TECHNOLOGY FOCUS - BIOLOGY - Preferred Microorganisms: The microorganisms capable of degrading acidic sludge include microorganisms capable of degrading aromatic, aliphatic, naphthenic and other fraction of sludge at acidic pH. The microorganism is yeast. The microbial consortia includes Candia digboigensis MTCC 4371 and Candida digboigensis MTCC 4372.Preferred Materials: The carrier for support of microorganisms is biodegradable. It is made of materials that can retain microorganism relatively mildly and allow easy release of proliferated microorganisms. The carrier may be, e.g. cornhusk, sugar industry waste or any agricultural waste. It has a water content of 1-99 (preferably 10-85) wt.%.    TECHNOLOGY FOCUS - ENVIRONMENT - Preferred Method: The sludge is mixed with soil on an impermeable sheet of material. An inoculum comprising mixed yeast culture is introduced into the soil sludge mix. The soil-sludge mixes are periodically tilled to loosen and to increase aeration for bacterial growth. The moisture content, which is greater than or equal to80 wt.% water retention capability of the soil-sludge mix, is maintained. The soil-sludge mix is periodically tested to monitor reduction in amount of hydrocarbon contaminants contained in the soil.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: The nutrient system comprises ammonium chloride; 5-20 parts by weight (pbw) hydrated magnesium sulfate (MgSO4.7H2O) per 100 pbw ammonium chloride; 5-20 pbw sodium chloride per 100 pbw ammonium chloride; and 15-50 (preferably 20-30) pbw monobasic potassium phosphate (KH2PO4) per 100 pbw ammonium chloride; and traces of vitamins and trace elements. The molar ratio of elemental nitrogen to phosphorus is 5:1 - 15:1 (preferably 8:1 - 12:1).    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The nutrient system comprises ammonium chloride; 5-20 parts by weight (pbw) hydrated magnesium sulfate (MgSO4.7H2O) per 100 pbw ammonium chloride; 5-20 pbw sodium chloride per 100 pbw ammonium chloride; and 15-50 (preferably 20-30) pbw monobasic potassium phosphate (KH2PO4) per 100 pbw ammonium chloride; and traces of vitamins and trace elements. The molar ratio of elemental nitrogen to phosphorus is 5:1 - 15:1 (preferably 8:1 - 12:1).