工艺条件对磷回收过程中鸟粪石沉淀颗粒粒径的影响  

Influences of process conditions on particle size in struvite precipitation for phosphorus recovery from wastewater

作　　者：李超群[1] 林木兰[1] 林金清[1] 

机构地区：[1]华侨大学材料科学与工程学院,厦门361021

出　　处：《环境工程学报》2012年第3期936-940,共5页Chinese Journal of Environmental Engineering

基　　金：福建省科技计划项目(2006HG028);厦门市科技计划项目(3502Z20093030)

摘　　要：在鸟粪石沉淀法回收废水中磷的过程中,鸟粪石颗粒的大小将直接影响其沉淀的速率,进而影响鸟粪石的沉淀效果和磷的回收率。本文采用激光粒度分析仪测定鸟粪石的平均粒径,详细考察在小型连续搅拌反应-沉淀磷回收装置中不同的工艺条件下鸟粪石颗粒粒径的变化规律,并结合Stokes公式计算鸟粪石颗粒在废水出口处的沉降速率,为沉淀池的设计提供参考依据。结果表明:鸟粪石的平均粒径在12～25μm之间,沉降速率在5.46×10-5～2.37×10-4m/s之间。随着反应室水力停留时间的延长,鸟粪石颗粒的粒径逐渐增大,当停留时间超过18 min时,颗粒的粒径基本不变;随着沉淀室水力停留时间的延长,鸟粪石颗粒的平均粒径缓慢增大,当停留时间超过70 min后颗粒粒径的变化不大;鸟粪石颗粒的平均粒径在一定程度上受废水中磷初始浓度变化的影响,在磷初始浓度为62～128 mg/L时颗粒的粒径变化不大,当磷浓度为496 mg/L时粒径有较大增加,此时鸟粪石颗粒的沉降速率也大幅度增加;鸟粪石颗粒的平均粒径受pH值的影响不大;随氮磷摩尔比的增大,鸟粪石颗粒的平均粒径略有增加;随镁磷摩尔比的增大,鸟粪石颗粒的平均粒径逐渐减小,沉降速率则有明显的下降。In the process of struvite precipitation for recovery of phosphorus from wastewater,the particle size of struvite would directly affect the settling rate,thereby affects the phosphorus recovery efficiency.The average size of struvite was measured by laser particle size analyzer,and variation of struvite particle size with different process conditions in a small scale continuous stirred tank reaction-precipitation device was studied detailly,and then the struvite particle settling rate at the outlet of wastewater flow was calculated with Stokes formula in order to provide some references for the design of settlement tank.The results showed that the average particle size of struvite is in range of 12~25 μm,and the settling rate is between 5.46×10-5 and 2.37×10-4 m/s.With the hydraulic retention time（HRT） in the reactor increasing,the struvite particle size increases,but it becomes almost the same size when the HRT is more than 18 mins.With the HRT in the settlement tank increasing,the average size of struvite particles increases slowly,and when the HRT is more than 70 mins,the particle size changes little.The particle size changes little when the initial concentration of phosphorus is within 62~248 mg/L,but it significantly increases when the initial phosphorus concentration is greater than 496 mg/L.The pH has little effect on the average particle size.With molar ratio of nitrogen and phosphorus increasing,the average size of particles increases slowly,however,it decreases with increaing of the molar ratio of magnesium and phosphorus,and the settling rate is significantly reduced.

关 键 词：废水 磷回收 鸟粪石沉淀 粒径 沉降速率 

分 类 号：X703[环境科学与工程—环境工程]