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Climate conditions are becoming ever more extreme, with severe droughts, incessant rains and floods, melting glaciers, rising sea-levels, and devastating cyclones.
The Paris Agreement in 2015 and the Intergovernmental Panel on Climate Change (IPCC) have implemented a limit to the temperature rise caused by anthropogenic activities to approximately ~ 1·5–2·0 degrees from pre-industrial levels, by the year 2050. This can only be adhered to if the hydrological cycle, along with the other factors affecting climate change, is inspected more closely.
While addressing issues with the water cycle is very important for climate change, these issues also present a separate threat to humanity, especially in water-scarce regions.Water-scarce regions are areas in which there is not sufficient water availability to meet demand. This can be due to the lack of water resources or the lack of adequate infrastructure to provide water access.
Every continent suffers from increasing water scarcity, largely due to climate change, as well as over-use, misuse and abuse of water. Some of the causes of water scarcity include excess ground-water tapping, polluting fresh-water bodies, and excess industrialization and agriculture.
Water scarcity is more prominent in arid regions but sustainable water delivery has already reached its limit in most regions. At present, over 2 billion people are living in water-stressed areas (UN 2018).
There is a highly complex relationship between global development and water demand. Some fo the various measures employed to mitigate this crisis include: limiting the supply of water, recycling water, adopting desalination techniques, using water treatment plants, and creating water awareness programs.
Recycling water is an essential measure to address this crisis, and brings with it numerous potential benefits. It can be carried out in different ways, depending on the water source, the contaminants present, the scale of water availability, the economy of recycling, and the use of the utility post-recycle. Advanced water recycling methods are employed to address existing water challenges in water-scarce regions.
However, recycling water in water-scarce regions is a major challenge, as there is little availability of water at the source. The water to be recycled will have high levels of contaminants, increasing the energy used by and the cost of the recycling process. On the other hand, recycling this water may still provide economic and financial benefits in these regions.
A few examples of local water recycling are: using process water for cooling or heating purposes; collecting rainwater for gardening, washing and cleaning purposes; treating rainwater to make it potable; and utilizing waste water from washing machines for flushing toilets and washing cars.
Waste Water Management
In these water scarce regions, the availability of clean water is ‘inextricably linked’ to waste water management. Waste water management is a part of the water recycling process.
Waste water is a ‘gold-mine’ industry in-the-making, seen as an ‘untapped’ resource. Waste water management includes reducing pollution at the source, removing contaminants from waste water flows, reusing reclaimed water and recovering useful by-products. For example, Israel, an arid/semi-arid region, re-uses 85% of its wastewater, making the country a world leader in water reclamation.
Non-conventional water resources for agricultural use due to its high nutritional content and due to lack of accessible water sources, are a good way to recycle water. Pre-treatment, however, is required to avoid the spread of disease-causing agents among farmers, workers and soil.