Treatment of Potato FarmWastewater with Coagulation

Abstract

Abstract. The processing wastewater from an on-farm potato storage facility contains substantial concentrations of colloidal particles that are hard to remove through sedimentation alone. This study evaluated coagulation as a potential approach for reducing total suspended solid levels. Wastewater was coagulated with two proprietary Nalco polymers, as well as aluminum sulfate (alum) and ferric chloride (FeCl 3 ). One of the Nalco polymers required the smallest volume to achieve 50%, 75%, or 90% total suspended solids removal. However, alum was consistently the least expensive product, despite the larger volume required. Although cost is an important factor for farmers, the convenience of using a smaller volume and the effects of coagulation on pH are also important factors to consider. Both polymers had minimal effect on pH, whereas alum and FeCl 3 resulted in a pH below 6 at high concentrations. In consequence, alum and FeCl 3 require additional chemicals to maintain a biologically neutral pH, thus also requiring extra work and expense. Future research should focus on on-farm coagulant trials to verify laboratory results and optimize protocols for on-farm use.