Accessible fresh water plays a critical role in the emerging circular economy, which – simply put – is the opposite of the “take, make, dispose” economy we know today. Instead the circular economy
- Treats or repairs consumed and polluted waste streams to a “fit for purpose” level,
- Extracts nutrients and other valuable resources from waste streams, to create new regenerative products.
The United Nations (UN) recently published a report with the title, “Wastewater The Untapped Resource”, which highlights the importance of wastewater as part of a circular economy. The report explains, that sustainable wastewater management requires technologies, that:
- prevent or reduce pollution at the source;
- enable fit-for-purpose treatment of wastewater to optimize resource utilization;
- and can recover valuable by-products.
The question one must now ask is, whether these enabling technologies already exist, and if so, why they are not yet deployed on a large scale?
The first question can be answered with a simple yes; enabling technologies do exist.
For instance energy efficient membranes can filter wastewater, removing contaminants from the water so it can be re-used. Since residential wastewater carries a different contaminant load than industrial wastewater, treatment systems at the source of the pollution may need to be installed to avoid overwhelming municipal water plants. In some cases a decentralized fit-for-purpose treatment option may be the best option to treat industrial wastewater to the extent necessary to enable reuse. Even residential wastewater, which contains wastewater from toilets and the less contaminated ‘greywater’ (wastewater from sinks, and appliances), can be reclaimed, using cost-effective technologies such as fine screening in combination with other treatment technologies.
Extracting energy from wastewater, is now also commercially viable; anaerobic digesters produce energy from sludge and other organic wastes found in wastewater from farms, and the food and beverage industry. Employing membrane technology in combination with anaerobic digesters can close the loop even further, by dewatering and treating the remaining sludge, reducing solid waste, and increasing the amount of reclaimed water.
Nutrients, and other valuable byproducts can also be recovered from wastewater by using innovative technologies. For instance, recoverable pollutants such as phosphorus and ammonium can be used to produce fertilizer, rather than simply be discarded. The same applies to recoverable cellulose, which can be used as a source for biofuels, bio-plastics and other regenerative materials such as fatty acids.
Now to the second question: what prevents us from employing these cost effective innovative technologies, which promise to enable the transformation to a circular economy? Or specific to our example of wastewater – why aren’t we using wastewater as a resource?
The answer is not simple.
We as a society have to start putting a price tag on natural resources such as water, that reflects their true value, or in the case of clean water, its scarcity. This in turn would accelerate the implementation of resource-conserving, and reuse-enabling technologies. Further we have to overcome the “yuck factor” to make reclaimed water more accepted and to be able to close the loop and ultimately achieve a circular economy.
Technology providers on the other hand need to cooperate on finding solutions for complex problems. There is no such thing as a single technology solution. Just as there are many contaminants found in wastewater, there are as many different treatment options to remove them.
The good news is innovative technologies exist, which enable the transformation into a circular economy. However, we have to remove the uncertainty factor from the equation and start implementing these enabling technologies now.