Phosphorus removal from wastewater by fly ash ceramsite in constructed wetland

Abstract

Fly ash ceramsite-assisted phosphorus (P) removal from wastewater was investigated in this paper. First, the basic physical and chemical properties of two types of fly ash ceramsites were outlined. The adsorption capacity of P in wastewater was then examined by static interval experiments, in which the influence of temperature and contact time was investigated. The maximum adsorption capacity of the fly ash ceramsite of P was 0.892 mg g^–1, and their adsorption processes were described by a single - level variable dynamic model, in which the correlation coefficients were > 0.85. Furthermore, the fly ash ceramsite with higher P adsorption capacity was applied in a constructed wetland as a substrate to continuously treat wastewater. It is noteworthy that the adoption of fly ash ceramsite in such an environment significantly improved P removal from wastewater: the total P and dissolved orthophosphate in the effluent after treatment were < 0.40 mgL^–1 and < 0.20 mgL^-1 respectively and the P-removal rate reached 90%. The results indicate that fly ash ceramsite can be used as a high - efficiency substrate in constructed wetlands to enhance P removal, and can reduce the area required for constructed wetlands.

Key words: Fly ash ceramsite, constructed wetland, ceramic substrate, phosphorus removal.