الفهرس 
ACKNOWLEDGEMENTSOnly 14 pages are availabe for public view
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Abstract
In recent years, Egypt has suffered from severe water scarcity. It is considered that the unequal distribution, misuse of water resources, and inefficient irrigation techniques are some of the main factors that play a destructive role in water security. There is tendency in Egypt to solve the problem by providing other sources such as desalination and wastewater treatment to meet the requirements. Groundwater is the second water source in Egypt after the Nile River, it is considered the primary source of water in many areas, especially in desert regions such as the Western Desert and Sinai.
Soil aquifer treatment system (SAT) is a natural advanced treatment technology of partially treated wastewater with no chemical addition and little energy. The artificial aquifer recharge by partially treated wastewater presents an attractive tool that can be applied in Egypt to be safely reused in unrestricted irrigation. SAT system is accepted as the most favorable solution for wastewater treatment in developing countries as well as developed countries. It is cheap, easy construction, maintenance, and exceptional performance in removal of chemical as well bacteriological parameters. It is also very sustainable for environment.
In this research real secondary treated wastewater effluents from west of Sohag wastewater treatment plant was used for SAT system and are shown in the present thesis. It contains of two parts, in the first part of this thesis, reclaimed water quality was determined by analyzing water samples obtained from the site’s recovery wells which located at horizontal distance of 500, 750, 1000, and 1500 m from an infiltration basin. This part aims to (a) evaluate the reclaimed water quality after SAT system to be reused in unrestricted irrigation in Egypt, which will be environmentally safe and publicly accepted rather than disposing it into surface water ways, (b) estimate the efficiency and purification capacity of this system, (c) examine the physical, and biological, that occurs in this system. Our measurements were concerned to; Hydrogen ion (pH), dissolved oxygen (DO), total dissolved solids (TDS), total suspended solids (TSS), biochemical oxygen demand (BOD5), chemical oxygen demand (COD), boron (B), total coliform (TC), fecal coliform (FC), heterotrophic bacteria (HB), organic nitrogen (ON), nitrite (NO2¯), nitrate (NO3¯), ammonia (NH3), phosphate (PO4¯), total nitrogen (TN), total Kjeldahl nitrogen (TKN), heavy metals (Al3+, Cd2+, Cr6+, Cu2+, Mn2+, pb2+, and Zn2+), and major cations (Ca2+, Mg2+, Na+). Results indicated that, pH of the reclaimed water varied between 7.53 and 7.71. DO concentration of the reclaimed water exceeded 4 mg/l. SAT system’s efficacy in eliminating BOD5, COD, TSS, TC, FC, and HB was 98.3%, 91 %, 90.7%, 99.99%, 99.99%, and 99.8, respectively. While, TDS and B concentrations increased slightly after SAT system as it moved through the aquifer’s vadose zone. ON, NH3, NO2¯, PO4¯, and TKN were totally removed with an efficiency of 100%. While, TN concentration was removed with an efficiency of 50%. SAT system is not effective in removing NO3 from the recharged water. On the other hand, heavy metals (HM) concentrations were completely removed with a removal efficiency of nearly 100%. According to the Egyptian Code of Practice (ECP) and Food and Agriculture Organization (FAO), the reclaimed water is suitable for irrigation. Moreover, reclaimed water suitability for irrigation was assessed based on electrical conductivity (EC), sodium adsorption ratio (SAR), magnesium hazard (MH), total hardness (TH), and Kelley’s ratio (KR). It is found that, extracted water at 1500 m horizontal distance from the infiltration basin is suitable for irrigation when considering the SAR, EC, and MH values. On the other hand, the extracted water from the surrounding area is present under hard to very hard category, reflecting its unsuitability for irrigation purposes. Based on KR, samples are unsuitable for irrigation if KR is considered. By studying cost effective of SAT and comparing with tertiary treatment as shown in Appendix (A). SAT costs 34% less than the tertiary treatment of the partially treated wastewater.
In the second part of this thesis, quality improvements on the recharged water that occur in the vadose zone during its percolation were assessed based on fundamental removal mechanisms. The influence of the upper 300 cm vadose zone thickness on the removal of wastewater contaminants was evaluated. Hydrogen ion (pH), total suspended solid (TSS), total dissolved solid (TDS), biochemical oxygen demand (BOD5), chemical oxygen demand (COD), total coliform (TC), fecal coliform (FC), boron (B), major cations (Na+, Ca2+, Mg2+), and heavy metals (Al3+, Cd2+, Cr6+, Cu2+, Mn2+, pb2+, and Zn2+) were analyzed at 0, 30, 60, 100, 150, 200, and 300 cm soil depth. Results showed that, the upper 300 cm soil layer was effective in removal of some contaminants from wastewater. Application of wastewater in SAT system caused an increase of soil pH with depth from 7.38 to 8.25. Removal efficiency of COD and BOD5 was 83.27% and 83.24%, respectively. During the percolation, TSS decreased from 146.70 to 76.50 mg/l, with removal efficiency of 47.90%. High removal efficiency of TDS 91.40% was observed. Removal of TC, and FC concentrations were high with a maximum reduction of 99.50%, and 99.40%, respectively. On the other hand, B concentration increased from 0.15 to 0.50 mg/l. Removal efficiency of cations was 84.50%, 43.50%, and 15%, for Mg+2, Na+, and Ca+2, respectively. Heavy metals concentration within the soil layer was fairly restricted to several centimeters. The removal efficiency was as follow; Cd2+ (100%)> Zn2+ (59.80%)> pb2+ (52.90%)> Mn2+ (10.80%)> Cu6+ (8.90%)> Al3+ (5.53%). Moreover, no major removal values were obtained in chromium (Cr6+) concentration.