RBC+SBNR+[Fenton+BAF]^(2)工艺处理长填龄渗滤液效能全流程分析

Whole process analysis on the efficiency of RBC+SBNR+[Fenton+BAF]^(2) full-scale facilities for mature landfill leachate treatment

“生物处理+高级氧化技术”可弥补主流“膜生物反应器+膜分离技术”浓缩液的不足,但目前缺乏对其实际工程的全面评估.基于三维荧光光谱分析及理化性质指标去除贡献计算,本文评估了“生物转盘+短程硝化反硝化+2级(Fenton+曝气生物滤池)”工艺的三组工程规模处理设施各单元对长填龄渗滤液中污染物的去除转化效能.结果表明,生物转盘(RBC)几乎没有展现脱氮效果,而全工艺主要依靠串联多级曝气池以实现长填龄渗滤液的短程硝化反硝化(SBNR)脱氮,三组设施中两设施的SBNR单元对溶解性氮(DN)去除贡献均达100%以上.后端1级及2级BAF单元分别主要削减溶解性有机氮和氨氮.该工艺出水DN和氨氮经丰富组合的生物处理方法可稳定低于40和25 mg/L.同时,SBNR单元削减绝大部分有机物,对溶解性有机碳(DOC)去除贡献率达48.7%~75.3%,且RBC(9.49%~48.1%)与该单元除碳效果互补.但经“RBC+SBNR”处理出水芳香度显著提高.渗滤液中高芳香腐殖质及“RBC+SBNR”衍生的溶解性有机物(DOM)主要由1级Fenton去除,进而提高出水生化性,同时保证曝气生物滤池(BAF)处于低毒性、低有机物负荷工作状态.然而,2级BAF单元未展现去除有机物指标的较为稳定的运行效果.未来工程实践中,可优化外加碳源类型及其投加混合方式以发挥RBC脱氮效果,保证出水氮达标的同时,削减工艺末端除氮单元(如2级BAF)以精简处理流程.

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 25 mg/L, 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.