Water Quality and Identification of Organisms Found at the Intake Water Area of South Bangkok Thermal Plant

Abstract

                The water quality of samples taken from the intake water area of South Bangkok Thermal Plant showed the pH range of 7.01-7.37 and temperature range of 27.3-29.7°C throughout the year. Dissolved oxygen (DO), however, was rather fluctuated, being high (7.10-8.6 mg/l) in the dry season and dropped to a low level (4.78-6.5 mg/l) in the rainy season. On the contrary, the amount of chloride which indicated water salinity was low (22-75 ppm) in the rainy season but gradually increased from 310 ppm to the highest value of 11,000 ppm in the dry season resulted in the changing from brackish to marine condition in January.

                Types of organisms at this area was found corresponding to the chloride level in water. There were 3 main groups of marine invertebrates, i.e., muddy tube fan worms, calcareous tube fan worms, and a hydroid (Bougainvillia pyramidata). The co-existence and high proliferation of these 3 organisms in the dry season greatly contributed to the contamination of the screen plate and obstructed the inflow of water supply to the cooling system of the power plant. Changing the water salinity at the intake water area could make it unfavorable for the growth of marine organisms and, hence, an alternative method of controlling the fouling organisms and avoid the use of chemical while maintaining a good environment condition in the area.