长期Hg(Ⅱ)暴露对断流CANON工艺恢复性能的影响

Influence of Long-term Hg(Ⅱ)Exposure on Recovery Performance of Interrupted CANON Process

为研究长期Hg(Ⅱ)暴露对断流后全程自养脱氮(CANON)工艺恢复性能的影响,采用无Hg(Ⅱ)暴露(R1)与Hg(Ⅱ)暴露(R2)2个反应器,通过延长水力停留时间和控制溶解氧浓度为0.1 mg/L的策略,在进水氨氮为200 mg/L条件下进行脱氮性能的恢复。结果表明,R1经过55 d的运行,总氮去除率和总氮去除负荷分别从-24.7%、-0.201 kg/(m^(3)·d)恢复至(68.8±10.8)%、(0.273±0.043)kg/(m^(3)·d);R2经过52 d的运行,总氮去除率始终低于30%,而亚硝态氮积累率达到(93.5±6.5)%,CANON系统转变为短程硝化系统。在恢复初期R2出水中检测到6.0μg/L的Hg(Ⅱ),厌氧氨氧化菌受到了Hg(Ⅱ)的持久性抑制。高通量测序结果表明,R1中厌氧氨氧化菌和好氧氨氧化菌的相对丰度在断流前分别为16.0%、0.6%,恢复前为9.4%、21.0%,恢复后为4.8%、4.8%;而R2在断流前分别为10.3%、0.5%,恢复前为10.8%、0.5%,恢复后为8.4%、11.9%。Hg(Ⅱ)长期暴露后断流的污泥无法恢复高效脱氮性能,但可作为短程硝化污泥的来源。

To explore the impacts of long-term Hg(Ⅱ)exposure on the recovery performance of an interrupted CANON process,two reactors,namely one without Hg(Ⅱ)exposure(R1)and the other with Hg(Ⅱ)exposure(R2),were employed to prolong the hydraulic retention time and regulate the dissolved oxygen to 0.1 mg/L,and the nitrogen removal performance was restored when the influent ammonia nitrogen was 200 mg/L.After 55 days of operation,the total nitrogen removal efficiency and total nitrogen removal rate of R1 recovered from-24.7%and-0.201 kg/(m^(3)·d)to(68.8±10.8)%and(0.273±0.043)kg/(m^(3)·d)respectively.However,the total nitrogen removal efficiency of R2 consistently remained below 30%after 52 days of operation,while the nitrite nitrogen accumulation rate was(93.5±6.5)%,and the CANON system was transformed into a partial nitrification system. Hg(Ⅱ) was detected at a concentration of 6.0 μg/L in the R2 effluent during the initial stage of recovery, and the anaerobic ammonia-oxidizing bacteria (AnAOB)were constantly inhibited by Hg( Ⅱ). The outcomes of high-throughput sequencing indicated that the relative abundances of AnAOB and aerobic ammonia oxidizing bacteria in R1 were 16.0% and 0.6% prior to cut-off, 9.4% and 21.0% before recovery, and 4.8% and 4.8% after recovery, respectively. The corresponding values in R2 were 10.3% and 0.5% before cut-off, 10.8% and 0.5% before recovery, and 8.4% and 11.9% after recovery. The idle sludge after long-term exposure to Hg(Ⅱ) was unable to restore high nitrogen removal performance, but could be utilized as a source of partial nitrifying sludge.