Efficiency Analysis Of Nitrogen Removal By Ammonia Oxidation Driven By NZVI

At present,the traditional biological nitrification and denitrification reaction requires a large amount of carbon sources,and the anaerobic ammonia oxidation process has such limiting factors as nitrate nitrogen products and slow reaction rate,so it is imperative to explore a new green nitrogen removal process.In recent years,researchers have discovered a new type of green denitrification reaction worth studying when exploring iron enhanced anaerobic ammonia oxidation reaction,which realizes iron driven ammonia oxidation reaction without aeration and additional carbon source addition.It is a new green denitrification process worth studying.In addition,both electroplating wastewater and Fenton treated wastewater in industrial wastewater contain a large amount of iron as an application scenario for iron ammonia oxidation,providing a prerequisite for establishing a sustainable iron driven ammonia oxidation reaction.In this study,Fe Cl₃,Fe₂O₃,Fe（OH）₃,and n ZVI were used to analyze the performance of different iron source driven ammonia oxidation.Through SEM and XRD analysis of the sludge surface,the optimal iron source was selected.The optimal iron source was used for enrichment and cultivation,and sodium acetate was added at low C/N for mixed denitrification and denitrification coupled with iron driven ammonia oxidation reaction for further nitrogen removal treatment,ultimately achieving a green and economic nitrogen removal process at low C/N.The main test results are as follows:（1）Iron driven ammoxidation reactions were successfully initiated with different iron sources,and n ZVI was selected as the optimal iron source.By comprehensive comparison,when using n ZVI as an iron source,the final conversion of ammonia nitrogen reaches 40 mg/L,and the final removal rate of total nitrogen reaches 6%.Both ammonia nitrogen and total nitrogen removal rates are the best;According to the positive correlation between Fe²⁺and NH₄⁺-N,as well as the increase in the abundance of Acidobacillus in Acidobacter,the enrichment of microorganisms related to the Femmox reaction in the reaction system proves the occurrence of the Femmox reaction;When using n ZVI as an iron source,the surface of the sludge is relatively smooth and there are no iron minerals attached to the surface of the sludge.Therefore,nano iron sources can be used as the most suitable iron source for long-term operation of the Feammox reaction;（2）Improve the efficiency of ammonia oxidation denitrification treatment under the guidance of nano iron drive through enrichment and cultivation.Under different Fe/N conditions,it is preferred to achieve a 78%ammonia nitrogen conversion rate with a Total nitrogen concentration of 50 mg/L and an influent ammonia nitrogen concentration of 70 mg/L.At the same time,the ammonia nitrogen conversion rate has the strongest correlation with the amount of Fe²⁺generated.The increase in the relative abundance of Ignavibacterium during the comprehensive enrichment process indicates that iron reducing bacteria have been enriched.Therefore,under this condition,the Feammox reaction activity is the highest and there is an autotrophic denitrification reaction;（3）Strengthen the ammonia oxidation denitrification performance and improve the total nitrogen removal rate through the addition of organic substances.Sodium acetate,an organic substance,was added to the Feammox sludge after the domestication and enrichment of n ZVI with a C/N of 0,0.5,0.7,and 1.The maximum ammonia nitrogen removal in the reactor reached 68 mg/L,and the total nitrogen removal amount reached 55 mg/L.There was a characteristic peak in the infrared fluorescence spectrum for nitrate reaction.SEM analysis showed that Fe was attached to the surface of the sludge,and the increase in the relative abundance of Thauera after the addition of organic substances indicated that denitrifying bacteria were enriched,There are Feammox reactions and other iron salt driven denitrification reactions in the reactor.