Investigation of biochar- modified biosand filter performance for groundwater treatment for drinking water purposes: A laboratory and pilot scale study

This study investigated the feasibility of improving the performance of biosand filter (BSF) using date palm biochar for groundwater treatment. The effect of date palm biochar placement (at the top, middle and bottom region of the filter media) on the modified biosand filter (MBSF) against BSF was investigated on a lab scale for simultaneous removal of Cu, Zn, Fe, Mn, NH₄⁺, PO₄³⁻, NO₃⁻, SO₄²⁻, Cl⁻, Na, Mg, K, turbidity, color, and total coliform from synthetic groundwater. Filters were charged intermittently twice per day for 90 days. The average removal percentage of Cu was 95.05 and 99.23 %, Zn was 99.99 and 100 %, Mn was 74.54 and 89.99 %, Fe was 60.18 and 78.94 %, NH₄⁺ was 22.33 and 30.62 %, PO₄³⁻ was 99.45 and 99.53 %, NO₃⁻ was 8.03 and 8.18 %, K was 16.33 and 16.41 %, Total coliform was 93.97 and 92.89 % and effluent pH was 8.03–8.18, for lab scale BSF and MBSF(D) respectively. Turbidity and color removal was 100 %, while no removal was observed for SO₄²⁻, Cl⁻, Na, and Mg in the lab-scale filters. Using biochar and positioning it at the bottom region of the filter media as in MBSF(D) showed significant removal for Mn and Fe. The pilot scale MBSF(D) showed earlier clogging (43 days) and reduced treatment percentage for contaminants in comparison to the lab scale MBSF(D), except for total coliform (100 % removal). After regeneration, effluent concentration still met WHO drinking water limits and was operational for 82 days on the lab scale MBSF(D) and 32 days on the pilot scale MBSF(D).