Abstract
In a previous report, it was confirmed that vitamin B_<12> was easily lost when dried activated sludge was exposed to rain during its solar evaporation under high temperature. On the basis of the above fact, examination on an extraction of vitamin B_<12> from the sludge has been made, not by heating and stirring, but by immersion in hot water or by washing therewith. The results were as follows : The content of vitamin B_<12> in the extract thus obtained was concentrated up to ca. 3.5 μg per ml., that is, its value was equivalent to 200μg/g of the dehydrated extract. The yield of vitamin B_<12> exceeded 70%. As the procedure was simplified because of easy separation of the extract from the sludge thus treated, and of smaller content of moisture in that sludge, the time required for this procedure was shortened, and successive operations were possible.
