THERMOCHEMICAL CONVERSION OF SWINE MANURE: AN ALTERNATIVE PROCESS FOR WASTE TREATMENT AND RENEWABLE ENERGY PRODUCTION

Abstract

A thermochemical conversion (TCC) process was applied to the treatment of swine manure slurry for oilproduction and waste reduction. The objectives of the first stage study were to explore the feasibility of oil productionfrom swine manure and to determine the waste reduction rates through the TCC process. A bench TCC reactor wasdeveloped and tested at operating temperatures of 275C to 350C. The corresponding operating pressures ranged from5.5 to 18 MPa. Carbon monoxide was used as a reducing agent at pressures from 0.34 to 2.76 MPa. The oil product wasevaluated by element analysis, heating value, and benzene solubility. The waste reduction rate was evaluated in terms ofchemical oxygen demand (COD) before and after the TCC process. The highest oil yield was 76.2% of the total volatilesolids of the feedstock. The hydrogen to carbon molar ratio was 1.53. The TCC oil product had a similar quality as that ofpyrolysis oils from liquefaction of other biomass such as wood sludge and newspaper waste. The average heating value ofthe oil product was estimated at 34 940 kJ/kg. The COD in the post-processed water after the TCC process was reducedas much as 75.4%. Carbon dioxide was the sole detected gaseous by-product. The solid by-product of the TCC processwas only 3.3% of the total solids input by weight.