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Thai government sues stingray-killing ethanol producer

In Thailand, the government’s Pollution Control Department (PCD) is suing Rajburi Ethanol Co. for allowing molasses wastewater to leak into the Mae Klon River, devastating the waterway’s giant stingray population.

According to the PCD, tests have indicated that wastewater leaked into the river in Ban Pong district of Ratchaburi, polluting it and killing aquatic life including many native giant stingrays between 1 and 7 October.

PCD director-general Wijarn Simachaya told the Bangkok Post that Rajburi Ethanol earlier admitted there was a leak from its last pond of treated molasses wastewater on 30 September, and the water was afterwards tested by many agencies.

The tests discovered that dissolved oxygen downstream from the plant was 1.0-2.8mg/l between 4 and 10 October, which was below the level measured year-on-year

Biochemical oxygen demand (BOD) in Samut Songkhram from Bang Khonthi district down to the estuary ranged between 11 and 28mg/l on 7 October.

Molasses wastewater leaked from Rajburi Ethanol in September continued to accumulate in the Mae Klong River at least until 7 October.

It took six to eight hours for the water mass in the river to flow from Ban Pong district, Ratchaburi, to Bang Khonthi district, Samut Songkhram, and a high tide during the period blocked the water mass from reaching the sea.

Consequently, some of the molasses wastewater settled in the riverbed and high levels of free ammonia killed aquatic animals, including stingrays, which were unable to discharge ammonia from their bodies during the time of low dissolved oxygen, Simachaya said.

Tests to simulate the condition of the river during the pollution period showed that the level of free ammonia soared to over 18 times higher than usual and caused the sudden death of fish.

A total of 45 giant stingrays, one of the largest freshwater fish in the world at around 2m in diameters, were found dead in the area in early October.





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