Study On The Hydrolysis Of Residual Activated Sludge

With the development of our society, the output of residual activated sludge is increasing, many efforts have been devoted to reduce the excess sludge by treatments such as digestion and dewatering which can not resolve the disposal problem of sludge basically.The residual activated sludge is constituted with a large number of microbes which contain abundant proteins. In the paper, the protein was distilled from the sludge by hot alkali hydrolysis, during which some subjects include organic composition, pathogenic microbe and sick ovum were broken up absolutely and the ions of heavy metal were transformed to stabilized state. There was no pollution in the residue and protein solution.A series of parameters about reaction of sludge hydrolysis was obtained by one-factor experiment and optimized by orthogonal method. The results show that the hydrolysis conditions which reaction temperature is 120℃, reaction time is 2h, the ratio of solid to liquid is 1:0.25, and calcium oxide is used as catalyst (pH=13) are the best. The significance of influencing factors on the reaction of sludge hydrolysis are arrayed as pH> reaction temperature > the ratio of solid to liquid > reaction time. Finally, the progression of the reaction through kinetics analysis was gained. In addition, based on the experimental date, a mathematical model was set up and the data calculated from the mathematical model is in satisfactory agreement with experimental data.After hydrolysis, filtrate and film cakes was separated. The condensed protein filtrate can used to produce foam extinguishing agent, foam concrete and so on and the dreg can be used to manufacture materials of building. It realizes the recycle of the sludge absolutely.In the paper, a new technique was proposed to realize the recycles and harmless of residual activated sludge, which provides a research base for the final disposal of residual activated sludge.