The most commonly used wastewater is irrigation in agriculture, and at least 50 countries use wastewater for this purpose to estimate an estimated 10% of the total land use. However, data is still incomplete for many parts of the world. But this use is accompanied by concerns about human health, when the water contains pathogens that cause contaminated plants to grow. Therefore, moving from unofficial irrigation to a well-planned and safe use is a challenge, like Jordan, which has used 90% of refined wastewater since 1977. In Israel, refined wastewater now accounts for nearly half of the total water used for irrigation.
🔺 In industry, large amounts of water can be reused instead of drainage, for example heating and cooling. By 2020, the market for industrial waste water treatment is expected to increase by 50%.
Refined wastewater can also help increase the supply of drinking water, but is still used in part. In the city of Windhoek, the capital of Namibia, it has been used for drinking water since 1969. In response to frequent shortages of fresh water, a refinery has been set up to treat 35 percent of the wastewater, which is then used to complete the supply of drinking water. Residents of Singapore and San Diego (United States of America) are also drinking with confidence that they have been rolled out.
🔹 This path can be met by people’s resistance, because it may not be worth drinking or using water that once considered dirty. For example, the lack of public support led to the failure of a water reuse project to irrigate and raise fish in Egypt in the 1990s. Informative measures can help public acceptance for this type of route by referring to successful examples, such as the International Space Station’s astronauts who reused recycled water more than 16 days ago.
🔴 Wastewater and sludge as raw materials
🔸 Waste water, in addition to providing a safe alternative source for fresh water, can also be seen as a potential source of raw materials. Thanks to advances made in refining techniques, some nutrients such as phosphorus and nitrates can now be recovered from wastewater and sludge, and turned into fertilizer. It is estimated that 22 percent of global demand for phosphorus, a finite and finite mineral, can be provided by treating urine and human stools. Some countries, like Switzerland, have laws to retrieve nutrients such as phosphorus.
🔹 Organic materials in the waste can be used to produce biogas. Biogas can be used to provide fuel for a wastewater treatment plant. By doing so, such installations can be turned off from major energy consumers to neutral or even energy generators. The Japanese government is targeting recovery of 30% of biomass energy from wastewater by 2020. The city of Osaka produces 6500 tons of biomass every year from 43,000 tonnes of sewage sludge.
🔺 Such technologies should not be outside the reach of developing countries, as it now allows low-cost solutions for refining, extraction of energy and nutrients. They may still not allow direct drinking water reuse, but they can produce acceptable and safe water for other uses, such as irrigation. The sale of raw material from wastewater can provide additional revenue to help cover the cost of investment and the operation of wastewater treatment.
🔻 There are still no 2.4 billion people available for sanitation facilities. Reducing this figure, in line with the sixth goal of sustainable development of water and sanitation in the United Nations 2030 agenda, will mean more drainage, which should be refined as low cost.
Progress has already been made. For example, in Latin America, wastewater treatment has almost doubled since the late 1990s and covers 20 to 30 percent of the wastewater collected in urban sewage networks. But it also means that 70 to 80 percent is released without purification, so there is still a long way to go. Recognizing the value of safe use of refined wastewater and its valuable substitute products as a solution to raw fresh water, a major step has been taken in this direction.