COMPARING THE EFFECT OF TOTAL SOLIDS CONCENTRATION ON BIO- HYDROGEN PRODUCTION POTENTIAL OF FOOD WASTE AND ITS DERIVATIVES UNDER MESOPHILIC THERMOPHILIC CONDITIONS

The effect of three total solid (TS) concentrations of 7.5, 10 and 12.5% on bio-hydrogen production potential of food waste (FW) in comparison with noodle waste (NW) and rice waste (RW) derived from FW were studied after co-digesting the wastes with heat shocked sludge under mesophilic (37°C) and thermophilic (55°C) conditions. The increase in TS concentration from 7.5% to 10% found an effective way to improve cumulative bio-hydrogen production from all tested wastes. As a whole, 7.5% TS concentration represented higher conversion efficiency of volatile solids into bio-hydrogen and the highest experimental yield of 95.8mL/VSfed was observed in 7.5%NW digester under thermophilic conditions. The increase in temperature within experimental range found an effective way to increase bio-hydrogen production potential of FW and NW only, whereas the same increase in temperature caused negative impact on bio-hydrogen production potential of RW. The optimum time period for active bio-hydrogen production found to be 24-72h of incubation. After 72h of incubation, the bio-hydrogen production reduced considerably in all reactors due to an abrupt increase in volatile fatty acid, and due to inhibition of bio-hydrogen production the drop in pH was also decreased.