STUDY OF BIOOIL PRODUCTION FROM SEWAGE SLUDGE OF A MUNICIPAL WASTEWATER TREATMENT PLANT BY USING HYDROTHERMAL LIQUEFACTION

To overcome the problem of rapid depletion of natural energy reserves and consequent pollution caused by them, this work explored the possibility of utilizing sewage sludge biomass to produce biooil using hydrothermal liquefaction pathway. In this study, effect of different reaction parameters such as reaction temperature, residence time, and sludge -to -water ratio on solid biomass conversion and bioyield and its higher heating value were investigated. Although maximum conversion of (99.7%) and highest biooil yield (22.01 wt.%) was achieved at 330 degrees C, however optimum temperature was chosen as 300 degrees C which produced conversion efficiency and yield of biooil very close (98.07% and 21.5 wt.%, respectively) to what was obtained at 330 degrees C as lower temperature is beneficial for overall economy of the process. Similarly, a residence time of 60 minutes and sludge -to -water ratio of 1:6 was screened to be producing optimized yield of biooil. The higher heating valu of different fractions biooil was much improved (30.18 MJ/kg of acetone phase and 38.04 MJ/kg of dichloromethane phase) as compared to that of raw feedstock (12.74 MJ/kg). Carbon balance performed on the products indicated that maximum amount of carbon went to biooil phase (53.4 wt.%). However, a significant portion of carbon was lost (33.9 wt.%) due to the limitation of experiments at lab scale which involves evaporation and drying to reach final products. The Fourier transform infrared spectroscopy spectral analysis of different biooil phases showed that it was mainly made up of alcohols, alkane, ketones, aldehydes and carboxylic acids.