wastewater - UNESCO
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Sewage: the new black gold of the planet?

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What if we stop looking at wastewater, whether it is domestic, industrial or agricultural, as a problem or a cost and look at it as a resource? The latest United Nations World Water Development Report calls for this change of perspective, "Wastewater, an untapped resource", presented on 22 March in Durban, World Water Day, instituted by the United Nations and whose theme this year is "wastewater". 
Faced with the constant increase in demand, more systematic recourse to recycled water seems inevitable. 
 
A drop of water is flexible. A drop of water is powerful. Nothing is more necessary than a drop of water.
Water is at the heart of sustainable development. Water resources, and the range of services they can provide, contribute to poverty reduction, economic growth and environmental sustainability. From food and energy security to human and environmental health, water contributes to improved social well-being and equitable growth, affecting the livelihoods of billions of people.
United Nations
 
Aost human activities that use water produce wastewater. As the demand for water as a whole is increasing, the amount of wastewater produced, and its overall pollution load, is steadily increasing worldwide. 
 
In the fifth century B.C., Heraclitus is said to have stated that "change is the only constant in life". Today, this statement is more valid than ever. As populations and urban settlements grow, so do our needs, transforming our societies and our planet before our eyes.
 
The 2017 edition of the United Nations World Water Development Report examines the issue of wastewater and its potential as a sustainable resource. UN highlights wastewater issue and the different ways of reducing and reusing them. Not less than 80% of wastewater from residential premises, from cities, industry and agriculture are discharged into nature, polluting the environment and depleting the soil.
The collection, treatment and reuse of wastewater must be improved. At the same time, we need to reduce the amount of wastewater we produce in order to protect the environment and our water resources.
Sustainable Development Goal 6 - Ensuring universal access to water and sanitation and the sustainable management of water resources - includes a target to halve the proportion of untreated wastewater and to significantly increase the global recycling and safe reuse of water.
 
However, the Report's findings indicate the magnitude of the task ahead: "Most wastewater around the world is neither collected nor treated. Moreover, wastewater collection in itself is not synonymous with wastewater treatment. Very often, the collected wastewater is simply discharged directly into the environment without any treatment. Agricultural runoff is almost never collected or treated, which is why there are almost no measurement indicators for these types of wastewater.

 
In all but the most developed countries, the vast majority of wastewater is discharged directly into the environment without adequate treatment, with adverse effects on human health, economic productivity, the quality of environmental freshwater resources, and ecosystems.
Although wastewater is a key element in the water management cycle, water, after it has been used, is too often seen as a burden to be eliminated or an inconvenience to be ignored. The results of this neglect are now evident. The immediate impacts, including the deterioration of aquatic ecosystems and waterborne diseases caused by contaminated freshwater supplies, have significant implications for the well-being of communities and the livelihoods of individuals. Continued failure to address wastewater as a major social and environmental problem could undermine other efforts to achieve the Agenda 2030 for sustainable development.
 
In the face of ever-increasing demand, wastewater is gaining momentum as a reliable alternative water source, changing the paradigm of wastewater management from "treatment and disposal" to "reuse, recycling and resource recovery". In this regard, wastewater is no longer seen as a problem in search of a solution, but rather as part of the solution to the challenges facing societies today. Wastewater can also be a cost-effective and sustainable source of energy, nutrients, and other useful by-products.
 
The potential benefits of extracting these resources from wastewater far outweigh human and environmental health, and have implications for food and energy security and climate change mitigation. In the context of a circular economy, where economic development is balanced with the protection of natural resources and sustainable development, wastewater is a widely available and valuable resource. The outlook is undeniably optimistic if action is taken now.
"Wastewater is a precious resource in a world where the availability of fresh water is limited and demand is rising, says Guy Rider, President of UN-Water and Director-General of the International Labour Organization. "Everyone must do their part to achieve the Sustainable Development Goal of halving the level of untreated wastewater and promoting the reuse of safe water by 2030. This means carefully managing water and recycling water discharged from households, factories, farms and cities. We all need to recycle more wastewater to meet the needs of a growing population and preserve ecosystems. 
 
"The United Nations World Water Development Report 2017 shows that improved wastewater management involves reducing pollution at the source, removing contaminants from wastewater streams, reusing reclaimed water and recovering valuable by-products [...]. It is therefore essential to increase social acceptance of wastewater use in order to promote progress in this direction, said the Director-General of UNESCO, Irina Bokova.

An issue for health and the environment

Even today, a large proportion of wastewater is still discharged into the environment without being collected or treated. On average, high-income countries treat about 70% of the municipal and industrial wastewater they produce. This percentage falls to 38% in upper-middle-income countries and 28% in lower-middle-income countries. In low-income countries, only 8% of this wastewater undergoes any form of treatment. These estimates are consistent with the oft-cited assessment that more than 80% of the world's wastewater is likely to be discharged untreated. In fact, in many regions, water laden with bacteria, nitrates, phosphorus or solvents is discharged into rivers, lakes and eventually the oceans, with serious consequences for the environment and human health.
 
In high-income countries, the motivation for using advanced wastewater treatment is either to maintain environmental quality or to provide an alternative source of water to meet water shortages. However, the release of untreated wastewater remains a common practice, especially in developing countries, due to the lack of infrastructure, technical and institutional capacity, and financing.
However, the volume of water to be treated is expected to increase significantly in the coming years, especially in cities with high population growth in developing countries. "Wastewater treatment is one of the greatest challenges associated with the development of informal settlements (slums) in the developing world," says the Report's authors (p.56). A city like Lagos, Nigeria, produces 1.5 million cubic metres of wastewater every day, most of which is dumped untreated into the city's lagoon. The growing population, which is expected to reach 23 million people by 2020, makes such a situation explosive.
 
Pollution with pathogens, from human or animal dejecta, affects nearly a third of the rivers in Latin America, Asia and Africa, putting the lives of millions of people at risk. In 2012, 842,000 deaths were linked to contaminated water and inadequate sanitation in low- and middle-income countries. Lack of treatment also promotes the spread of certain tropical diseases such as dengue fever and cholera.
 
Solvents and other hydrocarbons produced by industrial and mining activities, as well as nutrient discharges (nitrogen, phosphorus and potassium) from intensive agriculture and animal waste, accelerate the eutrophication of freshwater sources and marine areas. The area of marine ecosystems affected by this phenomenon is now estimated at 245,000 km². The discharge of these polluted waters also promotes the proliferation of harmful algae, which leads to a decline in biodiversity.
 
The release of pollutants such as hormones, antibiotics, steroids or endocrine disrupters poses new problems as they are rarely controlled and their impact on the environment and health is poorly understood.

READ ALSO: "Antibiotic resistance and environment" of the Ministry of the Environment - February 2017

Pollution is devastating for the environment and is also reducing the availability of fresh water as pressures on this resource increase, particularly as a result of climate change.
However, the interest of decision-makers has so far focused primarily on the supply of water rather than on its management after use. The two aspects are, however, inseparable. The collection, treatment and reuse of water are at the very foundation of a circular economy, reconciling economic development and the sustainable use of resources. Recycled water represents a resource that is still largely under-exploited and can be reused many, many times over. In the United States, for example, it is estimated that the water of the largest rivers crossing the country was used twenty times before reaching the sea.
 

Sewers to the tap

In a context of a circular economy, where economic development is balanced with the protection of natural resources and sustainable development, wastewater is a widely available and valuable resource.
The most widespread use of wastewater is in agriculture today. In addition to improving food security, reusing water for agriculture can bring considerable benefits, including improved nutrition.
Although there are data gaps in some regions, particularly in Africa, at least 50 countries in the world are practicing it on an estimated 10% of all irrigated land.
 
Over the last fifty years, irrigated areas have more than doubled, total livestock numbers have more than tripled, and inland water aquaculture has increased more than twentyfold. Water pollution from agriculture occurs when fertilizers (nutrients) and other agrochemicals are applied in greater quantities than crops can absorb, or when they are washed away by rain. Efficient irrigation systems can greatly reduce water and fertilizer losses. Nutrients can also be released from livestock production and aquaculture.
 
Agriculture can be a source of many other types of pollutants, including organic matter, pathogens, metals and emerging contaminants. Over the past 20 years, new agricultural pollutants have emerged, such as antibiotics, vaccines, growth factors and hormones, which may be emitted from livestock and aquaculture operations. If properly treated and safely applied, domestic wastewater is a valuable source of water and nutrients. In addition to improving food security, reusing water for agriculture can bring considerable benefits to human and animal health, including improved nutrition.
The challenge is therefore to move from informal irrigation to planned and safe use, as has been the case in Jordan since 1977, where 90% of treated wastewater is used for irrigation. In Israel, almost half of the irrigated land is irrigated with recycled water. Artificial recharge of aquifers (1) with wastewater has already been developed for about twenty years around the Mediterranean, particularly in Israel and Australia, in sectors subject to significant water stress, as explained in the following pages. an article from the newspaper La Croix in 2016: water is reinjected into the subsoil by natural filtration, via basins, or directly via wells, when evaporation is very high. The advantage is that this water can be stored underground, so that it is not taken up by evaporation on the surface and can be reused later for watering, agricultural irrigation or even drinking water. It is an active way of managing the water cycle and optimising it.
 
A agricultural land irrigation project using treated sewage water is under construction in Oujda-Angad, Morocco: construction of a plant for the reuse of wastewater for agricultural purposes, which will make it possible to treat some 40,000 m3 per day. This water will be used to irrigate some 1 500 ha of farmland, benefiting more than 245 farmers and planting 750 ha of olive trees and as many fodder plants.
 

 
The use of municipal wastewater is a common model in countries in the Middle East and North Africa, Australia, and the Mediterranean, as well as in China, Mexico and the United States. The practice has been very successful in urban and peri-urban areas, where wastewater is readily available, usually free of charge, and where there is a nearby market for agricultural products.
 
In the industrial sector, large quantities of water can also be reused, for example in cooling or heating processes, instead of being released into the environment. In 2020, it is estimated that the market for industrial water treatment is expected to grow by 50%.
Although the practice is more marginal, treated water can also be used to supply the drinking water system. Namibia's capital, Windhoek, has been experimenting with this since 1969. To cope with recurring shortages, the city has set up infrastructure that treats up to 35% of wastewater, which is then fed into the drinking water supply. Residents of Singapore or the city of San Diego (USA) also drink recycled water.
Such a process can meet with resistance from the populations, who are reluctant to drink water that is considered unclean. A project to reuse water for irrigation and fish farms in Egypt, set up in the 1990s, thus failed for lack of support from the population. Awareness-raising campaigns can contribute to the adoption of such practices by the general public by building on successful experiences such as the recycling of wastewater by astronauts on the International Space Station.
 
(1) The aquifer containing the groundwater, the aquifer being the content.

A deposit of raw materials

As an alternative to fresh water, wastewater is also a potential source of raw materials. Developments in treatment techniques now make it possible to recover certain nutrients, such as phosphorus and nitrates, from sewage or sewage sludge. It is estimated that 22% of the global demand for phosphorus could be met through the treatment of human urine and faeces. Already, some countries, such as Switzerland, require the recovery of certain nutrients such as phosphorus.
According to the United Nations (UN), 25 % of the world's cultivated land is now characterized by degraded biological activity. The transformation of sewage sludge into organic fertilizer or its spreading on fields is therefore of undeniable interest.
Wastewater and sewage sludge can also be used to produce heat, electricity and fuels as a substitute for fossil fuels (oil, gas, coal), as their calorific value is the same as that of wood.
They can also be recycled in industry, particularly in three main sectors: the ceramics industry, the cement industry and energy recovery units.
The China Singapore Industrial Park in Suzhou (China) operates on this principle. The structure generates up to 300 tons of sludge per day. Thanks to the Innodry drying technology created by Degrémont, these elements are recovered as fuel for the park's power plant. A heat recovery system then enables this energy to be reused in the treatment process. 
 
Wastewater can also be reused to heat or cool buildings. The technology Blue Degrees developed by Lyonnaise des Eaux, a subsidiary of Suez Environnement, thus makes it possible to recover calories from wastewater to cool or heat all types of buildings. This technology is notably deployed at the Elysée Palace and its annexes in Paris. Result: a reduction in fossil fuel energy consumption of 63 % per year and a reduction in CO2 emissions of 206 tonnes per year.
 

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Another example: In China, SUEZ won a contract for water management in the Shanghai industrial park, for which it developed a vegetated wetland technique. Named "Zone Libellule®", it will be made up of several hundred species of plants chosen for their purifying capacity and will refine the treated wastewater leaving the treatment plant operated by SUEZ.
 
Biogas can also be produced from the chemical energy contained in the organic substances in the wastewater. In Japan, the government has set a target of recovering 30% of energy from wastewater by 2020. The city of Osaka produces 6,500 tonnes of biosolid fuel from 43,000 tonnes of sewage sludge every year.
 
 
While such advanced technologies are beyond the reach of developing countries, low-cost treatment solutions do exist. They do not provide clean drinking water but can produce a valuable resource for other uses, such as irrigation. In addition, the sale of raw materials from wastewater is one way to further lower water treatment costs.
 
Even today, 2.4 billion people still lack access to improved sanitation. Reducing this number, in line with sustainable development goal 6 on water and sanitation of the United Nations 2030 agenda, will result in more wastewater being discharged and requiring treatment. The movement therefore seems inevitable.
Already, the use of treated water as an alternative to fresh water is gaining ground. In Latin America, wastewater treatment has almost doubled since the late 1990s and now covers between 20 and 30% of wastewater collected in urban sewerage systems.

Creating an environment conducive to change

Improved wastewater treatment, increased water reuse, and the recovery of useful by-products promote the transition to a circular economy, contributing to the reduction of water abstraction and the loss of resources in production systems and economic activities.
 
Appropriate regulatory and legal frameworks
An effective regulatory framework requires that the implementing authority has the technical and managerial capacity, and acts independently, with sufficient powers to enforce rules and guidelines. Transparency and access to information encourage compliance, fostering trust and confidence among users in the implementation and enforcement processes.
Progress will require a flexible and incremental approach. Policy and regulatory instruments must be implemented at the local level, and must be adapted to different circumstances. It is therefore important that political, institutional and financial support is given to bottom-up initiatives and to the local (i.e. decentralised) provision of small-scale wastewater services.
 
As explained actuary-environmentIt was the World Health Organization (WHO) that first published guidelines for REUT (reuse of treated wastewater) for irrigation in 1989. In 1991, the Conseil Supérieur d'Hygiène Publique de France (CSHPF) published its own recommendations for France, setting conditions for distance from residential areas, recreational areas and roads and restricting watering to times when the public is not present, thus limiting the possibilities. A decree was published in 1994 but the implementing order was not published until... 2010! It was not until the Grenelle 1 law that this practice was relaunched. Article 27 provides that "the recovery and reuse of rainwater and wastewater will be developed in compliance with health constraints, taking into account the need to meet the priority needs of the population in the event of a crisis".
In France today, 65 installations are in operation throughout the country, mainly for watering agricultural land, urban green spaces and golf courses.
 

There is also a need for new regulations on the reuse of water and the recovery of products derived from wastewater. Legislation on quality standards for these products is often scarce or non-existent, which creates uncertainties in the market that can discourage investment. Markets for these products could be encouraged by financial or legal incentives (e.g. mandatory mixing of recovered phosphates in artificial fertilisers).
 
Cost recovery and appropriate funding mechanisms
Wastewater management and sanitation are generally considered to be expensive and capital intensive. The problem is compounded by a chronic lack of investment in institutional and human capacity development. However, the cost of inadequate investment in wastewater management is much higher, especially when considering direct and indirect damage to health, socio-economic development and the environment.
Many different business models have been put in place in which the costs and value recovered offer a significant financial advantage. However, revenues from the sale of treated wastewater are generally not sufficient to cover the operating and maintenance costs of the water treatment plant. The recovery of nutrients (mainly phosphorus and nitrogen) and energy can represent a significant new added value to improve the cost recovery proposition. Although revenues from wastewater use and resource recovery may not always cover the additional costs, the benefits from investments in water reuse can be quite comparable with the cost of dams, desalination, inter-basin transfers, and other alternatives to increase water availability. Even when it is brought to the tap, drinking water remains, in general, underestimated and underpriced when compared to the total cost of the service.
Treated wastewater must be priced lower than drinking water in order to be accepted by citizens. Setting a price for water from all sources to better reflect its real costs encourages investments that can result in affordable service provision for all members of society, including the poorest.
 
Minimizing risks to people and the environment
Untreated wastewater discharges can have serious effects on human health and the environment, including outbreaks of food- and water-borne vector-borne diseases, pollution and loss of biodiversity and ecosystem services.
The exposure of vulnerable groups, especially women and children, to partially treated or untreated wastewater requires special attention. Limited knowledge of the health risks associated with the use of waste water due to poverty and poor education contributes to increasing these risks, particularly in developing countries. Wherever human exposure is considered likely (e.g. through food or direct contact), more stringent risk management measures need to be taken.
 
Better information to understand
Data and information on wastewater generation, treatment and use are essential for policy makers, researchers, practitioners and public institutions to develop national and local action plans for environmental protection and the safe and productive use of wastewater. Knowledge about the volumes and, perhaps even more importantly, the components of wastewater are necessary tools for the protection of human health and environmental safety.
However, there is a widespread lack of data on almost all aspects of water quality and wastewater management, especially in developing countries. Research is needed to better understand the dynamics of pollutant occurrence and to improve methods for removing these pollutants from wastewater.
It is also essential to understand how external factors such as climate change will affect wastewater management. In order to improve wastewater management, it is essential to ensure that appropriate levels of human capacity are put in place. There is often a lack of organizational and institutional capacity in the wastewater management sector, and therefore all investments, whether in large-scale centralized wastewater management systems or smaller in situ systems, are at stake.
 
Public Awareness and Social Acceptance
Even if wastewater use projects are technically well designed, appear to be financially feasible, and incorporate adequate safety measures, water reuse systems can fail if planners do not take into account the dynamics of social acceptance.
The use of waste water often meets strong resistance from public opinion due to a lack of awareness and confidence in the risks to human health. Awareness-raising and education are the main instruments for overcoming social, cultural and consumption barriers.
 
Awareness campaigns need to be tailored to consumers from different cultural and religious backgrounds. The health risks associated with water reuse should be regularly assessed, managed, monitored and reported in order to gain public acceptance and to maximise the benefits of wastewater use while minimising negative impacts. In the case of drinking water (e.g., drinking water reuse), extensive information campaigns are needed to build confidence in the system and overcome the repulsion of the "yuck factor."
 
The example of Switzerland is reassuring: In the 1950s, Swiss waters were still heavily polluted by wastewater from cities and industry. It was not uncommon to see "No bathing - polluted water" signs on lake shores, says the Federal Office for the Environment in a dossier published on the occasion of Water Day on Wednesday 15 March. Politicians have taken up the problem and have since invested billions in the construction of sewage pipes and water treatment plants. Today, the pipeline network is 130,000 kilometres long, three times around the world, and there are 800 WWTPs in the country.
 
In a world where the demand for freshwater is constantly increasing, and where limited water resources are under increasing stress due to over-abstraction, pollution and climate change, neglecting the opportunities offered by wastewater management is simply unthinkable in a circular economy.
 
The United Nations World Water Development Report is a collaborative effort of the 31 United Nations entities and 37 international partners that make up UN-Water. Until 2012, the report, which provided a comprehensive overview of the state of the world's water resources, was presented every three years. Since 2014, it has become an annual and thematic report. Its presentation now coincides with World Water Day, whose theme is aligned with that of the report.
The United Nations World Water Development Report is a UN-Water report coordinated by UNESCO's World Water Assessment Programme.
 
 
 

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