Ultimate removal of phosphate from wastewater using a new class of polymeric ion exchangers

The presence of trace concentrations of dissolved phosphate is often responsible for causing eutrophication problems in lakes, reservoirs, other confined water bodies and coastal waters. In this regard, both biological and physico-chemical treatment processes have been studied extensively to remove phosphate from contaminated water/wastewater. There, however, remains a major need to identify/develop a viable fixed-bed process which can essentially eliminate phosphate from contaminated water/wastewater. Previous investigators have shown the advantages as well as shortcomings of the fixed-bed process when strong-base anion exchangers, activated alumina and zirconium oxides are used as sorbents. The present study reports the results of a detailed investigation pertaining to selective phosphate removal by a new class of sorbent, referred to as polymeric ligand exchanger (PLE). Laboratory studies show strong evidence that the PLE is very selective toward phosphate, chemically stable, and also amenable to efficient regeneration. Anion exchange accompanied by Lewis acid-base interaction is the underlying reason for PLE's enhanced affinity toward phosphate. In several ways, this new ion exchanger (PLE) overcomes the shortcomings of previously used inorganic and polymeric sorbents. (C) 1998 Elsevier Science Ltd. All rights reserved.