Natural Coal Aggregates to the Rescue of Fe°-Bed Filters in Quaternary Reactive Zones Fe°/S/Pz/CX to Repel Clogging and Boost Reactivity

Abstract

The absorption and remediation power of natural coal (NC) and its contribution to the harvesting of corrosion products (CPs) resulting from electrochemical processes of Fe° oxidation in the reactive zone (RZ) of Fe°/S/Pz/C (Iron/Sand/Pozzolan/Natural Coal) in Fe°-bed filters have now been proven. As a result, an in-depth study of NC varieties (CX) for increased performance of Fe°/S/Pz/CX (Iron/Sand/Pozzolan/Natural Coals varieties) for water quality was investigated. Nine (9) systems were used, with respective RZs consisting of (1) Fe° (Pure Iron), (2) AC (pure Ayous wood’s Coal), (3) CC (pure Coconut bark’s Coal), (4) MC (pure Movingui wood’s Coal), (5) PC (pure Padouk wood’s Coal), (6) Fe°/S/Pz/AC (Iron/Sand/Pozzolan/Ayous wood’s Coal), (7) Fe°/S/Pz/CC (Iron/Sand/Pozzolan/Coconut bark’s Coal), (8) Fe°/S/Pz/MC (Iron /Sand/Pozzolan/Movingui wood’s Coal) and (9) Fe°/S/Pz/PC (Iron/Sand/Pozzolan/Padouk wood’s Coal). OM (orange methyl) of 2 mg/L concentration was used as operative indicator. The experiments lasted forty (40) days per device. We measured the pH, discoloration, dissolved iron content of the collected water, while observing the flow rate and stability of every Fe°/S/Pz/CX. Thereby, the beneficial effects of the Pz/CX combination in the RZ are proven regardless of the variety used. Thus, CC is the best absorbent material almost as good as Fe°. PC has the best throughput and therefore the most permeable. All varieties contribute to the minimization of iron released. The pH is in line with WHO recommendations. Fe°/S/Pz/CX discoloration’s performance is thus evolving: Fe°/S/Pz/CC ˃ Fe°/S/Pz /AC ˃ Fe°/S/Pz/MC ˃ Fe°/S/Pz/PC ˃ pure Fe°; the flow changes inversely. With 98% ≤ 25% Fe° / 25% S / 25% Pz / 25% CC ≤ 100% discoloration rate, Fe°/S/Pz/CC is the most stable over time. CC appears to be the best non-expansive porous material to be combined with the ternary Fe°-based filters, and widely with Fe°/H2O systems to allow a resurgence of efficiency, to delay clogging and extend lifespan.