Objectives of the service
Although wastewater treatment technologies have evolved over the past century, important limitations remain, which are mainly due to mixing human excreta with drinking water with hardly any recycling. Climate change induced water scarcity, population growth, emerging pollutants such as pharmaceuticals and the need for resource recovery are challenges, which call for alternative sanitation systems.
The volume of wastewater is mainly water and accounts for a very small amount of urine (1%). The urine however contains up to 80% of the compounds that need to be treated in wastewater treatment plants, such as nitrogen, phosphorus or the pharmaceuticals.
The system works by collecting urine from urinals and separation toilets, treating it through a series of biological and physical steps to remove pollutants and bad smells, and concentrating the nutrients into Aurin. The only inputs required are air and electricity, and the only outputs are Aurin and distilled water.
The VunaNexus technology is proving that recycling the nutrients at the source and concentrating them into fertilisers make economical sense for the building owner and on the fertiliser market.
The global energy needed to recycle nitrogen with the vuna technology is comparable to the energy needed in the Haber Bosch process per ton of Nitrogen produced.
Users and their needs
The treatment system's customers are real estate developers, owners, and constructors who are interested in sustainability, circular economy, and alternative revenue streams. Similar to what can be done with solar panels on the roof of a building, a revenue is generated by reselling the minerals treated in the building. The building owners also benefit from considerable CO2 reductions per m² built thanks to the impact of reducing N2O emissions.
Regarding the fertiliser, customersinclude both professional and private users who buy Aurin directly from VunaNexus. VunaNexus will have a treatment capacity of around 3000 m³ of urine per year across the multiple pilot plants. Some of the fertiliser customers include the City of Zurich, the city of Lausanne, and over 500 private individuals who are interested in natural alternatives to synthetic fertilisers. Large industrial groups are interested in alternative sources of Nitrogen since the start of the war in Ukraine and surge in fertilizer prices.
Service/ system concept
VunaNexus manages the treatment, maintenance and logistics of the fertiliser. By reselling the latter, VunaNexus can also provide an alternative revenue stream for building owners and operators while relieving saturated sewage systems.
The Vuna treatment train consist of the following steps:
Urine collection: urine is separated at the source by means of dry urinals or urine-diverting toilets. The urine pipes lead to a central airtight storage tank in which a level sensor is installed as well as a pump leading to the bioreactor (nitrification, stabilisation).
Stabilisation: in order to recover all nutrients, avoid bad odours from ammonia, as well as air pollution, urine is stabilised biologically with nitrification. During this process, with aeration as the only input, bacteria convert ammonia to nitrate. This process is completely automated with the help of our patented nitrite sensor.
Filtration: the treated urine goes then through an activated carbon filter, where micropollutants are removed.
Concentration and pasteurisation: in order to remove the water content of the product and concentrate the minerals, the stabilised and filtered liquid is distilled with a vacuum distiller. This step ensures a product of stable quality as well as a pasteurisation of the product. The two outputs of urine treatment are distilled water that can be re-used and the liquid fertiliser, Aurin.
Aurin is the first and only urine-based fertiliser certified for all types of plants by various european countries. Aurin has been extensively tested on fields over the last 5 years and is now used by major European cities. The technology saves water and avoids greenhouse gas emissions.
Space Added Value
The Vuna process, developed as part of the MELiSSA project for circular life support systems in space, aims to recover nutrients and recycle water during space missions. The process is being developed through the EXPERT programme and is a Swiss contribution to the ESA Manned Space research programme.
The technology is currently being investigated by three MELiSSA POMP PhD students, two of whom are studying parts of the treatment system at Eawag, while the other is testing the application of Aurin for food production on long space missions at ETH Zurich. The goal is to commercialise the technology for terrestrial purposes and prove its effectiveness on a large scale before considering its use in space.
Following the contract signature with ESA in March 2023, the team has consolidated the user needs and requirements. The designs of the service concept and the associated technologies have also well progressed. These steps allowed to start the preliminary installation of the various associated pilot sites as described below.
Currently VunaNexus has two pilot scale reactors in Zurich, with one that has been operating for many years.
A fourth pilot is going to be installed in Fribourg (Switzerland) as part of the Blue Factory project, in January 2024. The treatment will start soon after that.
A fifth pilot is installed in the district of Barnim, north east of Berlin, as part of the ZirkiulierBAR project. This treatment plant has the specificity of being containerised.
As part of another research project, with the help of Schauer Agrotronics, VunaNexus has installed a nitrification reactor on a swine farm, treating 3000 litres of swine urine per day, a second farming installation will be completed in January 2024.
VunaNexus is also working on the industrialization of a patented Nitrite sensor. This work is done in collaboration with CSEM in Switzerland.
The Baseline Design Review took place at ESA HQ (Paris, France) on 21 November 2023 and was successful. Next step is the Critical Design Review to be held in January 2024.