鸟粪石成粒法回收污泥液中的磷及颗粒品质表征

Struvite Pellet Crystallization for Phosphorus Recovery from Sludge Liquor and Characterization of Pellet Quality

摘要:

为了探究鸟粪石（MAP）结晶成粒法回收污泥液中磷的效果，首先利用模拟污泥发酵液分析了鸟粪石成粒最佳工况，进而研究了污泥脱水液中磷回收及鸟粪石生长情况.采用模拟发酵液得出鸟粪石成粒最优条件为：pH为8.2，水力停留时间（HRT）为41 min，上升流速为400 cm·min-1，磷氮摩尔比为1∶6，此时形成的鸟粪石最大粒径在4~5 mm之间，纯度均在97.5%以上，硬度达到（43.8±1）kg·mm-2.在最优条件下，回收污泥脱水液中的磷，PO3-4P最高去除率可达90.5%.并发现高浓度悬浮固体（SS）不利于鸟粪石生成，且培养时间延长不能有效增加各离子去除率及鸟粪石粒径，颗粒最大粒径在2.0~3.2 mm之间，纯度在80%以上(悬浮固体质量浓度小于150 mg·L-1)，颗粒重金属含量符合国家对化肥中重金属含量的规定.

Abstract:

In order to explore the recovery of phosphorous from sludge liquor using struvite(MAP) pellet crystallization, the synthetic sludge fermentation liquid was first used to obtain the optimal conditions for struvite pellet formation, and then the recovery of phosphorous and growth of struvite fed with sludge dewatering liquor was investigated. When fed with synthetic fermentation liquid, the optimal conditions for struvite pellet formation were as follows: pH was 8.2; hydraulic retention time (HRT) was 41 min; inflow rising velocity was 400 cm·min-1, and phosphorus to nitrogen molar ratio was 1∶6. The maximum struvite particle size reached 4~5 mm; the purity was all above 97.5%; the particle hardness was (43.8±1) kg·mm-2. Under the above optimal conditions, real sludge dewatering liquor was used to recover phosphorus. The highest removal efficiency of PO3-4P could reach 90.5%. High concentration of suspended solid (SS) went against the formation of struvite, and the extension of incubation time could not effectively increase the removal efficiencies of ions and struvite particle size. The maximum particle size was 2.0~3.2 mm while the purity of harvested pellets was more than 80% (ρSS<150 mg·L-1). The concentrations of heavy metals were below the limits of heavy metal contents for fertilizer standards in China.