间歇曝气对微污染源水生物接触氧化修复系统脱氮性能的影响

针对寡营养生境下生物脱氮过程碳源不足等问题,开展不同间歇曝气方式对微污染源水生物接触氧化修复系统脱氮性能的影响研究,探究修复系统短程硝化反硝化的可行性与过程机理.结果表明:在停曝-曝气时间为8 h-16 h的间歇曝气方式(Ⅰ)下启动的生物接触氧化修复系统,其铵态氮(NH+4-N)、高锰酸盐指数(CODMn)、总氮(TN)的平均去除率分别稳定在93.0%、78.1%、19.4%;而在停曝-曝气时间为16 h-8 h的间歇曝气方式(Ⅱ)下运行修复系统,其NH+4-N、CODMn平均去除率仍能分别维持在81.2%、76.4%,体系内NO-2-N发生积累,TN去除率增至50%以上.对工况Ⅱ下修复系统周期内氮素转化特性分析发现,在确保出水NH+4-N、溶解氧(DO)浓度达标的前提下,缩短曝气时间可将体系DO长时间控制在0.5～1.5 mg·L-1,亚硝酸氧化菌(NOB)生长及其活性受到抑制,NO-2-N明显累积,最终实现了微污染源水生物接触氧化修复系统的短程生物脱氮.

Effects of intermittent aeration on nitrogen-removal capability of biological contact oxidation remediation system for micro-polluted source water

Aiming at the carbon source limitation of denitrification in oligotrophic habitat, this paper studied the effects of intermittent aeration on the nitrogen-removal capability of biological contact oxidation remediation system for micro-polluted source water, and approached the feasibility and process mechanism of shortcut nitrification and denitrification in the system. Under the condition of 8 h-16 h anoxic-aerobic phase (I), the remediation system performed stably, and its average removal efficiency of ammonium (NH4+ -N), permanganate index (COD(Mn)), and total nitrogen (TN) was 93.0%, 78.1%, and 19.4%, respectively. Under the condition of 16 h-8 h anoxic-aerobic phase (II), the NH4+ -N and COD(Mn) removal efficiency still maintained at 81.2% and 76.4%, respectively, the accumulation of nitrite (NO2- -N) was significant, and the removal efficiency of TN reached more than 50%. The nitrogen transformation characteristics in the system during a cycle under condition II demonstrated that at the prerequisite of effluent NH4+ -N and DO concentrations reaching the standards, shortening aerobic phase length could maintain the DO concentration at 0. 5 -1.5 mg L(-1) in a long term, inhibit the growth and activity of nitrite-oxidizing bacteria, and thereby, NO2- -N had an obvious accumulation, and the nitrogen removal via shortcut nitrification-denitrification in the biological contact oxidation remediation system for micro-polluted source water was finally achieved.