Characterization of Dissolved Organic Matter in Mature Leachate during Ammonia Stripping and Two-Stage Aged-Refuse Bioreactor Treatment

Dissolved organic matter (DOM) is the major regulated pollutant of landfill leachate in solid waste management industries. Recently, aged-refuse bioreactor (ARB) has received increasing attention for reduction of DOM from mature leachate due to low energy consumption, easy operation, simple maintenance, low cost, and high treatment efficiency. However, the information regarding alternation of the DOM nature during ARB treatment is highly limited. To figure out appropriate posttreatment for effluent of ARB and meet elevated discharge standards, especially in developing countries, this study investigates the characterization of mature leachate DOM during ammonia stripping and two-stage ARB treatment by means of synchronous scanning fluorescence spectra, excitation-emission matrices spectra, and molecular size distribution. The analytical results indicated that ammonia stripping could not significantly remove DOM, though the process was effective in ammonia nitrogen reduction. In contrast, ARB could remove substantial DOM. The first stage ARB preferentially attacked both fulivc-acid-like and humic-acid-like organic molecules and the second stage ARB played a polishing treatment role with a similar treatment fashion. The final effluent after ammonia stripping and two-stage ARB treatment still contained fulvic-acid-like DOM with low molecular weight (<5 kDa) that should be further removed by appropriate posttreatment.