An inverted A2/O (anoxic/anaerobic/aerobic-pre-anoxic)- MBR process was applied in Hefei Tangxihe reclaimed water treatment plant to remove nutrients from low C/N ratio municipal sewerage. The variances of organics and nitrogen in each operational unit with and without addition of external carbon source were studied Results showed that the TN removal efficiency was only 52. 3% without addition of external carbon source. The conclusion that sodium acetate had the best effect and the highest denitrification rate can be obtained by comparing the effects of three different extra carbon sources-sodium acetate, methanol and acetic acid. Therefore, sodium acetate was added as external carbon source with a theoretical amount of 50 mg COD/L in influent and the TN removal efficiency was enhanced significantly to 74. 5%. Besides, the material flow of COD and TN were systematically analyzed after the sodium acetate was added The results indicated that the anoxic tank and anaerobic tank were the main process units for COD removal, while the aerobic tank enhanced the effect of COD removal efficiency. The removal rate of TN in system significantly increased 26. 5% after the dosing of external carbon.%合肥塘西河再生水厂采用倒置A/O(缺氧/厌氧/好氧—预缺氧)—MBR工艺处理低C/N城市生活污水.研究了投加碳源前后各生化反应池中有机物及氮元素的变化规律,结果表明未投加外碳源时TN的去除率为52.3％,脱氮效果不理想.通过比较乙酸钠、甲醇和乙酸三种不同外加碳源的脱氮效果,可知乙酸钠反硝化速率最高,效果最好.当乙酸钠作外碳源,投加量为50 mgCOD/L时,TN的去除率明显提高,达到74.5％.此外,还分析了投加外碳源后整个工艺系统内COD、TN物质流动情况,结果表明,缺氧池和厌氧池是COD去除的主要单元体,好氧池对COD的去除贡献增强,体系中的TN去除总量在投加外碳源后有了明显的增加,较未投加外碳源时增加了26.5％.
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