Microbial Corrosion in Cooling Water of Lushan Shahid Beheshti Power Plant

The corrosion and especially microbial corrosion in thermal power plants due to the frequent use of contaminated water sources has long been a source of economic problems, efficiency reduction, equipment and technical failure. The main reasons of these problems are a of existence of microbial organism in the water of cooling tower. In this work, the aim is to collect information on the microbial corrosion in the cooling water of Shahid Beheshti power plant of Lushan and to provide several solutions to reduce the occurrence of microbial corrosion Therefore, physicochemical properties, microbial tests and ion measurement are conducted in order to investigate the parameters affecting this phenomenon for the cooling tower of Shahid Beheshti power plant of Lushan. The microbial tests include the TBC test to measure the total number of bacteria (general test) and specific tests to measure specific bacteria such as APB, FP, IRB, NRB, Aero, SRB and TRB. Moreover, physicochemical parameters (pH, electrical conductivity, salinity percentage, hardness and water temperature), anions and cations are determined. It is observed that the calcium ion in the sample is in the range of high concentration (517 ppm) which leads to increase sedimentation and retention of water in the cooling cycle. On the other hand, the high concentration of sulfate (2126 ppm) causes the growth of SRB in the sample. For this purpose, it is very important to control and tackle these problems by applying sediment-forming and destructive microbial agents in the cycle. Common methods such as chlorination and ozonation are the first priority to deal with microbial corrosion in this power plant. Due to the high concentration of sulfate ions, it is suggested that selective removal of sulfate ions counts as a second priority. High concentration of calcium ion might be resolved by applying the chemical regimes in the clarifier such as adding CaOH, FeCl3 and coagulant and control and inhibit the microbial corrosion.