| Due to the extensive using of nitrogen fertilizers and pesticides,and nitrogen containing industrial wastewater and domestic sewage discharged into water bodies,large tracts of soil,surface water and groundwater contamination caused by multiple.Atrazine as one of the more common weed pesticides and nitrates in groundwater often be detected.Research at the same time to remove nitrate and atrazine technology is of great significance.Solid carbon source is not only to provide energy and carrier for microorganisms,and has certain adsorption of organic matter,nitrate and atrazine to deal with at the same time has great potential.This article utilize rice straws as a solid carbon source for solid-phase denitrification to remove the nitrate and atrazine in the groundwater,and analysis of the impact factor of solid-phase denitrification,emphatically discusses the atrazine influence on solid phase denitrification and analyzes its removal mechanisms,adsorption characteristics and influence factors of rice straws on atrazine,and investigates efficiency of solid-phase denitrification system stable operation.Under the condition of static test using rice straws as carbon source and carrier of denitrifying bacteria,at the 5 hours nitrate removal rate reached 77.7%.Nitrite concentration and pH value were reduced after the increases with time.In 25oC to 40oC,removal rate were higher than 85%.When the initial concentration of nitrate in 10mg/L to 100mg/L,nitrate removal rate was relatively close to,but when the initial concentration of nitrate was 100mg/L,nitrite accumulation was 18.72mg/L at 5 hour,the effect of the denitrification was bad.When the additive amount of rice straws was 5g,nitrate removal rate was 95.3%,and there were no nitrite accumulation.When atrazine initial concentration were 1mg/L and 5mg/L,the removal rate of nitrate and atrazine were higher,and had not a lot of nitrite accumulation,the effect of the denitrification is better.But when atrazine initial concentration was 10mg/L,atrazine removal rate reduced to62.33%,nitrite accumulation of 7.89 mg/L,affected the denitrification.Atrazine removal mainly through the adsorption effect of rice straws,when atrazine initial concentration were 0.5mg/L and1mg/L,had a certain microbial degradation.When study on the adsorption characteristics of rice straws found that rice straw dosage was8 g,the removal of atrazine was the highest.And with the increase of temperature and pH,atrazine removal was reduced.By establishing the Langmuir adsorption isotherm determined the maximum adsorption amount of rice straw for atrazine was 16.61μg/g.Through dynamic test inspects the effect and influence factors of use straw stalk as denitrifying bacteria carbon source and carrier of denitrification system at the same time to remove nitrate and atrazine,change volume load and hydraulic residence time of nitrate and atrazine in flooding water,When nitrate volume load were 1.2kg/(m~3·d)and 2.4kg/(m~3·d),the removal rate of nitrate and atrazine were higher,and the best of atrazine volume load was 0.024kg/(m~3·d),When the hydraulic retention time was 8 hour,the removal efficiency of nitrate and atrazine were the best,when the volume load was 2.4kg/(m~3·d),atrazine volume load was 0.024kg/(m~3·d)and hydraulic residence time was 8 h,running effect of solid-phase denitrification system at the same time to remove nitrate and atrazine was stable.To sum up research shows:straw in the denitrification process not only provide a carbon source and a carrier for the microorganisms,can effectively remove nitrate in groundwater,and the main mechanism of atrazine removal was the adsorption of rice straws.The solid-phase denitrification technology is used to removal of nitrate and atrazinein in the groundwater has greater application prospect. |
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