| With the rapid development of the global economy and the increasingly severe environmental pollution situation nowadays, it is significant to protect the environment and prevent pollution. Currently, Silicon is playing an indispensable role in our daily life. In 1840 s, siloxane was synthesized for the first time. Since then, Polydimethylsiloxane(PDMS) is widely used in many industrial productions, biomedical devices and personal care products including emulsion, cream, cleanser, shower gel, shampoo, hair conditioner, lipstick, nail polish, toilet paper, perfume, sunscreen product, and antiperspirant, etc. In addition, it also appears in some food as a component of the antifoam agent. Because of its abundant derivatives, PDMS is much widely employed in buildings, industrial production and other aspects.China has become a titanic production country of organic silicon with increasing amount of yield, usage, and environmental emission of methyl siloxane year by year. Therefore, it is particularly necessary to discuss the removal way of the siloxane. In order to get rid of the fact that the PDMS transfers from one medium to another(such as adsorption, etc.) instead of getting a thorough removal or conversion, the effects on the environment should be considered at the same time. At that point, developing a biodegradation method of methyl-siloxane is of great significance.As personal care products and cosmetics are vital sources of PDMS, approximately 90% of PDMS in personal care products and cosmetics is brought into wastewater while around 90% of PDMS in wastewater treatment plant(WWTP) will be adsorbed by activated sludge. Therefore, this paper selects the activated sludge collected from the Wenchang WWTP in Harbin as the enrichment medium and PDMS is selected as the target pollutant. The enrichment and degradation efficiency of methyl siloxane degradation bacteria are studied as the research object. In general,biological community characteristics of the biomass which are responsible to degradation was analysed by utilizing high throughput sequencing approachIn the first section of this study, the detection method of methyl-siloxane is constructed and subsequently optimized. Since the specific detection method of the methyl silicone is neither universal nor uniform, additionally the detection effect is not ideal. In this study, the detection method of methyl-siloxane is built by employing the Agilent Technologies 7000, GC/MS-MS instrument in the MRM mode to detect the PDMS. This approach tends to be more accurate and less disturbed by underground values.In the second section, the methyl silicone degradation bacteria were enriched under varied cultured conditions while the degradation efficiency of the microbial degradation bacteria group was studied through adding nutrients and pollutants to the anaerobic bottle of 250 m L for shaking table experiments. The detection method developed in the first section was applied to the detection in this part.By analyzing the data, the biodegradation of siloxane was the highest in anaerobic conditions in which a removal rate of 58.3% can be achieved, following by the efficiency under the condition of nitrate and the anaerobic sulfate, the effect under aerobic condition turned out to scarcely achieve any degradation.In the third part, analysis of biological community characteristics of activated sludge under different conditions was conducted. The biological characteristics of community was analyzed via utilizing the high throughput sequencing method to construct microbial community structure. Combining with the second experimental results, a comprehensive analysis was carried out to identify the microbial groups that are responsible of degrading methyl siloxane. Microbial community analysis showed that Acidaminobacter, Rhodocyclaceae, Ferribacterium, Thauera, Azotobacter and other genera of microorganisms may have the ability of biodegradation of methyl siloxane. |
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