A seemingly eco-friendly way of dealing with wet wipes clogging up sewage systems is in the pipeline, or so claims Edinburgh-based circular economy start-up Carbogenics, which recently received funding for a trial project with Scottish Water.
At the moment, non-degradable materials such as wet wipes, nappies and sanitary items are “screened” – filtered out – as they arrive at wastewater treatment works via the sewer system. They are then taken away for costly and unsustainable landfilling.
In a year-long trial project that began in February, Carbogenics will put these “screenings” through the high-temperature low-oxygen process of pyrolysis, to produce a patent-pending biochar. This will then be added back into the wastewater treatment process to absorb contaminants and stimulate microorganisms to efficiently remove wastewater contaminants.
The hope is that by preventing the screenings from going to landfills and adding biochar to boost biological wastewater cleaning, treatment plants will require less energy to operate, which in turn will help reduce their carbon footprints. Untreated screenings are also a source of methane emissions, a greenhouse gas that is 25 times more potent than carbon dioxide. Moreover, spent biochar can be used to enhance the quality of biosolids, an organic fertiliser that many treatment plants produce, and which is applied to soils where it sequesters carbon for centuries.
The project is being enabled by a £100,000 Smart:Scotland grant from Scottish Enterprise, a funding pot aimed at supporting “highly ambitious” research and development projects by small and medium-sized enterprises. The funding will cover costs including the employment of a full-time experienced project engineer to carry out trials including at Scottish Water’s Waste Water Development Centre in Bo’ness.
Carbogenics says it already uses pyrolysis to turn waste paper into a patent-pending product called CreChar. This additive helps improve the anaerobic digestion of food and farming waste, producing biogas and liquid fertiliser, which in turn helps reduce climate change emissions and remove CO2 from the atmosphere.
Ed Craig, chief executive of Carbogenics, said: “Mirroring the success of the biochar we have developed for the anaerobic digestion process used for food and farm waste, we are excited to be working with Scottish Water on a solution for wastewater screenings. The problem of non-degradable materials that end up in the wastewater system is one that we feel has a more sustainable answer.
“By helping prevent these waste materials going to landfill, we are playing a part in helping Scotland demonstrate real green credentials. If this trial with Scottish Water goes well, the applications for this solution across the wastewater industry not just in the UK but across Europe could be immense.”
Tamsyn Kennedy, Circular Economy Lead at Scottish Water, said she believed “that research into biochar can broaden the opportunities for low carbon and circular wastewater treatment and support a flourishing Scotland.”
Carbogenics is a spin-out from the University of Edinburgh. Last year it recruited experienced sustainability leader Ed Craig as chief executive. The business, which was founded in 2016, plans to consolidate its production process in Scotland, demonstrating the advantage of a regional supply chain that currently involves materials being sent between various sites in the UK and Europe.