添加硒、钨元素对猪粪厌氧发酵的促进机制

Stimulation mechanisms of trace elements selenium and tungsten on anaerobic fermentation of swine manure

为更精确地了解微量元素硒(Se)、钨(W)在厌氧发酵系统中的影响效应,提高发酵底物的生物产甲烷效率(BDA),以猪粪为发酵底物,添加微量元素Se、W,应用一级动力学模型和Gompertz模型拟合厌氧发酵过程。研究显示:适量添加微量元素Se、W对厌氧发酵产甲烷过程具有积极的促进作用,其中,M组(Se 0.8 mg·L-1、W 1.8 mg·L-1)促进作用最为显著,累积产气量、平均甲烷体积分数和甲烷产率(以挥发性固体计)分别为177001 mL、68.3%和398.3 mL·g^-1,比CK组分别提高了10.2%、6.1%和21.4%。相关性分析表明:添加微量元素Se、W能够加快产甲烷菌对总挥发性脂肪酸(TVFAs)的利用率(对丙酸降解作用最为显著),促进产甲烷进程,TVFAs浓度与甲烷产率呈负相关,M组具有最低TVFAs累积量(809 mg·L-1)、最大产甲烷速率(31.0 mL·g^-1·d-1),相比CK组水力停留时间(HRT)缩短了4 d、BDA提高了21.4%,厌氧发酵过程符合Gompertz模型(R2=0.9992)。

To understand the effects of trace elements on the anaerobic fermentation system and improve the biomethanation efficiency,this study added trace elements Se and W to a pig manure fermentation substrate.The first-order kinetic model and the Gompertz model were used to simulate the anaerobic fermentation process.Results showed that moderate additions of the trace elements Se and W positively affected methanogenesis.The most significant stimulating effect was found in the M group(after adding 0.8 mg·L-1 Se and 1.8 mg·L-1 W).The cumulative biogas production,methane volume fraction,and methane yield(in terms of VS)were 177001 mL,68.3%and 398.3 mL·g^-1,which were 10.2%,6.1%and 21.4%higher than those of the CK group,respectively.Further correlation analysis revealed that the addition of trace elements could effectively improve the conversion rate of total volatile fatty acids(TVFAs),particularly for propionic acid.Further,the concentration of TVFAs was negatively correlated with the methane yield.The M group showed the lowest TVFA accumulation(809 mg·L-1)and the highest methane production rate(31.0 mL·g^-1·d-1).Moreover,the hydraulic retention time(HRT)was 4 d shorter and the BDA increased by 21.4%compared to the CK group.The anaerobic fermentation process was best fitted by the Gompertz model(R2=0.9992).