| Complexation-ultrafiltration is a novel kind of technology which could removeheavy metals from aqueous solutions, and the process of water-soluble polymerscomplexation-ultrafiltration would combine chemical reaction with membranetechnology,that would fully play a role for each other,while realizing the advancedtreatment and reuse of waste water.Complexation-ultrafiltration technology in advanced treatment of heavy metalwastewater from non-ferrous metal mines was studied.The effects of pH, complexingagents/heavy metal ion mass ratio(P/M),ionic strength and processing time on retentionand permeate fluxes of Pb2+and Cd2+were investigated.The results showed that withthe complexing agent of chitosan, the retention of Pb2+and Cd2+was96.62%and96.26%under the condition of pH=7,P/M=6with raw water containing Pb2+1.0mg/L,Cd2+0.1mg/L. The effluent meet the requirements of Surface water environmentalquality standard (GB3838-2002) Class III. The increase of concentration of NaCl willlead to decrease of the retention. As the extension of processing time, the permeatefluxes decreased and gradually tended to be stable finally. But the processing time haslittle effect on retention of both Cd2+and Pb2+.In the experiment, it was used to flushmembrane module with0.5%concentration of NaClO, and could be recovered89%permeate fluxes. After the dissociation of the concentrated chitosan-heavy metal ionssolution under the condition of pH=2, it could be reused more than90%of chitosanwith the whole-diafiltration methed.While using the complexation-ultrafiltration process, it needs11.55million yuan totreat the project with200m3/h of heavy metal wastewater from nonferrous metal mines.It includes the operating costs for power, medicament, labor and depreciation costtotally about1.003yuan per cubic metre. The recovery period of investment cost for theproject is about3years, that has high economic benefit, social benefit andenvironmental benefit. |
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