污水处理厂碳源回收潜力与活性初沉系统构建及应用

On the carbon source recovery potential and the possibility to build up activated primary tanks in the sewage-treating plants

针对城市污水处理厂初沉池中颗粒态物质沉降导致碳源流失、严重制约脱氮除磷效率的问题,对初沉池中流失碳源情况进行了分析。结果表明,初沉池对污水中SS、TCOD的去除率分别为56.7%±7.73%、43.71%±5.42%,该部分颗粒物质的沉降是碳源流失的主要因素。为探明污水中碳源的回收潜力,对颗粒态物质的生物降解性进行了检测。结果表明,污水中易生物降解有机物质量浓度较低,仅占进水COD的13.1%,而慢速生物降解有机物占51.4%。由此可知,加速慢速生物降解有机物向易生物降解有机物的转化可充分挖掘碳源的回收潜力。因此,构建了一种新型活性初沉池系统,组合搅拌淘洗和污泥发酵工艺,并应用于西安市第四污水处理厂。结果表明,初沉池出水中SCOD和VFA质量浓度分别提升了25%~35%、55%~65%,显著增强了脱氮除磷效果。

The present paper is aimed at presenting an investigation and an analysis of the problem of the carbon source loss in the primary-treating tanks of the sewage treating plant. The need for the study comes from the reason that the current nitrogen and phosphorus removal efficiency in such plants remains extremely low. The results of our investigation and analysis show that the removal rate of the suspending solids and the total carbon chemical recovery rate for the time being are merely about 56. 7% ±7. 73% and 43. 71% ± 5. 42%,respectively. And,in turn,it can be deduced that the low sedimentation rate of the above mentioned granular substances in the primary tank should account for the inneficiency of the granular matter removal. For this purpose,we have made an investigation to trace the biodegradability of the granular matters to disclose the carbon source recovering capacity in the sewage treatment. In so doing,although the concentration rate of easily biodegradable organism remains low in the sewage（ 13. 1% of COD in the sewage）,the slowly biodegradable organism can be made to reach up to 51. 4% of COD in the sewage.What is more,it would be possible to speed up the transformation process of the slowly biodegradable organism so as to promote the carbon source recovering capacity. To solve the problem,we have managed to use the primary sludge fermentation and sludge elutriation to enhance the carbon source recovery capacity as well,which comes up to the need of the renovated activated primary tank. Furthermore,the said renovated activated primary tank can be used in combination with the sludge elutriation unit and the fermentation unit,which we have successfully adopted in Xi ＇an No. 4 sewage treating plant. The results of our trial experiment have shown that the efficiency of the SCOD and VFA in the primary tank has been made to increase by 25%-35% and 55%-65%,respectively,which has succeeded in significant strengthening of the nitrogen and phosphorus removal efficiency. And,in turn,Xi＇an No. 4 sewage treating plant has also promoted the removal content concentration rates of TN, NH_4~＋-N and TP to（ 13. 2 ± 1. 2） mg/L,（ 0. 68 ± 0. 29） mg/L,（ 0. 41 ± 0. 14）mg/L,respectively,thus coming up to the novel effluent standard in the secondary sedimentation tank of the country.