Treatment of Ammonia Nitrogen Wastewater by Box–Behnken-Optimized Bubble Discharge Plasma

Abstract

In this study, the Box–Behnken design model was used to plan the experiment, and the corresponding model was constructed using Design-Expert software. Using this model, the interaction of various factors in the treatment of high-concentration ammonia nitrogen wastewater using bubble discharge plasma was investigated. Response surface model analysis and regression equation significance tests were conducted to optimize the treatment conditions for high-concentration ammonia nitrogen wastewater treated by plasma. Based on the single-factor test results, voltage, frequency, and air pressure were selected as the influencing factors; the removal rate of ammonia nitrogen was taken as the target value; and the response surface was analyzed. The results revealed the influence of the interaction between these factors on the removal rate of ammonia nitrogen and determined the optimal reaction conditions: voltage 12.1 kV, frequency 165.9 Hz, and pressure 0.01 MPa; under these conditions, the 50 min treatment rate of ammonia nitrogen reached 99.14%. Subsequently, these conditions were validated, and their high efficiencies were demonstrated through degradation kinetics.