Performance Of Activated Carbon Rotating Biological Contactor(AC-RBC) In Treating Polluted River Water

At present,the rapid economic development of China poses a serious threat to the rivers and lakes ecosystem.In response to the increasingly serious pollution problems of rivers and lakes,the activated carbon was combined with rotating biological contactor to treat contaminated river water which based on the survey and monitoring of Li Lake and river in Jiangnan University in Wuxi.The effects of inoculum and modification on the start-up of activated carbon rotating biological contactor were investigated.The effects of rotating speed,hydraulic retention time?HRT?,temperature,C/N,and antibiotic?amoxicillin?on different activated carbon rotating biological contactor were discussed.The characteristics of the biofilm and the structure of the microbial community at each stage were systematically analyzed to provide a theoretical basis for the change of the removal rate of each pollutant.The entire experiment provided scientific basis and technical support for the implementation of the Li Lake Ecological Restoration Demonstration Project,and provided a technical reference for realizing the activated carbon rotating biological contactor in situ treatment of polluted river water.The main conclusions are as follows:?1?Three inoculum?river,sediment,activated sludge?multiply by 3 activated carbons?unmodified,KMnO₄ modified,H₂SO₄ modified?were used for start-up of activated carbon rotating biological contactors.The results showed that the reactors inoculated with river water and sediment had a similar microbial community structure,but the sediment was faster than the river water to achieve stability.The reactors inoculated with activated sludge and sediment were almost achieve stability at the same time.While the removal rate of each pollutant was different?activated sludge>sediment mud?river water?.The modifications increased the hydrophilic groups on the surface of activated carbon?H₂SO₄ modification>KMnO₄ modification>Unmodified?,improved the removal performance of various pollutants during the start-up phase of biofilm formation,and increased the activity of microorganisms.?2?After the biofilm maturation,the effect of rotating speed and HRT on the 9 groups of activated carbon rotating biological contactors was investigated.The results showed that the activated carbon rotating biological contactors achieved the best disposal efficiency when the speed was 3 r/min and the HRT was 12 h.On the other hand,biofilm analysis showed that if the rotational speed is too low,biofilm activity will be limited.In a certain range of HRT,the longer the HRT,the larger the VS/TS and the higher the biofilm activity.However,in order to improve the treatment efficiency,the HRT was 12 hours.Under the optimal conditions,biofilm high-throughput sequencing indicated that all 9 reactors could achieved simultaneous nitrification and denitrification.The reactors inoculated with river water and sediment mud had similar species composition.There was a certain difference between the reactors inoculated by activated sludge and sediment mud.Besides,the modification increased diversity and richness of species?H₂SO₄ modification>KMnO₄ modification>unmodified?.?3?When the speed was 3r/min and HRT was 12h,the influence of temperature and C/N on the activated carbon rotating biological contactors were investigated.The results showed that the optimum temperature was 28°C and the C/N ratio was 6:1.Biofilm analysis showed that the microorganism had highest activity.Fluorescence in situ hybridization?FISH?analysis showed that the structure of the bacteria would change as C/N change.In addition,the difference of effect in inoculum and whether it was modified was negligible at low temperatures.?4?At speeds of 3 r/min,HRT of 12 h,temperature of 28°C,and C/N of 12:1,the effects of different concentrations of amoxicillin on the activated carbon rotating biological contactors modified by H₂SO₄ of different inoculum were investigated.The results showed that different concentrations of amoxicillin have different degrees of inhibition on the performance of activated carbon rotating biological contactors.The biofilm activity also decreased.Three-dimensional fluorescence diagrams showed that low concentrations of amoxicillin stimulate microbes to secrete small molecule proteins?I?.With concentration increasing,more solubilized microbial products were produced.The biofilms with and without 0.5 mg/L amoxicillin were used for high-throughput sequencing.The number of species,functional bacteria,diversity and abundance were drastically reduced,while activated carbon rotating biological contactors had certain removal of amoxicillin.