World Water Day: A Proposal by ZWAI’s Chairman

Today, March 22nd, marks World Water Day. Read our blog below by Ollan Herr, ZWAI’s chairman, who wanted to share with our readers an important proposal to mark this day.

Image courtesy of DCIM\311GOPRO

Our ground water and surface waters are being exposed to the wasteful flush and forget culture of the modern man and woman.  

Reports show that there are worrying and often growing levels of pharmaceutical pollution being measured in our surface waters. Discharges from farms, municipal sewage treatment plants and septic tanks are the source of these chemicals. Antibiotics and hormone medicines that are consumed and excreted by humans and farm animals are causing un-natural damage to the health of wildlife in rivers.

We are also struggling to adequately prevent nitrogen and phosphorus pollution in our rivers. Indeed, some scientists are claiming that the levels of phosphorus and nitrogen pollution in many surface waters have already exceeded the sustainable planetary boundaries. Some estuaries and water bodies around the world have already become dead zones. The algal blooms are so dense in these areas that no other life forms can survive in the water.

At the same time there is increasing uncertainty about the affordability and the future global supply of phosphorus.  

We need a complete change in dealing with wastewater. End of pipe treatment systems might not succeed in achieving the clean rivers that we want, so I therefore advocate for the adoption of the following first steps towards a paradigm shift:

Urine collection and treatment from urinals in new housing schemes around the world, to recycle phosphorus to agriculture. 

Proposal Overview

In countries around Europe and in Ireland, as hundreds of new houses are constructed within close proximity to municipal wastewater sewage treatment plants, it is proposed that all these residences be equipped with modern hygienic urine-separating toilets. These toilets consume minimal flush water and require no alterations to the typical restroom practices of people.

The urine will need to be kept separate from the rest of the wastewater and be collected in buried tanks at the front of the house or building. This urine, similarly to septic tanks, will need to be collected & taken away by the national water management agency. At the municipal sewage treatment plant, this collected urine will be separately treated to produce a pure, pharmaceutical-free, and toxic-metal-free form of phosphorus rich fertiliser, which can then be recycled and applied to food crops.

A mini gravity-based rainwater harvesting system with mains water back up needs to be provided for rinsing the urinals. This water supply will have a 20-micron filter that can be occasionally washed in the kitchen sink every so often. 

Funding for New Pilot Demonstration Schemes

There would be no on-going running costs to the developer or the homeowner. The running costs will be carried out by Government funding agencies or the state itself.  

A Pilot Demonstration Project

The purpose is to collect and process bio waste (urine) to produce economically valuable recyclable fertiliser. Historically, human urine has been deemed as undesired waste to be disposed of through flushing. However, scientists now say that the nutrients present in urine, such as phosphorus and nitrogen, are valuable resources. They advocate for the separate treatment of these nutrients, followed by recycling them into agriculture, ensuring the absence of any residual toxic metals or pharmaceuticals.

The list of co-operating stakeholders, and the function they each play in this project, are included below:

  • A SME (small or medium enterprise) to provide the separating toilets and technology and technical support. 
  • A Housing developer, building 200/ 400 houses – installing the toilets, tanks, and rainwater systems.
  • A University or Institute of Technology – to do further research for the removal rates of phosphorus and pharmaceuticals from human separated urine and further to confirm the extremely low levels of toxic metals remaining in the recovered struvite/ phosphorus fertiliser. To research the possible production of ammonium sulphate from the volatile emissions that come from urine.  
  • The National Water Management Agency, (NWMA).  In Ireland this might be Uisce Éireann (UÉ) – is to monitor the urine tanks, to collect the urine and to treat it to recover the phosphorus (struvite). The agency will also remove the pharmaceuticals and then to treat the remaining urine with the rest of the wastewater. Eventually NWMA or UÉ may process the volatile ammonia from the urine to produce ammonium sulphate or ammonium nitrate fertiliser.    
  • The Local Government, Planning Department – may have to approve the use of urine separating toilets as well as encourage the use of rainwater for toilet flushing. The Department is to assess this project and regulate for the further roll out of this system as the sulphuric acid and phosphorus supply and price crisis becomes more apparent.     
  • The Dept of Agriculture to oversee, to assess, and help market the safety of the recovered fertiliser for re use in the food chain. Assuming that laboratory testing confirms the purity of the struvite, the Dept of Agriculture are to propose the urine derived struvite for approval with a CE mark. This is a European Union approval mark.    
  • The Fertiliser Companies – will need to be assured so they are confident to buy and sell the recycled fertiliser to farmers.  

Food Security: A Crisis in 30 years’ time

An alarming report has been recently published: “Sulfur: A Potential Resource Crisis That Could Stifle Green Technology and Threaten Food Security as the World Decarbonises” by Mark Maslin, Livia Van Heerde, Simon Day. How seriously will we consider its implications?

The authors make the argument that in reducing greenhouse gases to net zero over the coming 30 years, that the burning of fossil fuels in large power stations will need to significantly end. This may present a very difficult dilemma for mankind. Do we fudge in bringing greenhouse gas emissions to net zero, or do we accept that there will be increasingly restricted supplies of sulphuric acid and phosphorus rock-based fertilisers? On top of all this, we are being told that phosphorus recovery as struvite cannot be implemented in any small town and village wastewater treatment systems.

If mankind closes most of the fossil fuel burning power stations in 30 years, it is claimed that there will be a huge reduction in the current supply of the low-cost sulphuric acid, which is produced when scrubbing sulphur dioxide from flue gases, to avoid acid rain. This source of sulphuric acid has become a very dominant and significant chemical for a whole range of important mining metals needed for green technologies and the renewable energy economy.

The UN General Secretary Antónia Guterres makes it clear that the extraction and the burning of fossil fuels must end, and it is a well known fact that coal and natural gas must remain in the ground. UN chief rips into ‘planet wrecking’ fossil fuel companies | SBS News – YouTube 

The Consequences of a Sulphuric Acid Shortage for fertilisers

Any shortage or increasing price for sulphuric acid will in turn impact on the global availability and the price for phosphorus fertilisers. They claim that the scale of the shortage of sulphuric acid that might occur has the potential to threaten global food security.

The authors recommend therefore that we recycle the phosphorus present in wastewater, because this does not require the need of sulphuric acid. Over the coming decades urine is likely to become the lowest cost, the most sustainable and concentrated source of metal-free phosphorus in rich and poor countries. Recycling phosphorus from urine would help to secure future phosphorus supplies, maintain low-cost affordable food, and reduce the contribution of phosphorus that is causing surface water pollution. 

In addition, the reduction in the burning of coal in China or natural gas in the West will also impact the production of nitrogen fertilisers. Farmers have already experienced a rise in the cost for nitrogen fertilisers with the cut off of natural gas coming from Russia.

The proposal is to take the following radical small initial steps to resolve our problems as follows:

  1. That large numbers of new houses/ buildings be built in a local authority area as a pilot demonstration system, to be reasonably close to an existing sewage treatment system operated by the National Water Management Authority (NWMA).  
  2. That all these new houses will have urine separating toilets, rainwater collection systems for toilet flushing. From the toilet/s there will be large 110 mm diameter urine collection pipes over a short distance, 5 m to urine storage tank. That plastic storage tanks will be located adjacent to the street/road. To prevent any metal contamination of the urine, that all of the rainwater system and all of the urine system must only have plastic piping systems and fittings.
  3. That the piping and urine storage system at each house is to be designed primarily to avoid and minimise the need for maintenance or attention by the homeowner. A straight single 5 m pipe of 110 mm diameter must be easily cleaned using rods from the urine tank. Ideally the sucking out of the urine or the rodding of the 5 m of 110 mm pipe should be carried out without NWMA staff needing to enter the front garden. Measures to be taken, possibly using charcoal filters, so that ammonia emissions from urine must be minimised. 
  4. That every urine storage tank is to be equipped with a smart level meter and an overflow pipe into the public sewer collection network or percolation system.
  5. To ensure minimal contamination of the struvite from metals, that NWMA will collect the urine in plastic tanks with no metals in pumps.
  6. That the transport distance from the new houses to the place for treatment is to be minimised as much as possible to reduce the greenhouse gas emissions.
  7. That NWMA or Úisce Éireann will operate a separate treatment system on their existing municipal wastewater treatment sites to make struvite. The remaining urine, without about 90% of the phosphorus, that still contains all other pollutants can be added with the rest of the wastewater to be treated in the conventional trickling filters or in some form of activated sludge treatment system.
  8. After continuous testing for toxic metal content and for residual pharmaceuticals, the separated struvite shall be dried as a white powder and be stored in large quantities or be processed as pellets for easier sale to farmers as a safe-to-use nontoxic fertiliser. 
  9. Once this pilot phosphorus demonstration has been proven and is successful, it can be further developed to remove the pharmaceuticals by passing the urine through biochar. The researchers are claiming that biochar is a low-cost form of charcoal that seems to be very effective in removing a wide range of pharmaceuticals from urine and wastewater.
  10. Furthermore, the scheme could be increased by adding more urine separating housing developments in other town sewage treatment systems.


I hope that you give serious consideration to this proposal. I am inspired by the people in Nepal that have been recycling phosphorus from urine in their own local community, or small town. Have a look at the video below to see it for yourself:

Blog by Ollan Herr

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