Adsorption isotherms in landfill leachate treatment using powdered activated carbon augmented sequencing batch reactor technique: Statistical analysis by response surface methodology

Abstract

Abstract Landfill leachate was treated using non-powdered activated carbon sequencing batch reactor (NPAC-SBR) and powdered activated carbon (PAC) augmented SBR (PAC-SBR) processesto examine Langmuir and Freundlichadsorption isothermsin the SBR technique.Response surface methodology (RSM) was used for the experimental design and statistical analysis.Based on the obtained results, the maximum adsorption capacitiesof ammonia nitrogen (NH3-N), color, and chemical oxygen demand (COD) for the Langmuir adsorption isotherm were 5.63 mg/g, 25.30 Pt.Co/g, and 13.21 mg/g,respectively, whereas for the Freundlichadsorption isotherm, thesewere 6 mg/g, 46.29Pt.Co/g, and 15.41 mg/g, respectively.Generally, Freundlich isotherm values for NH3-N, color, and COD were higher than Langmuir isotherm values.The NH3-N adsorption on PAC was lower than the color and COD adsorptions because a great part of NH3-Nwas biologically removed in the SBR process.Increasing aeration rate and contact times in the SBR processes increased the adsorption isotherms of NH3-N, color, and COD on PAC