Refinery Sludge Waste Stabilisation and Solidification by Concrete and Brick Development

Petroleum sludge is to be disposed off at centralised waste treatment centre as it is considered as scheduled wastes under Environmental Quality (Scheduled Waste) Regulation 2005. Regulation Seven (One) of the Act, allow the waste to be handled according to special waste management guidelines issued by Department of Environment. The waste sludge can be stabilised and solidified into other product therefore no discharge of the hazardous material to the environment. Two forms of product developed from the waste namely concrete and brick. Concretes are produced by the mixing of cement, sand and aggregate to 10, 20, and 30% of sludge. Clay bricks are produced by mixing of 10, 20 and 30% of waste with clay. Concrete samples are cures at 14-days, 21-days and 28-days and bricks sample at 28-days. After expected curing period, the samples are tested for compressive strength and TCLP for leaching property. Based on the results of compressive strength, maximum load of concrete produced using 10% sludge recorded is 404.6 kN and clay brick with 30% sludge content of 402.5 kN, both of these samples were treated at 28-day curing period. The increased in waste ratio tend to decrease the maximum load of concrete, but increased in waste ratio tend to increase the maximum load of clay brick. Based on TCLP and metals concentration test conducted to the optimum strength of concretes (10%) and clay bricks (30%), it was found that waste concretes produced are able to completely immobilise metals ions of cupper, zinc and lead contain in the sludge waste. Whereas the clay bricks produced are able to completely immobilise lead and cupper except zinc with 2.82% leaching.