Sustainable and Safe Use of Non-conventional Waters -Reclaimed Water and Desalinated Water

Abstract: Fresh water scarcity, pollution and an uneven distribution have caused an increasingly serious global water crisis. One of the most widely adopted response strategies is the exploitation and use of non-conventional water sources. Water reuse and desalination were in focus in the study which was aimed to develop the strategies to promote the sustainable and safe use of reclaimed water and desalinated water from the perspective of key factors affecting the development. China and Sweden are used for case studies. With the help of literature reviews, water quality analysis, microbial risk assessment models and statistic evaluation methods the suggested strategies were evaluated and improvements to the strategies suggested. If sustainable development of non-conventional waters should be promoted, improvements and clarifications must be made in the aspects of legislation, management, water security and policy. Key factors for desalination were identified and analysed. The most important are technology promotion, energy efficiency, feed water treatment, full cost coverage in the price. Strategy and technology for lowering cost and developing intelligent pricing system are critical to desalination market. A sound management system, qualified water and supported policy and transparency to the public are key factors for water reuse. The relevant strategy for further sound development were suggested not only for China but also available for the countries with similar situations. For improving the security of using non-conventional waters especially reclaimed water, the study was carried out from two perspectives: developing water reuse guidelines assessing microbial risk for using treated wastewater for different applications. The approaches for setting guidelines and how they should be formulated were discussed. A combination of epidemiology study and risk assessment was recommended for developing microbial indicators standard. Guidelines must include regulations of treatment processes and instructions on how to protect users and the public. Statistic methods imply that water quality monitoring can be simplified. Quantitative microbial risk assessment is an effective supplementary tool to guidelines and was applied for judging the possibility of reuse the studied water for different applications. The protective guidelines could be developed based on the process and results of risk assessment by controlling exposure pathway and dose. Besides the strategy developed by water managers, other stakeholders, especially public and users, play an important role. The key stakeholders were identified and their interaction and influence for water reuse industry were analysed. Their participation is crucial for enhanced water reuse. Strategies for clear legal basis and guarantee, establish communication platforms, formulate incentive mechanisms and improve education of public, for promoting stakeholders’, especially public, acceptance and participation were discussed. As a summary, the potential market of non-conventional waters is huge and will be greatly promoted by the strategies and means discussed in the thesis for sustainable development, improvement of water security and the stakeholders’ co-operation and participation. For China, the wastewater discharge is about 80 billion m3 per year, which means if intelligent strategy adopted, the potential reclaimed water could not only meet the 40.4 billion m3 of annual water shortage, but also save the water from long-distance water diversion, as well as reduce the pollution burden of natural waters. Seawater desalination is here more marginal, but could supply 803 million m3/a by 2015 as planned.