| To investigate the fermentation features of duck droppings at different loading rates, a lab scale fermentation process for the anaerobic treatment of duck droppings was carried out with an integrated bio-reacor. The experiment set up three step-wisely increased loading rates. The effects of volatile fatty acid ,total alkalinity, ammonia nitrogen, retention time and loading rates on fermentation process were studied. With the mass balance equations, a theoretical yield of biogas（0.44 m3·kg-1 TS） was achieved. At steady state, the yields of biogas were found to be 0.29 d-1, 0.17 d-1, 0.06 d-1, values for first order kinetics were obtained as 0.29 d-1、0.17 d-1、0.06 d-1 when loading rates were set at 4.17 kg TS·m-3·d-1（TS=5%）， 8.33 kg TS·m-3·d-1（TS=10%）, 12.5 kg TS·m-3·d-1（TS=15%）, respectively. According to the energy value analysis, 45.36% heat value from duck droppings were converted to methane, 47.05% to residues and 7.6% were lost as waste heat when loading rate was set at 8.33 kg TS·m-3·d-1. The research shows that the optimal loading rate and retention time can be obtained when biogas yield is equivalent to 60%~70% of the theoretical biogas yield. The present research achievements can apply for dimensioning completely stirred tank reactors digestion organic wastes from food processing industries, animal waste slurries or biogas crops. |
