Activated sewage sludge prepd by microbial treatment of sewage, useful as fertilizer and as a source of vitamin B12: Schendel, Johnson, J. Agric. Food Chem. 2, 23 (1954). Isoln of B12-active product: Miner, Wolnak, US 2646386 (1953 to Sewerage Commission of Milwaukee); US 2941933 (1960 to UCLAF).