Removal of heavy metals from synthetic leachate using a biologically generated electric field

Removal of heavy metals from aqueous solutions was investigated in batch reactors using a biologically generated electric field. An electric field with a potential difference of 50 mV to 100 mV was generated using an anaerobic culture and an aerobic culture couple. The electric field was applied to a synthetic leachate solution made up using cadmium, zinc or nickel salts using titanium-coated mesh electrodes. After 72 hours of exposure, at 15 mm electrode spacing, less than 40% removal of cadmium and zinc was observed while nearly 80% nickel removal occurred. After 72 hours and at an electrode spacing of 25 mm, nearly 40% removal of cadmium occurred, 60% of zinc was removed, and 80% of nickel was removed from solution. After 72 hours and at 45 mm electrode spacing, nearly 70% of cadmium, 60% of zinc, and over 80% of nickel was removed. The tendency for zinc and cadmium to form more hydroxy complexes as compared to nickel may have contributed to these results. Cadmium and zinc removal were lower at an electrode spacing of 15 mm and 25 mm, compared to removal at an electrode spacing of 45 mm. Electrode spacing did not affect nickel removal.