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Articles by N. S. Mahmoud
Total Records ( 3 ) for N. S. Mahmoud
  Ghaly A. E. , N. S. Mahmoud , D. G. Rushton and F. Arab
  A laboratory scale experiment was carried out to study the transformation and transport of nitrogenous compounds in soils receiving high application rates of cheese whey (twice the nitrogen requirement for crops). The experimental apparatus consists of 36 soil columns constructed of 20 cm inside diameter PVC pipes. Three types of soil (sandy loam, loam and sandy clay loam) and three soil depths (60, 120, 180 cm) were studied. The average monthly rainfall for the summer period in Halifax was used. The nitrogen in the soil was subject to biological transformations and downward movement in the soil. There were indications of the mineralization and nitrification processes taking place in the soil. The soil type and depth appeared to affect these processes. The ammonia volatilization occurred during the first 75 days with most (90 %) of the NH3 loss taking place during the first 30 days. The amount of nitrogen losses to the air is about 3.41 kg/ha (0.59% of the total nitrogen). The amount of organic nitrogen lost in the leachates was 3.0-4.14 kg/ha (0.52-0.71% of the total nitrogen) whereas the amount of inorganic nitrogen (ammonium nitrogen, nitrate nitrogen and nitrate nitrogen) lost in the leachates was 18.63-24.09 kg/ha (3.54-4.56% of the total nitrogen). The presence of nitrite nitrogen in the leachate at high concentrations is a potential health hazard. Although cheese whey has been reported to have the potential to improve soil conditions, excess application has the potential of degrading soils and causing health problems. Additional research is, therefore, needed to better characterize the physical and chemical characteristics of soils receiving continuous high applications of cheese whey and their impact on crop yield and the qualities of groundwater and air.
  A. E. Ghaly and N. S. Mahmoud
  The suitability of the triphenyl tetrazolium chloride (TTC) for dehydrogenase activity measurement of the vegetative cells of the fungal species Aspergillus niger was investigated. The triphenyl formazan (TF) yield increased with the increases in TTC concentration, pH, temperature and incubation time within the studied ranges. The effects of individual parameters, as well as the combined effects, on the TF yield were found to follow exponential expressions. The sensitivity analysis showed that the TF yield is more sensitive to changes in temperature followed by pH, TTC concentration and incubation time. Although the rate of increase in the enzyme activity decreased gradually with the increase in temperature, no enzyme denaturation was observer below 55 °C. The optimum TTC-test conditions for measuring the dehydrogenase activity of A. niger vegetative cells are a TTC concentration of 15 g/L, a pH of 9, a temperature of 55 °C and an incubation time of 4 h. Although the procedure has been successfully tested with mycelia of different stages of growth, it would be interesting to test the effects of different stages of growth on TTC reduction under both aerobic and anaerobic conditions.
  A. E. Ghaly , M. A. Kamal , N. S. Mahmoud and R. Cote
  The suitability of a passive technology, consisting of filters composed of a mixture of limestone and sandstone rocks, for the treatment of landfill leachates containing 6.6 mg L-1 iron and 1.8 mg L-1 manganese were investigated. The limestone and the limestone/sandstone filters successfully removed iron from the prepared solutions. The filters removed on average a minimum of 97.60% of the iron from solution on a daily basis. The removal of manganese from solution was not as efficient as iron removal. The filters removed between 22.22% and 100% of the manganese from solution. Neither the filter type nor the solution type affected the iron and manganese removal efficiencies. Although iron precipitate was evident during the 7 day experimental period, armoring did not affect the removal efficiency of the elements. The pH of the water samples did not exceed 7.7. Therefore, the wetland ecosystem should be able to adjust to water having a slightly higher pH without suffering adverse effects.
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