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Following is a question by the Hon Albert Chan and a written reply by the Secretary for the Environment, Transport and Works, Dr Sarah Liao, at the Legislative Council meeting today (January 17) :
Question:
Recently, I received complaints that the Chemical Waste Treatment Centre (CWTC) in Tsing Yi emits large quantities of toxic chemicals, which not only cause serious air pollution, but also pose a serious health hazard to residents nearby. In this connection, will the Government inform this Council:
(a) of the number of relevant complaints received by the Government in each of the past five years;
(b) of the quantities of various gases emitted by CWTC each month in the past five years; and
(c) whether it will adopt measures to ensure that the emissions from CWTC will not harm the health of residents in Tsing Yi; if it will, of the details; if it will not, the reasons for that?
Reply:
Madam President,
(a) Over the past five years, the Environmental Protection Department (EPD) has received a total of two cases of complaint about the CWTC;
(b) The Government has put in place a set of stringent environmental monitoring facilities and procedures for monitoring the operation of the CWTC. The CWTC operator submits environmental performance report to EPD on a regular basis. The report comprises quality data with respect to effluent discharge, stabilised residue and emissions from the incinerator stack. The report is also submitted to the Kwai Tsing District Council for reference regularly. The aforementioned environmental performance report together with ambient dioxins concentration data measured at the air monitoring station in Cheung Ching Estate, Tsing Yi are also uploaded onto the following EPD's website for reference by the public: (http://www.epd.gov.hk/epd/english/environmentinhk/waste/data/data_cwtc.html)
For easy reference, we have summarised the CWTC's stack emission monitoring data and tabulated the monthly averages over the past 5 years as follows :
Emission Limits Monthly Average
(milligram/ (milligram/
Parameters cubic metres) cubic metres)
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Particulates 75 3.21
Chlorine and Compounds 100 3.50
(as Chlorine)
Fluorine and Compounds 25 0.37
(as Hydrogen fluoride)
Acidity (as Sulphuric 100 16.66
Acid)
Sulphur Dioxide 750 117.94
Hydrochloric Acid 38 4.72
Total Phosphorus 7.5 0.62
(as Phosphorus)
Hydrogen Fluoride 7.5 0.82
Hydrogen Bromide 7.5 3.58
Toxic Metals I :
Mercury 3 0.009
Cadmium 3 0.052
Antimony 3 0.522
Toxic Metals II :
Lead 10 0.620
Copper 10 0.072
Arsenic 10 0.015
Nickel 10 0.124
Chromium 10 0.052
Total of Toxic 10 1.466
Metals I & II
Dioxins 0.1 0.0066
nanogram/ nanogram/
cubic metres cubic metres
(c) The CWTC has been designed and operated to meet stringent international environmental and safety requirements. The Government has also put in place a set of stringent environmental monitoring facilities and procedures for monitoring the operation of the CWTC. In order to ensure compliance of the stack emissions with the relevant environmental legislation and no adverse impact on the environment and public health, the CWTC's incineration system is equipped with comprehensive emission control measures and is under EPD's regular monitoring.
The CWTC emission control measures comprise the following :
(i) The rotary kiln operates at above 1,000 degrees Celsius.
(ii) The secondary combustion chamber operates at 1,100 - 1,250 degrees Celsius which can retain the flue gas for more than 2 seconds so as to disintegrate harmful substances in the flue gas, e.g. dioxins.
(iii) The flue gas is cooled abruptly to below 200 degrees Celsius to prevent dioxins reformation.
(iv) The gas cleaning system has two independent activated carbon injection systems, spray dry absorber and fabric filter bag and is designed to remove the remaining pollutants in the gas before emission into the air.
To closely monitor the incineration conditions throughout the whole incineration process, the computer monitoring system monitors continuously some key parameters (e.g. temperature and carbon monoxide) of the stack gas. The monitoring system will cut off the feeding of waste into the incinerator automatically if these parameters deviate from the pre-set limits. The CWTC operator will immediately inspect the incineration process and identify the reasons for abnormal readings. Feeding of waste for incineration will only be resumed upon completion of all necessary improvement work. In addition, stack emissions are sampled and analysed every month. Please refer to reply to Question (b) above for the environmental monitoring results.
Although the CWTC is already complying with very stringent standards, in order to further improve its environmental performance, we plan to upgrade the air pollution control system of the CWTC in 2008. The emission limits of many pollutants will be further tightened in 2009 to meet the latest emission standards adopted by the European Union.
We will continue to monitor CWTC closely to ensure its operation will not cause adverse impact on the environment and public health.
Ends/Wednesday, January 17, 2007
Issued at HKT 12:58
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