Continuous treatment of sewage to reduce the vol. of aq. sewage sludge in a sewage treatment plant comprises the steps: (a) providing a mixt. (A) comprising: (i) active amts. of an enzyme mixt. comprising amylase, lipase, protease and cellulase; (ii) active amts. of bacteria comprising Bacillus subtilis and Pseudomonas fluorescens, and (iii) a nutrient source having a chemical oxygen demand of 10000 mg/kg; (b) immersing (A) in fresh water for 6-48 hrs. at 60 F, to produce an activated mixt. (B); (c) mixing a vol. of aq. sludge from the plant with a vol. of (B) for 6-48 hrs. 60 F to produce an acclimated mixt. (C); and (d) adding a vol. of (C) to a sludge treatment tank in the plant, and maintaining the sludge in contact of 2 days 60 F, to reduce the vol. of sludge and suspended solids in the plant. Also claimed is a method for continuous removal of organic contaminants from waste water by steps (a)-(c) as above, the waste water taking the place of the sludge in step (c); these steps are followed by (d') adding (C) to the waste water stream and maintaining in contact for 3 hrs. to reduce the organic contaminants. When the water contains a limited dissolved oxygen and high biological oxygen demand (BOD) it is treated by steps (a) and (b) as above, the water in step (b) being from the body; these steps are followed by (c") adding a vol. of (B) to the body of water; and (d") repeating steps (a), (b) and (c") as necessary until dissolved oxygen is increased, and BOD is reduced to acceptable levels. Also claimed is a compsn. (E) for treating waste and contaminants comprising (i) and (ii) as above and used mushroom compost.    USE -   Reducing the amt. of sludge in sewage treatment reduces the amt. of solids for disposal, and reduces the need for extra equipment in plants already running to full capacity. Waste water treated may be derived from processing of wood, pulp, paper, chemicals, petrochemicals, pharmaceuticals, textiles, glues, foodstuffs, milk, coffee, eggs, meat, chicken, fish, beer or wine.