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Soil and ground water resource pollution by petroleum compounds and chemical solvents has multiple negative environmental impacts. The aim of this research was to investigate the impacts of kerosene and gas oil pollutants on some physical and chemical properties, breakthrough curve (BTC), and water retention curve (SWRC) of silty clay soil during a 3-month period. Therefore, some water-saturated soils were artificially contaminated in the pulse condition inside some glassy cylinders by applying half and one pore volume of these pollutants, and then parametric investigations of the SWRC were performed using RETC software for Van Genukhten and Brooks-Corey equations in the various suctions and the soil properties were determined before and after pollution during 3 months. The results showed that gas oil and kerosene had a slight effect on soil pH and caused the cumulative enhancement in the soil respiration, increase in the bulk density and organic matter, and reduction in the soil porosity and electrical and saturated hydraulic conductivity. Furthermore, gas oil retention was significantly more than kerosene (almost 40%) in the soil. The survey of SWRC indicated that the contaminated soil samples had a little higher amount of moisture retention (just under 15% in most cases) compared to the unpolluted ones during this 3-month period. The parametric analysis of SWRC demonstrated an increase in the saturated water content, Θ s, from nearly 49% in the control sample to just under 53% in the polluted ones. Contaminants not only decreased the residual water content, Θ r, but also reduced the SWRC gradient, n, and amount of α parameter. The evaluation of both equations revealed more accurate prediction of SWRC's parameters by Van Genukhten compared to those of Brooks and Corey.

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Phytoremediation is one of the simple and cost-effective methods introduced in recent years as a solution for eliminating environmental pollution. This study aims to assess the feasibility and effectiveness of Vetiver grass and Pampas grass plants in removing main pollutions and improving the physical and chemical properties of the treated municipal wastewater, for use in agriculture and drip irrigation systems. This study was conducted in the form of a factorial experiment with two factors of plant type (Vetiver grass and Pampas grass) and residence time (in five levels: 3, 6, 9, 12, and 15 days) and in a completely randomized design with three replications. The results showed that although both plant types had a high potential to reduce the undesirable properties of treated wastewater with a residence time of 15 days, Pampas grass exhibited better performance in most of the studied characteristics. This plant, even with a residence time of 3 days, reduced the concentration of chloride, sodium, calcium, carbonate, and bicarbonate and also the sedimentation index by 58.82, 38.64, 40.03, 73.91, 45.44, and 88.16%, respectively. Moreover, Pampas grass reduced the salinity and hardness of water by 48.84 and 23.32%, respectively, and the electrical conductivity and TDS by at least 18.32% in 3 days. According to the findings of this study, Pampas grass is a better option than its competitor, Vetiver grass, to reduce pollution in the treated urban wastewater and improve the wastewater quality for use in agriculture and drip irrigation systems.