不同运行模式对同步脱氮除磷CAST工艺快速启动及其稳定维持的影响

以实际生活污水为处理对象,考察了传统进水/曝气和改良型分段进水的交替缺氧-好氧(A/O)2种运行模式对CAST工艺的快速启动及脱氮除磷性能稳定维持的影响。结果表明,传统进水/曝气运行模式下,系统达到最佳营养物去除性能所需启动时间30 d,稳定运行阶段TN平均去除80.66%,磷的去除率维持在66.30%左右;采用改良型交替运行模式,反应器达到稳定运行状态仅需18 d,系统稳定运行时TN平均去除81.36%,磷去除率稳定维持在90%以上,出水磷浓度在0.3 mg/L以下,出水水质达到国家污水综合排放标准一级A(GB8978-2002)。研究还发现,传统运行模式下,由低温引起的污泥沉降性能变差导致系统污泥严重流失,反应器几乎丧失污染物去除性能;而低温对交替运行模式下的反应器除磷性能几乎没有影响,总氮去除则因氨氮不完全硝化而大大降低。

Effect of operational strategy on startup and maintenance of a CAST process with simultaneous nitrogen and phosphorus removal performance

The effect of two different operational strategies on the startup and maintaining stable nitrogen as well as phosphorus removal performance of a cyclic activated sludge technology (CAST) treating real wastewater was investigated. The results showed that a 30 days startup period was required for the system to achieve a stable nutrient removal performance under the traditional operation mode,and the average total nitrogen and phosphorous removal efficiencies were 80.66% and 66.30%, respectively. However, a shorter startup period with only 18 days was needed for the system to reach the steady state under the modified operation mode, namely alternating anoxic-oxic operation with step-feeding. During the steady state, the total nitrogen removal efficiency was 81.36% and phosphorus removal was higher than 90%, accompanying the effluent phosphorus less than 0.3 mg/L. The effluent quality could meet the requirement of National Integrated Wastewater Discharge Standard-Class A (GB 8978-2002). It was also found that the deterioration of sludge settling performance due to low temperature resulted in a serious sludge loss and even a failure of reactor under the traditional operation mode. Nevertheless, phosphorous removal was not affected by the low temperature under the modified operation mode whereas total nitrogen removal decreased greatly due to the incomplete nitrification of ammonia.