分段进水SBR处理低C/N值含盐废水的脱氮效果

Nitrogen Removal Efficiency of Step-feed SBR in Treatment of Low C/N Saline Wastewater

针对低C/N值含盐废水利用传统生物脱氮工艺处理时存在有机碳源不足、脱氮效率低的问题,提出以优先利用原水中的可生物降解有机物和减少外加碳源为目的的分段进水SBR工艺。对比分析了5种不同进水方式下的脱氮效率、N2O释放量及转化率,结果表明:在外碳源充足的条件下,5种进水方式均可实现较好的脱氮效果,但进水比例为1∶2∶3的三段式进水脱氮过程中N2O的转化率较一段进水方式减少了约46%。在二段进水方式中,进水比例为1∶1的N2O转化率最高,达到了5.1%,而进水比例为1∶2的仅有2.5%。对比最后一次硝化结束时系统内的NOx--N浓度,一、二、三段式的分别为41.5、23.3、19.7 mg/L,因此通过分段进水可节省后续反硝化时间和反硝化外碳源需求量。可见,当处理低C/N值含盐废水时,采用适当的分段进水方式和进水比例,可在实现高效脱氮、降低运行成本的同时防止N2O的大量释放。

Lack of carbon source and low nitrogen removal efficiency occurred when conventionalbiological nitrogen removal processes were used to treat low carbon to nitrogen ratio （C/N） saline wastewater. A step-feed sequencing batch reactor （SBR） was proposed to make full use of the influent carbon source and reduce external carbon source addition. Five different step-feed modes were compared in terms of nitrogen removal efficiency, N2O emission and conversion rate. The results showed that high nitrogen removal efficiency was achieved in all five step-feed modes when sufficient external carbon source was provided. However, the N2O conversion rate of the three-step mode with the influent flow ratio of 1 ： 2 ： 3 reduced by 46% compared to that of the one-step mode. Regarding to the two-step mode, the highest N2O conversion rate of 5.1% was observed at the influent flow ratio of 1 ： 1, and the lowest that of 2.5% occurred at the influent flow ratio of 1 ： 2. Additionally, NOx^- N was accumulated at the end of the last aerobic stage, and was reduced from 41.5 mg/L （one-step mode） to 23.3 mg/L （ two-step mode） and 19.7 mg/L （three-step mode）, indicating that the external carbon source and denitrification time could be saved. Taken together, high nitrogen removal efficiency, low operation cost and low N2O emission could be achieved using step-feed operational modes in SBR when treating low C/N ratio saline wastewater.