The Harbour Area Treatment Scheme (HATS) protects Hong Kong's water quality by collecting and treating sewage discharged to the harbour.

Victoria Harbour has become a magnet for public concern about water pollution. For years, the symbolic heart of Hong Kong was a dumping ground for untreated sewage. The situation has improved recently but, as many people heard in 2004, much more investment is still needed to make all areas of the harbour clean. The debate over this issue will continue in the coming year. But at the same time, Hong Kong must start looking beyond sewage collection and treatment as the only solution to water pollution.

Re-using treated effluent wherever possible forms an essential component of a holistic water management strategy.

End-of-pipe facilities are an essential component of any water management strategy, but they need to be complemented with efforts to reduce discharges in other ways. For instance, treated effluent can be re-used to water plants or flush toilets. Water use can be reduced to minimise the flows to the sewage treatment plants. And storm water flows, which are polluted by sewage and street pollutants, can be cleaned up. These measures can bring both environmental and financial benefits, and the EPD and other government departments are investigating their application in Hong Kong.

The most urgent priority, however, is the Harbour Area Treatment Scheme (HATS). Even with water conservation measures and re-use of treated effluent, sewage discharges will still be generated. The EPD's task is to ensure these discharges are properly treated in a way that protects the environment and is acceptable to the community.

HATS Stage 1 has improved water quality from Central to Shek O.

The first stage of HATS became fully operational on Stonecutters Island at the end of 2001 and involved collecting and treating 75 per cent of the sewage that was entering the harbour virtually untreated. This has resulted in significant improvements in water quality from Central to as far east as Shek O beach. Ammonia, excessive nutrients and E. coli have all been reduced by substantial amounts. Dissolved oxygen, a vital component for marine life, has increased by about 10 per cent on average, and considerably more at the eastern end. But it is a different story in the western harbour, particularly around the sewage treatment plant outfall off Stonecutters Island and at the beaches of Tsuen Wan. If water quality is to improve there, as well as along the northwestern shore of Hong Kong Island, the rest of HATS needs to be built.

Oxygen levels in local waters have greatly improved after commissioning of HATS Stage 1.

The preferred option for HATS Stage 2.

There has been a good deal of debate about the next stage of HATS. In 2000 an International Review Panel of experts was appointed to weigh in on the issue. It recommended four options for siting treatment plants and suggested the use of biological aerated filter (BAF) technology because of its compactness. The EPD has completed studies on the options and in 2004 consulted the public on its findings.

The government's preferred option is to have a centralised system, instead of building two or more treatment plants around the harbour. This avoids placing a treatment plant near sensitive areas such as schools, hospitals, homes or restaurants, and it is cheaper. As for treatment, we prefer to split this into two phases. In the first phase (Stage 2A), the remaining 450 000 tonnes per day of untreated harbour sewage would be collected and brought by deep tunnel to Stonecutters Island. Here, it would receive chemically enhanced primary treatment - the same treatment currently being used - plus disinfection (see box). All sewage around the harbour would then be receiving treatment.

		Stonecutters Island Sewage Treatment Works. Treated sewage from Stonecutters Island still contains some contaminants, such as pathogenic organisms. One way of reducing this problem is to disinfect the effluent - a method that is also cheaper than upgrading the level of treatment. However, disinfecting requires the use of chlorine, which itself can be a problem. The solution here is first to chlorinate and then, making use of a very simple chemical reaction, to dechlorinate by removing any remaining chlorine left behind in the effluent before it is discharged. Some traces of chlorinated by-products may still remain in the discharge, but these would be diluted and at such a low level that they should not be a concern. Initial research supports this approach and, if the next phase of HATS goes ahead, the concept would be subject to a comprehensive environmental impact assessment that will also compare the environmental benefits of different disinfection techniques.

The second phase (Stage 2B) would be a biological treatment plant that could be built underground next to the existing works at Stonecutters. Its timing would depend on the trends in water quality in the western and west-central harbour areas. The area immediately around the outfall is unlikely to meet Water Quality Objectives after the first phase is completed, given the large quantities of treated effluent being discharged. The government would monitor the size of the affected area, as well as changes in sewage discharges and population, to determine when the second phase would be built.

HATS Stage 2 involves a significant investment of public money.

The government consulted the public on these options and spread a wide net. People were given five months to submit their views. Briefings were held with District Councils, green groups, academics, professional bodies, business and industry groups, and legislators. An education programme comprising a series of exhibitions, talks, performances and quizzes at various shopping malls was launched. Environmental Protection Ambassadors from schools, property management, owners' corporations, community organisations and companies were also trained to help spread the message about HATS and to encourage the public to express their views.

Dr Sarah Liao, Secretary for the Environment, Transport and Works, launches the public consultation on HATS Stage 2.

The feedback is being reviewed by the government and will be reported to the Legislative Council in the first half of 2005. Generally, the comments have focused mostly on treatment rather than cost. Some people are uncomfortable with a centralised system, although the government feels this avoids a "not-in-my-backyard" reaction and is cheaper and easier to manage. Others have questioned the use of chlorination in the disinfection process. However, dechlorination would be adopted to remove any residual toxicity and a full environmental impact assessment would be conducted to address such concerns. Green groups are also concerned about the lack of a timeline for the second phase. The government believes the first phase should address most of our existing pollution problems and it will carry out extensive monitoring to determine the timing of the second phase.

		Trawling for marine biota to obtain tissue for toxic substances analysis. A programme to monitor toxic substances in the marine environment began in the summer of 2004. The tests will be carried out annually and are part of a general move towards controlling this type of pollution. During the year China - and by extension Hong Kong - also ratified the Stockholm Convention to reduce and ultimately eliminate persistent organic pollutants (POPs), which comprise pesticides and organic chemicals. Signatories agree to prohibit, restrict and reduce certain specified POPs to the maximum extent possible, and a unit has been set up to compile an inventory of those POPs that arise in Hong Kong. In addition, a Hong Kong Implementation Plan, required by the Convention, is being drafted and will be included as part of China's National Implementation Plan for submission to the Convention Secretariat by November 2006.   The Stockholm Convention is a global commitment to rid the world of persistent organic pollutants. In a related development, a biological indicator monitoring programme was implemented in 2004. This tracks the effects of pollution on marine organisms, and complements existing water monitoring based on physical and chemical measurements.

A further comment suggested the money might be better spent helping our neighbours improve their water quality, given the polluted flows from the Pearl River Delta region (see box). This is not really a solution for the harbour. The only way to improve water quality there is to collect and treat the sewage that comes from people in Hong Kong. The EPD's responsibility is to ensure we put our own house in order.

Apart from addressing the issue of sewage treatment, it makes good environmental sense to try to reduce the quantities of effluent that are discharged into local waters. Water recycling, water conservation and treatment of storm water flows all bear investigation. However, it must be emphasised they do not negate the need for a sewage treatment system.

A secondary sewage treatment plant at Shek Wu Hui.

One way of making better use of water resources is to use treated effluent, rather than discharge it into the seas or rivers. A pilot scheme to "reclaim" treated effluent for flushing, irrigation and other purposes, is planned to start in 2005. A high-level treatment unit will be added to the existing secondary treatment plant at Shek Wu Hui and it is expected to begin operating in 2006 for a two-year trial, with several parties already expressing interest in using the reclaimed water. Both the Drainage Services Department and Water Supplies Department have been involved in the project, and they are also key players in a separate project at Ngong Ping. Here, treated effluent will be used for the flushing of public toilets when the treatment plant opens in 2005.

		Development pressure on Deep Bay: A temporary access bridge is threaded between the oyster rafts for the construction of the Shenzhen Western Corridor. Hong Kong and Guangdong continue to co-operate in controlling pollution in their shared water bodies. The EPD worked with the Shenzhen Environmental Protection Bureau in 2004 to draw up plans for a review of the Deep Bay Water Pollution Control Joint Implementation Programme, which began in 2000. The review is anticipated to be completed in 2006 and will suggest further measures to achieve water quality targets. The declining dissolved oxygen recorded at Deep Bay shows that it is highly susceptible to water pollution.           The EPD and the Guangdong Environmental Protection Bureau also continued to develop a water quality model for the Pearl River Estuary that should be ready in about one year. The model will help us examine the impacts of water pollution that arise in nearby Guangdong, as well as in our own territory.

The proposed Ngong Ping Sewage Treatment Works will provide treated effluent for re-use in toilet flushing.

Storm water pollution is a third element in total water management. The EPD carried out an in-house investigation to quantify pollution from storm water drains and to identify the contribution of various sources at a test site in Mong Kok. About 12 per cent of the biological oxygen demand in the area is believed to go down storm water drains - a sizeable amount. The pollution comes from three sources: sewage escaping from defective sewers, expedient connections to the drains, and street pollution such as animal faeces and oil. The findings underscored the continuing need to be vigilant in maintaining and upgrading sewers, and to take enforcement action against expedient connections. Importantly, they also highlighted the fact that there is no magic bullet solution to this problem. Storm drain pollution is unlikely to be eliminated entirely and the only way to reduce its impact is through a comprehensive, integrated approach that deals with all sources of residual pollution that inevitably finds its way into the storm water system.

Storm water drain pollution from diffuse sources is still a concern.

Managing our waters means reducing the quantities of pollution that we dump in them. A holistic approach is the most effective way of doing this. We must try to conserve water, re-use treated effluent and reduce pollution in storm water. Most importantly, we must ensure there is a system in place to collect and treat the sewage discharges that come from every member of the community. Water pollution is something that we all contribute to and we have a collective responsibility to clean up our waters for future generations.

Report to the Legislative Council on the outcome of the public consultation on the Harbour Area Treatment Scheme. Carry out consultation for the pilot scheme to "reclaim" treated effluent for re-use in Shek Wu Hui. Continue the study on the Provision of Sewerage to Unsewered Areas/Villages in the North West New Territories. Implement new planning guidelines for sewerage infrastructure. Draft the Hong Kong Implementation Plan on Controlling Persistent Organic Pollutants as part of China's National Implementation Plan for submission to the Stockholm Convention Secretariat.