Phosphorus removal from wastewater in biofilters with biochar augmented geomedium: Effect of biochar particle†

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: (a) Removal efficiency of total phosphorus (TP) from wastewater, (b) stability of the system under overloading and flooding conditions, and (c) 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.