Effects of feedstock pH, initial CO addition, and total solids content on the thermochemical conversion process of swine manure

The effects of feedstock pH, ratio of initial carbon monoxide to volatile s olids (CO/VS), and total solids content of the feedstock on the thermochemi cal conversion process of swine manure were studied. The pH values of the f eedstock ranged from. 4 to 10. High pH values favored oil production in the biomass conversion process. Men the feedstock pH was 10, the process yield ed the highest oil production efficiency, but the benzene solubles of the o il product was 10% lower than those at pH 7, pH 4, and without pH control. The CO/VS ratio varied from 0.07 to 0.25, while the corresponding carbon mo noxide initial pressure ranged from 0.69 to 2.76 MPa. The oil production ef ficiency increased from 55% to 70% as the CONS ratio increased from 0.07 to 0.25. The COD reduction, on the other hand, decreased to 50%, while the CO /VS ratio increased to 0.25. A CO/VS ratio higher than 0.1 is not recommend ed. Total solids of the feedstock were studied from 10% to 25%. The total s olids content of the feedstock directly affected the effectiveness of the p rocess. The higher the total solids content, the higher the oil production and COD reduction efficiencies, limited by the handling capability of the f eedstock.