Study On Purification Ability Of Wetland Ecological Island In The Treatment Of “More Natural” River

This research on the basis of literatures and technologies, then in view of the urban river that had been polluted to black and odorous, we explore a kind of technology called wetland ecological island with sandstone as matrix and the pilot test was carried, at the same time, compared with conventional ecological island with soil as matrix. Analyzes the technology in oxygen transfer capacity, water exchange capacity, water quality purification capacity and ecological island microbial community diversity in several aspects. Meanwhile, a preliminary assessment of wetland ecological island technology application in the actual channel case, whether it can be beneficial to urban black and odorous river, and whether it can be a positive effect on urban river bioremediation technology in the future.According to the experimental study, Results showed:(1) oxygen transfer capability, in the situation of water wave and water static, DO level of wetland ecological island are better than the conventional ecological island increased by 74.5%, 75.2%, 75.4% and 75.2%, 71.0% and 39.2%, respectively. Wetland ecological island contributes to the transfer of oxygen,and much higher than the conventional ecological island.(2) water exchange capacity, pure sand pool, pool planted Iris and pool with reed wetland ecological island’s largest water exchange rate reached 90.6%, 31.0% and 31.0% respectively, and pure soil pool, pool planted Iris and pool with reed conventional ecological island’s largest water exchange rate was 11.6%, 12.1%and 12.1% respectively, the water exchange rate, respectively 7.8 times, 2.6 times and 6.8 times higher, therefore, wetland ecological island water exchange capacity is much higher than the conventional ecological island.(3) water purification ability, when the water wave, three type wetland ecological island of TP, TN and COD removal rate reached 75.84%, 80.26%, 63.90% and 80.26%, 63.90%, 48.68% and 69.23%, 82.69%, 75.00%, then three conventional ecological island, which was 33.77%, 50.03%, 49.35% and 45.52%, 46.13%, 44.59% and 46.13%, 73.08%, 61.54%;when the water static, the degradation rate of TP, TN and COD of two kinds of ecological island declined by more than 50%.The better ability of oxygen transfer and water exchange and promote the oxygen and polluted water into the interior, and the biofilm on matrix get more oxygen and nutrients, further promote the purification ability of ecological island.(4) microbial community diversity analysis, two kinds of ecological islands riches ammonifying bacteria, nitrifying bacteria,denitrifying bacteria, and other functions of microbial, there may be nutrition liquid, material barren and the hydraulic impact, the amount of microbial community diversity in wetland ecological island is lower than the conventional ecological island.(5)the real case of wangshan river shows, wetland ecological island has a good effect in the field of adaptability and ecological restoration. Though the bioremediation and continuous monitoring from January to October, the COD, TP, TN, NH4 removal efficiency reached 55.01%, 40.0%, 40.96%, 40.0%.Resules show that wetland ecological island for the bioremediation of polluted urban river is a kind of feasible technology.