Treatment Of Iron In Simulated Groundwater With Ozone Technology

Abstract

Ozone technology is widely utilized in water and wastewater treatment for various treatment objectives. Dissolved Ozone are considered as a strong oxidant for many unwanted contaminants such as iron, manganese, organics in groundwater. However, levels of Dissolved Ozone are limited due to low solubility in water and its behaviors in the system of Iron water treatment have not been well investigated. This lab-scale study aimed to optimize process parameters of the Dissolved Ozone for Iron removal from simulated groundwater in order to better understand Ozone behaviors in water treatment. Parameters of input Ozone, Ozone contactors, solution pH and Iron content in water of a semi-batch reactor in laboratory were investigated. The results showed that utilization of Venturi injector in semi batch reactor had increased Ozone concentration to maximum value of 9.053 mg/L±0.277 mg/L corresponding to mass transfer coefficient of 0.195 min-1 which was higher than 1.2 times compared with Spherical diffuser 3.480±0.206 mg/L and 0.162 min-1 when input Ozone power, gas and water flowrate were 3.170±0.289 g/h, 1.0 L/min and 0.5 L/min, respectively. As a result, removal efficiency of 25 ppm Iron from water in these above conditions were 98.53±0.298%, falling below Vietnam national technical regulation of domestic water quality (0.5 mg/L) and approximate regulation of drinking water (0.3 mg/L). For mechanism removal of Iron from water, precipitation was dominant at 92.38% in base of pH8 whereas Ozonation achieved the highest efficiency at 38.96±1.168% in slightly acidic condition (pH4). However, residual ozone at pH4 was found to be higher 11.48 times than that at pH8 and not different statistically at pH6. In addition, kinetic of self decomposition of Ozone in water after Iron treatment was well fitted by the first order equation (R2, 0986; p-value<<0.05) and its rate constant was 0.064 min- 1 . These preliminary results will help better understanding Ozone behaviors in Iron treatment and for system design.