Ammoniacal Nitrogen Removal from Synthetic Wastewater Using Limestone and Granular Activated Carbon in Batch Study

Discharging of excessive wastewater nutrient in the form of ammoniacal nitrogen (N-NH4) into the receiving water causes environmental problems such as eutrophication, corrosion and fouling. Presently N-NH4 is removed from wastewater in tertiary treatment. The purpose of the present study was to investigate the removal of N-NH4 from synthetic wastewater using limestone (LS) as low cost media and granular activated carbon (GAC). The physio-chemical treatment adopted in this study is preferred over the other methods because of its simplicity, easy maintenance and quality control. The batch experiments were investigated to evaluate the combine mixture ratio of limestone and activated carbon at pre-examined optimum conditions on the removal of both parameters. Results indicated that 58% of N-NH4 was successfully removed at optimum media ratio of 25:15 (LS:GAC). Results indicated that the smaller particle size of media was more effective than larger particle size because small size particle causes a higher adsorption capacity due to great available surface area. The equilibrium adsorption data is fit and followed Freundlich isotherm (Kf=1875, n=0.42 and R2=0.9827). The experimental data agreed with the pseudo second-order kinetic model (R2 > 0.90). This shows that the usage of GAC can be reduced by combining the media with limestone. The study indicated the potential use of LS and GAC for the treatment of N-NH4 and P-PO4 from wastewater at lower cost as compared to the use of GAC alone.