Utilizing waste eggshells as a calcium precursor for contact precipitation of phosphorus from digested sludge centrate

Abstract

Phosphorus (P) recovery from wastewater is an essential component of the global P cycle. A contact precipitation process using chicken eggshells as a calcium (Ca) precursor was used to recover P from synthetic wastewater and real digested sludge centrate. Up to 96.4 % of P could be recovered from the digested sludge centrate after three repeated cycles of the contact precipitation process. In addition, 36.1 % of total chemical oxygen demand and 37.6 % of total ammonia nitrogen were removed from the centrate. Finally, most of the precipitates could be collected by a simple washing step. Scanning electron microscopy–energy dispersive spectroscopy and x-ray diffraction results indicated that the eggshells played three roles in this process: Ca source, precipitation substrate, and filter medium. Precipitates were mainly brushite. This research provides a new perspective on P recovery from wastewater using waste eggshells, and if further optimized, has a potential for practical future applications.

Deng, L., Zakaria, B. S., Zhang, J., & Dhar, B. R. (2024). Utilizing waste eggshells as a calcium precursor for contact precipitation of phosphorus from digested sludge centrate. Science of The Total Environment, 919, 170906.

https://www.sciencedirect.com/science/article/pii/S0048969724010453