白云石石灰流化结晶污水除磷工艺

实验研究了白云石石灰流化床工艺除磷的可行性.石灰一方面可以提高水体的pH值并提供充足的Ca2+、Mg2+,另一方面可作为晶种加快结晶沉淀反应,提高磷去除效率,是一种廉价高效的药剂.设计了新型气体搅动式白云石石灰流化床结晶反应器,以模拟污水厂污泥厌氧消化上清液为处理对象,实验考察了药剂投加量、停留时间和曝气量对反应器运行的影响.结果表明:药剂投加量在600~650 mg·L-1、停留时间5.0 h及曝气量50 mL·min-1的条件下,可以获得较好的磷去除效果,去除率可达87.0%.采用扫描电子显微镜、X射线衍射和傅里叶变换红外光谱对产物进行了表征,发现磷主要以磷酸铵镁(MAP)和羟基磷灰石(HAP)两种形式去除;由于反应体系碱度较高,产物中混杂大量CaCO3.

Process of phosphorus removal from wastewater by dolomite fluidized crystallization

This article explored the feasibility of phosphorus (P) removal by dolomite fluidized bed crystallizer. On one hand, dolomite can increase the pH value of water and provide sufficient calcium and magnesium ions; on the other hand, as a cheap and efficient agent it can be a kind of seed to accelerate the crystallization or precipitation reaction of magnesium ammonium phosphate (MAP) and hydroxyapatite (HAP), and enhance the effect of P removal. A new fluidized bed crystallizer with gas agitation was designed, and P removal experiments from simulated anaerobically digested effluent of wastewater treatment plant sludge were carried out. Operational parameters of fluidized bed such as dolomite dosage, hydraulic retention time (HRT) and aeration rate were investigated. The optimized experimental conditions are as following: the dolomite dosage ranged from 600 to 650 mg·L^-1, the HRT at 5.0 hours, and the aeration rate at 50 mL·min^-1. As a result, P removal rate reached 87.0%. The products were characterized by using scanning electron microscope, X-ray diffractometer, and Fourier transform infrared spectrometer, respectively. It was found that P was removed mainly in the forms of MAP and HAP. Due to the high alkalinity in the reaction system, the products contained large amount of CaCO₃.