Drainage Services Department - Sustainability Report 2014-15

Managing the Environment / Odour Management

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Sub-sections in Managing the Environment

[Blue-Green Infrastructure] [Energy Management and Emission Control] [Water Resources Management] [Odour Management] [Green Office]

DSD puts strong focus on environmental management in every project it delivers in order to make Hong Kong a livable city. In recent years, we actively campaigned for Blue-Green Infrastructure, emphasising the protection of river ecosystems in addition to environmentally friendly construction practices. These initiatives, alongside various emissions reduction and energy conservation measures at our facilities, are instrumental in promoting sustainable development in Hong Kong.

Odour Management

Septic process of sewage will produce hydrogen sulphide which has a repulsive odour. To reduce the impact of DSD’s facilities to nearby residents, we have undertaken the following three odour control measures:

Adding deodourising agents to sewage to suppress odours at its source;
Covering facilities and components which are likely to emit odour; and
Installing deodorising systems.

In addition, we regularly measure the levels of hydrogen sulphide in our plants to monitor the effectiveness of the odour control measures and to timely adjust plant operations as necessary.

Odour Control Measures and Improvement Works in Siu Ho Wan Sewage Treatment Works, North Lantau

Located in North Lantau, Siu Ho Wan STW treats about 45,000 cubic metres of sewage daily generated from the airport, Tung Chung, Discovery Bay, and Disneyland Resort. We have implemented a series of odour control measures at Siu Ho Wan STW to improve the surrounding environment, including:

Dosing ferric chloride as a replacement of Alum in the sewage treatment process for suppressing unpleasant smells and increasing the efficiency of sludge sedimentation;
Installing two water scrubbers and one carbon filter system to further enhance the deodourising capacity;
Covering the channels of the ultraviolet disinfection system; and
Installing a 24-hour real-time monitoring system.

In December 2014, we completed installation of covers and deodorizing devices at the Primary Sedimentation Tank Nos. 1 and 2. We will make use of the covered tanks for sewage treatment as far as practicable in order to abate odour levels

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Fiberglass reinforced plastic (FRP) covers for primary sedimentation tanks at Siu Ho Wan STW

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Biotrickling filters at Siu Ho Wan STW