COMPARATIVE ECOLOGICAL STUDIES ON SOUTH-EASTERN AREA OF LAKE MANZALA AND WATER OF BAHR EL-BAQUR DRAIN BEFORE AND AFTER TREATMENT OF WASTEWATER BY ENGINEERED WETLAND

Abstract

Lake Manzala is one of the most important Delta wetlands in Egypt, because it is the largest one and due to its high productivity. The southern region of the Lake receives agriculture, industrial and sewage wastewaters without treatment from several drains; the most polluted one is Bahr El-Baqar drain. Pollution in the southern part of the Lake led to high levels of contamination and high organic load affecting consequently all aquatic organisms including fishes. Therefore, a five-year Global Environmental Facility (GEF) project was implemented last decade by United Nations Development Program (UNDP) and Ministry of water Resources Irrigation to tackle the problem of polluted drainage water that enters the Lake from Bahr El-Baqar drain, using Engineered wetland for biological treatment. Physico-chemical parameters have been analyzed in water samples collected seasonally along to lake, drain; before and after Engineered Wetland station during the period from winter 2012 to autumn 2013. Also, some heavy metals were measured in the water and Nile Tilapia organs (gills and muscles). The total and fecal coliforms were also studied. Water quality index (WQI) was used as a useful tool to assess the quality of water in both Lake Manzala and Bahr El- Baqar drain. Results showed that the concentrations of some water quality parameters exceeded the permissible limits of Low 48/1982, Ministerial decision 92/ 2013. The heavy metals Al and Ni levels in water were higher than the international permissible limits of Australia and New Zealand. The levels of the heavy metals in gills and muscles of the Nile Tilapia also exceeded the maximum permissible limits in all fish muscles. So, it can be conclude that the southern area of Lake Manzala is contaminated by high levels of heavy metals and the consumption of its fish not save and could cause health hazard to the local inhabitants as their diet depends mainly of fish. In conclusion, the quality of Bahr El Baqar drain is the main factor controlling the pollutants in Lake Manzala, and the main solution is the reduction of pollutants discharging by using different treatment techniques, such as Constructed wetland in large scales which considered the most economically treatment and alternative compared with other ways of improvement of water quality.