A field trial to engender micro-concentrations of lead (II) using a novel sorbent in highly acidic industrial wastewater at a smelter site in Derbyshire

This study examines the relationship between extreme acidity and heavy metals (with a primary focus on lead) in industrial wastewater and the role of chemical reagents derived from alumina refinery residue to neutralize acid and reduce heavy metals to micro-concentrations (i.e., less than 150 μg/L) at a lead smelter in Derbyshire, England. The role of alumina refinery residue reagents in reducing the need for added flocculants and coagulants is also investigated. During the field trial, influent pH to the smelter’s wastewater treatment plant averaged 1.7, with lead concentrations of 4.2 mg/L, cadmium concentrations of 8.7 mg/L, and zinc concentrations of 49.7 mg/L. As a result of adding two chemical reagents at a rate of 0.25 g/L to Tanks 1 and 2 in the wastewater treatment plant, pH increased to an average of 9.5, lead concentrations decreased to 0.11 mg/L (a 96% reduction), cadmium concentrations decreased to an average 0.05 mg/L (a 98% reduction), and zinc concentrations decreased to 0.05 mg/L (a 99% reduction), all of which were under the 150 microgram target established for this trial. These post-treatment acidity and metal concentrations were within acceptable consent limits imposed by the UK’s Environment Agency for discharge to the local receiving environment, and other floccing and coagulating agents, normally used during routine wastewater processing at the site, could be discontinued during the trial