Innovative urine separation technique revolutionises wastewater treatment.
Urine separation is emerging as a key solution for optimising wastewater treatment, helping to recover essential resources such as drinking water and vital nutrients for the environment, according to New Scientist.
In recent years, wastewater treatment has undergone a paradigm shift, transforming what was traditionally seen as a simple waste disposal process into a valuable resource recovery opportunity. In this context, urine separation, a lagging innovation, has re-emerged as a key solution for creating more circular and sustainable treatment systems.
As New Scientist points out, from drinking water to essential nutrients and biodegradable materials, every part of wastewater can be reused, contributing to a greener and more efficient economy.
Urine separation: a forgotten concept makes a strong comeback
Years ago, a New Scientist article talked about an innovative technology: ‘urine separation toilets’. This concept is based on the idea of collecting urine separately in toilets, rather than mixing it with the traditional flush water.
This saves large amounts of drinking water and energy for subsequent treatment. Although the approach, known as ‘pee-cycling’, failed to take off at the time, a recent article in Nature Sustainability confirms that urine separation is still a viable technique and continues to gain interest as a key solution in wastewater management.
The traditional wastewater treatment model and its limitations
For years, wastewater treatment has focused mainly on removing pollutants to ensure water quality and protect the environment. However, this traditional model is extremely inefficient in terms of resource efficiency.
Treatment transforms wastewater into potable water, but organic compounds and nutrients such as nitrogen and phosphorus are simply released into the environment or stored as sludge, rather than being used as reusable resources.
A paradigm shift towards circularity
The key to the future of wastewater treatment lies in a radical change of approach: instead of seeing wastewater as waste, it is seen as a source of valuable products. This new model aims to recycle the treatment system so that every component, from water to nutrients and materials, is reused.
Sewage treatment plants are being transformed from simple waste disposal facilities into chemical factories that recover valuable resources and reduce environmental impact.
The three main pillars of this wastewater recycling process are water, energy and nutrients:
- Water: Traditional wastewater treatment is already quite efficient at converting dirty water into potable water. However, in many parts of the world, improving this technology can provide an additional source of clean water, which is crucial in areas where water is scarce.
- Energy: 11% of wastewater treatment plants in Europe use microbial digestion to convert organic matter into biogas, a mixture of methane and carbon dioxide. This biogas can be used to generate electricity and heat, providing a significant proportion of the treatment plant’s own energy needs.
- Nutrients: Nitrogen and phosphorus are two of the most difficult nutrients to recover, but their recovery is becoming increasingly feasible. In many cases, it is estimated that 25-30% of the phosphorus used in fertilisers ends up in wastewater. Recovering these nutrients could significantly reduce the need for phosphate rock, a limited resource that could be depleted in the coming decades.
Valuable resources beyond water and nutrients
While water, energy and nutrients are the most accessible elements for recovery, wastewater also contains valuable materials that have previously been discarded unused.
- Cellulose: About 35% of the solids in wastewater come from toilet paper, mainly cellulose. Instead of landfilling or incinerating it, some wastewater treatment plants have started to recover this cellulose, clean it and sell it to the construction industry. This market, currently worth more than $17 billion, is expected to double in the next few years.
- Biodegradable plastics: Wastewater treatment also produces biodegradable plastic materials such as polyhydroxyalkanoates (PHAs) and extracellular polymeric substances (EPS), which can replace non-biodegradable plastics in products such as fertilisers and seed coatings. These materials not only have a high market value, but also help to reduce the use of traditional plastics, providing a more sustainable alternative.
The case for urine separation: an essential proposition
Despite the complexity of extracting nutrients from wastewater, urine separation is emerging as a key strategy in the process. Urine accounts for 80% of the nitrogen and 40% of the phosphorus in wastewater, but because urine mixes with large amounts of water in the sewer system, these nutrients are difficult to recover.
Urine separation would not only concentrate these nutrients for recovery, but also prevent them from being diluted in the treatment system, making their removal much more efficient.
Towards a more sustainable future
Wastewater treatment is rapidly evolving from simple waste management to a key strategy for recovering essential resources. From nutrient recovery to the production of biodegradable materials, wastewater has the potential to become a source of valuable products.
Urine separation is just one of the innovations that is transforming the sector and reducing the environmental impact of wastewater treatment. By adopting these more circular approaches, we can not only improve the sustainability of wastewater treatment, but also contribute to a more efficient and environmentally friendly future.
