Friday, April 19, 2024

How wastewater can quench world’s thirst


Swelling populations and economic growth are piling pressure on fresh water resources, with demand outpacing supply yet, 80 percent of global waste water goes down the drain.

Whether it’s at commercial or household level, not much thought is given to used water – dishwater, flushed toilet water, bathwater or industrial discharge.

But this shouldn’t be the case. Used water should be recycled as an alternative source amid future shortages.

Currently, 36 percent of the world’s population lives in water-scarce regions. Future forecasts paint a grimmer picture in the era of climate change, with the World Bank projecting that more than half of the world population could be at risk of water stress by 2050.

Repurposing wastewater could, therefore, offer countries an escape window out of the scarcity trap. Used water should not be considered a ‘waste’, but a vital resource. This is at the core of a circular economy – a system aimed at minimising waste, making the most of resources and prolonging economic value of used products through innovative technologies.

Wastewater treatment could offer a double value proposition. In addition to environmental and health benefits, water treatment can generate economic value through reuse in different sectors. Its by-products, such as nutrients and biogas, can be used for agriculture and energy generation, for instance. More importantly, safely managed water, sanitation and hygiene (WASH) services are essential in preventing disease and protecting human health during infectious disease outbreaks.

Rapid urbanisation, especially in low-and middle-income countries, has created a host of water-related challenges, including degraded quality and inadequate infrastructure. As cities continue to grow rapidly, and climate change alters availability and distribution of water resources, it will become increasingly difficult and energy intensive to meet the water demands.

To this end, decision-makers and corporate titans should strive to develop sustainable water policies and innovations. It is precisely why Kenya Climate Innovation Center (KCIC) Group has made water management one of its key strategic areas around which local enterprises are funded and trained.

There should be a paradigm shift from traditional linear approach of water use where freshwater is harvested from surface or groundwater source, treated, used, collected and finally disposed. Such a model is no longer sustainable in light of modern challenges.

To be climate-resilient, future cities would have to switch to models that minimise resource consumption and focus on resource recovery under circular economy.

The traditional approach is based on a linear economy with a “make, use, and dispose” model of production. On the other hand, a circular economy approach replaces the end-of-life concept with restoration, shifts towards use of renewable energy, and eliminates the use of toxic chemicals that impair reuse and return to the biosphere. It also aims to eliminate waste through superior design of materials, products, systems, and business models.

There are several global wastewater management success stories.

By using treated wastewater instead of groundwater, San Luis Potosi power plant in Mexico cut costs by a third, leading to $18 million (Sh2 billion) in savings over six years for the power utility. For the wastewater supplier, the additional revenue from selling treated wastewater helped cover operations and maintenance costs.

The next example is that of a wastewater treatment plant in Cusco, Peru. The facility saves $230,000 a year in transporting bio-solids (nutrient-rich organic materials resulting from the treatment of domestic sewage in a wastewater treatment facility) and landfill fees due to an agreement with the local compost producer. The compost produced with the plant’s biosolids is then used as part of the water management project to preserve the Piuray Lake.

Brazil-based CAESB water and wastewater utility’s use of biosolids for corn production led to higher-than-average grain yields and was 21 percent more efficient than mineral fertilisers.

Finally, La Farfana wastewater treatment plant in Santiago, Chile, after investing $2.7 million to retrofit the plant, it was able to sell biogas, accounting for an annual net profit of $1 million for the business.

In Kenya, Ecocycle, founded by a female entrepreneur, is in the business of recycling sewage into clean water. The water can be used for flushing toilets, washing cars or irrigating farms and lawns, enabling home owners cut on water bills and use of waste exhausters to pump out septic tanks.

In conclusion, wastewater can become a valuable resource from which water, energy, and nutrients can be extracted to help meet the population growing demands for water, energy, and food.

This article was originally published by the Business Daily

Dr. Edward Mungai
Dr. Edward Mungai
The writer, Dr. Edward Mungai, is a global sustainability expert. He is the Lead Consultant and Partner at Impact Africa Consulting Ltd (IACL), a leading sustainability and strategy advisory in Africa. He is also the Chief Editor at Africa Sustainability Matters. He can be contacted via

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