Advanced pollution control systems at sludge treatment plant

PUBLISHED : Thursday, 12 June, 2014, 4:12am
UPDATED : Thursday, 12 June, 2014, 4:12am

I wish to correct what was stated in Peter Reid's letter ("Incinerator for sewage sludge generating a lot of air pollution", June 3) about the sludge treatment facility which is in the final stages of construction.

Hong Kong is served by an intensive network of sewage treatment works, which generate a large amount of sludge requiring disposal in a proper and environmentally sound manner.

At present, approximately 1,000 tonnes of sewage sludge generated every day is disposed of at the three landfills. Considering landfilling is not a sustainable disposal option, in 2003 the government began the planning and development of a sludge treatment facility at Nim Wan, Tuen Mun.

With a treatment capacity of 2,000 tonnes per day, it is being commissioned and tested for operation by the end of this year. It adopts fluidised bed incineration, a well-proven technology with outstanding operational, safety and environmental performance records for large-scale thermal treatment of homogeneous materials such as sludge.

The facility is equipped with advanced pollution abatement and control systems coupled with continuous emission monitoring to ensure the flue gas emissions comply with stringent European Union emission standards.

The statutory environmental impact assessment study has shown the facility will have no adverse air quality impact to air-sensitive receivers in the vicinity and those in the Tuen Mun town area.

This high-temperature incineration process can reduce sludge volume by about 90 per cent.

The ash generated has to comply with the Incineration Ash and Residue Pollution Control Limits before disposal at a landfill. To further reduce the disposal of ash at a landfill, we are studying with local tertiary institutions the feasibility of reusing ash in construction or for other uses.

As regards public consultation, we have been liaising closely with local communities and stakeholders since 2004. We have taken on board views from Tuen Mun District Council on the architectural design of the facility and its environmental monitoring measures.

To further enhance communication with these people regarding the operation of waste treatment facilities, including the facility, we have set up a district liaison group for Tuen Mun and Yuen Long and two meetings have already been held. We will continue to work closely with the local communities to monitor the environmental performance of the facility and ensure it will meet the highest standards.

Ellen Y. L. Chan, assistant director of environmental protection