Abstract
The isolation of vitamin B_<12> from the activated sludge was examined. The extraction was performed in a pilot plant with hot water under stirring, as previously reported by Kamikubo, Tanaka and Matsuda. Various kinds of filtration process were tried in oder to make filtrate as clear as possible. The filtrate thus obtained was further purified either by active charcoal or ion exchange resin. The filtration process was further facilitated by addition of some precipitants. However, the clear filtrate was not obtained when the moisture content of the dried sludge exceeded 12%. Thus the mean value of vitamin B_<12> content from May 1958 to Sep. 1959 was 4g per ton of the sludge, though a part of vitamin B_<12> in the sludge was lost by rain water when the solar evaporation process was performed in summer.
