Study On The Decontamination Performance Of Organism In Sewage By The Micro-Aeration Enhanced Ecological Floating Bed

The prevention of water pollution, the protection and improvement of water environment and the safety of drinking water mean a lot for promoting the sustainable development of the economy and society, and they are also important for achieving "The China Dream". The organic pollutant is one of the significant indexes for measuring the quality of water environment and controlling the cuts by the government. When the concentration of organic pollutants is high, the water would be black and stinky, and the balance of water system would also be destroyed, which not only harm to the water ecological system, but also to the human health through the food chain. Therefore, the control and reduction of organic pollutants are important goals of the management of water environment. The ecological floating raft, one effective n-situ biological-ecological restoration technology, can effectively reduce the organic pollutants and nutrients in water to purify water quality by the plant which is fixed in the polluted water in the form of artificial floating raft. The ecological floating raft has been widely used in the water treatment of reservoirs and lakes, etc. in recent years because of it’s advantages:easy to built, low cost, easy to maintain, high landscape effect and low secondary pollution, etc.In this study, the micro aeration system and artificial medium were introduced into the traditional ecological floating raft to built the micro aeration enhanced ecological floating raft including "aeration unit (micro aeration system)+microbial processing units (artificial medium)+aquatic plant units (plant floating raft of Iris tectorum)", the removal efficiency of the organic pollutants under different operating conditions by this micro aeration enhanced ecological floating raft were analyzed to understand the change regularity and the removal mechanism of the organic pollutants in the water. Therefore, the optimal operating conditions were determined which can provide the theoretical basis and design support for the popularization and application of the micro aeration enhanced ecological floating raft technology. The major conclusions were shown as follow:The removal efficiencies of CODcr, TN and TP in the micro aeration enhanced ecological floating raft under the same operating conditionswere 59.2%,76.8% and 62.7%, respectively, which were higher than those in enhanced ecological floating raft and the traditional ecological floating raft. Results showed that the micro aeration enhanced ecological floating raft which consist of aeration unit (micro aeration system), microbial processing units (artificial medium) and aquatic plant units (plant floating raft of Iris tectorum) can significantly improve the biomass and bio-activities in water body, the introduction of the artificial medium and the aeration unit can strengthen the removal efficiencies of the organic pollutants, TN and TP. Moreover, Iris tectorum can be used as a good floating raft plant.The removal efficiencies of BOD5 and CODcr in the micro aeration enhanced ecological floating raft under different aeration quantity were shown as:7.0 Lmin-1＞10.0 Lmin-1>5.0 Lmin-1＞3.0 Lmin-1＞0.0Lmin-1. The DO value and the microbial biomass in the ecological floating raft system were two important factor which affect the removal efficiencies of BOD5 and CODCr, excessive aeration quantity would restrain the purification capacities of the micro aeration enhanced ecological floating raft.The removal efficiencies of BOD5 and CODcr in the micro aeration enhanced ecological floating raft under different artificial media were shown as:the combination filter> the combination filter+three-dimensional filter> the three-dimensional elastic filler. Compared with the three-dimensional elastic filter which has the radial structure, the combination filter with polyester filaments structure can better intercept the organic pollutants and it’s more suitable for the growth of the microorganism. Simply raising the surface area of the filter can not improve the purification capacities of the micro aeration enhanced ecological floating raft efficiently, factors like the filter material quality, interception of the organic pollutants and easy for microorganism to attach should all be considered.The over all trends of the BOD5/CODCr ratios (B/C) in the micro aeration enhanced ecological floating raft under different aeration quantity and artificial media via time were shown that the low values were in the middle and the ratios at the end of the experiment were lower than those at the begging of the experiment. The B/C value decreased after the experiment by the micro aeration enhanced ecological floating raft.