Investigation of Nitrate and Ammonium Removal from Groundwater by Mineral Filters

Abstract
Increasing surface and groundwater pollution by ammonium and nitrate makes it necessary to find
solutions with minimal environmental impacts. For this purpose, using abundant and high sorption
potential soil minerals offers cost-effective and environmentally sound remediation techniques. In this
study, Firoozkouh and Semnan zeolites were used for removal of nitrate and ammonium from
laboratory solutions and groundwater (Batch method). Zeolite minerals were modified by using the
organic surfactant hexadecyltrimethylammonium. A one to tenth ratio of absorbent to solution was
used. Results showed that the Semnan natural zeolite and the Firoozkouh modified zeolite treatements,
respectively, had the highest and the lowest ammonium sorption levels. The Firoozkouh modified
zeolite had the highest nitrate sorption while Semnan natural zeolite had the lowest ammonium
sorption. The highest sorption level for ammonium was found to be 0.96 meq g-1 for the Semnan
natural zeolite treatment at a concentration of 10 meql-1 and pH=5.5 while the highest sorption for
nitrate was found to be 0.8 meq g-1 for the Firoozkouh modified zeolite. Isotherms of nitrate and
ammonium sorption levels by natural and modified zeolites showed to match with those of the linear
and Fraundlich models.

Keywords: Zeolite, Fraundlich, Langmuir, Surfactant, Hexadecyltrimethylammonium (HDTMA).