Response of Anammox Process to Chloroacetonitrile and Accelerated Recovery With Pulse Electric Field

Chloroacetonitrile poses significant challenges to anaerobic ammonium oxidation (anammox) process due to its toxicity. This study evaluated the effects of chloroacetonitrile on anammox and further explored the potential of a 1.5 V and 1000 Hz pulsed electric field (PEF) in mitigating prolonged chloroacetonitrile stress. The efficiency of nitrogen removal by the anammox process was only slightly affected by 0.5 mg · L^{- 1} chloroacetonitrile over 14 days. However, when chloroacetonitrile concentration increased to 1.0 mg · L^-1, it severely inhibited nitrogen removal performance and specific anammox activity. PEF application during this phase did not directly improve nitrogen removal but increased protein content by 1.17-1.45 times, maintaining sludge stability. During the recovery phase without chloroacetonitrile, nitrogen removal gradually improved, with specific activity only reaching approximately 60% of the initial level. PEF could enhance cell membrane permeability and substrate transport, accelerating recovery. Furthermore, PEF increased the proliferation of Ca. Brocadia by 45%, which contributed to the accelerated recovery of AnAOB activity after chloroacetonitrile exposure was ceased. This study aims to aid in the advancement and utilization of anammox technology enhanced by PEF. This study is anticipated to contribute to the development and application of PEF-integrated anammox technology.