Anaerobic Biodegradation And Intensification Of Sulfadiazine

As an important antibiotic,sulfadiazine is more difficult to degrade,leading to its widespread presence in water bodies,soil and sediments.At present,the analysis of the intermediate products and degradation pathways of anaerobic biodegradation of sulfadiazine are still unclear.In view of this research status,this paper selects anaerobic biological method to remove sulfadiazine from water,and uses bioelectrochemical technology to remove sulfadiazine.In this experiment,sulfadiazine was used as the target pollutant.Under anaerobic conditions,the degradation performance of sulfadiazine was studied.To study the effect of different initial concentration of sulfadiazine,different SO₄^2-concentration,different nitrate concentration,different p H,different temperature and different carbon sources on its degradation,and performed Q-Tof analysis on the solution after sulfadiazine degradation,Combined with the changes of TOC,SO₄^2-,NH₄⁺concentration during the degradation process,The degradation pathway of sulfadiazine in anaerobic biological system was determined.The results showed that under the conditions of 25?,p H=6.0,and 100 mg/L sodium bicarbonate,The degradation efficiency of 20 mg/L sulfadiazine by microorganisms within 12 h was 99.7%.The degradation process of sulfadiazine at different concentrations conformed to the characteristics of zero-order reaction kinetics.When the concentration of sulfadiazine exceeded 50 mg/L,the inhibitory effect on microorganisms was enhanced,resulting in a decrease in the degradation efficiency of sulfadiazine.The concentration of SO₄^2-had little effect on the degradation of sulfadiazine.The addition of high concentrations of nitrate(100 mg/L,200 mg/L)significantly inhibited the biodegradation of sulfadiazine.The degradation of sulfadiazine by anaerobic microorganisms decreased with the increase of p H.25°C was the best degradation temperature for sulfadiazine.If the temperature was too high or too low,it would affect the growth and metabolism of microorganisms and enzyme activities,thereby affecting the degradation efficiency.In the process of sulfadiazine biodegradation,the removal rate of TOC was 55.1%,the concentration of SO₄^2-gradually increased,and the concentration of NH₄⁺showed an overall trend of increasing first and then decreasing.The biodegradation of sulfadiazine started from the cleavage of the S-N bond to produce substances such as sulfanilic acid,2-aminopyrimdine and 2-amino-4-hydroxypyrimidine.Then it was gradually transformed into low-toxic or non-toxic small molecular substances.Compared with sulfadiazine,the toxicity of the intermediate product of sulfadiazine was reduced,but the sulfadiazine was not fully mineralized.Anaerobic organisms could efficiently degrade low-concentration sulfadiazine.Using only biological methods,the degradation efficiency of high-concentration sulfadiazine was too low.The bioelectrochemical system had a better treatment effect on refractory organic matter,therefore,the bioelectrochemical system was used to remove sulfadiazine.This article first compared the degradation performance of bioelectrochemical system(BES)and microbial system(MS)for sulfadiazine under anaerobic conditions.Secondly,the effect of different applied voltage and different initial concentration of sulfadiazine on its degradation was studied.Studies had shown that,compared with the MS system,the BES system improved the degradation efficiency of sulfadiazine.Under 0.8 V voltage,the degradation efficiency of sulfadiazine was the highest,and the degradation efficiency of 50 mg/L sulfadiazine reached 96.9%in 10 h.The BES system had a certain tolerance to higher concentrations of sulfadiazine.