Monitoring of Thermal Power Plant Operation on Aquatic Ecosystem in Tropical Estuarine River of Thailand, 2008-2013

Sarawuth Chesoh

Friday 3 july 2015

11:30 - 11:45h at Europe 1 (level 0)

Themes: (T) Hydro-environment, (ST) Impacts of pollutants on the water environment

Parallel session: 15G. Environment - Renewable

This study aimed to assess the aquatic ecological impacts of the operation of 750 MW combined cycle power plant in southern Thailand. About 39,000 cubic meters of raw water in tidal river which connects to the gulf of Thailand has been drawn daily for cooling system and then thermal effluents are drained back into the river. Aquatic habitat alteration and biodiversity loss are key environmental concerns that may affect the well-being of the locals. Integrated field surveys were used for water sampling and data collection. Monthly water quality, heavy metals, fish larvae, and bi-monthly plankton, benthos and fishing activity in the river were investigated from January 2008 to December 2013. Standard methods, in situ and laboratory measurements were used for water sample analysis. Species and abundance of plankton, benthos and fish larvae were examined and categorized. The results revealed that water quality parameter index can be classified as medium clean, fresh surface water resources used for consumption, but passing through an ordinary treatment process before using and for agriculture. Salinity and turbidity gradients showed statistically significant association with living organism variation. An estimated daily loss of phytoplankton and zooplankton by processing once through a cooling system were about 335 and 5.3 billion cells (individuals), respectively. In addition, approximate 15 million individuals of fish larvae were destroyed annually (15% of total upstream). No detectable of chlorinated toxic and heavy metals leakage, massive heated cooling water was kept in a huge retention pond prior to be drained by gravity into natural waters. However, a change of river’s flow direction, increased potential of saltwater intrusion into the freshwater zone in dry season, and about 3% of annual upstream fish catch decrease, was identified. Our findings highlight that the river regime has been regulated mainly by the seasonal phenomena of marine and riverine effects. Although effluents from the power plant showed no significant effect on water quality of the river, we suggest that fish population enhancement and mangrove or forest rehabilitation program towards local participation are desirable. We strongly recommended that further studies and a continuation of ecological monitoring are necessary. Keywords: Biodiversity loss, Combined cycle gas turbine, Environmental Concerns, Riverine ecosystem, Thermal pollution