Research On High Temperature Strengthening Biological Hydrolyzation And Acidification Of Excess Activated Sludge

The amount of excess activated sludge increased rapidly with the high requirement of urban sewage treatment in China. If lots of sludge can't be disposaled properly, it will bring us serious environmental pollution and is a great waste of resources. Using anaerobic digestion technology can not only realize the minimization and stabilization of sludge,but it can compensate energy the wastewater treatment plant consumed by the methane produced generating power and driving blower etc. In the case of sludge anaerobic digestion, the biological hydrolysis has been identified as the rate-limiting step,and volatile fatty acids (VFAs)are the most important intermediate compounds in the metabolic pathway of anaerobic digestion. Science the two-phase anaerobic digestion was put forward, there have been lots of research focus on the acid generate phase, these researches were mainly under low or medium temperature, few of them regaiding a higher temperature which can enhance the biological hydrolyzation and acidification of the sludge and also influence the of fermentation products. Based on national high technology research development plan (National'863'project)-"The Research and Demonstration of Temperature Staging and Biology Phasing Anaerobic Digestion of Sewage Sludge", the paper is mainly concerned with excess activated sludge biological hydrolyzation and acidification that enhanced by high temperature. A series of batch experiments were carried out to study the influence on hydrolyzation and VFAs accumulation and distribution of several factors, such as temperature, pH and chloroform. By analyzing and comparing the products in different components of substrates, this paper conducts a preliminary study of metabolic pathways of different substances. At the same time, comparison of the practical operating situation in a continuous flow reactor shows actual sludge acidification reactor operating effect at medium and high temperature. The main conclusions are as follows:In the temperature range of 10~80℃, within a certain time, the concentration of soluble COD(SCOD) hydrolyzed increases with sludge retention time(SRT), and the higher the temperature, the hydrolysis rate faster. What's more, with temperature rise, the total VFAs concentration increases first, then decrease, and 45℃is the most appropriate for its accumulation. There is also significant difference in distribution of VFAs at different temperatures.At the high temperature 45℃, SCOD concentration is significantly higher under alkaline condition than acidic. When the SRT is same, the higher of pH, the grater SCOD concentration in the pH range 4~11, while the total VFAs concentration will increase first then decrease with the increase of pH. In the same condition, the total VFAs concentration is the highest when pH is 9.When the SRT is 4 days at medium temperature 35℃or the SRT are respectively 2days, 4days and 6days at high temperature 45℃, the sludge acidification reactor can run stably and reliably. The results show that high-temperature reactor takes more advantages particularly in the aspect of hydrolyzation, acidification, release of ammonia and VS removal.