| In recent years, pharmaceuticals and personal care products(PPCPs) are frequently detected as new organic pollutants in the environment which form a new environmental problem, epecially in surface water or urban sewage. PPCP contents have reached tens of micrograms per litre or more. PPCPs are not easily removed by traditional sewage treatment methods, resulting in the long term settling of PPCPs in water and apparent ecological toxicity to aquatic organisms, bringing potential health hazards to humans. Exploring new PPCPs removal processes in the water environment has become a new challenge and is a very important research project in the water-treatment field. Biological treatment has a better potential because of the advantages of this method, including high efficiency, low cost, mild reaction conditions and no secondary pollution. This technology is a development direction of PPCPs processing technology. The aerobic granular sludge with excellent performance is obtained in this study using granule microorganism immobilised technology. The formation and stabilisation running processes of granules sludge in the aerobic granular system and aerobic granular membrane bioreactor system are discussed. In addition, the efficiencies of the two kinds of biological treatment technologies are used in five typical antibacterial anti-inflammatory organic pollutants removal from sewage are deeply studied. The succession of the reaction system microbial community structure, and the function and mechanism of PPCPs are explored from the molecular ecological gene level.Activated sludge is domesticated into granular aerobic sludge(AGS) in this study using the granulation sequencing batch reactor(GSBR) system and granulation membrane bioreactor(GMBR) technology. The results show that granular sludge with a smooth surface and clear outline eventually forms in the GSBR system. The biomass accumulation of this sludge reaches 3.8 g/L. The particle with a 1.0~4.0 mm diameter accounts for 80% of the total sludge volume. The particles denote an excellent sedimentation performance and microbial activity. The protein substances in particles are mainly secreted by the EPS of microbial particles in the reactor, and may promote the formation of sludge particles and the hydrophobic properties of these particles. The moisture content of the mature granular sludge is always maintained at 96.7%~97.6%, which is significantly lower than that of conventional floc sludge. The granular sludge with a smooth surface and soft, khaki or irregular oval-shaped particles eventually forms in the GMBR system. The biomass accumulation of this sludge reaches 5.1 g/L. The particle with a 1.0~3.0 mm diameter accounts for 58.6% of the total sludge volume. The sedimentation performance of the particles is better than activated sludge.Five kinds of antibacterial anti-inflammatory substances are selected as pollutants, and then effect on the stable operation of the process and the removal effects of these pollutants in the two reactors are investigated in this study. The results show that the granular sludge could better and more stably run in the sewage system with PPCP substants, but a certain difference exists on the removal effects of the 5 substants for the system. In the GSBR, the removal effects of prednisolone is significant with average removal rate of 84%, whereas the removal rates of naproxen, sulfamethoxazole and norfloxacin reach 70.5%, 75.7% and 79.8%, respectively. The removal effect of ibuprofen is somehow poor and only reaches 45%. Meanwhile, the degradation process Removal of PPCPs and conventional pollutants of MBR process than GSBR process are improved, such as particle adsorption, biodegradation and membrane filtration separation are contribution to different removal of several compounds in wastewater. The removal effects of prednisolone, norfloxacin and naproxen are obvious, and the removal rates reach 98.5%, 87.8% and 84%, respectively. For sulfamethoxazole and ibuprofen, the degradation effect in the GMBR system is lower than that of the other three substances. The granulation process can improve the removal efficiency of the entire process on organic matter of GMBR process. The final effluent COD removal rate is maintained at 90%. The removal rate of TP gradually increases and is maintained at above 92%. The removal rate of total nitrogen(TN) reaches 95%. The removal rate of NH4+-N is more than 90%. In addition, the effect of sludge retention time(SRT) and EPS on membrane fouling is also studied. The results show that the granular sludge has alleviated membrane fouling in the GMBR. The PN content in the system gradually increases, which could maintain the stable structures of the granules and protect the granular sludge system; thus, the PN content has a certain alleviation for membrane fouling of the reaction system.The adsorption and biodegradation processes of two representative organics with sulfamethoxazole(SMZ) and naproxen(NPS) by aerobic granules are characterized. The removal process of SMZ and NPS are a process of quick chemical adsorption and slow biodegradation. At the same conditions, with the initial concentration of 10mg/L, biodegradation of SMZ and NPS account for aerobic granular sludge removal proportion were 59.4% and 41.3%, which indicates that sulfamethoxazole biodegradation by granular sludge is more obvious. Freundlich isotherm model can better describe the interaction between the aerobic granular and two substances. Data fit pseudo-second-order adsorption kinetic well, which showed this is a physical-chemical adsorption process.The microbial community structure and diversity variation of two biological process for treating containing PPCPs wastewater are further analysed via PCR-DGGE and High throughput sequencing technology. The mechanism of multi-hierarchy microbial and pharmaceuticals pollutants degradation are discussed. The results indicated that the structure and function succession of microbial community are occured based on the GSBR and GMBR process and the new dominant species and the corresponding functional bacteria appear. Firmicutes, Nitrosomonas and Aeromonas are two key features bacterial that play an important role in the process of drug degradation, which belong to resistance gene carriers can ensure better pharmaceuticals pollutants removal efficiency of the system. Besides the advantages of flora in GSBR process, the dominant strains of microorganisms in GMBR process are richer than those of GSBR process. Due to microbial community accumulated and enriched during the process of micro-organisms gradually adapting to the drug environment, the species abundance and diversity in contaminant degradation process have significantly improved. The results opportunely demonstrate that the removal of antibacterial anti-inflammatory pharmaceuticals in sewage is due to mutual synergy of different microorganisms in the reaction system. The microbial flora fir strong resistance promotes stable operation of the reaction system. This study is important in the process change of domestic sewage from the traditional and simple control chemical oxygen demand to water ecological security, and is significant in the effective treatment of antibacterial anti-inflammatory pollutants in the water environment. |
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