Study On Denitrifying Phosphorus Absorbing Process For Farmland Ditch Under Static And Dynamic States

In order to provide technical support for comprehensive treatment of agriculture drainage, and relief of eutrophication caused by discharge of large amount of nitrogen and phosphors, this paper put forward the concept of "Denitrifying Phosphorus-Uptake wall", which was used to investigate the strengthening and influence mechanism through using laboratory simulation of agricultural biomass wastes, such as straw, as carbon source. The Denitrifying Phosphorus-Uptake wall was formed by adding phosphorus adsorption minerals to construct ditch and furrow bottom for agriculture drainage which has good nitrogen and phosphorus removal efficiency. The main conclusion are as follows:By building a dynamic simulation reactor, intensifying key factors of denitrifying phosphorus-uptake were studied under different hydraulic retention time,different carbon source and different pollution load, The results show that the denitrification and dephosphorization effect of the reactor was affected largely by hydraulic retention time, carbon source and pollution load. Longer hydraulic retention time could ensure enough reaction time, so hydraulic retention time was one of the factors to consider when the denitrifying phosphorus-uptake wall was constructed practical.This technology could acquire better denitrification and dephosphorization effect being used in agriculture drainage ditch with rice straw filling than other carbon sources, so rice straw could serve as a kind of suitable external carbon source material. Comprehensively considering all kinds of influence factors, and combining with the actual situation of the agriculture drainage ditch, the removal rate of TN, nitrate nitrogen, phosphate and ammonia nitrogen could reach60%、88%、20%and45%in the expected. Rrom the test, denitrification and dephosphorization effect was grasped under different environmental conditions, and intensifying key factors of denitrifying phosphorus-uptake were further studied. It provided theoretical supports for the demonstration project of denitrification-phosphorus absorption wall under the agriculture drainage ditch.By using static experiment simulating denitrifying phosphorus-uptake wall, with three kinds of biomass materials of rice bran (A), rice straw (B) and wood chips (C) as carbon source, this test studied on the nitrogen and phosphorus removal effect from agriculture drainage under these biomass materials as denitrifying carbon source. The results show that the addition of biomass material could promote the degradation of nitrate nitrogen, and the nitrate nitrogen removal rate under A was the highest, followed by under B, under C and check experiment. When the carbon source was enough and the dissolved oxygen (DO) was relatively low, nitrate nitrogen removal would be relatively fast. Phosphate was removaled mainly by adsorption, while addition of biomass material enhancing this effect. The effect of A was the best, but it would lead to serious secondary pollution, especially in static time. So it was suitable for short-term efficient process. The effect of B was relatively better, but the secondary pollution was lighter than A. C had a general effect, but the secondary pollution was also light, so long-term landfill may have a desired effect. In conclusion, rice bran (A) is suitable for denitrification-phosphorus absorption wall under the agriculture drainage ditch. Rrom test.the law of the reactor was be grope,and the effect of denitrifying phosphorus-uptake was deeply understood.lt provided necessary supplement for condition appearingpossibly for the demonstration project of denitrification-phosphorus absorption wall。...