Pilot investigation on the treatment of fertilizer manufacturing process effluent using lime and electrodialysis reversal

Abstract

The treatment of a fertilizer company's effluent was evaluated using lime and electrodialysis reversal (EDR) for phosphate removal, water and chemical recovery, and effluent volume reduction. Phosphate could be reduced from 3 800 to less than 50 mg/1 at pH 8.5 with lime; however, phosphate removal from the lime treated effluent using EDR was poor (75% removal). The EDR product water complied with the requirements for cooling tower make-up except for TDS and phosphates. However, the required specifications should be met using 10 stage EDR. In addition, plant nutrients (NH 4 + NO 3 −) may be recovered from the brine, which comprised 20% of the initial effluent volume. Membrane scaling was virtually absent. A full scale EDR plant should run well with electrical adjustments and/or frequent acid cleaning. Electrical energy consumption for EDR treatment was found to be 4.5 kWh/m 3 feed (pumping costs excluded). The capital cost for a 30 m 3/h EDR plant and clariflocculator (PO 4 removal) was estimated at US $750 000.