CHINA: Scientists Push Desalination Meet Water Shortages

  • by Mitch Moxley (beijing)
  • Wednesday, December 29, 2010
  • Inter Press Service

Despite billions of dollars spent on damming rivers, building reservoirs and digging deeper wells, farmers in the north toil on parched land while hundreds of cities across the country face water shortages and deteriorating water quality.

Beijing’s water shortage will soon reach 200 million to 300 million cubic metres, according to state media reports, as the city awaits the completion of the 62 billion U.S. dollar South-North Water Transfer Project, which will displace some 330,000 people.

The World Bank has warned that the country’s water crisis could spark unrest, pitting rich against poor and urban against rural. Without serious changes in water use, tens of millions of Chinese will become environmental refugees in the next decade, the Bank argues.

Meanwhile, countries downriver from the growing superpower — including Burma, Laos, Cambodia and Vietnam — argue that China’s aggressive dam building in the Mekong River is robbing their citizens of water.

For some, the answer lies in desalination technology. China has been engaged in desalination research since 1958, and in 1975 it began research on medium- and large-scale distillation devices. In 1986, it finished construction of a seawater reverse-osmosis desalination device.

Tianjin, a coastal port city about 150 kilometres from Beijing, has become a national leader in desalination technology. In fact, the city has refused water from the south and instead focused on desalination efforts. According to the local government, the nearby Dagang Xinquan Seawater Desalination Project is the 'largest seawater desalination plant in Asia.'

'Indeed, the municipality has been developing desalination technologies since the year 2000, and this has been regarded as a more likely source of water to meet the water supply needs of the municipality,' said a report by Probe International, an independent environmental advocacy group.

Wang Shichang, director of the Desalination and Membrane Technology Centre at Tianjin University, says researchers in China are currently working on more than 200 desalination projects, receiving support from the Ministry of Science and Technology and the National Science Foundation of China.

The centre that Wang leads introduced the first multi- stage flash (MSF) distillation devices, which distills water through several 'multi-stage' chambers, each operating at progressively lower pressures. The vapor generated by flashing is condensed at each stage and turned into fresh water. The technology uses 25 percent less 'feed water' than other desalination devices, Wang says.

The country’s desalination capacity reached nearly 200,000 tonnes per day in 2008, up from 30,000 tonnes in 2005. According to the government’s current development plan, the figure is expected to reach 800,000 to one million tonnes by the end of this year.

But Wang says support is still not enough. He notes that the gap between China’s innovation capacity and development and manufacturing capabilities compared to those of foreign countries remains vast. He says greater state subsidies and access to bank loans are needed to bridge that divide.

While Wang works toward creating new usable water, Tian Juncang, a professor at Ningxia University, is trying to reduce water wasted in agriculture.

Tian’s work focuses on using plastic mulch in conjunction with drip irrigation to suppress weeds, maximise the effectiveness of fertiliser and conserve water in crop production. Plastic mulch and drip irrigation can reduce the amount of water used in irrigation process by up to 50 percent, Tian says.

China’s agriculture industry currently uses 70 percent of all the country’s water, and much of it goes to waste, he says. Drip irrigation under plastic mulch can reduce the industry’s use to 50 percent.

'China’s agricultural industry faces grave challenges,' Tian tells IPS. But by implementing new technology, 'the current amount of water can support double the farming land.'

The government has moved to promote water conservation. In 2007, it issued it’s 11th five-year plan for water conservation, proposing detailed targets, including increasing the agricultural water conservation rate to 50 percent from 45 percent between 2005 and 2010.

But Tian says water conservation must be a systematic effort with the support and cooperation of industry and society as a whole. Efforts to conserve water also require increased funding from the state, improved laws and regulations and more advanced and better-managed facilities, Tian says.

'Agricultural water conservation efforts have been strengthened in recent years,' he says, 'but it’s still not enough.'

© Inter Press Service (2010) — All Rights ReservedOriginal source: Inter Press Service

Where next?