Natural Clay Supported Zerovalent Iron Nanoparticles as a Potential Coagulant for Ammonia Reduction from Industrial Wastewater Effluents

Currently in South Africa, many wastewater resources are polluted by anthropogenic sources, including household, agricultural waste and industrial processes. Though several conventional wastewater treatment techniques (among others, physical decantation, chemical oxidation, and disinfection) have been applied to remove contaminants, there are still some limitations, for the removal of chemicals such as ammonia [1,2]. It has been noticed that the level of ammonia of the effluents treated was comparatively higher [3] (277mg/L) than what is required according to the South Africa National Standards [4] of Wastewater before being discharged into the environment (10mg/L). Public concern over the environmental impact of wastewater pollution has increased. To address this issue, experiments were carried out over a Jar Tester on sequential velocities (rapid mixing at 150rpm for 1min and slow mixing at 20rpm for 20min) using activated clay (bentonite) in the attempt to remove ammonia from the wastewater effluent. The natural clay was activated with 5 M sulphuric acid and amalgamated with Zerovalent Iron Nanoparticles (ZVINPs) in a mass ratio of 99:1. The physico chemically modified clay samples were characterized using X-ray fluorescence to have an idea about the mineralogical aspect of the coagulant before and after activation, and Brunner-Emmet-Teller (BET) method for surface area. The optimum dosage of coagulant to treat 1L of wastewater effluents was 61.6mg and the concentration of ammonia in the final product was about 8.71mg/L, approximately a reduction of 97%. All parameters, such as pH, conductivity complied with the Department of Water Affairs and Forestry.

Keywords:Activation; Clay; Zero valent iron nanoparticles; Ammonia; Wastewater effluents