Effect Factors Of Gas-Producing In Anaerobic Digestion System For Cattle And Duck Feces

Anaerobic digestion technology has conspicuous benefits of society, economy and environment protection. It is widely used in waste treating and reclaimed utilization of dejecta. Anaerobic digestion processing is influenced by material composition, temperature, alkalinity acidity and activity of micro-bacteria etc, and its reactive mechanism is very complex. For seeking the optimal conditions and establishing a mathematical model of anaerobic digestion, the COD (Chemical Oxygen Demand), pH, VFA (Volatile Faty Acid) during the procedure of anaerobic digestion have been analyzed in this paper. The research results can offer some scienctical references for the utilization of the waste of animals.TS (Total Solid) is an important factor for anaerobic digestion effect of cattle and duck feces. In ordre to relieving the burden of anaerobic digestion system and enhancing the activity of microorganism sufficiently, properly TS is needed. While TS in anaerobic digestion system is over low, the activity of microorganism would be restrained, and this reactive process wouldn't be perfect e. The results are shown that the cattle feces has a optimal effect of anaerobic digestion when the TS was 10%, and 24.60% of COD was removed and methane content of biogas was 56.1% .Meanwhile, duck feces has a optimal effect of anaerobic digestion when the TS was 6%, and 30.45% of COD removed and 69.3% of methane content in biogas was produced.Nitrogen is a kind of important nutrient element by microorganism for anaerobic digestion. The growth of microorganism was disadvantageously affected as Nitrogen is absence. Whereas, the activity of microorganism decresed while Nitrogen is superfluous. C/N is a very important influencing facter for anaerobic digestion. The experimental results showed that the cattle feces has a optimal effect of anaerobic digestion when the C/N was 30, with 35.21% COD removal ratio and 72.8% methane content in biogas. Duck feces has a optimal effect of anaerobic digestion when the TS was 25, with 24.06% COD removal ratio and 71.5% methane content in biogas.The relationship between gas yield(volume) and digestion time of anaerobic digestion in different condition have been analysed by mathematical model. A non-linear quartic equation equation, which can be used as describing kinetics characteristics of anaerobic digestion process, have been obtained.