Showing 4 results for Breakthrough Curve
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.
M. Aalipour Shehni, A. Farrokhian Firouzi, H. Motamedi, A. Koraei,
Volume 19, Issue 71 (6-2015)
Abstract
Macrospore created by decaying plant root provides pathways for rapid transport of pollutants in soil profile. The main objective of this study was quantitative analysis of the effect of plant root (Zea mays L.) on bacterial and chloride transport through soil. Experiments were conducted in 9 soil columns packed uniformly with loamy sand. The treatments were bare soil, bare soil with corn (Zea mays L.) root and bare soil after decaying the corn root. The Breakthrough curves of Chloride were measured. Breakthrough curve (BTCs) of Escherichia coli and chloride were measured, too. The HYDRUS-1D one and two site kinetic attachment–detachment models were used to fit and forecast transport and retention of bacteria in soil columns experiment. The results indicated that the difference between soil hydraulic properties (saturated hydraulic conductivity and flow velocity) of the treatment was significant (p < 0.05). The result also showed that the two-site kinetic model leads to better prediction of breakthrough curves and bacteria retention in the soil in comparison with one-site kinetic model. Interaction with kinetic site 1 was characterized by relatively fast attachment and slow detachment, whereas attachment to and detachment from kinetic site 2 was fast. Most of the cells showed retention close to the soil column inlet, and the rate of deposition decreased with depth. Low reduction rate of bacteria of the soil columns with plant root and with void root channel indicated the presence of macrospores in the soil created by deep corn root system.
H. Shirani, S. Shirvani, M. Moradie,
Volume 22, Issue 2 (9-2018)
Abstract
In recent years, microbial contamination of surface and groundwater is a serious problem in some countries, leading to dangerous diseases. Soil salinity and irrigation water can affect the amount of transport or survival of bacteria in soil. In this study, the effect of different levels of salinity of irrigation water with EC: 0.5, 2.5, 6 ds/m and three manures including poultry manure, cow manure and the mixture of poultry and cow manure with 10 ton ha-1 on the transport of Escherchia coli was investigated in disturbed soil columns with 30cm height and 10cm diameter under unsteady-state water conditions. The concentration of Escherchia coli was measured. The severity of the effluent contamination of the treated columns with water salinity was 6 ds/m, which was less than that with the salinity of 2.5 and 0.5 ds/m. This difference was significant at the 0.01 probability level. Also, the effluent contamination of poultry manure-treated columns was greater than the cow manure and the mixed manure, and the contamination of mixed manure was greater than that of cow manure. The interaction of different salinity treatments on the concentration of Escherchia coli in different fertilizer treatments was significant at the 0.01 probability level. The results showed that the concentration of the released bacteria was affected by irrigation water salinity and with increasing the salinity, the concentration of the bacteria was reduced.
A. Safadoust, S. Ghanizadeh, M. Nael,
Volume 26, Issue 1 (5-2022)
Abstract
This study was conducted to investigate the effects of vegetation type (Alfalfa and Wheat) and slope (5% and 20%) on runoff and drainage pollution in clay loam soil. Sampled soils were repacked in the box with one soil drainage outlet and one surface flow outlet and were cultivated by wheat or alfalfa. A solution containing 0.05 M KCl was poured quickly and uniformly, over the surface of each box, after plant growth. Simulated rainfall was applied to the soil box with the intensity of a constant rate of 64 mm h-1 for 2 hours immediately. Then the concentration of Cl- and K+ were measured in the collected samples of runoff and the drainage outlet. Results showed that the measured concentration of K+ was lower than the Cl- concentration as a result of its absorbable property. The breakthrough curves (BTCs) of Cl- and K+ showed that slope and vegetation type affected the transport of Cl- and K+. The peak of the BTCs for Cl- and K+ in runoff ranked in the order of wheat and 20% slope> alfalfa and 20% slope> wheat and 5% slope> alfalfa and 5% slope, and in the drainage changed to alfalfa and 5% slope> wheat and 5% slope> alfalfa and 20% slope> wheat and 20% slope. For each slope, the intensive vegetation cover of alfalfa than wheat considerably reduces Cl- or K+ pollution in runoff; whereas drainage development of larger and deeper root systems was the cause of higher leached concentrations for both tracers. Based on our research changes in soil surface vegetation cover from wheat to alfalfa are suggested in slope land to prevent surface water pollution; although other factors such as the climate, soil texture, and structure should also be considered.
