Reducing industrial wastewater and recovery of gold by direct contact membrane distillation with electrolytic system

To recover gold, this work used a novel direct contact membrane distillation (DCMD) reactor with a hybrid electrolytic process. Analytical results demonstrate that permeate flux increased as feed -2 -1 temperature and feed flow rate increased. Permeate flux increased from 2.8 to 17.6 kg m h when -2 -1 temperature increased from 30 to 70 °C, and increased from 9.2 to 19.9 kg m h when the feed flow -1 rate increased from 10 to 50 L h . A strong negative correlation between feed conductivity and permeate flux existed. Flux decreased about 21% following an increase in Au wastewater concentra-1 tion in the feed from 5,600 to 55,000 ìS cm . The gold and total organic carbon concentrations in-1 creased as the concentration ratio increased. The Au concentration reached around 165 mg L with a concentrating efficiency exceeding 17-fold. After the DCMD process, 90% of the concentrated gold solution was recovered by electrolysis. Performance recovery rate increased about 20 times from -1 -1 10.6 to 252 mg A h . These positive results show that the new hybrid process integrating a DCMD reactor with electrolysis methods can be applied effectively to treat low concentrations of gold in wastewater. .