Conversion of sewage sludge from healthcare facility to bio-crude oil using hydrothermal liquefaction technology

Abstract

Population growth, municipal waste management challenges, fossil fuel depletion and its associated pollution are increasingly becoming public health issues. These necessitate the production of renewable and sustainable biofuels. This study, therefore, employed the use of hydrothermal liquefaction for the conversion of sewage sludge to bio-crude oil. Samples of the sewage sludge were purposively collected from sewage treatment plant and subjected to laboratory analyses (in triplicates) using standard methods (ASTM and AOAC) to obtain the composition. Sewage sludge (25 kg) from the sewage treatment Plant of University College Hospital, Ibadan, was converted at 300oC to bio-crude oil and biochar using hydrothermal liquefaction. The bio-crude oil was analysed for its physico-chemical properties. Conversion product yield gave 34% bio-crude oil with cloud point, pour point, viscosity and density of -38.89oC, -36.11oC, 0.86cP and 1.04gml-1respectively. The Higher Heating Value (HHV) of the bio-crude oil was 30.60 MJ/kg. A total of 18 compounds were identified from the analysis of Total Petroleum Hydrocarbon (TPH) in the bio-crude oil with 17 compounds within the diesel range organics of crude oil which showed that bio-crude oil has great potential to serve as alternative to fossil fuels.

Keywords

• hydrothermal liquefaction
• sewage sludge
• bio-crude oil