Research On The Statistical Relationship Of Compound Heavy Metal Metal On Bioenergy Production

The present study focused on the universal heavy metal pollution,the difficulty of heavy metal biomass reuse and the urgent demand of bioenergy.In this study,anaerobic biogas production with biomass containing compound heavy metals was proposed.The aim of this study is to investigate the effect of compound heavy metals on anaerobic fermentation process,including the biogas properties,process stability,degradation of raw materials,microbial activity and enzyme activity through SPSS methods,such as completely random design and t test,and finally reveal the influence mechanism of compound heavy metals on anaerobic fermentation.The reults of this study is expected to support the bioreutilization of heavy metal contaminated biomass.The results showed that:(1)The addition of compound heavy metal promoted the cumulative biogas production,improved and brought forward the peak daily biogas yields.By addition nickel(Ni)in to the cadmium(Cd)or copper(Cu)contained anaerobic fermentation groups(Cd+Ni and Cu+Ni),the cumulative biogas yields and the maximum daily biogas yields were higher than the groups with iron(Fe)and zinc(Zn)addition as well as the control group.Ni or Zn addition promoted the methane(CH4)content while Fe addition did not.(2)Compound heavy metals addition enhanced the stability of fermentation process to a certain extent.At the beginning of the fermentation,compound heavy metals addition accelatrated the stabilization.Afterwards,the stability of Cu+Ni and Cu+Zn groups was enhanced significantly in the late stage of fermentation.Compared to the control groups containing only Cd or Cu,the stability of ORP values in the Cd+Ni,Cd+Zn and Cu+Zn groups were improved while Cu+Ni and Cu+Fe groups had no significant influence.(3)The addition of compound heavy metals increased the degradability of feedstocks.Compared with the control group containing Cd or Cu only,the average NH4+-N content of Cd+Ni and Cd+Zn groups increased.The compound heavy metals experimental groups containing Cu promoted the generation of NH4+-N in the early stage of fermentation,and improved the stability of NH4+-N in the later period of fermentation.The compound heavy metals experimental groups containing Cd promoted the consumption of VFA.The accumulation of VFA in compound heavy metals experimental groups containing Cu was higher than that in the control group;Compared with the control group,the COD values in the Cd?Ni,Cu+Ni and Cd+Zn groups decreased significantly in the prophase of the fermentation.By addition Fe in to the Cd or Cu contained anaerobic fermentation groups helped to improve the rate of cellulose degradation,Cd+Zn group contributed to the degradation of lignocellulose,especially cellulose and lignin,while Cu+Ni and Cu+Zn groups had no significant influence.(4)The addition of compound heavy metals changed the content of methanogenium,which changed the enzyme activities.Cd+Fe and Cu+ Ni groups increased the activity of cellulase,while Zn addition decreased the activity of cellulase,especially in the late of the fermentation;the addition of compound heavy metals increased the activity of coenzyme F420,which increased the conversion of H2 and CO2 to CH4 and increased the CH4 content.Compared to the control groups containing only Cd or Cu3 Zn addition increased the absolute abundance of the methanogenium and the activity of coenzyme M,while Fe and Ni addition did not significantly promote the activity of coenzyme M.This study explored the effect of adding Fe,Ni and Zn to anaerobic fermentation process in the fermentation system containing Cd and Cu.This study found that compound heavy metals increased the biogas production of corn stalk and cow dung mixed anaerobic fermentation through SPSS methods,such as completely random design,hypothesis testing and non-parametric ststistics.The varations of important indexes in fermentation system were revealed.The mechanism and effects of different heavy metals were analyzed.It provided a new insight for the treatment and disposal of plant residues and the development of biomass energy.