Study On Synthesis Of Polyhydroxyalkanoates(PHA) By Domesticated Microorganism In Activated Sludge

Polyhydroxyalkanoates(PHA), as a kind of biodegradable plastic, have broad prospects, especially in the more serious "white pollution" circumstance and huge increase in the cost of wastewater treatment today. It is of great significance to synthesis polyhydroxyalkanoates(PHA) by bacterial consortium from the excess sludge and saponification wastewater.In this paper, the acclimated activated sludge was acclimated by epoxy propane saponification wastewater to product PHA.The activated sludge treatment by epoxy propane saponification waste water was discovered with the ability to extract PHA which was identified the main monomers as 3HB and 3HV,and the ratio was about 10: 3. The activated sludge were directly detected by gas chromatography and discovered that PHA components accounted for 0.0350% of the dry weight of sludge.In order to improve the yield of PHA,the acclimation method was designed.Innovative domestication equipment was assembled and and applied successfully. Suitable external carbon source for PHA production was explored,Acetic acid, propionate and butyrate as carbon sources and found that the maximum yield of PHA from these three carbon source addition was 0.745 g / L, 0.462 g / L and 0.525 g / L respectively, and acetic acid was selected for the final domesticated external carbon source. Phase detection method was applied to determine acetic acid, and the appropriate standard curve was draw.In a period of 37 days of acclimation process, added the mixed culture with acetic acid and wastewater during each cycle,and samples were collected. The yield of PHA in the process of domestication can be up to 23.67% with a huge increase compared with that before domestication.The parameters of the typical acclimation cycle were monitored,PHA monomer components were mainly composed of 3HV, and ratio of 3HB and 3HV was about 19: 1.The addition carbon source had important influence on the composition of PHA.COD and acetic acid during the domestication process were monitored and showed a downward trend. The result provided well theoretical foundation for the production of PHA from hydrolytic acidification product by activated sludge.In order to explore the mechanism of PHA production,the ecological analysis was carried out,and the potentional PHA production superiority bacteria was discovered.The phylun analyse showed that Proteobacteria were the advantages in activated sludge microbial communities, consistent with the known literature described, and the proportion of the population increased 5.73% after the domestication; while Firmicutes increased to 10.58% from 1.90%.It was likely that the microorganisms in Firmicutes were related to PHA synthesis. In genus analyses,After the acclimation the Rhodobacteraceae increased 12.52%,up to 25.33%,and Bacillus increased 9.43%,up to 9.61%;while,Rhizobium sp. remained at the same proportio about 2.50%;The microorganisms in those genus had the potential to synthesise PHA. There will be a new way for the comprehensive utilization of industrial wastewater sludge, through our future research of activated sludge using PO saponification wastewater and sludge hydrolysis acidification products to synthesis PHA.