Whole process analysis on the efficiency of RBC+SBNR+[Fenton+BAF]<sup>2</sup> full-scale facilities for mature landfill leachate treatment

Abstract

<p indent="0mm">Although the “biological treatment + advanced oxidation technology” method can avoid the concentration difficulties generated by the widely used “membrane biological reactor + membrane separation” process, a complete full-scale assessment of this type of combined process is lacking. The study used three parallel treatment facilities as the research object, evaluating the transformation efficiency and contribution rate of pollutants in each treatment unit using “rotating biological contactor (RBC) + shortcut biological nitrogen removal (SBNR) + two stages of [Fenton + biological aerated filter (BAF)]” process. The results show that RBC does not contribute to nitrogen removal, and the entire process relies on multistage tandem aeration tanks to remove nitrogen in the mature landfill leachate via SBNR. The SBNR unit in two of the three facilities contributed more than 100% to the removal of dissolved nitrogen (DN). The backend BAF unit is primarily responsible for controlling dissolved organic nitrogen and ammonia. An abundant combination of biological treatment can keep DN and ammonia in the effluent below 40 and <sc>25 mg/L,</sc> respectively. Meanwhile, SBNR removes the majority of organic matter, with a contribution to dissolved organic carbon of 48.7%–75.3% and RBC, 9.49%–48.1%. However, the effluent of “RBC + SBNR” is more fragrant. Nevertheless, the first level Fenton can remove the dissolved organic matter formed from “RBC + SBNR” as well as the high aromatic humus compounds in raw leachate, thereby boosting biodegradability and assuring that BAF is in low toxicity and low organic loading operating state. The second level BAF, in contrast, did not show a stable operation impact for eliminating organic materials. The type of external carbon supply and its mixing mechanism in RBC can be optimized in the future to improve nitrogen elimination. The process can be simplified by reducing terminal nitrogen removal units (e.g., the second level BAF) while ensuring that nitrogen in the effluent is up to standard.