Phosphorus Removal from Wastewater in Biofilters with Biochar Augmented Geomedium: Effect of Biochar Particle Size

Abstract

The use of biochar as a filter medium amendment has shown potential for removing organic and inorganic pollutants from wastewater. The purpose of this study was to investigate the effect of biochar particle size on: (i) removal efficiency of total phosphorus (TP) from wastewater; (ii) stability of the system under overloading and flooding conditions; and (iii) desorption potential of phosphorus from the filtration medium under inundation conditions. Biochar was prepared in two different sizes: fine and coarse with a mean diameter size of 0.31 and 0.49 mm, respectively. Two treatments using sand augmented with 8% by weight fine biochar (sand–FBC) and sand augmented with 8% by weight coarse biochar (sand–CBC) were tested. The TP removal efficiency of sand–CBC was 10% higher than sand–FBC medium. The average removal efficiencies were 83.3 ± 3.2 and 75.7 ± 7.4% for sand–CBC and sand–FBC media, respectively. Positive correlations between TP load and removal efficiencies were observed. All treatments showed resilience to overloading, flooding, and inundation conditions.