Optimizing ammonia removal from landfill leachate using natural and synthetic zeolite through statically designed experiment

Abstract

Water is an essential commodity that supports the very existence of life on earth; hence, contamination of ground and water bodies with harmful substances liberated by landfill leachate can seriously impact the environment and well-being of mankind. In this context, explorations in search of economically attractive avenues to treat landfill leachate merit scientific pertinence. A response surface methodology approach based on a three-factor three-level central composite design was applied to compare and optimize the removal of ammoniacal nitrogen (NH3–N) from landfill leachate. In this study, the efficacy of natural zeolite, clinoptilolite, and synthetic zeolite, Sigma 96096, as adsorbents was investigated for parameters, viz. zeolite dosage, particle size, and ratio of leachate to distilled water, respectively. Under optimized conditions, clinoptilolite (2 g/L, 50 μm, and 50%) and Sigma 96096 (4 g/L, 150 μm, and 50%) effectively removed 58.2% and 37.8% of NH3–N, respectively. The equilibrium isotherms of both sorbents for the sorption of NH3–N were also well described by the Freundlich and Langmuir adsorption isotherms, respectively. The study found clinoptilolite was more efficient than Sigma 96096 in removing NH3–N, envisaging its suitability for complementing the current treatment processes to treat landfill leachate.