Integration of high-rate filtration using waste-derived biochar as a potential sustainable technology for drinking water supply

Abstract

This research aimed to evaluate the efficiency of eucalyptus (E) and bamboo (B) residual biomass biochars as filter materials for drinking water treatment. The efficiencies of these two biochars in the rapid filtration process were evaluated using water (raw, flocculated and settled) at the rate of 120 m3/m2/d. Finding that bamboo biochar manufactured under a slow pyrolysis process "b" (Bb) had the best performance. Subsequently, Bb was evaluated with three different granulometries, and it was found that the effective size with the best performance was the finest (0.6–1.18 mm). Subsequently, this biochar was compared with conventional filter materials such as gravel, sand and anthracite, using different types of water (raw, flocculated and settled) and at different filtration rates (120 and 240 m3/m2/d), and it was found that the filter material with the best performance was precisely biochar, with average removal efficiencies of 64.37% turbidity and 45.08% colour for raw water; 93.9% turbidity and 90.75% colour for flocculated water, and 80.79% turbidity and 69.03% colour for settled water. The efficiency using simple beds of sand, biochar, anthracite and gravel at the rate of 180 m3/m2/d was 75.9% copper, 90.72% aluminium, 95.7% iron, 10.9% nitrates, 94.3% total coliforms and 88.9% fecal coliforms. The efficiencies achieved by biochar were higher compared to those of conventional filter materials. It was also found that biochar contributes to improving the performance of sand and anthracite in mixed beds. Additionally, it was possible to demonstrate that the volume of washing water required for the biochar is lower compared to the other filter beds. Finally, it is recommended to carry out more tests for the purification of water with biochars from rural areas affected by the mining and oil exploitation, as well as the purification of seawater with biochars from coastal areas with residues from dry forests and organic residues from municipalities. Graphical abstract: [Figure not available: see fulltext.]