Selection Of Solid Phase Carbon Source Materials Used For Denitrification Of Groundwater

Shallow groundwater nitrate pollution is very common in the Dianchi lake area. The shallow groundwater in agricultural lands is mostly polluted by nitrate. During rainy seasons, nitrate concentration in greenhouse area can be above 30 mg/L while carbon nitrogen ratio is lowe han 4, making it difficult for denitrification reaction to occur.Nitrogen mainly relies on denitrifying bacteria in a reduced environment. In the denitrification process, nitrogen often needs reducing agents such as organic carbon, sulfur and iron chemicals to provide electrons.ln theory, the choice of the shallow groundwater electron donor scope is wide. But in practical application, due to shortage in the support funding of Hubin agricultural non-point source pollution control district, high underground water level and enormous contaminants entering the lake each year, there is limited option of electron donor. High efficiency, low cost, has the long-term, small side effects become the main factor when selecting electron donor materials.This study mixs natural materials and artificial material, effect and cost, give attention to two or more things to rice husk, sawdust and industrial starch as the main carbon source, with polyvinyl alcohol as skeleton material and supplementary carbon source, according to the different proportion were used to remove a groundwater hydrochloride sustained-release materials.Main content and the experimental results are as follows:(1) 5%-40%, the polyvinyl alcohol series concentration has the solution, the concentration of 10%.15%,20% for granulation, can be stored under the condensed state in a year. And 15% concentration of polyvinyl alcohol solution produced by solid carbon source with slow-release effect is best. Accordingly, the nitrogen and phosphorus release quantity is small, small side effects.(2) In 10 cm/d hydraulic load conditions, the 1 (industrial storch:rice husk: sawdust=1:1:1) have the best denitrification effect,Denitrification endurance is stronger.Dynamic Test run for 156 days, the average nitrate removal rate is 87.92% for total nitrogen and 89.03% for the average nitrate nitrogen removal, test was not found in the process of nitrite accumulation.(3) Using solid carbon source of formula 1, polyvinyl alcohol accounted for 31% the rest of the hybrid material composition is 69%, carbon source release period 100-120 days, it is valid for three times as many rice husk mixed with sawdust.source. Basically meet the need of rainy season, convenient application in the field of agricultural non-point source pollution control.(4) The scheme of the raw material price is RMB 5600-5700 yuan/ton. About 20-21% of the artificial materials (PLA).