Qualitative Assessment of Biodiesel Produced from Primary Edible Oil Wastewater Sludge

Abstract

Biodiesel is a suitable substitute for fossil fuels and is more environmentally friendly. However, the use of dedicated crops to produce biodiesel threatens food security and alternative feedstocks are therefore being evaluated. This study compared the performance of biodiesel produced from primary wastewater sludge from the edible oil industry with conventional biodiesel produced from pure canola oil, and commercial diesel from fossil fuel (50 ppm sulfur). The fuels were tested using a single-cylinder four-stroke diesel engine operated under steady state conditions at full load. The energetic performance parameters were computed and evaluated. The biodiesel produced from the wastewater sludge performed well. The thermal efficiency was 30.75% (compared to 28.4% and 26.95 for conventional biodiesel and petroleum-based commercial diesel, respectively). The fuel consumption was higher than commercial diesel at a maximum brake power of 12.8 kW (0.15 and 0.31 kg/kW.h for commercial diesel and wastewater sludge biodiesel respectively) but it was more environmentally friendly in terms of gaseous emissions–both fuels showed a linear decrease in emissions proportionate to the increase in engine speed, reaching averages of 51.5 ppm/g/h and 89.9 ppm/g/h nitrous oxides, respectively at 2000 rpm, and 249.3 ppm/g/h and 310.4 ppm/g/h carbon monoxide, respectively at 800 rpm. From the engine evaluation, it was concluded that the energy generation from the wastewater sludge biodiesel and commercial diesel was similar, but that the former was more environmentally friendly in terms of greenhouse gas emissions.