Biological treatment of fuel wastewater generated from a thermal power plant by continuous and discontinuous aeration

The National Electricity Office of Mohammedia (Morocco) is an electricity production plant with the aid of boiler cells using coal and fuel oil as energy source. The operation of this process consumes a large quantity of water for washing the fuel oils to feed and heat the boilers, which could have a significant production of pollutant-laden wastewater. Wastewater must be treated before discharge into the marine environment. In this study, the process of biodegradation of organic materials by continuous or discontinuous aeration was carried out. The fuel oil washing wastewater is too loaded with pollutants with a chemical oxygen demand (COD) of 7.5 kg/m(3) and biochemical oxygen demand (BOD5) around 4 kg/m(3). After 9 d of operation, the continuous and discontinuous aeration resulted in an elimination of 96%, 97% and 86% respectively for turbidity, BOD5 and COD. In addition, both treatment methods showed removal rates of pollutants such as phenol, nitrate, total phosphorus and total Kjeldahl nitrogen, 82%, 86%, 83% and 47% respectively. No significant difference was observed between continuous and discontinuous aeration. This shows that discontinuous or continuous aeration could be very interesting for the decontamination of fuel oil washing water.