Abstract:
The Cascade Aerator model is a ladder-shaped gravity aerator model used to treat water with a high content of dissolved inorganic solids. This model can increase the level of dissolved oxygen in water up to 80%. This study aims to determine the effect of pH, the length of oxidation time and the efficiency of reducing the dissolved metal ions of Fe and Mn in a community dug well water sample. With the oxidation aeration method using the Cascade Aerator model. The effect of the pH of the water sample on the efficiency of reducing Fe and Mn during oxidation was studied by adjusting the pH of the water sample at pH 2, 4, 7 and 10 with the oxidation time of 15, 30 and 60 minutes. Characterization of well water samples including Fe and Mn levels was carried out using the AAS method. The results of the treatment of the three well water samples showed that effective oxidation occurred in well water samples with pH ≥ 7 where Fe and Mn were oxidized to> 90%. The oxidation of Fe and Mn in well water samples with acidic pH (≤4) tends to run slowly due to low pH, inorganic solids are in the form of dissolved ions. Based on the stoichiometric equation, the reaction between Fe and O2 requires less oxygen than the reaction between Mn and O2 so that the aeration time does not significantly affect the oxidation of Fe. Fe oxidation requires a shorter time (maximum oxidation can be achieved in 5 minutes of aeration time) compared to Mn oxidation. The efficiency of reducing Fe and Mn levels in dug well water samples can reach ≥90%, especially for water samples with pH ≥7 and the remaining Fe and Mn levels have been below the required quality standard according to the Minister of Health Decree No. 492 of 2010, namely Fe 0.3 mg/L and Mn 0.1 mg/L.
