Effect Of Several Feed Additives On Thermophilic Anaerobic Digestion

The amount of municipal sewage sludge, livestock manure, and agricultural wastes inour country is huge, and the number is increasing year by year. We can convert thesesolid wastes into energy by anaerobic digestion technology. Meanwhile, veterinaryadditives like roxasone were added into feed and excreted into manure, which madeanaerobic digestion system unstable. The purpose of this paper investigated the effect ofthree common veterinary medicine,3,5-dinitrobenzamide, nicarbazin and HAPA (3-amino-4-hydroxybenzyl arsenic acid) on the anaerobic digestion system. Theconclusions were summarized as follows:(1) The effect of adding3,5-dinitrobenzamide formamide on the anaerobic digestionprocess was investigated, as well as the variation of E.coli during anaerobic digestionprocess. The results showed that3,5-dinitrobenzene produces a certain degree ofinhibition at the beginning of the digestive process, and the rate of gas productionwithout3,5-dinitrobenzene is significantly higher than without addition. Meanwhile,the addition of3,5-dinitrobenzamide extended the time of anaerobic digestion. Butmethane production increased with3,5-dinitrobenzamide addition. When theconcentration of3,5-dinitrobenzamide was50mg/L, the gas production reachedmaximum.55℃is more beneficial than35℃for anaerobic digestion process adding3,5-dinitrobenzamide. Compared with the starch and sucrose, sodium acetate is the bestchoice of substrate because it may save much time and improve the utilization of thesubstrate.(2) The impact of HAPA concentration on anaerobic digestion was investigated andHAPA degradation in the thermophilic anaerobic digestion (55℃). The results showedthat inhibition for anaerobic digestion exists with HAPA. With increase of concentrationof HAPA the removal was lower significantly. As the concentration of anaerobic sludgeis so low, the change in concentration of the anaerobic sludge has little influence on thedegradation of HAPA. But it still can be seen that with the decrease of the concentrationof anaerobic sludge the degradation rate of HAPA decreased. The highest degradationrate reached64.7%when the initial pH was6.5.(3) This experiment investigated the effect of nicarbazin on anaerobic digestion. Theresults showed that nicarbazin inhibited anaerobic digestion process and the inhibitionincreased with the increasing concentration of nicarbazin. Experimental results showedthat the anaerobic digestion process in this experiment did not fit the first order kinetics equation, Modified Gompertz equation meets the characteristics of methane production inanaerobic digestion with nicarbazin addition. We can get lag phase by fitting and obtainthe degradation rate constant of substrate by first order kinetics equation fitting, butshould take the moment when after the lag phase as zero of the kinetic equation. Lagphase is an important indicator reflecting the anaerobic digestion performance, and thefitting curve of four groups in this experiment show "S" type, suggesting that this kindexperiment should be acclimated before beginning.