The dioxin concentration in stack emissions from Tsing Yi Chemical Waste Treatment Centre are well below the prevailing international standard.

The Civil Engineering & Development Department today told Kwai Tsing District Councillors today that this was the outcome of the trial incineration of dioxin-containing residues.

The November 26 trial found the concentration was 0.0003ng per cubic metre while the prevailing international standard for dioxin emissions is 0.1ng per cubic metre.

The department said the centre was equipped with a continuous emission monitor system which showed the level of carbon monoxide emitted during incineration was 0.01mg per cubic metre, far below the control limit of 150mg per cubic metre.

Stringent standards

The monitoring results found the centre is capable of decomposing dioxin-containing residues within stringent emission standards. It is equipped with automatic stop waste feed system which will shut down automatically and suspend the incineration process if any listed parameter for continuous emission monitoring reaches the specified safety level.

About 10 tonnes of dioxin-containing residues were used in the trial which took 13 hours to complete. Subsequent testing was conducted by an accredited laboratory following quality assurance and quality check procedures in accordance with the guidelines of the US Environmental Protection Agency.

Independent Expert Assessor Professor Jonathan Wong also briefed the council. For the trial results click here.