Study On The Purification Efficiency Of Membrane Aeration Biofilm Reactor-ecological Floating Beds Integrated Device For Highly Stagnated Water

In recent years,with the rapid development of economic level and the acceleration of urbanization process,the pollution of small and medium-sized rivers in cities has been increasing.In addition,the small inflow and slow flow speed make them highly stagnated water bodies,so the self-purification ability is weak and the aquatic ecosystem has been seriously degraded.Taking highly stagnated water bodies as the research object,this paper develops a vertical integrated purification device ?IPD?for membrane aeration biofilm reactor?MABR?and ecological floating beds?EFB?device by analyzing the research results of purification technology of polluted rivers at home and abroad.MABR uses gas separation membrane as the carrier and oxygen supplier of biofilm,in order to remove pollutants in water.EFB is often used for river regulation because of its good ecology and economy.In this study,MABR is combined with EFB for the first time,and its effect on water restoration is verified by a large number of experiments.A test of different devices was carried out to testify the increased efficiency for NH₄⁺-N?TN?TP and COD_Mn of IPD rather than the individual MABR?EFB and water purification.The experimental results have shown that the IPD has the best purification effect:the removal rates for NH₄⁺-N of IPD?MABR?EFB and water purification were 98.0%,96.6%,66.6%and 48.5%respectively;the removal rates of TN were 34.7%,26.9%,19.3%and 9.6%respectively;the removal rates of TP were60.7%,33.9%,86.9%and 38.5%respectively;the removal rates of COD_Mn were 78.3%,53.1%,58.4%and 40.2%respectively.Moreover,the IPD can increases DO and greatly improve the transparency of water.And it has a significant inhibition on chlorophyll a.A hydrodynamic test was carried out to investigate the purification effect of each device under different hydrodynamic conditions.The results have shown that the EFB with plants as the main purification agent is susceptible to the influence of external environment,according to several purification indexes,it is considered the optimal hydrodynamic force of the EFB is the low flow rate of 5 m/h;the reaction efficiency of MABR can be improved by appropriate increase of the flow rate,for the removal of N,the optimal hydrodynamic force is 15 m/h,but the removal of TP or COD_Mn in water body is better under the condition of low flow rate?5m/h?hydrodynamic force;the IPD is less affected under the condition of high flow rate hydrodynamic force, which makes its application scope wider,considering several purification indexes,it is considered the flow rate of 10m/h is the best hydrodynamic condition.Under the best hydrodynamic condition,the removal rates for NH₄⁺-N of IPD?MABR?EFB 100%?99.29%and 98.43%respectively;the removal rates of TN were 46.53%?30.08%and 36.63%respectively;the removal rates of TN were 96.43%?99.29%and93.85%respectively;the removal rates of COD_Mn were 99.73%?92.72%and 85.67%respectively.Exploring the effect of spacing on the purification efficiency of the IPD at 10m/h flow rate.The results show that the change of spacing has little effect on COD_Mn and TP,thinking the 2m spacing is the best one.Fixed the test results of 10m/h hydrodynamic conditions and 2 m interval as the purification effect of the IPD.Taking the measured water quality of Yueya River as the main purification body,the layout scheme of the IPD is designed:assuming that the length of each device is 1.5 m,280sets are required along the longitudinal river;along the river wide direction,each 5m layout of a row of IPD,need to set up 6 rows.