Effect of Biofilm on Nanoscale Zero-Valent Iron-Microorganism Removing NO-3-N in Groundwater
生物膜对纳米铁-微生物去除地下水中NO-3-N的影响

Nanoscale zero-valent iron (NZVI) was synthesized by reduction in liquid phase, and autotrophic denitrifying bacteria were domesticated from activated sludge by self-made chemostat. Compared the denitrifying effects of adding NZVI only with that of adding booth NZVI and bacteria in nitrate culture fluid, including investigation of three forms of nitrogen(NO-3-N,NO-2-N,NH3/NH+4-N) by spectrophotometer, and investigating the variety of pH in nitrate culture fluid by pH meter. Combining acridine orange (AO) dyed fluorescence photomicrograph, proved that biofilm has a leading role both in corrosion process of NZVI and in process of biotic denitrification of NZVI-bacteria system. Based on this, compared denitrifying effect in the circumstance of adding NZVI and bacteria separately with that in the circumstance of adding biofilm-NZVI composite which was made with glucose providing nutrition. Result shows that in the circumstance of adding NZVI and bacteria separately, NO-3-N in the system can be removed completely within 10 days, there are 37% of NO-3-N was transformed into ammoniacal nitrogen, the rest 63% of NO-3-N should have left solution in the form of gaseous denitrifying products. In the circumstance of adding biofilm-NZVI composite, NO-3-N in the system can be removed completely within 5 days, there are 28% of NO-3-N be transformed into ammoniacal nitrogen, the rest 72% of NO-3-N should have left solution in the form of gaseous denitrifying products. Experimental result also shows biofilm-NZVI composite has a greater abundance of microorganism and is more active in denitrification, it is suitable for removing the nitrate pollutant in groundwater.