Nutrient recycling and Baltic Sea protection
Nutrients that have leached into the Baltic Sea cause eutrophication, which is significant challenge.
The most important document that addresses this problem is Baltic Sea Regional Nutrient Recycling Strategy stipulated by the decision of the HELCOM 2018 Ministerial Meeting. The Strategy emphasizes that principles of nutrient recycling and efficient utilization should revolve around creating a systematic approach to optimizing nutrient deployment in plant cultivation while simultaneously reducing nutrient loss across all aspects of the food system, spanning from agricultural fields to consumers’ plates.
Key factors encompass:
- Applying fertilizers based on plant requirements and soil nutrient content.
- Cultivating favorable soil structures and other conditions to optimize nutrient absorption.
- Efficiently managing manure to maximize its benefits.
- Employing effective practices to mitigate the impacts of animal grazing and trampling.
- Returning nutrients from by-products of the food industry back to agricultural fields.
- Decreasing food waste at every stage of the food system.
- Properly treating sewage sludge from wastewater treatment plants to safely reintroduce nutrients back into the cycle without posing risks to human health and the environment.
More information: Baltic-Sea-Regional-Nutrient-Recycling-Strategy.pdf (helcom.fi)
Biogas production and water pollution risks
It is important to note that operations of biogas plants may also significantly increase the emissions of nutrients, nitrogen and phosphorus that substantially leak to the water bodies.
According to the risk assessment of biogas production risk assessment made by John Nurminen Foundation in 2018, nutrient emissions are caused, among other things, by spreading nutrient-rich digestate on arable land, which in many countries in the Baltic Sea region is not controlled and restricted in the same way as, for example, the use of manure on arable land. Municipal wastewater treatment plants, which treatment capacity is not always sufficient for treating wastewater from biogas plants, and the storage of digestate also cause emissions.
In order to minimize nutrient emission risks, it is essential to develop the environmental impact assessment of biogas plants and their environmental permit practices so that special attention is paid to the treatment of nutrient-rich digestate and wastewater generated. Permit procedures for plants must ensure that the permit applicant has access to a sufficient arable area for spreading nutrient-rich digestates. When granting environmental permits, it must also be ensured that municipal wastewater treatment plants receiving wastewater from plants have sufficient capacity. Especially when a biogas plant has not originally been designed in connection with a treatment plant but are built afterwards, it is essential to ensure that there is sufficient capacity and, if necessary, to require biogas plants to pre-treat wastewater sufficiently through e.g. efficient nitrogen removal.
In the location of larger biogas plants, it is important to take into account the regional nutrient balance, i.e. the fact that one area does not accumulate too much nutrients in relation to the available area of cultivated land. It may not be sensible to locate large-scale biogas plants that collect digestable biomasses widely from outside the area in areas already with nutrient surplus, such as areas with high livestock production.
Biogas is a welcomed renewable energy source, and biogas production creates new opportunities for nutrient recycling. However, it may pose a significant risk of nutrients entering watercourses if the treatment of digestare and wastewater from plants has not been carefully considered until the end. As biogas plants are being built at an accelerating pace due to climate and energy policy and geopolitical changes, it is extremely important to pay attention to this issue.
More information: Summary of the findings of the risk assessment of biogas production in the Baltic Sea Region from nutrient management perspective