The Chemical Waste Treatment Centre on Tsing Yi, opened in April 1993, will have its air pollution control system upgraded in 2008 to tie in with tightened sulphur dioxide and nitrogen dioxide emission limits.

Assistant Director of Environmental Protection Ellen Chan told news.gov.hk the centre has been operating smoothly, handling 780,000 tonnes of chemical waste in the past 13 years. It also has a good track record in keeping incineration emissions well below the stringent emission limits.

Stringent standard: Assistant Director of Environmental Protection Ellen Chan shares with news.gov.hk ways to ensure the Tsing Yi Chemical Waste Treatment Plant's emissions - including dioxins - are well below the control limits.

The centre was designed to handle 100,000 tonnes of chemical waste a year, though Ms Chan said it processed only about 61,000 tonnes of chemical waste a year on average.

Different sources

"While many factories here have been relocated to the Mainland, we still have chemical waste coming from all walks of life, such as vehicles, photo-finishing shops, printed circuit board industry, school laboratories and so on," she added.

In this year's first seven months, the centre handled 9,655 tonnes of land-based chemical waste, 35 tonnes more than a year earlier. The figures for 2005 and 2004 were 17,038 and 18,494 tonnes.

The centre also functions as the reception facility for oily waste and noxious liquid substances from ocean-going vessels, as required under the International Convention for the Prevention of Pollution from Ships. The amount of such marine waste treated by the centre from January to July rose 42% from a year earlier, to 19,330 tonnes. The figures for 2005 and 2004 were 20,386 tonnes and 19,038 tonnes.

"When we plan and design any waste treatment facilities, we will estimate the amount of waste to be produced in the next 10 to 15 years. We also take into account changes in the economy and latest developments in the industrial sector when reviewing the estimates," Ms Chan said.

As the centre's current operation and management contract will expire in April 2008, the department conducted a review of chemical waste arising in the city, the scope and extent of services the centre needed to offer, and any modifications or new facilities that may be required.

Sufficient capacity

"The review has confirmed the centre's design capacity of 100,000 tonnes a year, which was set in the 1980s, can still cater for Hong Kong's future needs. Therefore, we do not need to increase its capacity. But we are going to revise its emission-control limits," Ms Chan said.

The centre is an integrated facility with three main treatment processes - oil/water separation, physical/chemical treatment, and incineration.

"The centre has been designed and operated to meet stringent environmental and safety requirements. It was opened in 1993 with the dioxin emission cap set at 0.1 nanogram per cubic metre, the same as the European Union's dioxin emission limit laid down recently.

"Some of EU's new emission standards are more rigorous than ours. However, our monitoring results show the centre's emissions are well under the control limits and most can meet the EU's new requirements. We only need to further reduce the emission of nitrogen dioxide and sulphur dioxide to tie in with EU's new standards," she added.

Tougher control

"We will follow the EU's move and have our control limits on sulphur dioxide and nitrogen dioxide cut 90% and 50%. When we award the centre's new operation and management contract in 2008, we will also upgrade the centre's air pollution control system, such as fitting de-sulphurisation and denitrification facilities, to meet the latest emission standards," Ms Chan said.

The works will be completed within a year after the award of the new operation and management contract, she added.

The incinerator has an automatic waste feed cut-off system in the event of abnormal air emissions readings or incineration temperatures, to allow urgent trouble-shooting.

In terms of dioxin emissions at the stack, the monthly average level recorded from January to July ranged from zero to 0.0009 nanogram per cubic metre, well below the control limit of 0.1 nanogram per cubic metre.

Dioxins in the ambient air are also monitored at Cheung Ching Estate on Tsing Yi. The readings are comparable to those in the ambient air measured at Central & Western and Tsuen Wan.

Dioxin level remains low

The monthly average concentration of ambient dioxins at Cheung Ching Estate was 0.038 picogram per cubic metre in July. The figures for Central & Western and Tsuen Wan were 0.050 and 0.036 picogram per cubic metre.

"This shows Tsing Yi's ambient dioxins is comparable to other districts despite the operation of the chemical waste incineration facility there. Apart from incineration, dioxins can be produced by hill fires and barbecues. Dioxins are also found in vehicle exhaust and cigarette smoke," Ms Chan said.

More public education

To bolster Kwai Tsing residents' and district councillors' understanding of the chemical waste treatment plant's operation, the department meets with them regularly. Public education activities, including visits and briefings, have also been launched to offer more information and ease their concern. Meanwhile, a roving exhibition is being staged in the district until October 31. More details are available here.

"Chemical waste treatment facilities are necessary for modern cities to ease pollution and aid the development of small and medium enterprises," Ms Chan said.

Without such a treatment plant to handle chemical waste properly, Hong Kong would revert to the 1980s' situation, when chemical sewage flowed through industrial areas, causing damage to drains and the harbour.

The White Paper: Pollution in Hong Kong A time to Act, published in June 1989, set out the Government's intention to introduce complete controls on chemical waste. The Waste Disposal (Chemical Waste) (General) Regulation, enacted in March 1992, offers a statutory scheme of control. It aims to ensure chemical waste is properly managed by all parties, from the source of production through to the place of final disposal.

Phased charging

In line with the polluter-pays principle and to create an economic incentive for waste producers to practise waste minimisation, reuse and recycling, a phased direct charging scheme has been adopted for chemical waste disposal at the treatment plant. The average charge paid by chemical waste producers is only about 34% to 54% of the variable operating cost.

The Government has been providing a subsidy to chemical waste producers, not the treatment plant operator, and the treatment charge will be recovered progressively. It is expected that 100% of the variable operating cost for handling land-based chemical waste can be recovered by 2009-10, and that for marine waste by 2008-09.