| The high salinity electroplating wastewater containing organic compounds and heavy metals is complicated. So it becomes one of the most difficult wastewater to treat in industrial wastewater. By physicochemical method, the actual electroplating wastewater still can’t meet emission standards; more can’t achieve the advanced treatment and reuse standards. HOW to come out a depth treatment and reuse of electroplating wastewater has been the focus of research at home and abroad.Because of its continuous operation, low-running costs, covering a small area and good quality of water production, the combined membrane process has been researched and developed. Microfiltration can reduce the SDI effectively, remove macromolecular substances and suspended substances; reverse osmosis can intercept the degradation of organic matter and high degree of desalination, desalination rate in more than 95%.According to the quality of electroplating wastewater after physicochemical process and separation characteristics of microfiltration and reverse osmosis technology, this paper used "microfiltration-reverse osmosis" membrane combination craft for electroplating wastewater’s advancing treatment. In this experiment, we use orthogonal and single factor test to study the influence factors on removal effect with simulated electroplating wastewater. The factors are operating pressure, water temperature, water salinity and recovery rate. Then we can determine the optimal operation condition of the combined process and apply the best working into practical electroplating wastewater treatment.Orthogonal test showed that the order of factors affecting the removal rate on CODCr is operating pressure, water temperature, recovery rate and water salinity; the order of factors affecting on desalination is operating pressure, recovery rate, water temperature and water salinity, and the optimum operating conditions for both is the operating pressure of 0.8MPa, the recovery rate of 60%, water temperature 35℃, the influent concentration of 0.5g/L.Single factor test indicatded that as the operating pressure increased, the removal rate of CODcr, Cu2+, Ni2+ and desalination rate of wastewater increased, water flux increased and salt flux was constant, concentration polarization increased. Under the lower metal ions content, metal ions exist mainly in the form of ions, rather the form of hydration. So, the rejection rate of metal ion increased. When temperature rises, the viscosity of water reduced, turbulence increased, membrane flux increased, the membrane pores increased and the retention rate decreased. The concentration polarization caused by higher recovery rate, and then desalination rate decreased. The membrane has a good performance in a certain concentration range. If the influent salt concentration is beyond, treatment effect decreased. It is comprehensive consideration of the actual situation and the effects of effluent that can determine the optimum parameters of this process are operating pressure of 0.8MPa, the recovery rate of 60%, water temperature 33℃, and the influent concentration of 0.65g/L.Under the best conditions, the results of actual electroplating wastewater indicated that the production water turbidity and suspended solids removal effect is good, the concentration of CODcr below 20mg/L, concentration of Ni2+ 0.1mg/L, desalination rate above 96%, which reaches the limit value of pollution discharge standards for electroplating pollutants, and can be reused in electroplating process. |
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