LAUSR

Abstract Nitroaniline (NA) is an aniline derivative with high toxicity, potential carcinogenicity and mutagenic effects. At present, the physical, chemical and biological methods used in NA-containing wastewater treatment usually suffer from problems such as low removal efficiency, high energy consumption and secondary pollution generation. In this study, a membrane-aerated biofilm reactor (MABR) was constructed to enhance the treatment of wastewater containing o-nitroaniline (2-NA) and p-nitroaniline (4-NA). The stratified biofilm and counterdiffusion of oxygen in the MABR were conducive to NA degradation. At a lower concentration, NA was primarily removed through direct oxidative degradation in the absence of the cometabolic substrate acetic acid, while at a higher concentration, NA was predominantly removed through oxidative degradation after reduction of NA in the presence of acetic acid. With an influent NA loading of 0.120 kg/(m3·d), an aeration pressure of 40 kPa and an acetic acid dosing ratio of 2.0, the 2-NA and 4-NA removal loadings reached 0.058 and 0.060 kg/(m3·d), respectively. Additionally, the chemical oxygen demand (COD) and total nitrogen (TN) removal rates were 82.40 and 88.52%, respectively. The MABR technology promoted simultaneous NA degradation and nitrogen removal from NA-containing wastewater treatment, illustrating its prospects for industrial application.