| Summary: | The potential to recycle greater volumes of water may provide a financial incentive for the removal of metal ions from waste water. Selective recovery of metals, in a cost effective manner has the potential to improve the economics of the operation, by providing a commodity rather than waste requiring ever more expensive disposal. Six technologies were investigated, via reference to the available literature, and a process combining chelation of metal ions by a water-soluble polymer with ultrafiltration (polymer enhanced ultrafiltration) was selected for further investigation. The overall aim of this investigation was to assess the feasibility of applying polymer enhanced ultrafiltration for preferential concentration of metals from wastewater. Wastewaters investigated were effluent from steelmaking operations, and landfill leachate. Three “key factors” were considered critical to the viability of the process: 1. Polymer reuse, and safety; 2. Application to real systems; 3. Membrane selection. The research reported here investigated the first two key factors and the applicability of mathematical models reported in the literature. Experimental work showed that correct preparation of the polymer would likely reduce leakage to acceptable levels. Selective recovery of metals from wastewater was shown to be feasible, although retention of metals was apparently due to several mechanisms. Indeed in some instances selective concentration of metals was achieved without the addition of a polymer. In several instances other waste treatment techniques would be required to provide an effluent suitable for disposal. In addition there was considerable potential for pre-treatment of wastewater to improve the economics of the process.
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