Denitrification of water using a low-cost adsorbent

Abstract

The recent studies about water quality indicated a clear increase in the concentrations of many pollutants in the sources of freshwaters, such as nitrate, phosphate, and inorganic pollutants. This increase is attributed to the expansion of the global population, industries, and climate changes. These studies represented a call for the need for efficient treatment for water and wastewater. The current study investigates the possibility of using activated red mud (ARM) as an adsorbent to eliminate nitrates from water/wastewater. The operational parameters such as treatment times, pH, and doses of ARM were tested to assess their effects on the Nitrate removability by ARM. The optimum treatment times, pH, and dose for best removal within this study were 60 min, 7, and 75 g/L for treatment times, pH, and doses, respectively. Freundlich and Langmuir isotherm models and kinetic models including the pseudo-first-order, the pseudo-second-order, and interparticle diffusion using non-linear regressions were utilized to analyze the observed data which were gained from batch equilibrium tests. The obtained results revealed that the equilibrium data have good and reasonable fitness and agreement with the Langmuir isotherm models. The highest adsorption capacity of ARM was 1.79423925mg/g. The maximum percentage of removal was found to be about 71% at ambient temperature.