurities such as soap, oil, grease and dissolved solids. Greywater produced during dishwashing poses a particularly difficult problem for treatment processes due to a relatively large concentration of pollutants, particularly soap. The soap solubilizes nonpolar oils and greases in the water while simultaneously increasing the alkalinity of the water. Many treatment processes are very sensitive to pH and require either neutral or acidic pH to operate effectively. Traditional coagulants based on iron or aluminum do not perform well in an alkaline environment and can require permeate post-processing to remove dissolved metals. We investigated the use of novel electrode materials in an electrocoagulation process to treat dishwashing water without any pH adjustment. The coagulated water was then further purified by ultrafiltration. We report the impact of the pre-coagulation on membrane performance and longevity.