الفهرس 
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Abstract
The objectives of this study are to evaluate and improve the performance efficiency of wastewater treatment plants operating in El-Gharbia governorate. In addition to study the effect of sewage sludge and triple superphosphate (inorganic fertilizer) application on soil and plant (lycopersicon esculentum Mill) properties. The present thesis consists of three chapters. Chapter 1: embraces the introduction and the literature survey on the previous studies of the present work. Chapter 2: reports the results and discussion which comprises 43 Tables and 47 Figures and will be presented in the following topics: Chapter 3: describes the experimental part including chemicals, equipment and techniques employed during the present work. Separated parts include references, English and Arabic summary in addition to the recommendations of the present study. 1. Evaluation of the performance efficiency of different thirty WWTPs Theoretical correlations between influents and effluents TSS, COD and BOD5 were determined. These correlations can be used to provide a good advantage for treatment plant control and operation. The obtained results show that: Non-significant variation in the influent’s mean TSS, BOD5, COD and COD/BOD5 ratios are observed. While significant variations in the removal efficiencies and the effluent concentrations considering all the analysed constituents are obtained during the experimental period (12 months) within all investigated treatment plants. The influents of the investigated WWTPs are human wastes. 2. Assessment of wastewater treatment technologies The results of this investigation show that: The oxidation ditch technology is the most common. TSS and BOD5 removal efficiencies of the aerated lagoons technology are significantly the highest, while the TSS and BOD5 removal efficiencies of the conventional activated sludge technology are significantly the lowest. This may be attributed to the difference in the operational conditions and standards of the applied technologies. Non-significant difference in the mean influent COD/BOD5 ratios is observed. 3. The highest and the lowest efficiency WWTPs The results of this investigation indicate that: Kotour WWTP exhibits the highest performance efficiency, while Tanta stage 2 WWTP exhibits the lowest one. This may be due to the presence of some miserable operational disorders in the operating system of Tanta stage 2 WWTP. In addition to the increase of BOD5, COD, sulphides, oil and grease and ammonia in its influent as compared to Kotour WWTP.
Effluent’s COD/BOD5 ratio of Kotour and Tanta stage 2 WWTPs are higher than that of the influents. The investigated heavy metals and the highly diluted industrial effluents have no obvious effect on the performance efficiency of the biological treatment of wastewater. The removal efficiencies of heavy metals differed according to their types and to WWTP performance efficiency. Increasing of TBC and TCF in the oxidation tanks outlet increases the WWTP performance efficiency. The bacterial diversity positively affected the performance efficiency of the biological treatment of wastewater. Ammonia is removed from the oxidation tanks of Kotour and Tanta stage 2 WWTPs biologically by the nitrifiers. Bacteria in wastewater are capable of removing heavy metals by accumulating them from aqueous environment. 4. Effect of sewage sludge and triple superphosphate application on soil and plant properties The obtained results imply that: High values of electrical conductivity, available Fe, Cu, Mn, Zn, Ni, Co, Pb, nitrogen, and phosphorous are noticed in sludge compared to the three experimental soils. Sludge pH is lower than that of the three experimental soils. Before planting, compared to the control soil, sewage sludge application increases the available content of Fe, Cu, Mn, Ni and Co, while decreases the available content of Pb and phosphorous. Sewage sludge application affected the nitrogen content and uptake of plant more than inorganic fertilizer. This indicates that some of nitrogen requirements of plant can be provided by using sewage sludge. For lycopersicon esculentum Mill fruits, Compared to sewage sludge application, the application of triple superphosphate increases the total content of Fe, Cu and Zn. Compared to triple superphosphate application, sewage sludge application increases the total content of Mn. Compared to control, the application of sewage sludge increases the total content of Cu, Zn and Mn, while the application of triple superphosphate increases the total content of Fe, Cu, Zn and Mn. For lycopersicon esculentum Mill seedlings, the application of triple superphosphate improves the germination compared to sewage sludge application by 12.5%. Applying sewage sludge to soil shows adverse effect for germination compared to control soil by 10%. Sewage sludge application decreases the number of growing plants compared to the control soil and triple super phosphate application. Triple superphosphate application improves the shoot length and the root length and enhances flowering, fruiting and spoilage of fruits after harvesting than sewage sludge application which improves and enhances these reported elements than the control soil. Sewage sludge application significantly increases the number of branches of the investigated plants than triple superphosphate application which significantly increases it compared to the control soil. At the day 85 of planting, the plants grown on sewage sludge amended soil have the highest fruit ripening. After 85 days of planting and till the day 96, ripening is inhibited in plants grown on sewage sludge amended soil and is improved in plants grown on the other two experimental soils. After 96 days of planting, ripening is improved in the three experimental soils. The investigated fertilizers significantly decreases fruit weight compared to the control soil. Sewage sludge application insignificantly increases fruit weight compared to triple superphosphate application. The application of the investigated fertilizers generate positive fruit yield responses (Kg/group and Kg/plant) compared to the control soil. Triple superphosphate application increases the fruit yield (Kg/group) compared to sewage sludge application which increases the fruit yield (Kg/plant) than the triple superphosphate application. Land application of sewage sludge may be the least energy consuming and the most cost-effective means of sludge disposal or utilization. However, heavy metals may be leached into the soil and absorbed by crops and may affect the crop seed germination and development. It is well documented that sewage sludge contains appreciable amounts of N and P and have significant inorganic fertilizer replacement value for these major plant nutrients. Considering the heavy metals accumulation in soil and their availability for crops, sewage sludge should be applied to soil at a limited application rates. Sewage sludge should be handled and applied in a proper manner to reduce the risks to human and animal health. More continuous long-term experiments are needed to improve the understanding of the effects of sewage sludge on soil fertility and crop yield to contribute to the development of sustainable agricultural practices. Finally, it is clear that the biological treatment utilizing bacteria exhibits a successful power to treat wastewater and records a highly significant reduction for different pollutants. The proper wastewater treatment and disposal is one of the key aspects of protecting water resources. It presents a dual public health and environmental protection challenge for emerging and developed countries.