الفهرس 
AcknowledgementOnly 14 pages are availabe for public view
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Abstract
In Egypt, the majority of people live in villages and small towns, there are more than 4300 villages in Egypt. In villages, the sanitation and high ground water table cause problems because of the increase of domestic sewage without appropriate treatment and disposal. The problem of sanitation increases due to the increase in population density and the increase in water consumption as a result of supplying municipal water to the villages. Accordingly, appropriate sewage treatment and disposal must be taken seriously, therefore it is important to choose the appropriate technologies for treatment and disposal which can be easily adapted to the Egyptian rural environment. In response to growing public health awareness about the sanitation problems and high ground water table in Delta vill ages, the gove rnmen t of Egypt enac t ed a new approach through a local development program cooperated with the United States AID program. The wastewater projects executed by the government cover five different treatment technologies implemented in both delta and desert regiqns. These technolo gies are: (1) Extended aeration activated sludge system, which includes screen, aerated degreaser, aeration basin, clarifier, chlorine basin, sludge thickener, and drying beds. (2) Oxidation Ditches System, which includes screen, oxidation ditches, clarifier, chlorine basin, sludge thickener, and drying be~s. (3) Aqua Life system, which includes screen, Anaerobic basins, Aqua Life basin, chlorine basin and drying beds. (4) Aerated Lagoon System, which includes screen, Anaerobic Ponds, Aerated Lagoon and Maturation Ponds. (5) Stabilization Ponds System, which includes Screen, Anaerobic Ponds, Facultative Ponds and Maturation Ponds. The aim of thi s research is to evaluate the efficiency of different wastewater treatment systems which are used in Delta villages through: (a) Studying the design and operation of each system to determine the weak points of the existing design and the difficulties and troubleshooting for operation. (b) To submit the recommendations to modify the design and operation of these technologies in order to upgrade their efficiency in removing pollutants. (c) To analyze the cost of wastewater treatment systems to formulate the cost effective system for wastewater treatment which might be applicable in the Delta region of Egypt. In order to evaluate the five wastewater treatment systems in Del ta Egypt, five wastewater treatment plants which are currently in operation were chosen for the study and three steps are carried out for each system: 1. SANITARY SURVEY: Sanitary survey was carried out for the five wastewater treatment plants by reviewing engineering records, collecting and analyzing data for the- present situation. Actual flow measurements were carried out for each pump station in every wastewater treatment plant under the study. 2. FIELD EVALUATION: Field evaluation for the five wastewater treatment plants was carried out by collecting composite and grab samples from the influent, effluent and different stages of each wastewater treatment plant for 10 t.imes during the period between December 1991 to September 1992. Laboratory analyses were carried out in both El Annania laboratory and High Institute of Public Health laboratory to determine their physical and chemical characteristics. A comparison of the design criteria with the actual design and operation parameters was made and the weak points in the and the troubleshooting of design operation was determined. Appropriate possible engineering modifications is recommended in order to improve its operation and efficiency. 3. COST SURVEY: Cost survey was carried out for the five wastewater treatment plants. This cost survey includes three components, construction cost, land cost, operation and maintenance cost. A present worth values are estimated for the operation and maintenance cost of each wastewater treatment system. Assume the useful life of the systems is 20 years and the inflation rate is 12 . In order to reach final conclusion about cost of wastewater treatment systems, the total present values over 20 years period are estimated including construction cost, land cost and 0 & M cost. THE OBTAINED RESULTS CAN BE SUMMARIZED AS FOLLOWS I. THE SANITARY SURVEY REVEALED THE FOLLOWING: The sanitary survey of pump stations of the five wastewater treatment plants revealed that they were working intermittently for a limited period of time during the day attributed to their high pumping capacity which is higher than the design capacity. Accordingly, these have adverse effect on plant operation and control specially biological treatment units. With regard to activated sludge extended aeration plant and oxidation ditch plant, both. are under design, most of the actual parameters associated with the actual average dai ly flow are wit h i n the recommended I imi t the surface except solids loading rate of the thickener and the sludge drying beds. These values are higher than the recommended values and al se Ids i t of la 1 520 ’lds the :’lOd of ign ese ted ded in~ as was ty. ta, ign >ond ~ rse lon, ; ion :::ate but ~ in lfur of lead to plant operation problems. In addi t ion, the actual parameters, in some units. associated with the actual peak hourly flow are higher than the recommended values. These have adverse effect on the plant operation during the periods of peak hourly flow. In addition, due to non existance of grit removal unit in oxidation ditch plant, there are blockage of down stream units and wear of aerators and scrapers. With respect to aerated lagoon, it is loaded with an actual flow (833 MJ/d) which is higher than the design flow (620 MJ / d). I n add i t ion, the rei saw i de flu c t u at ion i nth e loa d s applied to the system. The cause of overloading IS the inaccuracy of design data such as water consumption rate and population density. Accordingly, the retention time of anaerobic ponds and maturation ponds are less than the design values. These lead to reduce the removal efficiency of these ponds. In addition, the organic surface loadings of aerated lagoon and maturation ponds are higher than the recommended values which indicates that the aerated lagoon is not working perfect ly and some of the maturat ion ponds are working as facultative ponds.