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.
H. Beigi Harchegani, G. Banitalebi, M. Ghobadinia,
Volume 21, Issue 1 (Spring 2017)
Abstract
Treated wastewater may influence soil structure, porosity and as a consequence, soil saturated hydraulic conductivity. This study aims to assess the effect of wastewater on saturated hydraulic conductivity; and to determine the suitable soil solids fractal dimension to incorporate into the pedotransfer function by Rawls et al (1993) for estimation of saturated hydraulic conductivity (Ks). Soil saturated hydraulic conductivity was measured by disc permeameter. Soil particle fractal dimension was calculated from linearized forms of mass- time, mass- diameter and mass- diameter as modified by Kravchenko- Zhang (1998) relations. Wastewater irrigation for 13 years increased the saturated hydraulic conductivity three times, from 7 mm/hour to 21 mm/hour, but longer application of wastewater did not further increase it. Rawls et al (1993) pedotransfer produced acceptable and relatively close saturated hydraulic conductivity values to that of disc permeameter when fractal dimension obtained from the linearized forms of mass- diameter and Kravchenko- Zhang relations were used. Therefore, Rawls et al (1993) pedotransfer was capable of reflecting the effect of wastewater application on soil saturated hydraulic conductivity.
