High-Strength, Chemical Industry Wastewater Treatment Feasibility Study for Energy Recovery

Abstract

This paper presents an experimental study on the treatment of industrial chemical wastewater with a high organic load; it is aimed at process cost optimization and possible energy and resources recovery. The facility generates five separate streams of liquid waste, which range in organic strength from practically nil to 400,000 mg/L, with individual flows ranging from 2 to 1400 m3/d. The combined strength and the flow of all the streams are approximately 1500 mg/L COD and 1500 m3/d, respectively; however, excluding the cleaner one (the cooling and condensation water), the maximum average COD concentration rises to 115,000 mg/L, at a flow of 16 m3/d. These wastes are currently trucked away for external processing, at a high cost. The aim of the study was to evaluate the feasibility of the onsite treatment of the facility’s waste streams with energy recovery and water reuse. Various approaches were examined, including anaerobic treatment for biogas recovery. The preliminary characterization, however, showed strong inhibition toward anaerobic biomass, and in particular to methanogenesis, induced by some waste components. Further testing led to the conclusion that stream segregation and separate processing could represent the most efficient approach for the management of the facility’s liquid discharges and the optimization of resources recovery. A final solution that maximizes treatment efficiency and resources reuse by combining separate aerobic and anaerobic treatment is proposed.