污水磷回收新产物-蓝铁矿

Abstract

The potential crisis of phosphorus resource is unprecedentedly pushing phosphorus recovery from wastewater and other sources. Although products of phosphorus recovery are variable, economic and high value-added products could promote owners to do so voluntarily. Among others, vivianite (Fe
₃
(PO
₄
)
₂
•8H
₂
O), which has been found to exist largely during biological sludge (biomass), is arousing attention to researchers. In fact, vivianite, a stable (K
_sp
= 10
^-36
) ferrophosphorus compound, widely exists in natural sediments. Besides such inherent factors as rich iron and phosphate, there are also some external factors determining formation of vivianite, like low oxidation-reduction potentials (ORP<-300 mV) and suitable pH conditions (6~9), etc. Fortunately, these inherent and external factors could be satisfied in wastewater and/or processes of wastewater treatment, and some wastewater treatment plants (WWTPs) in the Netherlands declared that they indeed found a large amount of vivianite presence in biological sludge. To promote both fundamental and applied researches on vivianite, the article reviews vivianite in: i) chemical properties, economic value and recovered potential; ii)controlling factors like pH, ORP, microorganisms, sulfide, etc.; iii) pathways of vivianite formation in biological sludge; iv) separation and purification of vivianite.