DRYING AND LOW-TEMPERATURE CONVERSION - A PROCESS COMBINATION TO TREAT SEWAGE-SLUDGE OBTAINED FROM OIL REFINERIES

Sewage sludge from oil refineries poses special problems in the dispos al of solid, and often hazardous waste. Drying followed by low tempera ture conversion (i.e., pyrolysis at 400 degrees C) renders sludge to f uel oil and char. This process was operated in full scale, using an in put of 40 tonnes. An overall oil yield of 35% and a rate of 45% of cha r referring to the input of dried solids was achieved during the conve rsion process using a sludge having 16% dried solids concentration Hal ogenated organics and PAH present in the the feed sludge were reduced during the conversion process by 98.4% and 83.7% respectively. Mercury was completely removed from the fuel oil and char through adsorption to the residue of oil/water separation (centrifugal sludge). The conve rsion oil produced meets fuel oil standards and can be used for indust rial purposes. The char produced can be used as a reducing agent in st eel manufacture. Copyright (C) 1996 IAWQ.