Tamer A. Elbana

Reuse of Treated Wastewater in Egypt: Challenges and Opportunities

Limited water resources in Egypt is the main factor driving the exploration of unconventional sources that can fulfill the water demands of the increasing population. Applying treated wastewater (TWW) to agriculture is a reliable, effective method of reducing the gap between current water demand and supply. Besides saving freshwater resources, long-term reuse of TWW can enhance the physiochemical properties of light-textured soil.

Lead Mobility in Calcareous Soils: Influence of Cadmium and Copper

Abstract The mobility and reactivity of heavy metals such as Pb, Cd, and Cu in the soil system is of great significance because of their potential influences on their concentration levels in the soil solution as well as water in streams and lakes. In this study, surface and subsurface soil samples were collected from an area near Bustan in the northwestern desert of Egypt. Soils were used to investigate Pb mobility in a calcareous soil and the subsequent influence of Cd and Cu on Pb release. Miscible displacement column experiments indicated that Pb was strongly sorbed (99.5%), with less than 0.5% recovery of Pb mobility in the effluent solution. The influence of subsequent Cd and Cu pulse applications did not result in Pb release from both surface and subsurface Bustan soils. Distribution of the amount of heavy metals retained versus depth in the soil column indicated that more than 85 to 93% of Pb applied was retained in the surface 2 cm. In addition, Pb was mainly associated with oxidizable as well as the carbonate and oxide fractions. Based on effluent results, the surface and subsurface soil exhibited affinity in the order of Pb > Cu > Cd. Lead exhibited high mobility when applied to the reference sand, and the amounts retained by each reference sand column were similar regardless of Pb concentration of the input pulse. Therefore, we conclude that sorption capacity for Pb in this reference sand material was attained.

Adsorption-Desorption of Lead and Tin in Soils: Experimental and Second-Order Modeling

Abstract The fate of heavy metals, such as Pb, in the soil-water environment is significant in the assessment of their potential mobility and toxicity in the ecosystem. In this study, adsorption batch and sequential extraction experiments were carried out to assess the retention and reactivity of Sn and Pb in soils. Isotherm results exhibited highly nonlinear sorption for both heavy metals. Lead isotherms indicated a Freundlich exponent parameter b of 0.204 and 0.249 for Windsor and Olivier soils, respectively. The respective values for Sn were greater than 1 (2.46 and 3.72), which implies irreversible sorption. Moreover, Sn was completely sorbed, indicative of strong irreversible retention where more than 99% of the added Sn was retained in both soils. No Sn release after 30 days of desorption was detected. The presence of Sn resulted in reducing sorption of Pb by both soils, as evidenced by the decrease in their maximum sorption capacity; whereas, Pb exhibited kinetic behavior where 3 to 15% and 13 to 28% of Pb were released for Windsor and Olivier soils, respectively, during desorption. The use of a second-order two-site model that accounts for nonlinear equilibrium and kinetic reactions was capable of describing the kinetic behavior of Pb during adsorption and desorption in both Windsor and Olivier soils. Sequential extraction results revealed that the most susceptible Pb fraction for release was highest corresponding to highest Pb input concentrations. This concentration-dependent release is consistent with the observed strong nonlinearity of Pb retention and implies that mobility of Pb tends to increase as the input Pb concentration is elevated.

Soil Chemical Pollution and Sustainable Agriculture

Sources of the agricultural soil pollution in Egypt include the utilization of agrochemicals, the reuse of agricultural drainage water, the recycling of the partially treated wastewater, the contaminated air, and the improper disposing of solid wastes. These various sources pose a real threat to the sustainable agricultural system and human health. In this chapter, we reviewed the sources and fate of the organic and inorganic pollutants in Egyptian soils. In brief, we explained sorption, mobility, and degradation properties of contaminants and their rules for realizing proper management of contaminated soils. Also, we reviewed the status of soils contamination with heavy metals and pesticides. Notably, the fate of the contaminants in soils depends on its characteristics and soil properties as well as the surrounding environmental condition. Therefore, the management of contaminated soils is a site-specific process. Such management can be ensured through prevention, remediation, and adaptation approaches. The literature review revealed the need to develop and implement a national plan for preventing soil pollution in the newly reclaimed areas. Besides, the necessity for providing a well-defined Egyptian guideline for managing contaminated sites in old agricultural lands.