Feasibility of Combining Reverse Osmosis-Ferrite Process for Reclamation of Metal Plating Wastewater and Recovery of Heavy Metals

Abstract

The feasibility of reverse osmosis (RO) separation combined with ferrite reaction was investigated for the reclamation and recovery of heavy metals from metal plating wastewater. Disc tube-type RO modules were used for simultaneous purification and concentration of wastewaters containing zinc and chromium ions. A subsequent ferrite reaction was performed to recover zinc ions from RO concentrates. The operating conditions of the RO and ferrite reaction were determined in several lab-scale experiments with several types of model wastewater. Pilot-scale RO test results revealed that the zinc plating wastewater treated by one-pass RO and the chrome plating wastewater treated by two-pass RO were acceptable for preplating rinsewater. After ferrite reaction, 99.7% of zinc ions were recovered from the second-stage RO concentrate in the form of zinc ferrite, while significant amounts of chromium ions were retained in the concentrate. As a result of economic analysis, we suggested a retrofitting option, including a combined RO and ferrite process, for a wastewater treatment facility in a local metal plating company.