Dissolved organic matter characterization of swine wastewater with step-feed two-stage anoxic/oxic (A/O/A/O) process by using EEM-PARAFAC

Swine wastewater has become one of the main agricultural pollutants in China and been widely concerned by the public. Biotechnology is a ommon economic and effective means to treat swine wastewater. However, it is difficult to discharge the swine wastewater that contains dissolved organic matter (DOM) by biological treatment technology. In this paper, the swine wastewater was treated by a step-feed two-stage anoxic/oxic (A/O/A/O) process, the removal rate of chemical oxygen demand (COD) reached 89%, and that of ammonia nitrogen (NH₄⁺-N) reached 97%. Fluorescence excitation-emission matrix (EEM) with parallel factor analysis (PARAFAC) was used to analyze the composition and changes of DOM in the influent and effluent samples of the step-feed A/O/A/O. The results show that the main components in the influent were tyrosine/tryptophan-like substance (C1), tyrosine-like substance (C2), and humic-like substance (C3). The main components in effluent were divided into tyrosine-like substance (C2), humic-like substance (C3), and terrestrial humic-like substance (C4). The results show that C1 and C2 were significantly degraded, C3 was hardly degraded by microorganisms, and C4 was a microbial metabolite.