Rehabilitation measures for lake Mariut

ABSTRACT

Lake Mariut has been in a highly degraded condition over the last 30 years. This is due to receiving discharges from agricultural, domestic, and industrial wastewater drainage from Alexandria City. Two plants for primary treatment of the city domestic wastewater, including industrial wastes, have been started since the end of 1993. The situation has been partially improved but not to the extent of significantly reducing the pollutional loads. This is due to the fact that the domestic wastewater that is treated does not represent the main bulk of pollution that comes from other sources like upstream Kalaa Drain and industrial wastes. Even if secondary treatment is applied, none of the treatment scenarios is expected to significantly alter the nutrients or metal concentration in the lake. This is due to a number of factors, including the high concentration of nutrients entering the lake from sources other than sewage, the large amounts of raw wastewater from squatters along the contributing drains, the excessive concentration of metals currently in the industrial wastes accompanied with wastewater, and the relatively low removal rates for metals and nutrients achieved by primary or even secondary treatment, consequently, the conditions following implementation of any of the wastewater management scenarios are not expected to be changed significantly from the existing situation with respect to water and sediment or eutrophication. Therefore, the most promising solution for the lake rehabilitation is to consider appropriate routing for Kalaa Drain outlet far from the lake and far from the city entrance if possible. Meanwhile, the lake should be fed from other more clean water e.g. Amlak Drain and Hydrodrome Drain or from Haris Pump Station so that they substitute the lake feeding water from Kalaa Drain. The cost of this proposal is expected to be offset by the improvement in the fish catch of the lake over the next few years