Wastewater usage set for major global growth
A rapid increase in the use of wastewater for farming and other uses worldwide is predicted amid growing competition for freshwater from industry and cities coupled with a rising world shortage of potash, nitrogen and phosphorus.
As water supplies fall and stress rises in many areas, the potential resource of wastewater is being widely recognised, according to a new study led by Japan's Tottori University and Canada's Institute for Water, Environment and Health (UNU-INWEH).
The study reveals that only 55 out of 181 countries studied have information on three key aspects of wastewater: generation, treatment, and reuse. A further 69 have data on one or two aspects, and 57 show no information on any aspect.
On average, high-income countries treat 70% of the generated wastewater, says the study, while upper-middle-income countries treat 38%, and lower-middle-income countries treat 28%. Just 8% of wastewater generated in low-income countries undergoes any kind of treatment.
In North America, of the estimated 85km3 of wastewater generated each year, 61km3 is treated. Annually, however, just 2.3km3 or 3.8% of that treated wastewater is used.
UNU-INWEH director Zafar Adeel said: “From the earliest of times, most wastewater has truly been wasted. However, it is a vast resource if we reclaim it properly, which includes the separation of municipal from industrial wastewater. Another way of envisioning the volume of the resource potentially available worldwide each year is to imagine 14 months watching the flow out from the Mississippi River into the Gulf of Mexico.”
In developing countries, particularly in water scarce countries, wastewater volumes are thought to have increased substantially in recent years due to rural-urban migration. Many farmers in water scarce developing countries irrigate with wastewater because:
- It is the only water source available for irrigation year-round
- Wastewater irrigation reduces the need for purchasing fertiliser
- Wastewater irrigation involves less energy cost if the alternative clean water source is deep groundwater
- Wastewater enables farmers in peri-urban areas to produce high-value vegetables for sale in local markets.
Manzoor Qadir, of UNU-INWEH, said: “The key point underlined throughout this report is the need to invest the time and resources to fill the global data gap. Better data will enable the research and policy community to enhance understanding and craft effective solutions that will benefit millions of producers and consumers worldwide.”
It is likely that the demand for wastewater as a source of irrigation will increase in arid and semi-arid areas of developing countries at a faster pace than the development of technical solutions and institutions that might ensure the safe distribution and management of wastewater.
The key technical and policy questions in developing countries include those pertaining to better methods for handling untreated wastewater on farms and in farm communities; better recommendations regarding the crops and cultural practices most suitable for settings in which wastewater is the primary source of irrigation; better methods for protecting farm workers and consumers from the potentially harmful pathogens and chemicals in wastewater; and capacity development of relevant professionals to tackle the complex issues arising from the agricultural use of wastewater.
- Irish Water completes new WWTW at Gorey Irish Water has announced the completion of a new wastewater treatment scheme for Gorey, County Wexford. Read More >
- Cycling creates 0.5l of drinking water in an hour A self-filling water bottle for bicycles that condenses moisture from the air could not only quench the thirst of cyclists... Read More >
- NWG selects five for ten-year frameworks Mott MacDonald Bentley, Interserve, Integrated Water Services and a joint venture between Esh Construction and MWH have... Read More >
- Front Line Defence Screens act as your first line of defence in a sewage treatment process, but not enough attention is given to making sure... Read More >
- Grit removal: the importance of protecting downstream equipment The water industry needs to wake up to the costly damage that wastewater grit can cause and take action to ensure that key... Read More >
- New Sludge Conference to be part of Wastewater 2018 The UK's largest wastewater event - Wastewater 2018, organised by WWT - is set to return to Birmingham on 30th January and... Read More >
- SMART-Plant points way to circular economy European wastewater experts have worked together to open seven pilot plants which demonstrate technologies which could... Read More >
- Odour control: Going Undercover Thames Water is using a combination of covers, air filtering technology and monitoring in order to ensure it meets... Read More >