Study On The Reusing Of Electroplating Cleaning Water By Membrane Treatment

Heavy metal pollution has became the increasingly prominent environment issue.The best way to solve heavy meatal pollution and the shortage of water resource for electroplating enterprises is achieve discharge standards and impro-ve the recycling rate.Nowadays.the heavy metal ions discharge has been the focus for the trentment of electroplating wastewater,using precipitation,redox,heavy metal trapping agent approach.But the practice of the electroplating wastewater recycling engineering is still less.Based on the "separate collection, subquality treatment" principle,this paper has talked these aspects.Firstly,the heavy metals has been removed by precipitation with the alkali.Scendly,the heavy metals level has been reduced by heavy metal trapping agent. Thirdly,the suspended solids in wastewater has been removed by sand filtration and ultrafiltration.Fourth,the recycling level of wastewater can achieve ninty five percentage.And lastly,the membrane concentrate can be discharged by low after trentment.The UF flux has been affected by transmembrane pressure, water turbidity.The transmembrane pressure should not exceed 0.2MPa from the operation.UF membrane continuous operation time should be shortened while the water turbidity is high,and ensured the operation time no longer than 60 minutes.UF membrane flux will decrease rapaidly with the increasing water turbidity and the decreasing of water temperature.The RO membrane flux can decrease rapidly and the produced water will deteriorate for the reason of the high conductivityof feed water.These has been proved from experiments.NF experiments verifiedthe same law with the RO experiments.Several things have been showed by engineering experience.Firstly,after thephysical and chemical treatment.electroplating wasterwater can been discharged by law. Secondly,the suspended solids,microorganisms can not be detected in water by the treatment of sand filtration and ultrafiltration.The SDI value was stabile and less than three.Thirdly,the desalination rate and recovery rate can achieve 95% level,and the quality of produced water is stable,such as the electrical conductivity less than 200μS/cm.Finally,after several monthes running,10.5yuanwill be costed for every ton water.So the combination process for electroplating wastewater treatment is economic and feasible.