Circular wastewater systems ‘underexploited’, says United Nations

As companies link up with charities to raise awareness of World Water Day, a new report from the United Nations (UN) has suggested that the "vast potential" of using wastewater as a resource remains "underexploited".

The “Wastewater: the untapped resource” report from the UN highlights how improved wastewater management can unlock economic returns, reduce water scarcity risks and help achieve water-related targets listed under the Sustainable Development Goals (SDGs).

“In a world where demands for freshwater are continuously growing, and where limited water resources are increasingly stressed by overabstraction, pollution and climate change, neglecting the opportunities arising from improved wastewater management is nothing less than unthinkable in the context of a circular economy,” the report states.

Released a day before World Water Day, the report notes that for every $1 spent on sanitation improvements, a further $5.5 will be returned to society. But, in order to reach this prosperity numerous technological and mind-set barriers need to be overcome to boost “extremely low” levels of treatment and investment.

Around two-thirds of the world’s population live in areas that experience water scarcity for at least one month every year. By 2030, it is estimated that 33 countries will be at risk from water-stress and 500m people already live in areas where water consumption exceeds local renewable water sources by a factor of two.

As population and country-based GDP continue to grow, the use of wastewater as a resource can generate increased access to clean water sources and even enhance food security, the report states.

Currently, around 70% of municipal and industrial wastewater is treated in high-income countries, compared to 28% in lower-middle income countries. For low-income countries, such as African nations, treatment can drop to as low as 8%.

According to the report, an increase in capital investment in these countries, combined with smarter and less-expensive treatment models, can promote wastewater as a viable and reusable resource and generate renewable energy as a by-product.

Current wastewater management systems are considered expensive, especially in the case of large, centralised systems. By switching investment focus to wastewater prevention instead of traditional end-of-pipe treatments, and introducing decentralised systems serving smaller groups of properties, freshwater can be saved and nutrients and energy can be recovered, suggests the report.

In fact, it has been estimated that the costs of these decentralised systems are between 20-50% of the total cost of conventional plants, and come with lower operational and maintenance costs – around 5-25% of conventional systems.

Agriculture influence 

The report, commissioned by Presidents and Prime Ministers from countries including Mexico, Australia, South Africa and the Netherlands as part of the UN’s High-Level Panel on Water, also notes that the agriculture sectors can enhance food security and generate biogas by investing in wastewater treatment.

In the last 50 years, the area equipped for irrigation has doubled globally, while livestock has more than tripled and inland aquaculture has grown by more than twentyfold. Because of this growth, agriculture now accounts for around 70% of global water use.

The report notes that efficient irrigation schemes can reduce water and fertilizer loss, and – if adequately treated – can create a valuable source of water and nutrients. This, the report notes, can enhance food security, and improve nutritional health values by promoting water reuse in the agriculture sectors. Private firms also have the option in investing in on-site generation to recover biogas through sludge treatment – Southern Water and Veolia have already highlighted the energy benefits that this can generate.

Sink or swim 

Despite the opportunities, barriers are still in place regarding legislation and the actions of small and medium sized enterprises (SMEs). The report notes that many SMEs still discharge wastewater directly into the environment. In areas, such as Africa, where current systems can’t keep up with growing demand, new technologies need to be introduced to create multi-purpose benefits to these firms. This is in direct contrast to Arab states, where water resource management plans have seen 71% of wastewater collected, 21% of which is used for irrigation and groundwater recharge.

Specifically, the report calls for stronger legislation to highlight the “phenomenal cost of inaction”, noting that market uncertainties exist due to a lack of political and industry clarity of quality standards of treatment systems. Compulsory blending of recovered phosphates was highlighted by the report as one legislative incentive that can stimulate the market.

Worldwide, the total cost of water insecurity to the global economy is estimated at $500bn annually. Numerous businesses have agreed to “water efficiency challenges” to highlight the business case for water stewardship, and a report from multinational banking group ING has found that the circular economy could save 11% of annual global water demand.

Businesses have been warned that in order to thrive in a low-carbon future they must first “navigate a mosaic of global realities“, that has seen water scarcity hit a variety of regions and threaten to destabilise infrastructure, extractives and agriculture.

Matt Mace

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