Reaction Kinetics of Membrane Separation Anaerobic Digestion

膜分离厌氧消化是一个由一个完整的混合消化池和膜分离单元组成的过程，它将混合利口酒分离成渗透和浓缩。前一个被排出，后一个被返回到消化器。组合工艺是一种固定化生物反应器，它容纳了所有的生物质和未消化的固体。处理后的渗透液COD小于500 mg/L，没有有机固体积累，也没有无机固体液化并通过膜。在35 ℃、容积为20 L的半间歇式反应器中进行了真实的城市污泥消化反应动力学研究。在进料基质后，以适当的时间间隔通过膜回收少量渗透液。通过气相色谱法测定每个样品的VFA浓度。以纯VFA溶液为底物，估算了VFA的反应速度。采用这些参数得到的，该过程的反应模型。估计VFA的崩解遵循一级反应。在酸化速率不受限制的条件下，污泥中有机固体的水解反应也是一级反应。当引入生物质自溶的一级反应时，透过液中VFA浓度的变化符合反应模型。该模型以生物质为基质，无机物浓度比稳定。为了证实这一事实，消化污泥通过高温稳定并进料至消化器。产气过程中，污泥产气量小于肉泥。试验为污泥的完全崩解提供了一种新的工艺。

Membrane separation anaerobic digestion is a process that consists of a complete mixing digester and membrane separation units that separates mixed liqueur to permeate and concentrate. The former one is discharged and the later is returned to the digester. The combined process is a kind of immobilized bioreactor that holds all of biomass and undigested solid. Treated permeate contains COD of less than 500 mg/L.There is not any organic solid accumulation nor inorganic solid that is liquefied and passes through membrane. Experiments were conducted by semi-batch reactors of which volume was 20L at 35ﾟC to determine reaction kinetics of real sewage sludge digestion. After feeding substrate, small amount of permeate was withdrawn through membrane at proper interval. VFA concentration of each sample was measured by gas chromatogram. Reaction velocity of VFA was estimated by using pure VFA solution as substrate. Employing those parameters obtained, a reaction model of the process was produced. Disintegration of VFA was estimated to follow first order reaction. Hydrolysis of organic solid in sewage sludge was also first order reaction on the condition that velocity of acidification was not a limiting factor. When first order reaction of biomass autolysis was introduced, change of VFA concentration in the permeate fitted well to the reaction model. Disintegrated biomass seemed to be used as substrate by the proposed model and observed stable concentration ratio of inorganic substance. To confirm this fact, digested sludge was stabilized by high temperature and was fed to the digesters. Gas production was observed, but amount of it was smaller than that of flesh sludge. The experiment indicated a new process of complete disintegration of sewage sludge.