厌氧消化体系的酸碱性及其缓冲能力

The acidalkaline equilibrium and buffer capacity of anaerobic digestion system

厌氧消化体系的酸碱性及其缓冲能力是影响系统运行状况的重要因素。为研究体系的ｐＨ值和缓冲能力的大小及其变化规律，依据溶液电中性理论，在充分分析厌氧消化体系内影响酸碱性的诸多因素和过程的基础上，建立了消化液的电荷平衡方程，以此表明体系内的多相化学平衡。通过对方程确定的ｐＨ值随有机酸浓度变化曲线的讨论，指出有机酸浓度对消化液ｐＨ值的影响受体系中氨、磷酸、钙、其它离子含量及气相二氧化碳分压的制约，曲线拐点处的有机酸含量反映体系的最大缓冲能力，该值可由近似公式求得，并提出对消化液的ｐＨ值及体系的缓冲能力实施控制的途径。

The acid-alkaline equilibrium and buffer capacity of anaerobic digestion system are the major factors that influencing the running condition of the system. In order to study the range and varying rules of the pH value and buffer capacity of the system, this article, according to the electroneutral theory in solution, fully analyzed the factors and processes influencing the acidalkaline equilibrium, establishes the electroneutral equilibrium formula which indicate the multiphase chemical equilibrium of the digestion solution. After the discussion on the pH value and organic acid relation curves defined by the formula, it is indicated that the range of pH value influenced by the organic acid concentration is controlled by the ammonium, carbonic acid, calcium ion and other ions concentration and the partial pressure of carbon dioxide in the gas, and the organic acid concentration at the inflection point on the curve reflects the maximum buffer capacity of the system which can be calculated by an approximate formula, and the control methods of the pH value of the digestion solution and the buffer capacity of the system are put forward.