曝气沉砂除油池对污水厂脱氮除磷的影响

The effect of aerated grit and degreasing tank on full-scale WWTP nutrient and phosphorous removal performance

为准确评价曝气沉砂除油池对城市污水厂脱氮除磷的影响,从水质特征、出水污染物浓度、去除效率、活性污泥组成、产泥量、物质平衡等角度,全方面考察具有长水力停留时间(大于10 min)的曝气沉砂除油池预处理对后续生物处理工艺的影响,并与旋流沉砂池预处理进行对比.结果表明:曝气沉砂除油池预处理后,原水碳源损失比较严重,减小二级生化处理系统进水的COD与TN比和COD与TP比,不宜在低碳氮比进水的城市污水厂中使用;二级生化处理系统的TN和TP去除率分别下降了5.87%和10.22%;改变系统的活性污泥组成,使活性污泥中TN含量增加,而TP的含量减少.物质平衡原理的工艺评价方法也表明曝气沉砂除油池预处理会减小二级生化处理可利用碳源.具有长水力停留时间的曝气沉砂除油池预处理对城市污水厂脱氮除磷有负面影响.

To evaluate the effect of aerated grit and degreasing tank（AGDT） with long hydraulic retention time （〉 10 min ） on nutrient and phosphorous removal performance at municipal wastewater treatment plant （WWTP） , influent characteristics, effluent quality, removal efficiencies, activated sludge characteristics and composition, as well as performance assessment based on mass balance evaluation, were investigated in a full- scale WWTP. The experimental results showed that： Compared with Pista grid pre-treatment, AGDT pre- treatment was unsuitable to be used in WWTP with low C/N rate wastewater because it consumed more carbon source and led to decrease of effluent COD/TN/TP rates; The total nitrogen（TN） removal efficiency and total phosphorus （TP） removal efficiency decreased 5.87% and 10. 22%; The activated sludge characteristics and composition were changed with TN content increased and TP content reduqed; Mass balance evaluation approach also showed that the available carbon source was decreased in secondary biochemical treatment after AGDT pre-treatment. Therefore, the effect of AGDT with long hydraulic retention time （ 〉 10 min） on full- scale WWTP nutrient and phosphorous removal performance was negative.