الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
The availability of water resources in Egypt has become a limiting factor for the country’s development. Reusing the treated wastewater for irrigation is increasingly becoming a main low cost and reliable alternative as a sustainable non-conventional water resource that would increase in the future due to the continuously increasing population, especially in urban areas. However, inappropriate wastewater irrigation management causes public health and environmental risks. The present study provides an approach that combines health risks management, environmental risks management, and economic analysis to promote sustainable management of wastewater reuse for agriculture irrigation in Egypt. The developed approach was examined on two case studies; the first case study is the new Al-Alamein city Wastewater treatment plant (WWTP) and the second one is Alexandria WWTP. In the new Al-Alamein city WWTP, four treatment alternatives; CAS, CAS-N, MBR, and MBR-N were proposed for restricted irrigation, and six treatment alternatives; CAS-Sand, CAS-N-Sand, MBR, MBR-N, CAS-UF, and CAS-N-UF were proposed for unrestricted irrigation. Two treatment alternatives; CAS, and CAS-N were proposed for restricted irrigation in Alexandria west WWTP. There are many differences between Alexandria west WWTP and the new Al-Alamein city WWTP such as; wastewater characterization, and capacity. There are differences between cities such as; irrigation systems, water sources, and freshwater value. These case studies are located in Egypt, but they have relevance to a wide range of arid and semi-arid regions with similar conditions and agro-ecological features. The design of the selected treatment alternatives was verified using GPS-X 8.0 simulation program. Total construction, operation, maintenance, material, chemical, and energy costs of proposed treatment alternatives were estimated using CapdetWorks 4.0 simulation program. Quantitative microbial risk assessment (QMRA) is a probability method that integrates data on pathogen abundance; human exposure and infection to ensure the safety of the management strategies of wastewater reuse. The QMRA exposures are farmers and vegetable consumers during irrigation. To apply the QMRA, it is essential to identify the pathogenic indicators - representing each of the major groups of organisms (i.e. bacteria, viruses, protozoa, and helminths) - of acute and chronic human health effects in Egypt. The most affecting pathogens on public health in Egypt are; Rotavirus, Salmonella, Giardia duodenalis, and Ascaris. The risk matrix was used to select the pollutants with the highest environmental risks. A combination of treatment alternatives, wastewater application methods, and crop selection methods were evaluated for environmental risk management. Cost-benefit analysis is a well-known economic method that can be used to evaluate and compare the performance of alternative wastewater reuse strategies. Cost-benefit analysis (CBA) is a well-known economic technique that can be used for assessing and comparing the performance of alternative wastewater reuse strategies, hence supporting the selection of the optimum strategy. WWTPs consume a large amount of electricity which is known as the indirect emission of greenhouse gases (GHG). The energy consumption in this study was estimated using the GPS-X 8.0 simulation program. In conducting CBA, socio-economic impacts of global warming were estimated as external costs using carbon tax. Costs in CBA include; capital costs, O&M costs, Abstract iii external costs (carbon tax), and benefits include; fertilizing benefits, crop value, shadow prices, freshwater value, and health benefits. In this study, for a more comprehensive view of unconventional water sources, the cost of a cubic meter of water from desalination; brackish water desalination, and Mediterranean seawater desalination, and cost per cubic meter for indirect potable reuse were estimated. Desalination Economic Evaluation Program DEEP 5.1 program was used for desalinated water cost estimation. Results from the present study show that irrigation with tertiary treated wastewater can achieve the target annual infection risk for unrestricted irrigation without using advanced treatment facilities. According to pathogen concentrations in wastewater in Egypt, log unit reduction 1, 3, 1, and 2 were required from the wastewater (WW) treatment in restricted irrigation while log unit reduction 2, 5, 2, and 4 were required from the WW treatment for Salmonella, Rotavirus, Giardia duodenalis, and Ascaris respectively in unrestricted irrigation. The usage of membrane filtration provides higher protection from health risks especially caused by Giardia duodenalis and Ascaris, higher removal efficiencies, and lower footprint but it requires higher construction and running costs. Although CAS provides the lowest capital and O&M costs, it gives lower efficiencies and higher health risks than other treatment alternatives. Crops such as grains (corn and wheat), vegetables (onion, potato, tomato) can take advantage of the high level of nutrients in irrigation water. These crops may be the best option for managing excessive nitrogen. Anoxic tanks were effective to reduce the potential impact of excessive nitrogen, especially with Legumes and Rice. The cost of treating a cubic meter of wastewater for agricultural purposes in Egypt ranges from 1.26 EGP to 2.23 EGP. Activated sludge with sand filtration has the highest Benefits/costs ratio (BCR) compared to other alternative strategies of wastewater reuse. Using activated sludge with sand filtration provides a suitable effluent for unrestricted irrigation with a reasonable cost per cubic meter of 1.35 EGP. Wastewater reuse appears to be a more reliable and cheaper water resource for agricultural supply than using desalinated brackish water where the cost of a cubic meter was 2.6 EGP. The price per cubic meter of indirect potable water reuse using advanced treatment and desalinated seawater were (5.94-6.23) and 10 EGP respectively.