Research on International Recycling of Living and Industrial Water (7)

Recycling products and grades

The necessary component of community education is the use of understandable terminology. At present, there is an intense discussion on the issue of how to properly describe the water quality-based grade of reuse water. Another suggestion is to describe the reuse product according to the end use. Perhaps combining water quality and end-use-based ideas can result in a viable and understandable return water system. Descripting water reuse in simple and easy-to-understand terms will contribute to community education and will increase public trust in water reuse.

Economics and sustainability

In most of Australia’s Coastal areas, the cost of developing new freshwater systems often exceeds $0.40/m3. Inland arid regions often cost much more. In Namibia, after the recent expansion of the Windhoek reuse plant, the cost of water reuse was 30% of the estimated cost of the Kavango River diversion system (Van der Merwe 1996).

Assessing the economics and sustainability of water reuse projects requires a lot of work. The most recent example is the reuse water strategy of Sydney Water Company in December 1999. It measures the annual cost of the reuse project in units of $/m3 and measures the impact of greenhouse gases in kWh/m3 equivalent energy units. White & Howe (1998) described this annual conversion expense method.

The analysis results of this method suggest:

• The selection of large industrial reuse water and urban landscape reuse water projects closer to the water treatment plant is more economical than the water supply system of the Shuangwang residents.
• Indirect drinking water reuse is more expensive than recycling many non-potable waters, but non-potable water reuse may have higher greenhouse gas effects.
·Distribution and circulatory systems should be further evaluated.
• It is still possible to use lower-cost water conservation measures as long as it can provide 10 to 20 years of development space. During this period, advanced water reuse measures can be introduced and further improved.

Desalting

In recent years, the development of reverse osmosis membrane synthesis technology has greatly reduced the energy and cost required for the desalination of seawater and brackish water. The development of energy restoration systems reduces the energy requirement for seawater desalination to less than 3 kWh/m3. These films offer the opportunity to make drinking water quality even better for drinking water standards. In some cases, the cost of water for desalinating and deep treatment of the water system is less than the cost of water for new conventional water sources.

in conclusion

The worldwide supply of fresh water is limited and is threatened by pollution. The continuous increase in the demand for water from agriculture, industry and cities exceeds the limited supply of freshwater resources. In order to avoid water crisis, many countries must protect water resources, manage water supply and demand, reduce pollution and reduce the environmental impact of a growing population.

The reuse of water has increased the effective supply of water, and the use of less fresh water has served to meet the greater needs of mankind. It has also lessened the human impact on the water environment. The conversion of the old “one-time-use and then-discharge” approach to the new sustainable “protection, rational use and recycling” of water conservation will benefit the entire world.

Water reuse projects have been successfully applied in many countries. This fully demonstrates the feasibility of large-scale reuse of water, and the use of recycled water plans plays an important role in the sustainable management of water resources worldwide. Engineering experience and comprehensive health studies indicate that recycled water can be used as a supplement to potable water.

In order to improve water reuse technology, in order to establish international norms, increase public awareness of water reuse, and improve the economics and sustainability of the project, much work still needs to be done. Although problems concerning water often seem complicated or sometimes difficult to solve, we have seen great progress in overcoming water shortages and saving water and water reuse in the last 20 years to meet the world’s water use. The next 10 years have seen tremendous progress. We hope to develop higher technology. It is believed that through our joint efforts, mankind can reverse the deterioration of the world's water environment and can meet the demand for water worldwide.