Résumé
Talkha power plant is the only power plant located in El-Mansoura. It generates electricity using two different methods by steam turbine and gas turbine. Both plants drew water from River Nile [208 m3/h]. The Nile raw water passes through different treatment processes to be suitable for drinking and operational uses. At Talkha power plant, there are two purification plants used for drinking water supply [100 m3/h] and for water demineralization supply [108 M3/h]. This study aimed at studying the efficiency of the water purification plants. For drinking water purification plant, the annual River Nile water characterized by slightly alkaline pH [7.4-8], high annual mean values of turbidity [10.06 NTU], standard plate count [SPC] [313.3 CFU/1 ml], total coliform [2717/100 ml], fecal coliform [0-2400/100 ml] and total algae [3 x 104 org/l]. The dominant group of algae all over the study period was green algae. The blue green algae was abundant in summer and autumn seasons. The pH range and the annual mean values of turbidity, TDS, total hardness, sulfates, chlorides, nitrates, nitrites, fluoride and residual chlorine for purified water were in compliance with Egyptian dinking water standards. All the SPC recorded values with an annual mean value of 10.13 CFU/1ml indicated that chlorine dose and contact time were not enough to kill the bacteria. However, they were in compliance with Egyptian degree [should not exceed 50 CFU/1ml]. Although the removal efficiency of the plant for total coliform and blue green algae was nigh [98.5% and 99.2, respectively], the limits of the obtained results with an annual mean values of 40/100ml and 15.6 org/l were not in compliance with the Egyptian degree [should be free from total coliform, fecal coliform and blue green algae]. For water demineralization treatment plant, the raw water was characterized by slightly alkaline pH. The annual mean values of conductivity, turbidity and TDS were 354.6 muS/cm, 10.84 NTU and 214.6 mg/l, respectively. There was an increase in the results of conductivity, turbidity, total hardness and TDS in carbon filter effluent which was attributed to the desorption of adsorbed ions on the carbon media. The removal efficiencies of turbidity, total hardness and TDS indicated the high efficiency of the cationic filter. The annual removal efficiencies of conductivity, turbidity, chloride and TDS proved the efficiency of the anionic filter for removing the dissolved and suspended ions. All of the recorded values of the pH, conductivity, turbidity, chlorides, hardness and TDS of the mixed bed effluent indicated that the water at this stage was of high quality for boiler feed. The study recommended adjustment of coagulant and residual chlorine doses as well as contact time and continuous monitoring and maintenance of the different units