American Journal of Environmental Sciences 4 (4): 316-325, 2008 ISSN 1553-345X © 2008 Science Publications Corresponding Author: Waled Morsy El-Senousy, Water Pollution Department, National Research Center, Cairo, Egypt 316 Performance Evaluation of a Waste Stabilization Pond in a Rural Area in Egypt Mahassen M. El-Deeb Ghazy, Waled Morsy El-Senousy, Azza. M. Abdel-Aatty and Mohammed Kamel Department of Water Pollution Research, National Research Center, Cairo, Egypt Abstract: The performance evaluation of the waste stabilization pond (WSP) as a model of domestic wastewater treatment unit in rural area was carried out. The unit comprised of anaerobic, facultative and maturation ponds in two series. The effluents of WSP which are discharged in the drain had the BOD reduced to 109-245 mg L -1 (Mean = 145.3 mg L -1 , 50.65% removal), while the COD was reduced to 221-400 mg L -1 (Mean = 289 mg L -1 , 48.95% removal) and the total suspended solids (TSS) were reduced to 118-190 mg L -1 (Mean = 157.8 mg L -1 , 44.3% removal). The reduction percentages of total coliform (TC), faecal coliform (FC), E.coli, faecal streptococci (FS), salmonellae and Listeria were 98.8, 95.6, 79.4, 96.8, 97.9 and 89.5% respectively. Also, the removal percentages of coliphage and infectious rotaviruses were 49.03 and 99.66% respectively. Identical sequences of rotaviruses VP-6 detected in the final effluent of the pond and the drain were observed. Euglena variables and Chlamydomonas reinhardii were predominant in anaerobic, facultative and maturation effluents. It has been noticed that pollution affected species diversity of zooplankton; the number of species in facultative pond was 8 species because of high pollution level, whereas in maturation pond increased to 21 species. Also, pollution in anaerobic pond increased density of ciliates (Protozoa) which are known to be bio-indicators of organic pollution. The percent removal of ciliates in the maturation pond was 70%. It is recommended to make some modifications in the design to increase the efficiency of WSP. Key words: zooplankton-protozoa-algae-bacteria-viruses INTRODUCTION The most appropriate wastewater treatment is that which will produce an effluent meeting the recommended microbiological and chemical quality guidelines both at low cost and with minimal operational and maintenance requirements. Different systems are used worldwide for wastewater treatment such as activated sludge, trickling filter and waste stabilization pond systems. Pond systems are commonly employed for municipal sewage purification, especially in developing countries, due to its cost- effectiveness and high potential of removing different pollutants [3, 6] . WSPs are designed to achieve different forms of treatment up to three stages in series, depending on the organic strength of the input waste and effluent quality objectives. Usually, classical WSPs consist of an anaerobic pond, followed by primary or secondary facultative ponds. If further pathogen reduction is necessary, maturation ponds will be introduced to provide tertiary treatment. WSPs are very widely used for small rural communities but large systems exist in Mediterranean basin, France and also in Spain and Portugal. However, in warmer climates (the Middle East, Africa, Asia and Latin America) ponds are commonly used for large populations [15] . In developing countries and especially in the tropical and equatorial regions like Egypt, a shortage of wastewater treatment systems is observed in rural communities. There is a great need to wastewater treatment systems to avoid the health risk problems in these communities. Wastewater treatment by WSPs has been considered an ideal way of using natural processes to improve wastewater effluents. In natural treatment systems such as WSP, the pathogens are progressively removed along the pond series with the highest removal efficiency taking place in the maturation ponds [21] . The aim of this study was to evaluate the performance of WSP in rural area in Egypt and to determine its role in the contamination of the drain. MATERIALS AND METHODS Wastewater treatment system in El-Mofti (Kafr El- Sheikh, Egypt) was designed to serve 3000 persons. Wastewater flow is about 225 m 3 /day mainly of domestic origin. This system consists of 500 primary