NINGBO: The country's largest seawater desalination plant is to be built in the coastal county of Xiangshan, in East China's Zhejiang Province.

On completion, the facility will have a daily processing capacity of 100,000 tons and will supply safe drinking water to more than 500,000 people across the county.

The Xiangshan government signed an agreement with Datang International Power Generation Co Ltd (DIPGC) during the recent Ninth Zhejiang Investment & Trade Symposium to jointly develop the plant in the Xizhou township. It is expected to cost 1.1 billion yuan ($144 million) and is currently awaiting final approval from the National Development and Reform Commission.

According to Fang Deliang, deputy chief engineer with DIPGC, the Xiangshan plant will be the largest seawater desalination plant in South China in terms of processing capacity, but only the second largest in terms of size.

China's largest plant by size is currently under construction in North China's Tianjin municipality, a coastal city, which also suffers from a serious shortage of drinking water.

Fang said multi-stage flash desalination technology will be used at the Xiangshan plant to make low-pressure steam a constant heat source for desalinating the seawater. Such techniques are expected to greatly reduce the plant's operating costs.

The Xiangshan plant will be built near an existing power plant and the desalinated water will mainly be sourced from the water used there, Fang said.

The desalination process will also generate some concentrated saltwater, which can later be distilled and dried to become the raw material for salt and other chemical products, he said.

Wang Renzhou, director of the Ningbo development and reform commission, said the seawater desalination project would relieve the freshwater shortage, which has long plagued areas south of Ningbo.

"It will improve the quality of people's lives," he said.

Xiangshan county, which comprises the Xiangshan Peninsula and 608 other islands, suffers from a chronic shortage of freshwater, with both its permanent water storage capacity and water per capita levels far below the national averages.

Experts estimate that Xiangshan county will have a shortfall of 40.5 million cu m of water by 2010, and possibly twice that by 2020.

According to the Xiangshan government, the cost of desalinating one ton of seawater will be less than 6 yuan, with the cost of the desalinated water supplied to residents being 2.5 yuan per ton, close to the price of tap water.

The differential will be covered by the government and private firms.

(China Daily 06/13/2007 page4)