Aniline Degradation Coupled With The Recovery Of Nitrogen In Bioelectrochemical System

In order to efficiently degrade aniline, save the cost of nitrogen removal, and recover the nitrogen from aniline degradation, this study constructed a bioelectrochemical system for aniline degradation coupled with the recovery of nitrogen. In order to improve the effect of aniline degradation, a small amount of oxygen was introduced to bioanode. Bacteria which can degrade aniline efficiently was acclimated under continuous-fed mode. The aeration frequency, resistance and aniline concentration in influent was investigated on the degradation of aniline and electrochemical performance of the system. Ammonium generated by the aniline degradation migrates from anode to cathode in the presence of electric field and concentration gradient. When the p H of catholyte is high enough, the ammonium ion will be converted to molecular ammonia. Through nitrogen blowing to cathode and acid absorption, nitrogen can be recovered. In order to recover more ammonia nitrogen, the effects of cation(Na+) concentration and current were investigated on the migration of ammonium. In the end, a complete system of aniline degradation coupled with the recovery of nitrogen was constructed, and the degradation efficiency of aniline and nitrogen recovery rate were evaluated.Bacteria was acclimated in bioanode with intermittent aeration under continuous-fed mode. The optimal aeration frequency was 1 minute every 8 minutes, and the average dissolved oxygen concentration in anolyte was 0.056mg/L. The degradation effect of aniline and the electrochemical performance of the system were increased with the decrease of the external resistance. When the external resistance was 200 ohm, the removal rate of aniline was 97.61%, and the coulombic efficiency was 6.03%. The optimal concentration of aniline wastewater was 400mg/L. when the influent aniline concentration was as low as 200mg/L, the system’s power production capacity was poor, and when the concentration was high to 500mg/L, it would inhibit the metabolism of microorganisms.Ammonium is generated from aniline degradation and will migrate from anode to cathode. Sodium is competitive with ammonium in the process of migration. The lower the sodium concentration was, the higher the migration proportion of ammonium and the ammonium concentration in catholyte were. When the sodium concentration was 1.64 m M, the migration proportion of ammonium to the cathode was 54.85%, and the ammonium concentration in catholyte was 1.07 m M. The increase of current promoted the migration of ammonium to the cathode, and then improved the total nitrogen removal efficiency. When the current was 0.65 m A, the ammonium concentration(1.07 m M) in the cathode increased 1.82 times compared with open circuit(0.38 m M), and the total nitrogen removal rate increased by 1 times. The bioelectrochemical system for aniline degradation coupled with the recovery of nitrogen was successfully constructed. The average aniline removal rate was 91%, and the average total nitrogen removal rate was 56.3%. If ammonium in cathode chamber and absorption bottle was viewed as nitrogen recovered, the total nitrogen recovery rate was about 30%.