Removal of Heavy Metals from Water with Microalgal Bioresins. II. Bench-Scale Testing

摘要

This bioresin technology utilizes immobilized non-living biomass derived from algae to bind heavy metals from dilute solutions. There is significant need for such technology as contamination of water supplies is a broad area of concern in former mining operations, industrial sites, ground waters and surface waters. Bench scale-tests used immobilized biomass to assess heavy metal binding. Column efficiency was high with 2-10 ppb of copper being passed through these columns in the first 25-50 bed volumes of influent water with 10 ppm Cu(Sup2+). Reproducibility within batches and over time was adequate, although measurable variations among batches of bioresins were evident. HCl concentrations of 0.0024N and above were required to elute copper (pH 2.6) from the columns, and the less expensive sulfuric acid was also demonstrated to be effective. Binding of Cu(Sup2+) at 10 ppm was largely unaffected by roughly equimolar Fe(Sup2+), as copper had a particularly high affinity for the tested bioresin. The process appeared to be cation exchange as the oxyanion selenate was not bound. Cost of processing/1000 gal. was calculated to be $0.42, of which $0.31 was system capital and the remainder operating cost for a base case of 10 ppm Cu(Sup2+)and 600 gpm.