Existing water treatment plants in Malaysia are not equipped to remove toxic chemicals or heavy metals from untreated water, said an environmental expert.

The plants are only designed to remove sediments and bacteria, said Faisal Parish, director of Global Environment Centre, which is part of the UN Environmental Programme.

He raised these points when asked to comment on concerns raised by thousands of residents around Broga - the site of a controversial incinerator proposal currently under assessment for environmental impacts

They have repeatedly expressed anxiety over the possible impact of its emissions and effluent on nearby water sources that feed the Semenyih treatment plant.

Faisal said advanced technologies such as distillation, reverse osmosis or the membrane technology would have to be used in order to remove toxic chemicals in raw water.

"Unfortunately, these are all extremely costly," he said when contacted.

Official data places the proposed incinerator within an area gazetted by the Selangor government as "environmentally-sensitive".

The Semenyih river and adjoining tributaries, which run through the area, form as a major network that supplies raw water used by millions living in 333 residential estates in the Klang Valley.

Heavy metals

In the late 1990s, a major river in Japan's Kanagawa Prefecture was polluted by raw effluent reportedly discharged by accident from a waste incinerator. This occurred over a period of seven years, leading to record levels of dioxin contamination being detected.

The 1,500-tonne gasification plant proposed in Broga is touted as the largest of its kind in the world. It is to be designed and built by Japan's engineering giant Ebara Corporation and is slated to begin operations in 2007.

Residents fear that the highly-toxic fly-ash, said to be as hazardous as nuclear waste, could find its way into the underground water system and contaminate it with a high concentration of heavy metals.

Faisal, an expert on water resources and river basin conservation, said the global practice is to minimise or prevent polluting industries or activities from being located upstream of the water intake "but that does not happen in reality".

"From my understanding, the Broga plant is not directly located upstream to the Sungai Semenyih water intake, which means it is less of a risk because there will be less concentration of pollutants," he said.

He noted that the government's statements had not denied the existence of pollution "but the facts and figures in the final EIA report would be more conclusive".

Due diligence

important

A Kuala Lumpur-based civil engineer noted that there were frequent disruption of operations at the Semenyih treatment plant due to the high level of pollution in the Semenyih river.

"For example, diesel-dumping occurs occasionally in the river, but the culprits always manage to escape," he told malaysiakini on condition of anonymity.

"Whenever this happens, the water treatment facility has to be shutdown temporarily because it is not designed to detect pollutants like diesel, kerosene or animal carcasses."

He said the government has had to use ozone technology at the Sungai Linggi treatment plant in Negri Sembilan due to the high pollution level, mostly from animal carcasses flowing in from around the Seremban area.

An expert on water treatment and supply, the engineer said the design of a treatment plant is largely based on the quality of raw water from the main source.

"If water comes from a dam, there is minimal risk of pollution. The authorities have to be careful about river-water intake because human beings are the worst polluters (of water sources)."

While conceding that many long-standing problems hamper the attainment of high quality of raw water, the engineer said it was "not necessary to upgrade to a more advanced technology at the moment".

However, in the case of the incinerator operations, he cautioned that this would depend on other factors - for instance, the plant would have to meet stringent safety measures, which should be spelt out in the proposal.

He said that no matter which system is used at a water treatment plant, the end result would depend on proper implementation and efficient maintenance of the facility.

Malaysia currently has more than 400 water treatment plants, some of which are in the process of being upgraded to improve the processing of raw water for public consumption. Basic checks are currently in place to test the quality of raw and treated water.