Slow-release Carbon Source Composite Materials’ Preparation And Used In Groundwater Nitrate Pollution Remediation Experiment Research

Groundwater is an important water resource of human. However, with the rapiddevelopment of social economy, the pollution problem of groundwater nitratenitrogen has become increasingly serious, which caused great threat to human andenvironment. It is an such urgent problem to develop suitable organic carbon sourcecarrier materials that groundwater nitrate pollution can be remediated safely,continuously, stably and efficiently.Two aspects of research have mainly been carried on in this article, including thepreparation of slow-release carbon source composite materials and used fordenitrification in groundwater nitrate pollution. First, carbon source raw materials andskeleton raw materials were analyzed, including the physical and chemical properties,carbon released properties and toxicological properties. The hemp fiber and potatostarch were chosen as carbon source materials. PBS, PLA and PE were chosen asskeleton materials. The raw materials were mixed, and then extruded, granulated byusing double-screw extruder. Finally, six kinds of composites were prepared,including HB20, HB40, HE40, HLE, HBE and CBE.The kinds of composites were analyzed by static experiments. HE40, HLE, HBEand CBE which had good carbon released performance were chosen for subsequentcolumn experimental study. The performance of HE40’s denitrification was not good.When the initial concentration was30.0mg/L, at most27.7%of nitrate could beremoved after72h at25±1℃, and accumulation of nitrite nitrogen was detected. Theendurance of HLE’s denitrification was not good. When the initial concentration was30.0mg/L, only13.1%of nitrate could be removed after24h at25±1℃in the30thday, and the maximum value of nitrite nitrogen concentration was greater than1.0mg/L in the effluent. The performance of HBE’s denitrification was good andstable. When the concentration was30.0mg/L, nitrogen could be almost completelyremoved after24h. High removal rate of nitrogen still could be maintained when theinfluent nitrate concentration was great or the temperature was low. The slow-releaseperformance of HBE was good, the value of COD_Mnwas stable at about3.0mgO2/L after initial stage. To ensure enough hydraulic retention time, nitrate nitrogen could beremoved efficiently by CBE, even if the influent nitrate concentration was great. Butthe value of COD_Mnwas great. Temperature and hydraulic retention time had greatinfluence on the performance of CBE’s denitrification. The denitrification rate at25℃was1.73times higher than that at11℃; The average nitrogen removal rate was only75.5%and the accumulation of nitrite nitrogen was detected when the hydraulicretention time was8h, the performance of CBE’s denitrification became bad.In conclusion, slow-release carbon composite material HBE is the most idealcarbon source carrier material used in the bioremediation of groundwater nitratepollution.