NOVEL HYBRID EXCHANGER FOR PHOSPHATE REMOVALFROM WATER AND WASTEWATER

Phosphate discharged into surface waters can stimulate plant growth, resulting in eutrophication of rivers and lakes. Environmental problems may develop as P moves off-site into aquatic systems. Removal of P from wastewaters has long been a concern of municipalities, and technologies have been developed to lower P concentrations in wastewaters. This study presents the development and performance of a new phosphate-selective sorbent, referred to as hybrid anion exchanger or HEX. HEX combines durability and mechanical strength of polymeric anion exchange resins with high sorption affinity of hydrated ferric oxide (HFO) toward phosphate. Laboratory kinetic studies show that HEX selectively removes phosphate from the background of much higher concentrations of competing sulfate, chloride and bicarbonate anions due to the combined presence of Coulombic and Lewis acid– base interactions. The film diffusion equation was used to examine the kinetic data and the exchange rate was found to be governed by the film diffusion process. Column and field trials also show consistent results in the operating capacity of HEX resin with minimal phosphate leakage.