Abstract

A co-flow pilot filter with a packing support material (coated jujube seeds) was constructed and tested for the biological removal of iron from Senegalese groundwater. Indeed, it is a PVC tube with an internal diameter of 40 mm and a height of 90 cm. The performance of the filter was tested at a constant hydraulic head of 261.67 m³/m² per day while the iron feed concentrations varied between 0.5-1, 0.5-1.5 and 0.5-2 mg/L, respectively. Coated jujube seeds, covered with a plastic layer and a biofilm containing microorganisms, were used as the filter material. The iron removal was carried out in a single stage, for which a period of two months was required for the maturation of the bed. In optimal working conditions (Q_L = 8.11 L/h; pH = 9.5; [Fe²⁺]₀ = 2 mg/L; P = 1.013 bar and T = 25±1° C; Redox potential = 300 mV), an operating cycle time of 1 day has proven to be sufficient for the filter bed backwash operation. The results show that the biological treatment gives reduction percentages of 39.3, 48.76 and 67.23%, respectively for the boreholes of Pout Kirène (PK2), Pout Sud (PS5) and Koungheul (KK5).

Key words:  Biofilm, continuous test, biological oxidation, iron removal, column, doped water.