| With the rapid development of our nation’s industrial and agricultural sector, massiveindustrial wastewater containing nitrogen which could not meet the discharge standard oreven raw sewage have been pouring into the environment, causing serious nitrate pollution.The overuse of fertilizer and pesticide in order to maintain grain output is very common,which makes the nitrate pollution even worse; moreover, it makes the water face the challengeof compound pollution. Atrazine is a most widely used herbicide and often been detected, theresearch of simultaneously removal nitrate and atrazine has positive significance. Solidcarbon source can avoid the shortcomings of traditional liquid carbon well, not only can it bethe biofilm carrier and electron donor of denitrifiers, but also has the ability to absorb theorganic pollutants of water，so, it has the potential to deal with compound pollution.The COD releasing characteristics results indicated that the starch granules turned to bethe most suitable carbon source as it had a proper COD releasing speed and the highestreleasing potential. Batch study indicated that the most suitable solid-to-liquid ratio was1:20,average denitrification rate was7.03mg/(L·h), the process fitted zero-order kinetics well, andthe most suitable temperature was between30oC-40oC. The study also showed that lowconcentration atrazine had no side effects on denitrification, but when it reached to20mg/L,the inhibition was very pronounced, which lowered the removal rate. Initial concentration of0.1mg/Land1mg/L atrazine was removed by93%and94.8%, respectively.90.7%of the totalreduction was contributed by absorption process, which indicated the absorption played thedominant role. When initial concentration increased to5mg/L and10mg/L, the removed ratedropped to88.2%and50.7%. GC/MS analyzing results indicated the atrazine degradationfollowed the dealkylation process.The solid carbon was taking as biofilm carriers, the continuous influent anddomesticating cultivation were started after a close aeration for7days. The effluent nitrateconcentration were stable at under5mg/L, indicated the biofilm formation was sucessed. Thedenitrification rate was over96%when initial nitrate concentration was50mg/L and100mg/L at stable process, average denitrification rate was21.86mg/(L·h). The atrazineremoval rate was not so satisfied in BAF, the effluent concentration was between3.12-4.28mg/L with the influent of5mg/L atrazine. The effluent concentration fluctuation becamesmall when influent reduced to1mg/L, the removal rate was between68%-81%. The effluentCOD concentration raised first and then fell down, the effluent pH slightly decreasedcompared to the influent. The effect of HRT and DO on nitrate and atrazine removal showed significant difference. The removal rate for nitrate was nearly100%with4h of HRT, but theatrazine removal rate was only62.58%. Atrazine removal rate rised to85.17%when HRT was12h. Denitrification rate raised at first then decreased with the raised concentration of DO,Denitrification rate was over90%when DO concentration was3.5mg/L and4.5mg/L, itdecreased to83.71%when DO concentration raised to6.5mg/L, and DO did not show anyinfluence on atrazine removal rate. The FT-IR and SEM analyzing results indicated the solidcarbon was fully used by microorganism，biofilm was mainly composed by bacillus andcoccus. |
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