| Foodwaste,excess sludge,cow dung are good anaerobic digestion substrate,but the digestion process of each is inefficient.Some trace elements can activate the biological activity of anaerobic digestion.The chelating agents can improve the chelating ability of trace elements in anaerobic fermentation process,enhance the bioavailability,accelerate the process of anaerobic digestion,and shorten the fermentation period.Two kinds of mixture have been designed,one is the mixture of foodwaste and excess sludge,the other is the mixture of foodwaste and cow dung.The effects of four trace elements and chelating agents on digestion processes of mixtures have been studied under the temperature of 35±1℃.The main contents and results of the experiments are as following:（1）Orthogonal experiment L9（34）has been designed to study the effects of different combinations of four kinds of trace elements on the efficiency of anaerobic digestion of the first mixture.The results showed that:when the concentration of trace elements Fe,Co,Ni,Mo were 15.0mg/L,2.0mg/L,0.5mg/L,0.6mg/L,respectively,the digestion efficiency was optimal.Moreover,different combinations have obviously different influences on fermentation indicators including NH4+-N,VFA,coenzyme F420and p H value but little influence on methane contents.（2）Orthogonal experiment L9（34）has been designed to study the effects of different combinations of four kinds of trace elements on the efficiency of anaerobic digestion of the second mixture.The results showed that:when the concentration of trace elements Fe,Co,Ni,Mo were 10.0mg/L,2.0mg/L,2.0mg/L,0.8mg/L,respectively,the digestion efficiency was optimal.（3）With the condition that the concentration of trace elements Fe,Co,Ni,Mo were15.0mg/L,2.0mg/L,0.5mg/L,0.6mg/L in the first mixture,respectively,the effects of different concentrations of NTA on anaerobic fermentation process have been studied.The results showed that:when the concentration of NTA was 800μM,the maximum of the gas production was 13464ml,the concentration of ammonia nitrogen content was 698.30mg/L,and the concentration of coenzyme F42020 was 1.547μmol/L which the increase was 67.06%larger than the number of the control group.（4）With the condition that the concentration of trace elements Fe,Co,Ni,Mo were10.0mg/L,2.0mg/L,2.0mg/L,0.8mg/L in the second mixture,respectively,the effects of different concentrations of CA,NTA and EDTA respectively on anaerobic fermentation process have been studied.The results showed that:when the concentration of CA,NTA and EDTA was 80μM,the gas production reached the maximum,which the increase of CA,NTA and EDTA was 21.29%,43.23%,40.44%larger than the number of the control group,respectively. |
