Showing 3 results for Filtration Coefficient
S. H. Tabatabaei, H. Fardad, M. R. Neyshabory, A. Liaghat,
Volume 10, Issue 1 (4-2006)
Abstract
To determine the water application efficiency in furrow irrigation more accurately, consideration of seasonal and spatial variation of infiltration properties are needed. In addition, the effectiveness of different farm management on infiltration are significant. The main objective of this research was to simulate the seasonal variation (SV) of infiltration coefficients in Kostiakov-Louise equation (KLE) in a cracking soil under two traditional farm managements. Farm studies carried out in a clay-loam soil in Karaj. The two management treatments were soil without wheat residual and soil with wheat residual by a 5 ton/ha rate. There were 22 furrows with 0.75 m width in the farm. KLE infiltration coefficients were measured using inflow-outflow and two point’s methods in six furrows. The results of this study indicated that the SV of a and k coefficients were not significant, but variation of f0 was significant which was simulated with a logarithmic model. The effectiveness of SV on cumulative infiltration (Z) was also evaluated and indicated to be significant that were simulated with a logarithmic model too. Finally, dimensionless parameter such as Z* were developed to predicate Z parameter in different irrigation time, irrigation events and different residual management. Base on the result, although residue management causes a significant difference between value of f0 and Z in two treatments, but it doesn’t effect on trend of variation during the season. It means that the trend of variation is independent of residue in soil. It is probably done because of change in some of soil physical properties such as soil bulk density and aggregate stability.
K. Rostami, M. R. Mosaddeghi, A. A. Mahboubi, A. A. Safari Sinegani ,
Volume 12, Issue 44 (7-2008)
Abstract
Transport and filtering of pathogenic bacteria through porous media and groundwater resources are important and، therefore the effect of various factors on bacteria transport and filtering has been given a great attention nowadays. In this study، effects of calcium sulfate and carbonate on Psedomonas fluorescens filtration and filtering parameters were investigated in saturated sand columns under steady-state flow. The calcium carbonate levels included 0، 5، 10 and 20 %w/w and calcium sulfate levels consisted of 0، 5 and 10 % w/w which were thoroughly mixed with sand (0.15-0.25 mm). The experiment was considered factorial in completely randomized design with three replicates. The treated sands were poured into pyrex cylinders with length of 20 cm and diameter of 7 cm. Then، steady-state saturated flow with constant flux was applied to the columns. When the steady-state flow was established، the bacteria suspension with concentration of 106 CFU cm-3 (C0) was injected as step input into the columns. The leaching then was continued up to 5 times of pore volume (PV). The effluent concentration of the bacteria (C) was measured at 0.25 PV intervals. Then، the sand columns were divided into 0-5، 5-10، 10-15 and 15-20 cm layers in order to measure the filtered bacteria in each layer. The results showed that the effects of calcium carbonate on retaining of the bacteria in the 5-10 and 10-15 cm layers were significant at 1% level. It was significant at 5% for the 15-20 cm layer. The effect of calcium sulfate was also significant at 5% for the 10-15 cm and 15-20 cm layers. The interactive effects of treatments on bacteria adsorption was significant for the 5-10، 10-15 and 15-20 cm layers. The retained concentration profile and the filtration coefficient were significantly affected by the treatments، showing higher bacteria adsorption at lower depths and predominance of physical filtering. The results showed the high filtering capacity of carbonate and sulfate minerals which could ultimately reduce bacteria transport in saturated porous media towards groundwater resources.
A. Safadoust , A. Mahboubi, M. R. Mosaddeghi, Gh. Khodakaramian, A. Heydari,
Volume 15, Issue 57 (10-2011)
Abstract
In this study, the transport of nalidixic acid-resistant Escherichia coli (E. coli NAR) through two soils of sandy loam and clay loam was investigated. Saturated and unsaturated flow conditions were applied at two temperatures of 5 and 20ºC. Leaching was done using large repaired soil columns which had been subjected to physical weathering. A 20-cm diameter disk infiltrometer was set up to establish the steady-state flow conditions. Effluent was sampled at three depths of 15, 30 and 45 cm of soil columns. Saturated flow condition, temperature of 20 ºC and clay loam soil resulted in increasing the bacteria concentration in the leachate. Filtration coefficient and relative adsorption indices in sandy loam soil (average flow conditions, temperature and depth) were greater than those of clay loam soil with the respective values of 33% and 23%. These results may be related to the instability of soil structure and abundance of micropores in the sandy loam columns. In other words, the bacteria were physically blocked and entrapped in the fine pores of sandy loam soil. Effluent bacteria concentration decreased by depth of soil column, indicating the effect of soil on bacterial filtration as a natural filter. Leaching with cold water led to decrement of flow rate and consequently increment of bacterial filtration in the two soils of clay loam and sandy loam (average flow conditions, temperature and depth) with the respective values of 100% and 68%.
