Study On Treatment Of Micro-polluted River Water By Artificial Floating Island With Composite Media

As urban rivers receive tail water discharged from sewage treatment plants,rivers are usually in a state of micro-pollution and develop into black and odorous water bodies in severe cases.In view of the fact that the nutrient level of the effluent is still high and the self-purification capacity of the river is limited,the artificial floating island purification system of the composite medium was constructed,and the research on the purification of the simulated and actual river water was carried out.The effects of influent concentration,hydraulic retention time and temperature on the treatment effect were investigated,and the microbial community structure of the system was analyzed.Combined with the experimental results,a process scheme for purifying micro-polluted river water based on composite medium artificial floating islands was proposed,which can provide reference and theoretical basis for the engineering application of floating islands.Constructed an artificial floating island purification system using volcanic rocks,combined packing,pyrite and limestone as composite medium in this paper.Floating island plants were Canna and planted directly in the volcanic rock filler.The composite filler with a diameter of 150mm was suspended under the floating bed.The other end of the composite filler was connected to the mixed pyrite and limestone filler at the bottom.In the study of simulated wastewater,when the optimum HRT of the system is 3d,with the increase of pollution concentration,the removal efficiency of pollutants is still better.The average removal rates of TN,TP,NH₄⁺-N,NO₃^--N and COD can reach 56.45%,68.47%,74.88%,52.13%and83.15%respectively.In the study of sewage removal of Fuhe raw water,the average removal rate of ammonia nitrogen can reach 74.35%at low temperature.The treatment efficiency of TN and NO₃^--N at low temperature is significantly lower than that at normal temperature.The removal rate of COD can reach more than 70%at both temperatures.The effluent concentration of TP is not significantly different at normal temperature and low temperature and the average effluent concentration of TP was 0.08mg/L and 0.05mg/L respectively.There are obvious differences in the microbial population structure of the system under different temperature conditions.The main phylum in the system at normal temperature and low temperature are Chloroflexi and Actinobacteria respectively.The main class in the system at normal temperature and low temperature are Anaerolineae and Actinobacteria respectively,which are consistent with the conclusion in the level of phylum.In both temperature environments,the diversity of bacteria in the reaction system at genus level is high and many potential new species may exist.According to the actual on-site investigation,an ecological sedimentation pond process based on composite medium artificial floating island technology is proposed to enhance the self-purification ability of micro-pollution river water.Under the condition that the influent water is worse than the Grade V,the non winter effluent can met the class IV specified in the Environmental Quality Standards for Surface Water?GB3838-2002?,and the flood season and winter effluent can met the class?specified in the Environmental Quality Standards for Surface Water?GB3838-2002?.