Industrial purificn. of acid waste water - by anaerobic fermentation of neutralised water with acetoclastic methano:genic bacteria, with continuous control of sulphate content

摘要

In the purification on the industrial scale of acid water contg. a high concn. of sulphates, (a) the waste stream is neutralised and opt. diluted and cooled, to give a stream with pH 6.5-10 wt. 30-40 deg. C, (b) the stream is led into an anaerobic fermenter in which at least acetoclastic methanogenic anaerobic bacteria are active at a pH which is held at 6.3-8.0 and (c) the stream processed in the fermenter is withdrawn. The conductivity of the neutralised waste stream is measured continuously, and the addn. of diluent water is controlled by the results. In the fermenter, the pH is measured continuously and the concn. of H2S gas in the appts. above the liq. is measured or less regularly; depending on the results of these measurements, base is added to the waste stream if necessary and/or the feed of diluent water is altered. The acidity in the fermenter is pref. held at pH 6.7-7.8 (7.2-7.5), the amt. of SO4 in the stream entering the fermenter is not more than 15-20 (not more than 10-15) g/l and the amt. of H2S in the liq. in the fermenter is not more than 175-200 (not more than 150-175) mg S/l.