KOH和NH3·H2O联合固态预处理对青稞秸秆厌氧发酵特性的影响

Effects of KOH and NH3·H2O Combined Solid-State Pretreatment on Anaerobic Fermentation Performance of Hulless Barley Straw

    摘要
  • 摘要: 为提高青稞秸秆的综合利用率，选用KOH和NH3·H2O作为青稞秸秆固态预处理试剂进行中温批式厌氧发酵产甲烷试验研究，并通过Box-Behnken响应面法来考察不同含量的KOH、NH3·H2O及预处理时间对青稞秸秆累积甲烷产量的交互影响. 结果表明：各因素对青稞秸秆累积甲烷产量的影响程度表现为NH3·H2O含量>KOH含量>预处理时间；通过响应面模型验证试验得到最优预处理条件为KOH含量5.13%、NH3·H2O含量3.35%、预处理时间13.87 h，该条件下累积甲烷产量实测值为282.34 mL/g(以VS计)，与预测值(286.4 mL/g)非常接近，相对误差小于5%，证明验证模型有效. KOH和NH3·H2O联合预处理能够显著提高青稞秸秆厌氧发酵产甲烷能力(P<0.05)，累积甲烷产量较7% KOH和5% NH3·H2O单一预处理及未处理分别提高了7.59%、20.82%和70.78%；二者联合预处理还能够有效降解木质素(降解率为29.21%)，提高发酵液营养价值；同时，可减少回收预处理试剂的成本，降低对环境的污染. 研究显示，Box-Behnken响应面法能较好地优化青稞秸秆厌氧发酵的预处理条件，KOH和NH3·H2O联合预处理是高效生产生物甲烷和环境友好的木质纤维素类废弃物的处理方法.

     

    Abstract: In order to improve the comprehensive utilization of hulless barley straw, KOH and NH3·H2O were selected as solid-state pretreatment reagents for hulless barley straw in this study, and the methane production in medium-temperature batch anaerobic fermentation was explored. Moreover, the Box-Behnken response surface method was used to investigate the interactive impact of different concentrations of KOH and NH3·H2O and pretreatment time on the accumulative methane production of hulless barley straw. The results showed the overall effect of each factor on the cumulative methane production was as follows: NH3·H2O concentration > KOH concentration > pretreatment time. The optimal treatment conditions for hulless barley straw were KOH concentration of 5.13%, NH3·H2O concentration of 3.35%, and pretreatment time of 13.87 h. The cumulative methane production under these optimal conditions was 282.34 mL/g (measured as VS), which was similar to the predicted value of 286.4 mL/g. The relative error between the predicted and actual values was <5%, indicating that the model accurately estimated methane yields. The combined pretreatment of KOH and NH3·H2O significantly increased the methane production from anaerobic fermentation of hulless barley straw (P<0.05). Specifically, the cumulative methane production was 7.59%, 20.82% and 70.78% higher than that of 7% KOH single pretreatment, 5% NH3·H2O single pretreatment and no treatment, respectively. In the meantime, the combined pretreatment also significantly degraded lignin (the degradation rate is 29.21%). Moreover, the cost of pretreatment agents can be partially recovered, and the pollution of environment can be reduced due to the increased digestate nutritional value because of the residual K and N in the digestate after anaerobic fermentation. The results show the Box-Behnken response surface method can better optimize the pretreatment conditions of anaerobic fermentation of hulless barley straw. The combined pretreatment of KOH and NH3·H2O is an efficient method to produce biomethane and environmental-friendly lignocellulosic waste.

     

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