Hong Kong does not need a controversial HK$30 billion upgrade of its centralised wastewater treatment system as the water in the harbour is clean enough, at least for now, environment officials say.
They said the planned upgrade under the Harbour Area Treatment Scheme (HATS) would deliver only marginal improvements to water quality in western Victoria Harbour and bring little benefit to near-shore pollution.
They said the priority was to cut off improperly connected pipes and crack down on unlawful discharges into the harbour off Central and Wan Chai. A consultancy study is being planned.
In a document filed to the Advisory Council on the Environment, officials said the current chemical-based treatment system was enough to meet most water quality objectives and stressed the upgrade to biological treatment was not "critical" at this stage.
The decision surprised one government adviser on the environment, who fears the upgrade has been declared "dead" and seemingly replaced by localised schemes.
"The two [near shore pollution and the upgrade] are different things. Are you taking this opportunity to declare the scheme dead?" asked Dr Hung Wing-tat, a member of the council.
Officials denied dropping the upgrade. "It is being put under review, taking into account the latest water quality conditions and new technology for wastewater treatment," Amy Yuen Wai-yin, assistant director of environmental protection, told the council yesterday.
Yuen said in terms of E coli levels close to the harbour's shores, the upgrade was "not an answer", citing water quality modelling results.
The upgrade was recommended by an international panel reviewing the city's sewage treatment strategy in 2002. It was shelved amid the Sars outbreak the following year and deteriorating fiscal conditions. Instead, officials opted to expand and improve the centralised treatment works on Stonecutters Island.
In 2007, the government promised to review the upgrade when they won legislators' support for an annual 9.3 per cent increase in sewage treatment charges for 10 years up to 2016.
The upgrade would boost the capacity of the treatment works to remove nutrients such as phosphates from effluent. Removing the nutrients, which cause red tides, would increase oxygen levels in the water, which would therefore sustain more marine organisms.
But the cost of the upgrade, according to the latest estimate based on 2012 prices, has almost tripled from the 2004 estimate of HK$11 billion to up to HK$30 billion.
At present, the Stonecutters plant adds chemicals such as ferric chloride to the waste water to remove pollutants. In 2010, chlorine-based disinfection was introduced to remove bacteria from the effluent. The plant handles about 1.8 million cubic metres of waste water a year.
Jonathan Wong Woon-chung, another council member, said officials should clarify to what extent illegal discharges and improperly connected pipes contributed to water pollution. He questioned whether the upgrade would have the intended effect, as improvements might be offset by cross-border pollution.