Sustainable fuel production from waste ship oil sludge: A comprehensive technical and socio-economic analysis towards zero-waste discharge

Waste ship oil sludge (WSOS) is a classified hazardous waste as it is detrimental to the environment. This work hopes to upcycle the waste as a renewable fuel and optimize its yield. The thermal degradation of WSOS was studied at various heating rates ranging from 5 - 30 degrees C.min(-1) to identify the activation energy and frequency factor. A response surface model for a temperature range 300 - 800 degrees C, a heating rate of 5 - 40 degrees C.min(-1), and a holding time of 30 - 120 min was used. The central composite design indicated temperature of 550 degrees C, heating rate of 22.5 degrees C.min(-1), and retention time of 30 min as the optimum operating parameters for WSOS upcycling with a corresponding oil yield of 56.65%. The fuel properties of the upcycled fuel indicated that the fuel was on par with commercial diesel. A techno-economic analysis indicated a payback period of less than 11 months and the safety index for the process was 4 indicating safe operation. The produced pyro-oil was observed to reduce 1134 kg CO2 per annum. A positive NPV and a high IRR of 79% indicated that the commercial sale of this pyrooil as a renewable fuel would be economically feasible.