Study On The Ethanol-type Fermentation Product Of Thermal Hydrolyzed Sludge As The Carbon Source For Denitriflcation Process

Nowadays, activated sludge technique is the most widely used technology insewage wastewater treatment, it has produced lots of waste activated sludge (WAS),while the expenses of WAS disposal take a more large proportion in sewage plantoperation costs. Meanwhile, carbon content in sewage is observed to be low andbecome the main factor influencing biological denitrification efficiency. This topic fordenitrification of low carbon content in sewage and disposal of WAS has been studiedfrom two aspects. In process, thermal hydrolysis reactor was employed to pretreat thewaste activated sludge, and promote the decomposition of sludge in the cells and therelease of intracellular material. Study the optimize treatment time and temperatureand the influence to the second base and conversion release process. In carbon source,Ethanol-type fermentation bacteria was used to handle the product of thermalhydrolysis of sludge and explore the optimal conditions to generate VFAs, then usingdifferent boiling point to recovery targets carbon sources. Finally, the supernatantgenerated from the thermal hydrolysis anaerobic acid-pahse digester, which was fullof high carbon source as supplementary carbon source was investigated. The mainconclusions were as following:Firstly, the preferable conditions for WAS thermal hydrolysis pretreatment wereas follows: the treatment time, temperature and pressure were separately45min,170℃and5Mpa.Secondly, Ethanol-type fermentation bacteria played the major role in the ceticacid production. In organic load to28.8kgCOD/m~3d, HRT to8h, the pH and ORPrange of the Ethanol-type fermentation flora was respectively to4.0~4.4and-200mV-320mV.A sludge sample was collected from the Acid fermentation reactor. Bacterialgenome DNA was extracted for the16S rDNA gene amplification, and then abacterial16S rDNA gene clone library was constructed. After the phylogeneticanalysis of16S rDNA sequences, bacterial diversity and community structure of thereactor were studied. The results showed the bacteria in the reactor could be dividedinto4groups, which were as follows: Actinobacteria (3.17%), Bacteroidia (49.36%),Bacillus (28.05%) and Clostridium (19.42%), Actinobacteria kinds of bacteria waspredominant in the ecosystem, and especially Prevotella sp. accounted for38.7%ofall bacteria.Thirdly, hydrolysis fermentation product from excess sludge is a cost-effectivealternative organic carbon source for biological nitrogen removal process. Comparingthe effect of hydrolyzed sludge VFAs and domestic wastewater as the carbon sourcesfor denitification, we found that the four-hour denitification process of two carbonsources all could be divided to three phases: the non-restric fast phase, the restrictslow reaction phase and the endogenous respiration phase, hdrolyzed sludge VFAspresent the better denitification rate.