Water permeates all life on Earth, yet about two thirds of the world’s population suffer water insecurity for at least one month a year. Promoting wastewater as a valuable resource can aid strategies to meet resource demands and unlock economic opportunities. These are the findings in United Nations’ latest water resources report entitled The World Water Development Report 2017. Wastewater: The Untapped Resource.
The report highlights a shift in consciousness among development circles and policy makers where, perceptions of wastewater are changing from issues around treating a troublesome effluent towards considering it as part of the “circular economy”. Unlike linear economies that capture, use and dispose of freshwater, the circular economy promotes wastewater recycling for downstream activities.
According to the report, wastewater is a sustainable source of energy, nutrients, organic matter and other sought after by-products. Sustainable Development Goal 12 states that sustainable consumption and production entails promoting efficient resource use. Thus, reclaiming wastewater by-products for use in other industries will advance our progress towards meeting the 2030 Sustainable Development Goals.
Africa’s agricultural sector accounted for 81% of all water used on the continent in 2010. Whereas, municipal and industrial use accounted for just 15 and 4 per cent respectively. Comparatively, the United States and Europe enjoy a more balanced extraction ratio, indicative of mature and innovative economies that support high volumes of secondary and tertiary-sector activity. Thus, regional-level strategies to process wastewater should be developed.
Regardless of the sector, most human activities that use water ultimately produce wastewater, highlighting the need for sustainable and cost effective mechanisms to treat and reuse it.
The report says the agricultural sector has grown to account for 70 per cent of all global freshwater extractions. Over the past 50 years, changing diets and growing populations have prompted irrigated crop areas to double, livestock production to triple and a twentyfold increase in inland aquaculture. Agricultural intensification also produces wastewater that discharges large amounts of pathogens, pesticides, sediments and other pollutants into our planet’s water bodies. Without adequate treatment, these microbial pollutants from upstream activities pose threats to human and environmental health.
Promoting the circular economy in agriculture could transform water-supply systems. Because of its cost-efficiency and high nutrient content, domestic wastewater has fertilized generations of smallholders’ crops in developing countries. In some countries, efforts are underway to develop this process. The Tunisian Ministry of Agriculture distributes treated wastewater for irrigation to farmers who cultivate some 40,000 hectares of arid land around Tunis. However, more research into technologies that adequately process wastewater and reduce the human and environmental health costs of wastewater irrigation is needed. The benefits of such a transformation are most noticeable in water-scarce regions such as Africa where people depend on agriculture for their livelihoods.
Through Resolution 64/292, the UN General Assembly recognizes access to clean water and sanitation as a basic human right. Yet, around 1.8 billion people globally consume water contaminated with faecal matter and some 2.4 billion people lack access to basic sanitation services. Increased urban growth, especially the spread of informal settlements, makes it difficult to provide services which meet this basic human right. Many developing countries collect and treat only a fraction of municipal wastewater. Wastewater typically flows into the nearest surface water drain or open canal, posing direct threats to human health.
For example, Lagos, Nigeria, generates 1.5 million cubic metres of wastewater each day. Since there is no central sewage system most of the wastewater flows directly into open gutters and eventually ends up in drinking water. As a result, Nigeria has a child mortality rate of 108.8 deaths per 1000 children from waterborne diseases, one of the highest rates in Africa. As Clever Mafuta, coordinator of the Africa programme at GRID-Arendal, states:
“Providing safe and clean drinking water alone is not enough. Wastewater erodes gains made in the provision of clean water as it often ends up in drinking water sources”.
A UN report points out that higher levels of consumption will double the volume of industrial wastewater by 2025. Increased societal and environmental stressors have led to a growing movement that urges industry to reduce and recycle the wastewater it produces. In developed nations, this translates into policies and regulations that promote by-product recovery and contaminant removal.
Industries in developed countries increase sustainability by embracing market opportunities and profitably entering the circular economy. However, according to the World Water Development Report, under-developed countries and informal industries lack the resources to seize these opportunities and discharge directly into the environment.
By using waste from one process as inputs for another, ‘Industrial ecosystems’ can minimize water use and contamination, lower operational costs and reduce greenhouse gas emissions. For example, at the Terneuzen site in south-western Netherlands, Dow Chemicals reclaims 10,000m3 of wastewater per day from a nearby municipal treatment plant. Once treated, the water generates steam that supplies energy to local manufacturing plants. Afterwards the reclaimed water is used in cooling towers until it evaporates into the atmosphere. In this way, Dow has reduced energy usage by 95 per cent or 60 000 tonnes of carbon dioxide each year, showing that by promoting the circular economy, sustainable resource use is achievable.
Capacity building in the global south is a central theme in the World Water Development Report. On average, 70 per cent of wastewater generated in high-income countries is treated. Middle-income countries treat approximately 28-38 per cent. In low-income countries, only 8 per cent is treated. Overcoming these disparities is necessary to achieve the Sustainable Development Goals.