Studies on Microbial Leaching of Heavy Metals from Municipal Sludge
- 1 December 1990
- journal article
- research article
- Published by IWA Publishing in Water Science & Technology
- Vol. 22 (12) , 229-238
- https://doi.org/10.2166/wst.1990.0117
Abstract
A comparative study between continuous stirred tank reactor (CSTR) with cell recycle and air-lift reactor was carried out in 30 1 capacity reactors for metal solubilization from anaerobically digested sludge. In CSTR at a residence time of 0.75 day, supplementing the feed sludge with 4 g/l of FeSO4.7H2O, using 20% sludge recycle and adjusting pH of the feed sludge to 4.5 resulted in following metal solubilization : 91% Cu, 94% Zn,, 93% Mn, 67% Cd, 67% Ni, 8% Cr, and 7% Pb. At 0.75 day retention time metals were solubilized to the recommended level in CSTR as well as in air-lift reactor. The treated sludge is easy to filter in plates filter press, centrifugation, or vacuum filter. The sludge nutrients do not seem to be diminished as a result of treatment and separation of solid-liquid. The ammonia-nitrogen fraction seems to be transformed in organic nitrogen. The decontaminated sludge produced has less odour.Keywords
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