Technology brings the sea closer to home

Prodita Sabarini, The Jakarta Post

The bright side of the city's water shortages is that people are now exploring alternative sources to groundwater.

One alternative is to build water desalination plants to turn seawater into potable water.

"It is possible because the technology is available in Indonesia. For desalination plants, the technologies applied include reverse osmosis technology as well as distillation," Sakt A. Siregar, Siemens Water technologies business development manager, said Friday.

Germany-based Siemens provided the technology for Singapore's water desalination plant.

Sakti said a water desalination plant could supply a large amount of water, depending on its size. "An average sized one can supply around 100 liters of water per second."

Desalination is a process that removes dissolved minerals -- including but not limited to salt -- from seawater, brackish water or treated wastewater. A number of technologies have been developed for desalination, including reverse osmosis (RO), distillation, electrodialysis and vacuum freezing.

Currently, Jakarta's main water supply comes from raw water sources located in Bogor, Depok, Bekasi and Tangerang, as well as Jatiluhur Dam in West Java.

Haryadi Priyohutama, the director of city water company PAM Jaya, has said there is no guarantee the dam will have the capacity to supply Jakarta in the long term.

Jakarta uses 16 cubic meters of water per second, while Jatiluhur Dam, in Purwakarta, West Java, has the capacity to supply 14 cubic meters per second.

It is estimated that by 2009 the city will be using 21.6 cubic meters of water per second. By 2015, demand will have reached 42 cubic meters of water per second.

The Jakarta administration has said the city suffers a water deficit of 36 million cubic meters per year from the total demand of 400 million cubic meters a year.

Sakti said many of the country's industries, such as petrochemical industries and power plants, had already built desalination plants to meet their water needs.

He said that building municipal desalination plants might be a good alternative for the city to consider. However, he doubted that would happen in the near future considering the plan required a capital investment of millions of dollars.

"For Jakarta I think the trend will be clustered desalination plants. The plants won't be constructed by municipalities, but by industries for their own source of water."

He said the management of Ancol amusement park, which is situated on the northern coast of Jakarta, was planning to build a desalination plant for its own use.

"That's what the trend will likely be."