Bangla Press Desk: Investigators are probing what produced lethal levels of hydrogen sulphide inside a ballast tank at the Ferdous Steel shipbreaking yard in Sitakunda, with decomposing organic matter emerging as a possible source.
Four days after the accident, members of two government investigation committees and an expert team reached the tank on Tuesday around 11am wearing protective equipment.
They collected air, soil and water samples from the tank and other parts of the ship.
Tests of the tank’s air found no hydrogen sulphide on Tuesday.
“We have collected samples. Not just from the ballast tank, but from different places. We did a lot of work [on Tuesday]. We are still working. We will be able to give details later,” said AKM Benjamin Riazi, an additional secretary leading the industries ministry’s investigation committee.
Ashraf Uddin, an assistant director at the Chattogram office of the Department of Environment and a member of the district administration’s committee, said soil and water samples had also been collected.
“[On Tuesday], we tested the air there and found no hydrogen sulphide. Perhaps the level of hydrogen sulphide has fallen after mixing with tidal water over several days or because of the air.”
The gas escaped while workers were cutting open the tank on Friday, killing nine people.
Could Decomposing Matter be the Source?
Ballast tanks hold water to keep ships stable. The nearly 30,770-tonne MT Rashi was brought to the yard in July last year with all four tanks full.
One had already been cut open. Workers were cutting open the second tank on Friday when the gas escaped. The remaining two tanks are still filled with water.
Officials from the Department of Explosives, Department of Environment and Fire Service and Civil Defence have attributed the deaths to hydrogen sulphide accumulated inside the tank.
An investigator said no chemical or sewage waste was found in the tank, but soil tests could indicate what had been present.
“The ballast tank had held water for a year. The results of the soil sample tests will confirm that. If ammonium nitrate or similar material is found, it will indicate what kind of waste had been dumped there.”
He said sulphur-producing bacteria in seawater could react with hydrogen to generate hydrogen sulphide.
“The high level of hydrogen sulphide found there is astonishing. We initially suspect that the gas may have been generated from some kind of decomposing organic matter. But nothing can be said conclusively until the samples are tested.”
The expert and investigation teams will also examine the two remaining ballast tanks for hydrogen sulphide or other toxic gases.
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