Degradation kinetics of organic matter in domestic sewage by sequencing batch reactor

Abstract

The sequencing batch reactor (SBR) has become a popular sewage treatment process in various industries due to its strong impact load resistance and numerous other advantages. This study examines the variations of chemical oxygen demand chromium (CODcr), ammoniacal nitrogen (NH3-N), total bound nitrogen (TN) and total phosphorus (TP) with aeration time to investigate the degradation patterns of different pollutants during the SBR’s reaction stage. Additionally, an organic matter degradation kinetic model was developed. The experimental results showed that the CODcr and NH3-N in the reactor met the national discharge standards after two hours of influent. Furthermore, the removal rates of CODcr and NH3-N exceeded 85% and 99%, respectively, at the end of the final aeration. At the same time, the TN and TP removal rates remained stable at approximately 45% and 68%. The analysis of the kinetic model showed that the degradation process of organic matter followed a first-order kinetic equation: S=S0e−0.00012Xt. The regression model's fitting value exhibited a high degree of conformity with CODcr removal’s experimental results, with the average relative error of 5.52% falling within an acceptable range. Furthermore, the correlation coefficient (0.9966) indicated high accuracy and effectively represented the changes in organic matter throughout the SBR reaction stage. Consequently, this model can serve as a theoretical foundation for determining CODcr’s maximum treatment capacity in experimental wastewater.