H. Taheri Sodejani, S.h. Tabatabaei, M. Ghobadinia, H. Kazemian,
Volume 18, Issue 67 (Spring 2014)
Abstract
Zeolites are substances that have been renowned for their remarkable nitrogen adsorption capacity resulting of decrease
in leaching rate of soil nitrogen. This research was conducted to study the effect of the zeolite dosage, zeolite particle
size and the method of application on the nitrate leaching of the soil irrigated by treated wastewater (TWW). All of the
adsorption tests were carried out in a 27 PVC columns with 11 cm diameter and 60 cm length. The experiments were
consisted of 9 treatments and 3 replications including 2 zeolite application method (mixed and layered), 2 zeolite’s
grain size (63-125 and <63 micrometer) and 2 zeolite dosage (2 and 4 percent). Zeolite powders were added to the soil
in mixed or layered fashion. The soil columns were irrigated 13 times with TWW in a weekly period. In the 4th, 9th and
13th irrigation event, three samples were taken from input and output TWW introduced to columns to measure the
change in nitrate concentration. The results were shown that nitrate absorption rate was increased by average of 164.3%
and 350.7% in mixed and layered treatments, respectively compared to the control. The result showed that zeolite
application method, irrigation event, zeolite’s grain size and dosage were statistically significant on nitrate absorption
efficiency (P<0.01). It shows that as the zeolite size decrease the soil nitrate adsorption increases significantly. It
increases when the zeolite percentage increases. The result show that the soil nitrate adsorption decreases as the
irrigation event increase and soil adsorption potential degraded with irrigation events.
