A severe environmental crisis has emerged as burnt sugar waste from the S Alam Super Refined Sugar Industries Limited factory in Chittagong has contaminated the Karnaphuli River, resulting in mass deaths of various aquatic species, including fish and crabs.

The adverse effects were first observed on Tuesday, with local residents witnessing dead and unconscious fish floating in the river.

The burnt sugar waste from the S Alam factory flows directly into the Karnaphuli River through a drain, causing the water’s color to turn reddish along several kilometers of the river.

Fish and other organisms are dying, specifically in the polluted areas.

The situation has raised concerns among environmental authorities, activists, and local communities.

Ferdous Anwar, director of the environment department’s Chittagong office, said: “Samples were collected from different locations. The matter can be confirmed after receiving the lab report. Fish and other biodiversity are dying or weakened due to the decrease in oxygen content in the water.”

Environmentalists have expressed alarm over the lack of proper waste disposal facilities at the factory.

Dr Idris Ali said that environmental damage could be irreversible, and law enforcement agencies need to be vigilant in addressing the situation.

Dr Manjurul, a researcher focusing on the Halda River, highlighted the potential consequences of the pollutants, said: “These extra compounds, whether sugar or something else, will degrade the quality of the water. This will result in a vacuum of oxygen in the water, significantly losing aquatic biodiversity.”

S Alam Group General Manager (Admin) Akhtar Hasan countered claims, stating that burnt sugar is not directly falling into the Karnaphuli and that the waste is dumped on their facilities, posing no harm to the river or aquatic biodiversity.

Fire Service Assistant Director MD Abdul Malek provided insight into the challenges faced in controlling the fire at the sugar mill, explaining that the stored unrefined sugar was highly flammable.

The fire, which broke out in warehouse number 1 on Monday, has caused extensive damage, with over 100,000 tons of raw sugar burnt, amounting to a market value of more than Tk1,000 crores.

Abdul Matin, a resident who came to catch fish, said: “Lobster and other small fish have been available since Tuesday night. I managed to catch 20-30. We have never witnessed fish floating like this before. The water has also turned red. I think it may be due to the mixing of water from the sugar mill.”

“We are aware of the situation and have informed our senior officials. It is expected to decrease at low tide. However, if it persists, the situation will worsen,” Srivas Chandra, Chittagong District Fisheries officer said.

Chittagong University Zoology Department Associate Prof M Abdul Waheed Chowdhury explained: “While sugar is a nutritious food, excessive mixing in water causes eutrophication, leading to an overabundance of plankton and poor water quality, ultimately causing damage to aquatic animals. Eutrophication in rivers may cause temporary problems but may not be long-lasting. However, if it persists for several months, the river’s biodiversity will undoubtedly suffer.”