Reaserch On The Treatment Of Urban River Water With Carbon Fiber Floating Bed Enhanced By Micro Nano Aeratio

As a kind of bio-ecological restoration technology, Artificial floating bed technology has been widely used in the river water restoration in the city. The combination of micro nanometer aeration and carbon fiber artificial floating bed technology has been designed for strengthening the river water treatment effect in this paper. This paper was based on the new Phoenix River water quality improvement project which created by Beijing Municipal Science & Technology Commission. Through lab tests on new ecological floating bed combination technology, provided theoretical basis and data support for its application in the water quality improvement project. At first, two kinds of aeration technology, micro nano aeration and traditional aeration, has been compared In the start-up process of the reactor. Then the process parameters of combination process of micro nano and floating bed has been optimized and screened. Finally the change of floating bed reactor effluent and microbial community structure which adhere to carbon fiber surface has been studied, which have been made by the addition of microorganism BABRC-1.After operated about 44 days continuously and stably, the removal rate of COD_Cr and ammonia nitrogen all reached above 60% in micro nano aeration floating bed system, which indicated that the floating bed reactor started successfully. After a period of stable operation, the average concentration of COD_Cr, ammonia nitrogen and TP in the effluent of reactor were 63.36 mg·L^-1,24.49 mg·L^-1,1.41 mg·L^-1, respectively, and their removal rate reached 71.35%,71.08% and 44.38%, respectively.At the same time, more time about 6 days has been spended on the start-up process for the traditional aeration floating bed. The reactor start-up process showed that the time of micro-nano floating bed reactor had better removal effect on COD_Cr, ammonia nitrogen and TP in the simulated river water quality. The greater removals of COD_Cr, ammonia nitrogen and TP and less starting time were observed in floating bed reactor with micro nano aeration technology for the simulation of river water.Since then the process parameters optimization experiment of micro nano aeration floating bed reactor was carried out. In the study of influent concentration, The results showed that with the decreasing of influent concentration, the removal rate of COD_Cr and TP decreased and the remove rate of ammona nitrigent increased obviously. Micro/nano aeration floating bed system have good water treatment effect in contrast tests of three concentration load conditions about high, medium and low. The influent of high concentrations of COD_Cr, ammonia nitrogen and TP were 101.64 mg·L^-1,36 mg·L^-1 and 2.02 mg·L^-1, respectively. And the average removal rates were 90.24%,91.54% and 48.34%, respectively. In combination with the actual investigation of the high water chemical oxygen demand in the river outfall, the high concentration load water was chosen as the experimental water in this test.The parameters of HRT was studied on its effect of the water treatment results of floating bed system. The results show that the effluent quality of micro nano aeration floating bed reaction device influented by HRT more obviously. With the continuous rising of HRT, the removal efficiency of COD_Cr on floating bed system increased at the beginning and then leveled off, removal rate of ammonia nitrogen showing a slow upward trend and TP removal rate is keep rising. On the condition of 24h for HRT, The removal rate of COD_Cr, ammonia nitrogen and TP for floating bed system basically reached a high level, which was 85.1%, 71.2% and 43.5%, respectively. To sum up, it is known that choosing HRT for 1 day is more suitable for the operation of micro nano aerated floating bed reactor stably and efficiently.It was found that the removal rate of COD_Cr and TP increased firstly after declining, and the removal rate of TP reached a maximum decreased at the 4:1 gas-water ratio. The removal rate of ammonia nitrogen tended to be stable before increased with the gas water ratio rising, and the removal rate of it reached 92.1% when gas water ratio was 4:1. With the gas water ratio increased, ammonia removal rate have no significant changes, thus 4:1 was selected as the optimum air/water ratio in the operation of aeration floating bed.The effects of 8h ?0:00-8:00?,16h ?16:00-daily 8:00? and continuous aeration on the effluent of floating bed reactor were investigated. The experiment results showed that the water treatment effect of micro nano aeration floating bed reactor was affected by the aeration time obviously, and the removal rate of reactor effluent about COD_Cr, ammonia nitrogen and TP increases gradually with aeration time prolonged. The indicators of pollutants COD_Cr, NH4+-N and TP removal rate reached 78.56%,61.44% and 45.15%, and the decontamination ability of the floating bed system was good and in terms of energy consumption compared with continuous aeration can save 33%, so that the intermittent aeration 16h in engineering practice has certain feasibility.The effect of microbial agent BABRC-1 on the water treatment effect was studied, and the result shows that the removal rate of COD_Cr and ammonia nitrogen increased by 95.61% and 96.42%, respectively. the removal rate of TP had no significant effect on the micro nano aeration floating bed reactor. The microbial community structure and composition which sticked on the surface of the carbon fiber filler were analyzed before adding BABRC-1 and after in the experiment. Genera abundances of pseudoxanthomonas, ottowia and flavobacterium increased obviously, thus further illustrates that the removal rate of ammonia nitrogen is enhanced by microorganism preparation.