Recovery of useful metals from bacterial leaching solution and abatement of waste water acidity by sulfate reducing bacteria were studied.
Treatment with continuous culture was effective for metal sulfide formation and improvement of waste water acidity but treatment with batch culture was impossible, because low pH and metal ions were obstructive of bacterial growth.
The optimum pH for treatment with continuous culture was 6.0, which agreed with the optimum pH for bacterial vgrowth. In the treatment with 40% leaching solution at optimum pH, the maximum rates of metal removal were obtained and their rates for Cu, Zn and Fe were 41.5mg/L/h, 18.1mg/L/h and 25.7mg/L/h respectively.
The maximum specific growth rate was obtained in the treatment with pH 6.0 and 20% leaching solution, which was 0.541/h. It was considered that the bacterial growth rate was accelerated as a result of harmless metal sulfide formation from hydrogen sulfide and metal ions which were harmful to bacterial growth, and cooperation between sulfate reducing bacteria and other microorganisms.
Contents of copper, zinc and iron in the black precipitation were 19.96%, 6.13% and 10.95% respectively and they were about 6.9, 38.0 and 1 times as those of the original sulfide ore.
