Effect of Periphyton in Artificial Substrate on the Purification of Eutrophicated Water

Features of periphytons in artificial substances for purifying eutrophicated water of algae and nutrient substances, like nitrogen & phosphorus were studied and influence of physical & chemical properties, like water depth, water flow velocity, DO, temperature and pH, on the purifying effect were analyzed. Results show that in still waterbody, the mean removal rate of NH₄⁺-N、TN、TDN、NO₃^--N、TP、TDP、PO₄^3--P was 98.90%、45.15%、42.78%、38.13%、76.18%、80.11%、87.02%, respectively, and Chl-a content decreased by 63.53%. Water depth affected the decreacing speed of Chl-a to some extent, but did not affect the removal rate of other nutrients. Water flow velocity, once increased from 0 to 200 L•h^-1, raised the removal rate of TP, TDP to a certain extent, from 76.18% to 85.13%; and from 80.11% to 83.76%, respectively, while Chl-a content was raised by 63.53% in still water, and by 72.17% in dynamic water. However, it lowered that of TN, TDN and NO₃^--N from 45.15% to 32.02%; from 42.78% to 28.73%; and from 38.13% to -5.26%, respectively, and did not affect much that of NH₄⁺-N and PO₄^3--P (NH₄⁺-N: from 98.90% to 98.59%; and PO₄^3--P: from 87.02% to 86.13%). Among the physical & chemical properties, DO was also a factor affecting the purifying effect.