Simulation study on effects of thermal discharge from an electric power plant on Microcystis aeruginosa

The influence of elevated temperature and residual chlorine of power plant thermal discharges on Microcystis aeruginosa was investigated. Laboratory experiments were carried out to study the growth and photosynthetic response of M. aeruginosa to a range of temperatures and chlorine concentrations. The results showed that temperature rise favored the growth of M. aeruginosa, especially at a lower ambient temperature. On the other hand, M. aeruginosa was very sensitive to free residual chlorine. When the chlorine concentration exceeded 0.1 mg/L, the photosynthetic activity was greatly reduced, indicating the inhibitory growth effects. The inhibition was compensated by increasing water temperature at a chlorine concentration of less than 0.2 mg/L. Our results suggest the growth of M. aeruginosa, near outlets of power plants, would be greatly inhibited with severely damaged cells. Moreover, with continuous addition of chlorine, the growth of M. aeruginosa was negatively affected at a chlorine concentration of 0.1 mg/L.