低温对生物接触氧化反应器硝化性能的影响

分散型污水生物处理技术在我国北方冬季低温期容易出现硝化性能下降的问题。构建2个平行运行的生物接触氧化反应器，以生活污水为原水重点考察了降温过程对反应器硝化性能的影响。当水温从20 ℃降至10 ℃时， 反应器出水COD浓度比较稳定，但NH4+-N浓度开始出现上升。将水力停留时间从8 h延长至14 h后，获得了完全硝化的效果，而且进一步将水温降低至5 ℃时，硝化效果没有受到明显影响。硝化速率测定结果显示，5 ℃生物接触氧化污泥与10 ℃污泥几乎保持了相同的比硝化速率。高通量测序结果表明，降温过程中，生物接触氧化污泥保留了数量庞大的核心种属；同时硝化细菌种群丰度表现为长期低温条件下的部分富集。结果表明，适当延长水力停留时间，生物接触氧化反应器可以在5 ℃水温下获得良好的硝化效果。

Effect of low temperature on nitrification in biological contact oxidation reactors

Biological treatment technologies for decentralized wastewater is prone to the deterioration of nitrification performance during the low temperature period in winter particularly in northern China. In this study, two parallel biological contact oxidation reactors were constructed and the effect of low temperature on nitrification performance of the reactors was investigated as a type of domestic sewage was taken as raw wastewater. When the wastewater temperature decreased from 20 °C to 10 °C, the COD concentration in the effluents was relatively stable, while the NH4+-N concentration began to rise. After the hydraulic retention time was extended from 8 h to 14 h, a complete nitrification occurred. As the wastewater temperature further decreased to 5 °C, the nitrification performance was not affected perceptibly. The test results of nitrification rate showed that almost the same specific nitrification rate was determined for sludge samples taken from the biological contact oxidation reactors running at 5 °C and 10 °C. Through high-throughput sequencing technique, it was found that that the biological contact oxidation sludge retained a large number of core species during the cooling process. At the same time, the abundance of nitrifying bacteria showed partial enrichment under long-term low temperature conditions. Thus, a satisfactory nitrification effect will be obtained for the biological contact oxidation reactors under the conditions 5 °C wastewater temperature and properly extending the hydraulic retention time.