Ammonium removal and recovery using natural zeolites and air stripping technique for greywater treatment

This paper provides comprehensive investigation of natural zeolites for ammonium removal from greywater and its recovery by using air stripping technique. The combination of air stripping method during regeneration phase of natural zeolites aims in saving excess regenerant solutions as well as obtaining ammonium recovery. Theoretical attributes such as adsorption isotherm, kinetic, and thermodynamics were elucidated. To seek for optimized parameters in batch test, quadratic equation was derived from RSM (Response Surface Methodology) (p-value < 0.01 and R2 ≈ 0.99) and it was further found that the interaction of zeolite loading and contact time had stronger effect on ammonium removal. In the column experiment, Thomas model predicted the breakthrough curve of ammonium adsorption with R2 ≥ 0.92. Additionally, the ammonium desorp tion experiment showed that the application of concentrated recycling brine solution with the combination of air stripping technique enabled up to 97% ammonium recovery within 3 h. In our conceptual design approach, dimensions of working bed and operational parameters could be estimated based on the characteristics of natural zeolites, greywater, and treatment objectives. Breakthrough curve estimation for scale-up condition based on experimental data fitting Thomas model was well constructed under specific criterion (constant ratio of bed height/column diameter and linear velocity). Competitively, unit process which combines natural zeolites and air stripping technique for ammonium removal and recovery can be adaptable for greywater treatment purpose