海水淡化：中国水源危机的一线希望

 　　More government support, including subsidies 1 and a favorable pricing mechanism 2, is needed for the country to use desalinated seawater to quench 3 its thirst, a top industry expert said。

　　"The lack of an effective pricing mechanism for desalinated water and support for an operable policy is affecting the development of the country's sea desalination 4 industry," said Li Linmei, director of the State Oceanic Administration's Institute of Seawater Desalination and Multipurpose Utilization 5 in Tianjin。
　　The country aims to produce 2.2 million cubic meters of desalinated seawater daily in 2015,about three times current capacity, according to a National Development and Reform Commission plan released last year。
　　Current domestic water prices range from 2.4 yuan to 4.9 yuan a metric ton in the coastal 6 regions, while the price of water for industry ranges from 3.3 yuan to 7.9 yuan a ton, according to China Water Net。
　　However, desalination plants can produce 674,000 tons daily at a cost of about 5 yuan ($0.80)a ton - not including infrastructure 7 such as pipelines 8。
　　Li said the government should consider bringing desalinated water into the water grid 9。
　　Aside from subsidies and funding for pilot programs, Li believes desalination is a key part of water security。
　　"The seawater desalination industry is as important as water conservancy projects for China to cope with its water shortage," Li said。
　　China suffers from severe water shortages, nearly 54 billion cubic meters on average every year. This means that more than 66 percent of cities experience water shortages。
　　To compound that difficulty, water consumption is expected to surge to about 700 billion cubic meters in 2030, up from 600 billion cubic meters。
　　Facing such a severe shortage, authorities are taking measures。
　　In March, the NDRC identified the regions and companies selected to carry out the first desalination projects, including heavily populated areas such as Zhejiang and Hebei provinces, and the municipalities of Shenzhen and Tianjin。
　　The commission asked regions and companies to encourage desalinated water use for industrial and domestic purposes。
　　The industry is expected to get a 10-billion-yuan boost from the plan。
　　Li said the policy showed the country's determination and confidence in boosting the industry。
　　Key technology
　　Reverse osmosis technology and other areas of development vital for desalination have been mastered, Li said。
　　Osmosis technology pushes water under high pressure through fine membranes 10, filtering the salt。
　　Coupled with the distilling 11 process of high-pressure steam and evaporators, this means that the technology is, in more ways than one, on tap。
　　The country has 16 seawater desalination plants with a daily capacity of more than 10,000 metric tons of fresh water, according to the NDRC。
　　"Although we have made great progress in technology, large-scale plants in China still depend on foreign technology," Li said。
　　Desalination is used in more than 150 countries to supply water to more than 200 million people。
　　The Tianjin Institute of Seawater Desalination and Multipurpose Utilization is strengthening international cooperation to raise China's domestic seawater desalination technology and boost exports, Li said。
　　There are concerns about the potential environmental effects of large-scale seawater desalination plants, especially wastewater discharges。
　　Li said the government should launch an environmental assessment 12 before any major upgrade。
　　尽管中国已将海水淡化视为解决沿海未来淡水资源短缺的措施之一，但是业内专家认为，淡化水的广泛应用仍存在一定难度。
　　国家海洋局天津海水淡化与综合利用研究所所长李琳梅在接受本报专访时指出，“尚未形成有效淡化水价格机制以及缺乏具体可操作的优惠政策在一定程度上影响了中国海水淡化产业的发展。”
　　相关数据显示，我国海水淡化装机能力为67.4m3/d，海水淡化水综合成本价格约为5元/吨左右。
　　中国水网显示目前我国沿海居民生活用水价格介于为2.4元/吨~4.9元/吨；工业用水价格3.3元/吨~7.85元/吨。与自来水相比，淡化水显然没有价格优势。
　　李琳梅提出，为了促进中国海水淡化产业的发展，国家首先要将海水淡化水视为保障国家水资源安全的重要组成，将淡化水纳入国家水资源配置体系和区域水资源规划。同时，政府应为公益性海水淡化工程提供补贴。
　　根据去年国家发展改革委员会发布的《海水淡化产业发展“十二五”规划》，到2015年，海水淡化产能规模将达到220万立方米/日以上，约为目前产能的3倍。
　　该规划还提出，到2015年，海水淡化对解决海岛新增供水量的贡献率达到50%以上，对沿海缺水地区新增工业供水量的贡献率达到15%以上。
　　李琳梅指出，目前中国海水淡化技术发展已基本成熟，但其市场的培育和发展需要实质性的产业政策支持。
　　她认为国家财政应设立专项资金，用于支持具有自主创新的海水淡化技术及其规模化示范的试点项目。
　　李琳梅说：“作为中国应对水资源短缺的措施，海水淡化与水资源保护同等重要。”
　　根据水利部发布的统计数据，我国年平均缺水量接近540亿立方米，66%以上的城市受到水资源短缺的困扰。
　　水资源缺口仍在不断扩大。到2030年，年水资源消耗量将由目前的600亿立方米增至7000亿立方米。
　　面对如此严峻的水资源短缺，国家开始采取措施以推动海水淡化产业发展。
　　三月份，国家发改委公布了第一批海水淡化工程试点区域和企业，浙江、河北、深圳和天津均榜上有名。
　　发改委要求试点区域和企业积极促进将淡化水应用于工业和住宅。
　　国家发改委预计，海水淡化设备的快速发展将使该行业年均增长达10亿元。
　　李琳梅说，这些政策初步显示了国家推动海水淡化产业发展的决心和信心。
　　中国海水淡化技术
　　李琳梅说，经过50多年的研究，我国已经掌握了反渗透海水淡化技术和低温多效蒸馏海水淡化技术。
　　反渗透技术利用高压推动水通过膜分离出盐，而低温多效蒸馏则由多级组成，通过利用低压蒸汽以产生高纯水。
　　国家发改委表示，2012年我国产水量高于10000立方米/天的海水淡化工程有16个。
　　“尽管我们在海水淡化技术领域已经取得了长足的进步，但目前国内大型海水淡化工程仍主要使用国外技术。”李琳梅这样表示。将国产海水淡化技术应用于工程实践，是提高我国海水淡化自主创新能力的关键。
　　至2010年，海水淡化工程已被应用于世界上150多个国家，解决了2亿多人的饮水问题。
　　李琳梅说，目前淡化所正积极开展国际合作，以提升我国自主海水淡化技术在国际市场中的地位，促进国产淡化设备大规模向国外输出。
　　面对迅速发展的中国海水淡化产业，也有人对大规模海水淡化工程的潜在环境影响表示担忧。因为浓海水排放可能会影响临海水域的水质，引起受纳海域盐度、温度的升高。
　　李琳梅表示政府应对高盐度浓海水的排放进行环境影响评估，并提供排放标准。