Experimental Study On Fe~0-PRB To Remove Nitrate In Groundwater

With the development of the economic, as well as the solid waste landfill andunreasonable pile up, a large amount of chemical fertilizers is unreasonableapplication, water and nitrogen industrial wastewater unreasonable treatment, theseproblems lead to many countries in the world groundwater polluted by nitrate, andshowed a trend of serious. This pollution will threat people’s health, therefore, it isnecessary for management nitrate pollution of groundwater.The main purpose of this study, through batch experiments and PRB columnexperiments, is to examine the function of Fe0for removing of nitrate nitrogen,analysis the reduction product, study the optimized conditions, provide technicalsupport for Fe0used as filler in PBR in field application.Batch experiments result showed that the nitrate removal efficiency increasedwith descent of pH; elevated temperatures and pre-acidification of Fe0;the bestquality of iron and nitrogen ratio was400:1, iron put too much can’t increase thenitrate removal rate; the best quality of iron and carbon ratio was1:2,the addition ofactivated carbon can help increase the removal rate of nitrate, reduce the ammonianitrogen concentration in the solution after reaction; greater the initial concentrationof nitrate nitrogen, can speed higher the average rate of the reaction; product analysisshowed that during the test, mostly of nitrate nitrogen conversion into ammonianitrogen,as the intermediate concentration of nitrite nitrogen is very low.PRB column experiments result showed that Fe0used as filler in PBR can helpremoving nitrate nitrogen in a certain period of time, but as the extension of reactiontime,iron powder gradually lose function. During the test, mostly of nitrate nitrogenconversion into ammonia nitrogen and nitrite nitrogen, the main production isammonia nitrogen, gradually accumulate in the reaction,nitrite nitrogen is very low.although adding activated carbon in a certain extent can reduce the ammonia output,but the result still beyond the life drinking water standard(GB5749-2006),the standardis0.5mg/L.Fe0-PRB have an certain effect to remove the nitrate nitrogen in the groundwater, but also have some problems, the most important one is produce the toxic by-productsammonia. Just add activated carbon can’t solve this problem effectively, and addingactivated carbon powder subsection can accelerate jam. The best fundamental way tosolve the pollution is to take a certain way to promote N to nitrogen release into theatmosphere, so consider using the wheat straw or corn stalks instead of activatedcarbon combination with Fe0as the reaction medium of PRB, combination of in situbiological treatment technology and PRB technology synergy, avoid produce toxicby-products in the course of applying Fe0-PRB cause secondary pollution to theecological environment.