Effect of macro- and micro-nutrients addition during anaerobic mono-digestion of grass silage in leach-bed reactors

摘要

The effect of macro- (NH4Cl) (set I) and micro-nutrients (Fe, Ni, Co and Mo) (set II) addition on chemical oxygen demand (COD) solubilisation during anaerobic mono-digestion of grass silage was investigated in two sets of leach bed reactor experiments at 35 degrees C. Results showed that addition of NH4Cl and micro-nutrients improved COD solubilisation by 18% (0.56g SCOD g(-1) volatile solids) and 7% (0.45 g SCOD g(-1) VS), respectively than control. About 20-50% of the added micro-nutrients were bioavailable in the produced leachates, while the rest (50-80%) were adsorbed onto the grass silage. Results of biological methane potential assays showed that, specific methane yields of grass silage were improved by 17% (0.36 +/- 0.02 m(3) CH4 kg(-1) VSadded) when NH4Cl was supplemented while Fe, Ni, Co and Mo addition improved methane yields by 15% (0.33 +/- 0.005 m(3) CH4 kg(-1) VSadded) when compared to control.