Updated on Mar 22, 2008 – SCMP
I refer to the letter from Tracy Lai (“Incinerator is a major polluter”, March 11).
I assume that the Hong Kong government would only consider the latest technology with flue gas filters for any such facility.
When comparing what we do now (landfills) versus waste incineration it might be wise to choose the lesser of two evils.
In landfills all toxins can escape, uncontrolled, into the water and the atmosphere. Considerable amounts of the greenhouse gas methane (much worse than carbon dioxide) are produced and escape into the atmosphere. Again, the process is uncontrolled.
There are different kinds of incinerators. However, what they all have in common is that the waste is reduced to around 5 per cent to 10 per cent of the original volume. They produce bottom ash, fly ash and combustion gases, similar to a coal-fired power plant.
Dangerous dioxins and furans are broken down to non-hazardous substances in the high temperature combustion chamber of the incinerator.
Bottom ash can be disposed off in landfills.
Fly ash and gases pass through sophisticated flue gas purifiers, which remove heavy metals, sulfur dioxide, hydrochloric acid and fine particulate. As in any combustion, carbon dioxide is produced.
The hot gases that leave the combustion chamber are used to produce steam to drive turbines and generators to produce electricity. Incinerators produce up to 50 per cent less greenhouse gases than landfills (a better carbon footprint). Also, incinerators produce a considerable amount of electricity, which will reduce coal and gas burning in power stations.
Incinerators reduce solid waste going to landfills by 90 to 95 per cent. The hazardous waste (heavy metals, etc) can be disposed of properly.
Landfills are ticking time bombs. The stench is a nuisance, not to mention a potential health hazard.
Peter A Thuler, Sai Kung