Lead removal in fixed beds by recycled iron material

A granular iron-bearing material recovered from surface finishing operation s in cast-iron manufacturing is demonstrated to be an effective sorbent for removal of lead from wastewaters in laboratory-scale rests. Fixed-bed expe riments indicate that lead removals are equal to or greater than those achi eved by other sorbents such as activated carbon and prepared granular iron oxides on a mass per mass basis. State-of-the-art equilibrium and rate mode ls have been shown to be useful for simulating adsorber performance and qua ntifying the effects of system variables in fixed-bed systems. For an influ ent lead concentration and pH of 10 ppm and 5.5, respectively, an empty bed contact time of greater than or equal to 2.5 min provides for efficient us e of the sorbent and yields a solid phase loading capacity of similar to 40 mg/g at exhaustion. Minor differences were observed in the adsorptive prop erties of two different particle size fractions. Efforts to chemically rege nerate the sorbent resulted In relatively low lead recovery and subsequent adsorption efficiency compared with investigations with ion exchange materi als and activated carbons. However, the low sorbent usage rate and availabi lity of the material should render the recycling and reuse of shot blast fi nes a cost-competitive process for fixed-bed treatment of metals such as le ad in industrial and hazardous wastewaters.