PHOSPHORUS SORPTION AND CHEMICAL CHARACTERISTICS OF LIGHTWEIGHT AGGREGATES (LWA) - POTENTIAL FILTER MEDIA IN TREATMENT WETLANDS

Five light-weight aggregates (LWAs), suitable for filter media in subs urface flow constructed wetlands, were tested for potential removal of phosphorus (P). P-sorption variation is dependent on the chemical cha racteristics of the LWA. All LWAs exhibited high pH and high total met al content; however, P-sorption capacity varied by two orders of magni tude. Of the LWAs' chemical characteristics (total metal content, cati on exchange capacity, and oxalate soluble Fe and Al), total metal cont ent has the closest relationship with the P-sorption capacity. Among t he four major metal ions (Mg, Ca, Fe and Al), Ca has the strongest cor relation with the P-sorption capacity. (C) 1997 IAWQ.