Coagulation and Dissolved Air Flotation as Pretreatment for Ultrafiltration of Vegetable Processing Wastewater
Fresh vegetable processing plants generate a large quantity of wastewater that must be treated in order to meet the sewer discharge limits. The objectives of this research are to evaluate the feasibility of coagulation, and dissolved air flotation (DAF) as pre-treatment options for ultrafiltration (UF) to treat spent leafy green wastewater, and potato wastewater. Both coagulation and DAF experiments were conducted to examine the effects of their key process parameters in terms of suspended solids, turbidity, COD, and colloidal TOC removal. Membrane filtration tests were conducted using a dead-end submerged hollow fibre UF membrane module. Results showed both coagulation and DAF treatment reduced the fouling rate. The suspended solids and phosphorous removal efficiencies were over 67% and 90%, respectively. COD, BOD5 and colloidal TOC were removed by around 70% for potato wastewater, and less than 20% for spinach wastewater.