Research On Micro-polluted Water Of Qingyi River Purification By Compound Ecological Floating Island And Ecological Filter Dam

Aiming at the remaining existing pollution of Qingyi River basin,the compound ecological floating island and ecological filter dam were studied.Support was provied for substrates combination of compound ecological floating island and ecological filter dam by substrate selection.Compound ecological floating island was construced by the research on combination of substrates,selection and combination of plants and new combined carrier with slow-releasing carbon source.Iron-carbon ecological filter dam were constructed by collocation of substrates and application of iron-carbon microelectrolysis in ecological filter dam.Purification effect of compound ecological floating island and iron-carbon ecological filter dam on micro-polluted water was studied,which would provide technical reference for the treatment of Qingyi River basin.The main results were as follows:（1）The adsorption effects of different substrates on NH₄⁺-N and TP were compared,the results showed that the NH₄⁺-N equilibrium adsorption capacity of zeolite（459.95mg/kg）and vermiculite（360.98mg/kg）were obviously higher than medical stone and volcanic rock,and the NH₄⁺-N adsorption process of zeolite and vermiculite could be fitted best by the pseudo-second-order kinetic equation.The TP equilibrium adsorption capacity of slag（35.89mg/kg）was higher than steel slag,vermiculite and gravel,and the TP adsorption process of slag could be fitted best by the pseudo-first-order kinetic equation.（2）The basic tests about substrate combination,plant selection and carrier construction in compound ecological floating island were carried out.The results were as follows:（1）The purification effect of COD and NH₄⁺-N in “zeolite + slag” were better than “vermiculite + slag”,and the former combination could be used as substrate in compound ecological floating island.（2）Canna had the higher removal for COD and TN,and reed had the higher removal for NH₄⁺-N and TP,thus,the combination of reed and canna could be used as the plant in compound ecological floating island.（3）When the start-up stage of the carrier tests was completed,a large number of zoogloeae were found and coccus,bacillus could be observed by scanning electron microscopy.The average removal efficiencies of COD and TN with combined carrier were 7.57% and 5.50% respectively higher than fiber carrier,and the average degradation rates of COD,NH₄⁺-N,TN and TP with combined carrier were higher than that of fiber carrier.The average removal efficiencies of NH₄⁺-N and TN with new combined carrier were 5.09% and 19.74% respectively higher than combined carrier,and the average degradation rates of COD,NH₄⁺-N,TN and TP with new combined carrier were higher than that of combined carrier.It was proved that the new combined carrier with slow-releasing carbon source could improve denitrification under the premise of ensuring COD removal,which could be used as the carrier material in compound ecological floating island.（3）The purification effect of compound ecological floating island under different DO was discussed.（1）The results showed that under the condition of low DO（1³mg/L）and high DO（3⁵mg/L）,the average removal efficiencies of COD,NH₄⁺-N,TN and TP in compound ecological floating island were better than that of ordinary ecological floating island.It was proved that the compound ecological floating island was suitable for treating river water with different DO.The average removal efficiencies of NH₄⁺-N in the compound ecological floating island with high DO was 28.15% higher than low DO,TN was 19.98% lower than low DO.It was proved that high DO was favorable for the removal of NH₄⁺-N,but not conducive to the removal of TN.（2）The dominant bacteria in compound ecological floating island were Pseudomonas,Janthinobacterium and Clostridium sensu stricto,and the dominant bacteria in ordinary ecological floating island were Janthinobacterium,Pseudomonas and Clostridium sensu stricto,Arenimonas.The species richness of samples in compound ecological floating island were higher,which proved that the purification effect of compound ecological floating island was better than ordinary ecological floating.The diversity of microbial communities on ordinary ecological floating was higher than compound ecological floating island.（4）The tests of substrate collocation on ecological filter dam and iron-carbon eclolgical filter dam were carried out.（1）The results showed that the average removal efficiencies of NH₄⁺-N and TN in mixed ecological filter dam were 9.75% and 8.01% respectively higher than layered filter dam,thus,the mixed form of substrate collocation could be used in ecological filter dam.（2）The average removal efficiencies of COD,NH₄⁺-N,NO₂^--N and TN in iron-carbon ecological filter dam were 18.68%,4.17%,15.56% and 8.99% respectively higher than ordinary ecological filter dam,and the average degradation rates in iron-carbon eclolgical filter dam were higher than that of ordinary ecological filter dam.It was proved that the addition of iron and carbon could improve the removal effect of COD and TN in ecological filter dam.（3）The dominant bacteria in iron-carbon ecological filter dam were Pseudomonas and Clostridium sensu stricto,and the dominant bacteria in ordinary ecological filter dam was Pseudomona.The diversity of microbial communities on the activated carbon of iron-carbon eclolgical filter dam was higher in comparison with the other materials.