Sewage phosphorus removal using hen eggshells through different contact systems

Abstract

Hen eggshell is a waste with high phosphorus (P) removal capacity from synthetic solutions. However, there is a lack of knowledge about how to use this material on P removal from real wastewater. The present study proposed to evaluate two types of system for P removal from wastewater using eggshells. On the first system, eggshells grinded, sieved in 0.425 mm, and contained in coffee filters, were fixed to baffles using calico cloth bags. On the second, the eggshells in the same conditions were attached to vertical wooden rods and distributed at different heights. For both systems, P concentration was daily monitored for four weeks, with and without medium acidification and hydraulic retention time of one day. The baffles system was more efficient, reaching a maximum removal of 15.93% in wastewater with pH 4.73. P removals did not differ significantly over the weeks; however, there is a tendency to vary the efficiencies according to the change in pH. The baffled tank, for presenting higher performance in P removal, is the most suitable for use in a domestic wastewater treatment system.