Natural Charcoal in Water Treatment Through Metal Bed Filters Fe°/S/Pz/C: The Concept of Wood-Energy-Sanitation

Abstract

The concept of the W.E.S (Wood-Energy-Sanitation) for raising awareness among populations far from the distribution networks of drinking water is established. The process of decontaminating filter columns made up of natural charcoal (NC) as porous non-expansive absorbent/adsorbent materials such as pozzolan (Pz) is experienced. The contribution of the NC to the filtering power of the Fe°-based filters, whose decontamination involves the electrochemical oxidation processes of Fe°, and corrosion products (CPs) that can cause a blockage of the reactive surface is studied. To do this, seven systems were tested with reactive zones (RZ) respectively consisting of (1) C (pure NC), (2) Pz (pure Pozzolan), (3) Fe°/C (iron/NC), (4) Fe°/Pz (iron/Pozzolan), (5) Fe°/S/C (Iron/Sand/NC), (6) Fe°/S/Pz (Iron/Sand/Pozzolan), (7) Fe°/S/Pz/C (Iron/Sand/Pozzolan/NC). OM (orange methyl) of 2 mg/L concentration was used as operative indicator. The experiments lasted 40 days per device. Performance parameters such as pH, residual iron, OM discoloration and flow rate were measured. As a result, it appears that the NC alone or associated in the Fe°/C, Fe°/S/C devices has a better filtering power than the Pz. The combination of NC and Pz in the same Fe°/S/Pz/C device improves strikingly the results, such as Fe°/S/Pz/C > Fe°/S/C > Fe°/S/Pz > Fe°/C > Fe°/Pz > C > Pz. Combining two non-expansive porous materials in the RZ stabilizes the Fe°/S/Pz/C-filter and improves its lifespan.