SUSTAINABLE WATER FOR THE FUTURE

SUSTAINABLE WATER FOR THE FUTURE

Source: (Isabel C. Escobar, Andrea I. Schafer. Sustainable Water for the Future: Water Recycling versus Desalination, 2010, Elsevier B.V., UK)

In many arid and semi-arid areas, providing large volume of water required for industrial, agricultural, recreational, and potable applications are very difficult where existing water supplies may be limited in quantity or quality for meeting the increasing demands from population growth and industry expansion. Municipal wastewater, which generally comprises between 75% and 80% of consumed water in most cities, is one of the most reliable sources of water, since its volume varies little throughout the year. Through suitable treatment, reclaimed wastewater can meet various water quality requirements for potential wastewater reuse or recycle in numerous applications to satisfy many water demands such as agricultural and landscape irrigation, industrial processes, toilet flushing, or replenishing a groundwater basin, depending on the level of treatment.

Seawater and brackish groundwater are important sources of drinking water in a few arid countries of the Middle East, such as Kuwait or the United Arab Emirates, which depend heavily on desalination. Few years ago, desalination plants were limited to the water-scarce but oil-rich countries of the Middle East and North Africa, and to some tropical and subtropical islands. Nowadays, desalinated water has become a commodity for many countries in order to satisfy their growing demand for water. This newly emerging desalination markets, driving factors are more diverse, including economic and demographic growth, prolonged droughts, climate change, or declining conventional water resources in terms of quality and quantity due to overuse, pollution, or salinization. Moreover, as conventional water production costs have been rising in many parts of the world and the costs of desalination have been declining over the years, so that desalination also becomes economically more attractive and competitive source of water.

Policies to stimulate water recycling in an industrial can be possible deploying by increasing taxes on wastewater discharge, development of wastewater treatment techniques that result in enhanced removal of a wide range of contaminants, and use of alternative water sources. Therefore industry itself can working actively on water reuse projects, mainly for economic reasons, but also from the perspective of environmental responsibility. The benefits of water reuse for the industry can be a supplemental and reliable water source to augment or replace existing freshwater supplies; reduction of the net amount of water consumed; and reduction of wastewater generation and associated costs of wastewater treatment. Besides that, these policies can drive the progress and stimulates the new projects to academic community by investigating feasibility on a small scale and suggesting new processes and approaches.

In water-scarce regions, two sources of water are normally available: sewage and seawater. In the last decade, the reclamation of effluents has developed rapidly as an alternative to seawater desalination for irrigation and indirect potable water reuse. The key in water reuse is to first treat the sewage biologically followed by membrane filtration to remove organic matter and suspended solids. For seawater desalination, pretreatment must be provided if the source is open seawater. Desalination has now been practiced on a large scale for more than 50 years, and in recent decades, membrane desalination has enjoyed tremendous success. Through continual improvements, the major technologies are now efficient and reliable. However, they are still too expensive to address the needs for additional supplies of freshwater in of many parts of the world. On the other hand, water reclamation, recycling, and reuse address depleted water supply challenges by creating new sources of high-quality water supplies. One of the most significant benefits of water reuse is the value created by the inclusion of water reuse in integrated water resources planning and other aspects of water policy and the implementation of water projects, resulting in the long-term sustainability of water supplies.