Heavy metal sepn. from waste water sludges - comprising conversion to sulphide(s) and then sulphate(s) with Thiobacillus species bacteria

摘要

Heavy metal sepn. from waste water sludges takes place by (a) converting the heavy metal cpds. in sludge to their sulphides; (b) converting the sulphides to sulphates by means of Thiobacillus species bacteria and (c) sepg. the sulphates from the remaining sludge solids, opt. by repeated washing, together with leach. Treated sludges can be used in agriculture and do not pollute soil with heavy metals. Bacterial treatment increases leached-out metal quantity, e.g. from 0.5mg/l to 400 mg/l. Leached-out metals are easily recovered. Sludge is dehydrated more easily than standard sewage sludge. Pathogenic bacteria are killed. No further composting is needed.