They’re both fairly unappealing and just a bit whiffy: thick, toxic algal blooms that increasingly clog Scotland’s lochs and rivers and smelly mountains of sewage sludge.
But now researchers are looking into turning human waste from the sewage system into a mineral-rich material that could be used to both attack the scourge of algal blooms and help tackle another environmental headache.
Scottish teams are exploring how biochar created from human waste that’s been burned at high temperature can be used as a water filter capable of removing large amounts of phosphorus which, when present in excess quantities, contributes to algal blooms.
As well as cleaning up the water, the phosphorous the filter collects could then be reused in the manufacture of anything from cleaning products and matches, to fertiliser.
The innovative use of human waste would also provide a potential solution to another problem: currently around 130,000 tonnes of sewage waste in Scotland is disposed of either by being recycled to the land or incinerated.
Apart from racking up a £6 million a year bill for its disposal, expected changes to regulations mean that alternative treatment and processing methods must be explored.
The biochar from human waste project is being funded by the Industrial Biotechnology Innovation Centre (IBioIC) and Scottish Water, which is supplying the raw material used to create the charcoal like substance to its commercial subsidiary, Scottish Water Horizons.
It is testing the biochar at its waste water development centre in Bo’ness. As part of the project, experts at the Environmental Research Institute at UHI, North, West and Hebrides are also providing insight into biochar in filtration systems, supported by water treatment specialist AL-2 Teknik.
Biochar derived from sewage sludge is safe and sanitary, with any residual toxins, pharmaceuticals or pesticides destroyed during the process which uses temperatures of up to 500°C.
Researchers involved in the project carried out tests using a variety of filtration systems to determine which perform best. They found biochar-based filter was able to remove large amounts of phosphorus from waste water.
If used at scale as part of larger filtration systems, it could could play an important role in treating water at the point of discharge to prevent algal blooms from forming.
Algal blooms can appear as green, yellow-brown or red in colour and create a variety of problems including depleting the water of oxygen which in turn affects aquatic life and releasing toxins.
Often smelly and unsightly, it also poses a risk to other wildlife, humans and pets.
The problem is more likely to appear when water is warm and slow-moving, and thrives when nutrients such as phosphorous and nitrogen are present, sometimes as a result of runoff from fertiliser.
Climate change with warmer temperatures and changes in rainfall patterns are exacerbating the problem.
Research from the UK Centre for Ecology & Hydrology (UKCEH) in 2022 showed that 97% of monitored Scottish lochs and reservoirs increased in temperature between 2015 and 2019. While most warmed by 0.25°C to 1.0°C per year over the period, 9% increased by more than that, with some rising by up to 1.3°C per year.
It has warned that a projected increase in air temperature of 2.5°C in Scotland between 2020 and 2080 would result in a 3°C rise in lochs and reservoirs over that period.
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That with changes in rainfall patterns increases the risk of algal blooms, potentially restricting the uses of lochs and reservoirs for recreation and water supply as well as impacting wildlife.
Meanwhile, with natural reserves of phosphorus depleting at an alarming rate, the sewage-derived biochar filter process could also open up new avenues for collecting the mineral.
Phosphorus is a crucial element for life - rock phosphorus is spread on farmers’ fields in huge quantities, helping to underpin the world’s food supplies.
But it is a finite resource and the largest amounts are often mined in politically unstable places, raising concerns over future supplies and whether countries holding large natural reserves could eventually control food production elsewhere.
Finding ways to recycle phosphate from animal and human waste, and exploring ways to retrieve it from other sources is a key challenge as new supplies become more precarious.
Dr Szabolcs Pap, lead academic on the project, said: “While phosphorus causes challenges for the environment and sectors such as aquaculture because of its impact on algal blooms, it is also an element that we all use in everyday products.
“Natural stores are depleting, so this circular bioprocess could lead to new opportunities to recover the nutrient from wastewater and create new supply chains here in Scotland.
“At the same time, water companies are under increasing pressure to reduce waste and find alternatives for bioresources from sewage, so there is an additional benefit in terms of sustainability.
“Biochar can be a valuable material with a range of potential applications, but the global market is still in its infancy.
“The approach to recovering phosphorus we are exploring in this project is just one example of what it can be used for.”
The next stage of the research will include on-site tests at some of Scottish Water’s smaller treatment works, alongside ongoing conversations with regulators and development agencies about the emerging market for commercialising biochar in Scotland.
AL-2 Teknik and its partner PyroDry have already supplied a number of systems in Europe and one in the US, creating biochar from different bioresources. As a result of this project, it’s hoped the company could open its first facility in Scotland in the future.
The project has been supported by the IBioIC, which was established in 2014 to stimulate growth of industrial biotechnology in Scotland. It has a target of £1.2 billion in associated turnover and 4,000 direct employees for the sector by 2025.
So far, it has provided support for more than 200 companies across a range of collaborative innovation projects that has involved academic-business partnerships and co-funded by business.
A total investment to date of £6.8 million is said to have leveraged an additional £35m from businesses, follow-on funding from other sources or partnering with other funding initiatives.
It says that as a direct outcome from the collaborative projects funded alone, 327 high-value green jobs have been protected or created by the businesses involved, leading to a further 3,000 jobs.
Dr Liz Fletcher, director of business engagement at the IBioIC, said: “This collaboration demonstrates how one type of waste can be used for the benefit of the natural environment, treating issues like algal blooms which are posing significant challenges as climate change continues and water temperatures rise.
“Although the creation of biochar is still in its infancy, we see huge potential for a growing market that could help several industries to reduce waste and adopt more circular processes.”
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