Study On Removal Of Organic Micropollutants In Riverbank Filtration System

Organic micropollutants(OMPs)are widely present in the aquatic environment,and although their concentrations are at trace levels,they still pose a potential risk to water safety and human health.Riverbank filtration(RBF),as a pretreatment process to improve drinking water quality,has been shown to be effective in reducing the concentration of OMPs in water sources,and there is growing interest in its great potential to remove OMPs.In this study,the removal of various OMPs by RBF was carried out from both field-scale and laboratory simulators to address the shortcomings in current RBF research.The RBF systems of Wuchang in Heilongjiang and Moutai in Guizhou were sampled respectively,and four RBF simulation devices were built in the laboratory.Taking RBF soil microorganisms and OMPs in water as research objects,the removal efficiency of RBF on various OMPs was investigated.The changes in microbial diversity and community composition in RBF soil were analyzed,and the removal mechanism of OMPs was explored.Provide a certain experimental basis for the practical application of RBF system in China,as well as the process transformation and subsequent research of drinking water plants.The microbial communities of both Wuchang and Maotai RBF soils were dominated by Proteobacteria,Actinobacteriota,Acidobacteriota and Chloroflexi.The relative abundance of microorganisms in the soil changed to different degrees from the riverbank to the bank filter well,and the relative abundance of the Planctomycetota decreased in both RBF systems,while the relative abundance of the Firmicutes increased in both RBF systems.The structural characteristics of the microbial community in soil showed that the bacteria that played a significant role in the removal of OMPs by RBF might be Udaeobacter spp.and Gemmataceae spp.The two RBF systems in this study had good performance and significant purification effects on surface water.A total of 20 OMPs were detected using ultra performance liquid chromatography tandem mass spectrometry(UPLC-MS/MS),and it was found that the Wuchang RBF system could effectively remove 12 OMPs such as atrazine,and the Maotai RBF system played an important role in the abatement of 7 OMPs such as diazepam.After long-term operation of the simulator,it was found that the RBF filled with sediment removed all seven OMPs at more than 55%,much higher than the RBF filled with quartz sand,proving that the microorganisms and organic matter contained in the sediment play an important role in the removal of OMPs.The analysis of the microbial community along the course of the sediment showed that the microbial community diversity decreased,and the abundance of the RBF community in the conventional condition decreased,but the abundance of the RBF community in the OMPs group increased.The overall microbial community diversity and abundance increased slightly along the inlet direction.At the phylum level,the relative abundance of Proteobacteria decreased under conventional conditions in the sediment of 10-20 cm,while Firmicutes showed the opposite trend;The relative abundance of Proteobacteria along the RBF system with OMPs slightly decreased,while the relative abundance of Firmicutes increased.At the genus level,the sediment has the same dominant bacterial genera,and most of the dominant bacterial genera have increased abundance.Along the inlet direction,the relative abundance of Thiobacillus spp.decreased in the RBF system under conventional conditions,and the relative abundance of stricto＿1 spp.increased in the RBF system with OMPs.