Experimental Research On The Technology Of Sewage Sludge Reduction And Reutilization With Enzymatic Hydrolysis

With more sewage being treated in China,the rapidly increasing amount of sludge production has become a serious issue.Greater attention has been focused on research and development of the technologies of sludge disinfection,reduction and reutilization.The aim of hydrolysis and acidification of sludge is to improve its biological degradability in the terms of higher Soluble Chemical Oxygen Demand (SCOD) and Volatile Fatty Acids(VFAs) productions.SCOD and VFAs, especially acetate and propionate in VFAs,are recognized as the most suitable carbon substrates for enhanced biological phosphorus removal(EBPR).In order to achieve more SCOD quickly,the experiment add distiller's yeast to enhance the anaerobic fermentation of sludge.The technology of sewage sludge reduction and reutilization with enzymatical hydrolysis was investigated in the test.The feasibility of dissolving the organic matters of sludge with enzyme hydrolysis by adding distiller's yeast was studied.The anaerobic fermentation from sterilizing dewatering sludge with yeast,sterilizing concentration sludge with yeast, concentration sludge with yeast and concentration sludge were conducted at 30±1℃.The results showed that the yeast can enhance the hydrolysis and acidification of sludg,it obviously in favor of the generation of SCOD.The optimal experiment condition of enzymatical hydrolysis was studied.An orthogonal experiment involved temperature,types of distiller's yeast,the additional proportion of yeast was operated to find the optimal experiment condition for obtaining the maximum production of SCOD.At the same time,the changing trend of SS and the removal rate of VSS were inspected.Based on the data from series of orthogonal experiment,the optimal experiment condition of enzymatical hydrolysis was that the temperature at 35℃,yeast was rice wine yeast,the addition proportion of yeast was 10%.And the effect of the three factors on the SCOD yield of sludge enzyme hydrolysis was:addition proportion of yeast＞temperature＞types of distiller's yeast.As the fermentation conducting,the SCOD of sludge firstly increased quickly,then increased slowly,and then decreased,it achieved its maximum production in 5 days.As the fermentation conducting,the SS and VS of sludge were continuously reducing,the reducing production of the first 5 days was more than the later 5 days.In 5 days fermentation,the removal rate of VSS was 12.31%～24.21%, after 10 days fermentation.the remova rate of VSS was 19.38%～28.35%.Under the optimal experiment condition,the maximum production of SCOD was 3723mg/L after 5days fermentation,the remova rate of SS was 9.54%,the remova rate of VSS was 16.33%.After 10 days fermentation,the removal rate of SS of the optimal experiment condition of enzymatical hydrolysis was 11.22%,the removal rate of VSS was 24.44%.The production of Volatile Fatty Acids under the optimal experiment condition of enzymatical hydrolysis was studied.The results showed that the maximum production of SCOD was 7214mg/L after 4days fermentation.The maximum production of VFAs was 2424mg/L after 3days fermentation,which was about 5.8 times of the initial value.In the first 2days fermentation,the sludge reduction was more,its reducing rate of SS was 16.62%,the removal rate of VSS was 26.87%,2days later,the sludge reduction was much less than before.