不同预处理方法对麦秆厌氧消化产气特性的影响

【目的】探索不同的生物和化学预处理方法对麦秆厌氧发酵产气的影响，为提高麦秆能源转化率提供依据。【方法】采用自行设计的可控恒温发酵装置，以经生物（复合菌剂、糖酵酶、沼液）和化学（NaOH（添加量为60 g/kg）和氨水(20 mL/L)）方法预处理过的麦秆和未处理麦秆（CK）为发酵原料，以常温厌氧发酵池的底物为接种物，在总固体（TS）质量分数为8%的条件下进行批次厌氧发酵（35 ℃），分析复合菌剂、糖酵酶、沼液、NaOH和氨水对麦秆厌氧发酵产气量、甲烷含量和pH值变化的影响，并对其产气指标（干物质产气率、挥发性干物质（VS）产气率和甲烷平均含量）进行比较。【结果】各预处理方法均可明显提高麦秆的日产气量峰值，并可提早产气高峰的出现时间。各处理总产气量的高低顺序为：NaOH＞复合菌剂＞糖酵酶＞沼液＞氨水＞CK；与CK相比，不同生物和化学预处理方法可提高麦秆产气量5.85%～48.16%，提高甲烷平均含量15.06%～39.47%。经NaOH预处理的麦秆发酵后总产气量为12 620 mL，比CK提高了48.16%；甲烷平均含量为46.8%，比CK高出39.47%。随着发酵时间的延长，所有处理pH均呈先下降后升高直至趋于稳定的变化趋势。经NaOH处理的麦秆发酵后TS、VS产气率显著高于其他处理(P＜0.05)。【结论】用NaOH（添加量为60 g/kg）对麦秆进行预处理后在35 ℃下厌氧发酵，可以有效提高麦秆的产气量。

Effect of different pretreatments on biogas production characteristics of anaerobic fermentation of wheat straw

【Objective】 The study was to explore the effect of different biological and chemical pretreatments on biogas production of wheat straw by anaerobic fermentation to find a more effective pretreatment to improve energy conversion of straw.【Method】 A batch of experiments under the condition of 8% mass fraction of total solid were conducted in a self-manufactured anaerobic fermentation reactor,with wheat straw pretreated by biological methods(complex microbial agent,sugar fermentation enzyme and biogas slurry),and chemical methods(NaOH(amount:60 g/kg),and NH3·H2O(20 mL/L))as fermentation materials,and the untreated as control(CK),and the substrate of constant temperature fermentation pool as inoculation substance.The biogas production rate,biogas yield,and the change of methane content and pH value were determined at 35 ℃ and compared the biogas production index at different pretreatments,which included total solid(TS) gas yield,volatile solid(VS) gas yield and average methane content.【Result】 Every pretreatment could increase the gas production peak obviously,and shorten the time of peak appearance.The results showed that the biogas yield after different biological and chemical pretreatments was raised by 5.85%-48.16%,NaOH >complex microbial agent>sugar fermentation enzyme>biogas slurry>ammonia>CK,the average content of methane improved by 15.06%-39.47% after different pretreatments.The total biogas production of wheat straw under NaOH pretreatment was 12 620 mL,which was 48.16%,39.47% higher than CK.In addition,the average methane content was 46.8% higher than CK.The pH value of all pretreatment decreased in initial stage,and increased in the next stage,then stabilized with anaerobic digestion carried on.The TS and VS gas yield of NaOH pretreatment were significantly higher than other pretreatments(P<0.05).【Conclusion】 The method of wheat straw pretreated by NaOH(amount:60 g/kg) can improve biogas production effectively at 35 ℃.