Study On The Mechanism And Test Of Biological Hardening Purification Directly For Polluted Streams

In recent years, because of the fast development of economy and fast expansion of the city, the pollution accidents of the medium and small rivers are happening constantly, river ecosystem is severed, which make how to prevent river shed getting worsen, protect the water resource further, take the road of sustainable development become the goal that the mankind pursues together.This paper regards medium and small rivers as the research objects, synthesizes domestic and international research results of cleaning technique for polluted river water bodies and combines the characteristics of lined riverbed mostly, shallow water depth generally, little water yield, slow flow velocity, serious pollution of our country and relatively weak economic base, the new-type biological packing was designed and laid in the river directly to purify the polluted water body.First of all, the new-type biological packing was designed by imitating a kind of algae(Chara foetida) in the river ecosystem, it has the large surface areas and very strong elasticity , toughness and flexibility, which make it stand on the "riverbed" without support or frame and swing with rivers flow freely ,etc. Then the new-type biological packing was dynamic cultivated in the natural river for 30 days, the degradation rate of CODmii was being steady on 10%, the degradation rate of NH₄⁺-N was being steady on 40%. And the appearance of the biomembrane on the packing silk has gone through the colourless and transparent, light green, yellowish green, brown and green, dark brown, at the same time the living beings on the packing silk has gone through nothing, the alga as the core, the fungus glue group, the miniature animal finally etc, a series of change course, which marks microorganism has been hung successfully on the new-type biological packing in the natural river.Secondly, a series of tests was done to verify biomembrance's degradation capability hanging on biological packing in different periods. During the tests the polluters density is low (belonging to No. three genus of the water environmental quality level of surface water in most time), this influences the degradation effect to a certain extent, and makes the degradation rate of the polluters on the low side. The degradation rate of the organic matters is less than 10%, the range of the ammonia nitrogen degradation rate is in 5.35%³9.91%,and total phosphorus degradation rate is up to 28.6% too. And the tests discover the quantity of the heterotrophic bacteria and degradation rate of the organic matters have the same changing trends, at the same time the quantity of the nitrifying bacteria and degradation rate of the ammonia nitrogen have the same variation tendencies too, which proves the biodegradation of the organic matters and the ammonia nitrogen are mainly finished by the heterotrophic bacteria and the nitrifying bacteria in river. In addition organic biodegradation mode expressed with COD_Mn and ammonia nitrogen biodegradation mode were derived according to the characteristics of the river and Monod dynamics equation, which offers the theoretical foundation for popularization and using of this technology.Finally, the best layout of the biological packing in river was confirmed by analyzing biological packing impact on river water motive force condition and purification effect. This shows the feasibility of the technology used directly to purify the polluted river ulteriorly.