كليدواژه :
آلودگي نفتي , انتقال آلودگي , آلودگي خاك , كمپوست , مدل عددي انتقال
چكيده لاتين :
In today's world, due to the production and extensive use of oil and its derivatives, soil pollution with oil
compounds is a challenging subject. In Iran and many other countries, the soil around oil exploration
reservoirs, refineries, etc., has been polluted by oil pollution and may also pollute groundwater. The greatest
concern and danger are when the oil contaminant reaches the groundwater aquifer, its solvent dissolves in
the water and contaminates the environment with groundwater. Therefore, the importance of studying how
the contamination moves and spreads in the soil is clear and valuable. The purpose of this study is to
investigate the effect of an organic amendment such as municipal waste compost on behavior and emission
of diesel as a light non-aqueous phase liquid (LNAPL) in the sand and to use an efficient model to predict
the distribution of pollutants in mixed sand with compost. Also, the effect of grain parameters and rainfall
intensity on the way of diesel emission into the sand without compost and the sand mixed with compost was
investigated. In this regard, in this study, 30 cm long columns with a diameter of 2.4 cm made of Plexiglas
were used to simulate a one-dimensional environment of transmission. Three types of sand with the particle
size of 0.1-0.25mm (fine-grained sand), 0.2-0.5mm (medium-grained sand), and 0.5-1.0mm (coarse-grained
sand), prepared and after decontamination was entered into columns. The columns were filled to a height of
24 cm with sand, and the top layer to a height of 4 cm was filled with a mixture of sand and compost with
specified ratios. Then, half a layer of mixed sand and compost in each column was soaked in diesel at a
concentration of 20 mg per 1 gr of the sand. The distilled water was entered into the column at three flow
rates of 1, 0.5, and 0.25 mL/min (equal to the intensity of 13.27, 6.33, and 3.31 cm/h, respectively) to
simulate the process of transfer of diesel into the columns. Laboratory data have been simulated using a
UTCHEM numerical model. UTCHEM is a three-dimensional and multi-phase model that simulates the
process of flow and chemical transfer in homogeneous and heterogeneous porous media. Increasing rainfall
intensity and particle diameter has led to an increase in the flow rate of contamination within the sand and
reduce the time of contamination. There are no significant changes were observed in the parameter of the
dispersion coefficient by increasing the amount of compost. As the amount of compost in the sand has
increased, the soil distribution coefficient and the retardation factor, which are the two effective parameters
on the absorption of pollutants, have increased. As an example, by doubling the amount of compost at flow
rates of 0.25, 0.5, and 1 mL/min, the retardation factor increased by 78, 100, and 80 percent, respectively.
These values for the mixture of medium sand and compost were 70, 79, and 71 percent, respectively, and in
the mixture of coarse sand with compost were 76, 82, and 73 percent respectively. The amount of
distribution coefficient has increased by 110% with doubling the amount of compost in all three types of
sand. There is an exponential relationship between the intensity of the rainfall and the distribution coefficient
in the mixture of fine-grained sand, medium-grained sand, and coarse-grained sand and three amounts of 5,
10, and 15 grams of compost. In a mixture of the three types of sand, there is an exponential relationship
between flow intensity and retardation factor for sand without compost and sand mixture and 5 grams of
compost. In the case of mixing all three types of sand with 10 grams and 15 grams of compost, the linear
relationship is the most accurate mathematical equation between flow intensity and retardation factor
