Dolores Pigretti Öhman
Managing Director
Water and Wastewater Management
Hässleholm, Sweden
Dolores.Ohman@hassleholm.se
Europe’s common agricultural policy aims to reduce nutrient losses and foster an efficient management of natural resources, reducing chemical dependency and creating a market for secondary materials. Sewage water and sewage sludge contains considerable amounts of some of the most important nutrients such as nitrogen, potassium, sulphur and phosphorus. The revised EU Urban Waste Water Treatment directive introduces stricter nitrogen and phosphorus discharge limits for bigger sewage plants addressing in this way the challenge of eutrophication and encouraging at the same time nutrient recovery.
Treatment and recycling of sewage sludge poses a challenge for most of European countries today. There are more than two hundred thousand tons of dry matter sewage sludge produced annually in Sweden. About a third of this sludge is recycled through spreading on arable land. The rest is usually used as covering material without nutrient recovery causing a risk for eutrophication and climate change. There is currently a risk that sludge use on arable land might be banned at the same time as the requirement for phosphorus recycling is introduced. Biochar production from sewage sludge through pyrolysis might be a good alternative. This technique shows positive effects regarding reduction of PFAS, microplastics, and pharmaceutical residues as well as climate benefits including reduced transportation, decreased emissions of methane and nitrous oxide, and possible stabilization of carbon in the soil, thereby providing a carbon sink effect.
Our analysis of the business case for pyrolysis of sewage sludge for wastewater companies identifies a series of current challenges that need to be addressed for the technology to realize its full potential.
Sludge biochar is a cleaner product than sludge when it comes to PFAS, pharmaceuticals, heavy metals, and microplastics. However, the impact of sludge biochar on soil and the availability of nutrients over time needs further investigation. The market is thus demanding evidence, and currently, there is a lack of willingness to pay. Moreover, the regulatory framework is complex and unclear. New regulations are being developed, increasing the uncertainty regarding the marketing of sewage sludge biochar.
The assessment of the economics of the business model is linked to the uncertainties surrounding both the production plants costs and the potential sizes of revenues. Operational cost must go down and waste heat recovery needs to be ensured. The market for carbon sinks connected to sewage sludge biochar is in its initial phase and revenues therefore also uncertain. There are some full-scale facilities in Denmark, and a first full-scale facility is currently being built in Sweden but pyrolysis technology still needs further development both considering process and maintenance costs as well as stability of the product quality.
These challenges could be overcome through the development of supporting structures for research, technological development, product certification and business model innovation.
Particularly important research fields include agronomy and material chemistry to describe the effects of sludge biochar in agricultural soils, as well as sludge biochar use and its role as carbon storage in a life cycle context. Funding is therefore required for test beds and research.
Each new sludge pyrolysis facility can contribute to technological development, but the entity making the investment also assumes financial risks. Support for business development, innovation and investment are needed for reducing the financial risk of water and wastewater organizations.
Sewage sludge biochar, as a potential product for fertilization and carbon storage, competes with many other proven and cost-effective products in the market. Therefore, it is crucial that future sludge biochar sellers can guarantee the value of their products, for example, through certifications.
In conclusion, the transition to sewage sludge biochar represents a significant opportunity for sustainable nutrient recovery and carbon storage. To realize its full potential, we must prioritize the development of robust supporting structures that facilitate research, technological innovation, and effective product certification. By investing in these areas, we can overcome the existing challenges, enhance market acceptance, and ensure that sewage sludge biochar becomes a viable alternative in agricultural practices. Collaboration among stakeholders, including policymakers, researchers, and industry leaders, is essential to create a clear regulatory framework and secure the necessary funding. Together, we can pave the way for a greener future that maximizes the value of our natural resources while addressing pressing environmental concerns.
Treatment and recycling of sewage sludge poses a challenge for most of European countries today. There are more than two hundred thousand tons of dry matter sewage sludge produced annually in Sweden. About a third of this sludge is recycled through spreading on arable land. The rest is usually used as covering material without nutrient recovery causing a risk for eutrophication and climate change. There is currently a risk that sludge use on arable land might be banned at the same time as the requirement for phosphorus recycling is introduced. Biochar production from sewage sludge through pyrolysis might be a good alternative. This technique shows positive effects regarding reduction of PFAS, microplastics, and pharmaceutical residues as well as climate benefits including reduced transportation, decreased emissions of methane and nitrous oxide, and possible stabilization of carbon in the soil, thereby providing a carbon sink effect.
Our analysis of the business case for pyrolysis of sewage sludge for wastewater companies identifies a series of current challenges that need to be addressed for the technology to realize its full potential.
Sludge biochar is a cleaner product than sludge when it comes to PFAS, pharmaceuticals, heavy metals, and microplastics. However, the impact of sludge biochar on soil and the availability of nutrients over time needs further investigation. The market is thus demanding evidence, and currently, there is a lack of willingness to pay. Moreover, the regulatory framework is complex and unclear. New regulations are being developed, increasing the uncertainty regarding the marketing of sewage sludge biochar.
The assessment of the economics of the business model is linked to the uncertainties surrounding both the production plants costs and the potential sizes of revenues. Operational cost must go down and waste heat recovery needs to be ensured. The market for carbon sinks connected to sewage sludge biochar is in its initial phase and revenues therefore also uncertain. There are some full-scale facilities in Denmark, and a first full-scale facility is currently being built in Sweden but pyrolysis technology still needs further development both considering process and maintenance costs as well as stability of the product quality.
These challenges could be overcome through the development of supporting structures for research, technological development, product certification and business model innovation.
Particularly important research fields include agronomy and material chemistry to describe the effects of sludge biochar in agricultural soils, as well as sludge biochar use and its role as carbon storage in a life cycle context. Funding is therefore required for test beds and research.
Each new sludge pyrolysis facility can contribute to technological development, but the entity making the investment also assumes financial risks. Support for business development, innovation and investment are needed for reducing the financial risk of water and wastewater organizations.
Sewage sludge biochar, as a potential product for fertilization and carbon storage, competes with many other proven and cost-effective products in the market. Therefore, it is crucial that future sludge biochar sellers can guarantee the value of their products, for example, through certifications.
In conclusion, the transition to sewage sludge biochar represents a significant opportunity for sustainable nutrient recovery and carbon storage. To realize its full potential, we must prioritize the development of robust supporting structures that facilitate research, technological innovation, and effective product certification. By investing in these areas, we can overcome the existing challenges, enhance market acceptance, and ensure that sewage sludge biochar becomes a viable alternative in agricultural practices. Collaboration among stakeholders, including policymakers, researchers, and industry leaders, is essential to create a clear regulatory framework and secure the necessary funding. Together, we can pave the way for a greener future that maximizes the value of our natural resources while addressing pressing environmental concerns.