Safe Fertilizer Products from Biogas Plants (BIOSAFE)

The Risk Assessment Research Unit of the Finnish Food Safety Authority Evira and MTT Agrifood Research Finland measured concentrations of ten hazardous organic compounds or compound groups (PCDD/F, PCB(7), PAH(16), DEHP, PFC, LAS, NP+NPEO, PBDE, HBCD, TBBPA) in biogas plant end products of ten biogas production lines in Finland.

Biogas plant end products can be used as fertilizers in agriculture. This is of prime importance in recycling depleting nutrients, such as phosphorous. The use of biogas plant end products also allows recycling of nitrogen, replacing the use of chemical nitrogen fertilizers which are produced using energy intensive processes.Biogas plants can use different feedstocks such as municipal sewage sludge, municipal biowaste, industrial by-products and animal manure. These end products can contain hazardous organic compounds. Plants can take up some hazardous organic compounds with their roots and some compounds may have the potential to accumulate in food of animal origin.

The soil burden of the compounds after a single addition of biogas plant end products was compared to the atmospheric deposition of these compounds. The median soil burden of PBDEs was 400 to 1000 times higher than the PBDE air deposition in Finland or in Sweden. For the other compounds studied the soil burden was the same order of magnitude as the atmospheric deposition in the Nordic Countries. According to the available literature, the compounds included in the study and derived from the use of biogas plant digestates have only a minor impact on food safety in Finland. However, more research is needed on the impact of PBDE and PFC. Persistent organic compounds such as PBDE and PFC can accumulate in soil if biogas plant end products are frequently used in agriculture.

Concentrations of 25 pharmaceuticals in biogas plant end products were also measured.  Literature on impact of pharmaceuticals in biological fertilizers to the food safety is scarce. Thus it was not possible to assess a risk of pharmaceuticals in biogas plant end product to food safety.

Compounds and compound groups included in the study:

polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs), polychlorinated biphenyls (PCB(7)), polyaromatic hydrocarbons (PAH(16)), bis-(2-ethylhexyl) phthalate (DEHP), perfluorinated alkyl compounds (PFCs), linear alkylbenzene sulfonates (LASs), nonylphenols and nonylphenol ethoxylates (NP + NPEOs), polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCD) and tetrabromobisphenol A (TBBPA)

Research group

Kimmo Suominen (Evira), Sanna Marttinen (MTT), Marja Lehto (MTT), Taina Jalava (MTT), Elina Tampio (MTT)


The project was completed in 2014.

Further information

Kimmo Suominen,

Project publications


Marttinen, S., Suominen, K., Lehto, M., Jalava, T. & Elina Tampio. 2014.  Occurrence of hazardous organic compounds and pharmaceuticals in biogas plant digestate and evaluation of the risk caused for the food production chain (Abstract in English). BIOSAFE-final report. MTT report 135. MTT Agrifood Research Finland, Jokioinen.

Scientific publications 

Suominen, K., Verta, M. & Marttinen, S. 2014. Hazardous organic compounds in biogas plant and products – soil burden and risk to food safety. Science of the Total Environment. 491–492: 192–199.

Suominen, K. & Marttinen. S. 2013.  Organic pollutants in biogas plant digestates –Environmental burden and risk to food safety. Proceedings of the 33th International Symposium on Halogenated Persistent Organic Pollutants. Daegu, Korea. Oral presentation (extended abstract). 

Suominen, K., Lehto, M., Salo, T., Huhtala, S., Perkola, N., Kasurinen, V., Maunuksela, L., & Marttinen, S. 2012.  Occurrence and water partitioning of PFOA and PFOS in biogas plant end products and uptake by radish. Proceedings of the 32nd International Symposium on Halogenated Persistent Organic Pollutants. Cairns, Australia. Poster (extended abstract). 

Other publications

Lehto, M., Suominen, K., Tyrväinen, U. & Tontti, T. 2013. Puhdistamolietteen laadun hallinta. In: Puhdistamolietteen käyttö maataloudessa. Vesilaitosyhdistys.