Simulation Test Study About Solid Carbon Source For Groundwater Nitrate Removal

Nitrate pollution of groundwater has become a worldwide environmentalproblem. Biological denitrification to remove nitrogen has gradually become themain development trend in groundwater nitrate removal. In biologicaldenitrification nitrogen removal process, using solid material as external origin cansolve the problem of secondary pollution caused by adding overdose liquid carbonsource, so the solid carbon source become recently research hotspot.In order to seek cheap and efficient solid carbon source, the study used fivekinds of solid material which are cotton, loofah, sugarcane bagasse, degradablelunch boxes, sawdust. Comparative test for denitrification conduct in the conicalflask, study on experiment of NO₃^--N, NO₂^--N，NH₄⁺-N and pH changes, analysisof NO₃^--N and TN removal rate. The results show that, pH is in6.9⁸.5rangefloating in the denitrification process, degradable lunch boxes and loofah relative toother solid organic carbon sources have higher removal rate on NO₃^--N and TN,but loofah total nitrogen removal rate was significantly lower than the degradablelunch box.Further study to compare the nitrogen removal effect about the loofah anddegradable lunch boxes as carbon sources, set dynamic test of the sand column,study on changes of NO₃^--N, NO₂^--N，NH₄⁺-N and pH with two kinds of carbonsource, analysis of NO₃^-N and total nitrogen removal rate. The results show that,degradable lunch boxes relative to loofah has better effect on nitrate removal.When the influent NO₃^--N concentration was20mg/L, pH was6.8and HRT was10.3h, the NO₃^--N removal rates of degradable lunch box as carbon source couldreach100%, no accumulation of nitrite ultimately, total nitrogen removal rate isalso high up to100%. Degradable lunch box is economic and effective optimumcarbon source.Study on different factors on biological denitrification with degradable lunchboxes as carbon source, experimental results show that: a great influence oftemperature on nitrogen removal in20℃²6℃, nitrate removal rate increasedgradually with the rise of temperature. Nitrate removal rate is70%at20℃andnitrate removal rate reach100%at26℃. With the increasing in nitrateconcentration of influent, nitrate removal efficiency decreased. While influent nitrate concentrations was of20⁴0mg/L, nitrate removal rate drops slightly, andwhile influent nitrate concentrations was of40⁶0mg/L, nitrate removal ratedecreased by nearly30%. While influent pH was in5.5⁸.5, nitrate denitrificationeffect lessly. The longer the HRT, the faster the removal rate of nitrate,denitrification is the more thorough.