锌胁迫下的湿地植物厌氧发酵产气过程动力学研究

Kinetics of Anaerobic Fermentation Process of Wetland Plants under Zinc Stress

摘要: 湿地植物芦苇生物量大、有机物含量高，如果缺乏有效处置易造成二次污染和生物质资源的浪费。本文以芦苇秸秆为厌氧发酵原料，向反应器中分别投加不同浓度的锌(Zn²⁺)，研究其对产气动态过程的影响，并通过动力学模型(Gompertz和Logistic模型)研究锌对理论最大产气量、产气速率和滞留时间的影响。结果表明，当Zn²⁺的浓度为10 mg∙L⁻¹时，产气潜力及速率最大，滞留时间最短；当Zn²⁺的浓度为50 mg∙L⁻¹时，产气潜力及速率最小。整个产气过程符合S型增长趋势，Logistic模型和Gompertz模型均能得到较高的拟合系数，但前者更加真实地反映不同浓度Zn²⁺条件下产气规律。因此，添加适量Zn²⁺可作为调控芦苇秸秆厌氧发酵产气的工程措施之一。本研究对湿地植物的内源污染控制和生物质资源化具有指导意义。

Abstract: Phragmites australis, one of the dominant plants in wetlands, has large biomass and high organic content. Without reasonable disposal, it will easily cause environmental pollution and waste of biomass resources. In this paper, the Phragmites straw was used as the anaerobic fermentation feedstock, and different concentrations of zinc (Zn²⁺) were added into the anaerobic bioreactor to study its effect on dynamic process of biogas production. Via kinetic models (Gompertz and Logistic), the theoretical biogas production potential, rate of biogas production and lag-phase period were studied. The results showed that when the concentration of Zn²⁺ was 10 mg/L, the biogas production potential and biogas production rate were the largest, and the residence time was the shortest. When the concentration of Zn²⁺ was 50 mg/L, the biogas production potential and biogas production rate were the lowest. The characteristic shape of cumulative gas production curves presented as the S shape curve. Both the Logistic and Gompertz models showed high correlation coefficients when being used for fitting the cumulative biogas yields. However, the Logistic model fitted better and was more suitable for reflecting the biogas production of anaerobic fermentation of Phragmites straw under different concentrations of Zn²⁺. Therefore, the addition of suitable concentrations of Zn²⁺ can be used as one of the engineering measures to regulate the biogas production of Phragmites australis anaerobic fermentation. This study provides information for guiding the internal pollution and biomass resource utilization in wetlands.