厌氧污泥释放磷的规律及鸟粪石法回收磷的应用研究

The release law of phosphorus in the anaerobic sludge and the research on the recovery of phosphorus by struvite precipitation

城市污水处理厂进行脱氮除磷工艺时,大量的磷从水体转入活性污泥中,如不能回收这部分磷,将造成磷的大量流失,这与磷矿稀缺的现状形成矛盾。通过建立污泥停留时间5 d和10 d的两个厌氧反应系统,对污泥中磷的释放规律进行研究,并采用鸟粪石法对上清液中的磷进行回收。研究结果表明,厌氧污泥上清液中的磷含量高达150 mg.L-1,SRT为5 d和10 d的系统,分别在4 d和2 d后磷的质量浓度由14 mg.L-1上升到100 mg.L-1,且基本上都以正磷酸盐的形式存在。将pH从8.3上升到9.0,磷的回收率可以从60%提升到90%,当pH达到8.8时,磷的回收率即可超过80%,表现出了较好的磷回收效果。研究还发现镁离子和磷酸根的摩尔比对磷的回收率的影响较小,在pH=8.8时,将镁磷比从1.43提升到1.83,磷的回收率仅从79.2%提升到85.5%;在pH=9.0时提高镁磷比对磷的回收基本没有影响。

There is mass of phosphorus transform from water to the activated sludge during the process of phosphors and nitrogen removal in the Sewage treatment plants.It will cause a big loss of phosphors and contradicts the current situation of shortage if not recover the phosphorus.The system of SRT=10 days and SRT=5 days are built to research on the release law of the phosphorus of the anaerobic sludge and recovery the phosphorus by struvite precipitation.According to the result of the research,the concentration of the phosphorus in anaerobic sludge supernatant can be up to 150 mg/L.After 4 days in the system of SRT=5 days and 2 days of SRT=10 days,the phosphorous mass concentration increased from 14 mg/L to 100 mg/L,and most of phosphorus exists as phosphate.The recovery rate of phosphorus increases from 60% to 90% as pH rises from 8.3 to 9.When PH=8.8,it shows a good effect in the recovery of phosphorus for the recovery rate can be above 80%.The results also show that the molar ratio of Mg2＋and phosphate has little influence in the recovery of phosphorus.The increasing from 1.43 to 1.83 of the ratio just lead to the little rise from 79.2% to 85.5% of the recovery rate when PH=8.8.If pH is above 9.0,it makes no difference to recovery the rate by raising the atio of Mg2＋ and phosphate.