鸡粪与麦秸混合厌氧发酵产沼气特性

Biogas production characteristics of anaerobic fermentation by mixing chicken manure with crop straw

为深入研究混合发酵对秸秆厌氧发酵产沼气的影响,将4种不同形态的麦秸分别与鸡粪混合进行厌氧发酵产沼气,分析了试验过程中产气量,发酵液pH值、EC、总挥发性脂肪酸(TVFAs)、NH4+-N和碱度的变化.结果表明:秸秆单独发酵产气量较低,不同形态秸秆单独发酵过程中发酵液各指标的变化趋势相似,总体为原秸秆高于一次发酵秸秆,搓揉秸秆高于未搓揉秸秆;鸡粪单独发酵累积产气量,发酵液pH值、EC、TVFAs、NH4+-N和碱度等均高于秸秆单独发酵;混合发酵提高了秸秆的产气速率和产气峰值,缩短了峰值出现时间和达到80%总产气量的时间;将鸡粪与不同形态秸秆混合发酵对提高秸秆累积产气量的效果不同,在扣除鸡粪产气的影响后,鸡粪与原秸秆、搓揉秸秆、一次发酵秸秆和一次发酵秸秆搓揉混合发酵处理的秸秆TS产气量较相应的秸秆单独发酵分别提高了-12.19%、10.54%、13.01%和-12.21%;混合发酵各处理发酵液各指标的变化趋势相似,且处理间差异不显著(P>0.05),混合发酵日产气量和发酵液各指标的变化更温和,厌氧发酵过程更稳定.综合以上结果,将搓揉后秸秆或一次发酵秸秆与鸡粪混合发酵可获得较好的产气效果.

In order to evaluate effects of anaerobic fermentation on biogas production of crop straw,four different levels of wheat straw and their mixtures with chicken manure were generated to make anaerobic fermentation;then,the gas production,pH value,EC,TVFAs,NH4+-N,and alkalinity contents of the digestive juice were analyzed during the experiment.The results showed that the biogas yields of wheat straw fermented alone were low,and the indicators of digestive juice in the mono-fermentation of different forms of wheat straw tended to be highly similar.In general,the values of indicators of the raw wheat straw were higher than those of the fermented wheat straw.The indicators’values of the extruded wheat straw were higher than those of the unextruded wheat straw.In addition,the biogas yield,the pH value,EC,and the TVFAs,NH4+-N,and alkalinity contents of chicken manure were much higher than those of all wheat straw fermented treatments alone.The biogas production rate and gas peak of wheat straw were improved by fermenting with chicken manure,while the peak occurrence time and the time to reach 80%of the total biogas production were also shorten.However,not all forms of wheat straw were available to the fermentation with chicken manure to improve the biogas production of wheat straw.After deducting the biogas production of chicken manure,the TS biogas yields of the fermentation treatments of chicken manure with raw wheat straw,extruded wheat straw,fermented wheat straw,and extruded fermented wheat straw increased by-12.19%,10.54%,13.01%,and-12.21%,respectively,compared with the corresponding wheat straw fermented alone.There were no significant differences in indicators’values between treatments(P>0.05).The values of those indicators in fermentation treatments were in between those of the treatments of chicken manure and wheat straw fermented alone.The changes in biogas production and each index were more moderate,and the anaerobic fermentation process was more stable.Therefore,a higher gas yield can be obtained by mixing chicken manure with extruded straw or primarily fermented wheat straw.