W. Krebs et al., Growth stimulation of sulfur oxidizing bacteria for optimization of metal leaching efficiency of fly ash from municipal solid waste incineration, HYDROMETALL, 59(2-3), 2001, pp. 283-290
Sulfur oxidizing bacteria were used to leach metals bound in municipal soli
d waste incineration fly ash. Pure or mixed cultures of Thiobacilli with or
without addition of anoxic sewage sludge were incubated with various amoun
ts of fly ash for several weeks. Co-cultures with Thiobacilli and sewage sl
udge grew faster than pure cultures of T. thiooxidans or cultures with only
sewage sludge as inoculum. The addition of sewage sludge increased the rat
e of growth of sulfur oxidizing bacteria and simultaneously enhanced the ac
idification of the suspension. As a result, the time for fly ash processing
was reduced by 50%, Thiobacilli were able to grow in the presence of up to
8% (w/v) fly ash. Depending on the amounts of fly ash added, the final pH,
and the concentration of sulfuric acid formed, different amounts of metals
were leached: over 80% for Cd, Cu, and Zn, 60% for Al and approx. 30% for
Fe and Ni (totally, approx. 50% of the heavy metals present in the fly ash)
were extracted. (C) 2001 Elsevier Science B.V. All rights reserved.