Biogas is a renewable resource of energy. Biogas production and use implies reduced CO2-emissions, re-use of organic resources and a reduction of the amounts of waste materials. The waste of the biogas production, known as digestate, may contain contaminants, which may threaten soil quality when the digestate is used as fertilizer. RIVM contributes to a comprehensive evaluation of the environmental benefits and risks of biogas production.
Amongst others, RIVM contributed to the description of a new protocol (Protocol evaluation of materials to be used as fertilizer) for the evaluation of base materials for biogas production. This protocol is currently operational, implying a more realistic evaluation of potential threats of contaminants than before.
Old and new situation
In the former situation, each base material was evaluated according to strict criteria, limiting use as base material for biogas production. When e.g. non-edible remains of maize production were evaluated, some pesticide remnants in the base material would limit re-use. In the current situation, the focus changed from base material to the final situation, considering whether the digestate and eventually the soil remains safe. When the end product and final environmental quality is safe, the base material can be used.
Due to this, more base materials can be used for biogas production, so that the net results are less waste materials, more biogas, and no change in contaminant risks for man and environment. This fits in with the European and Dutch policies to realize a circular economy.
At the same time, there is still substantial latitude to evaluate further options to reach a circular economy, without necessarily compromising environmental health and safety. In order to optimize further, Europe works at harmonization of terminology and a level playing field for identifying and using fertilizers and base materials for biogas production.
Research of RIVM not only focusses on hazardous chemicals, but also on external safety and pathogenic micro-organisms .
Collaboration
RIVM contributes to a concerted effort of various Dutch institutes with recognized expertise in the fields of fertilizers, agriculture, waste and integrated risk assessment. RIVM collaborates with Scientific Committee of the Manure Act (CDM), Alterra and the Nutrient Management Institute. The collaborative reports describe, amongst others, how further developments in the judgment of the quality of waste materials, fertilizers and digestates can eventually result in optimal re-use and biogas production, without compromising the environmental quality.
Reports:
"Appraising fertilisers: Origins of current regulations and standards for contaminants in fertilisers", describes the national and international underpinning of the appraisal of organic materials as resource for use as fertilizer in agriculture. Due to possible contaminants in the organic resources, those resources must be judged as "fit for purpose", that is: long-term safety for man and the environment, when used as fertilizer, e.g. the use of the waste material that remains after production of green gas. In this context, RIVM addresses both benefits (green gas) as well as risks (e.g., via contaminant transport to soil), in the context of sustainable development.
"Protocol beoordeling stoffen Meststoffenwet ", describes a standardized, regulatory accepted methodology to judge the environmental safety of organic materials, determining whether a material can be used as fertilizer. Due to possible contaminants in the organic resources, those resources must be judged as "fit for purpose", that is: long-term safety for man and the environment, when used as fertilizer, e.g. the use of the waste material that remains after production of green gas. In this context, RIVM addresses both benefits (green gas) as well as risks (e.g., via contaminant transport to soil), in the context of sustainable development.
"Risicobeoordeling van contaminanten in afval- en reststoffen bestemd voor gebruik als covergistingsmateriaal" (In Dutch), describes an evaluation of the environmental safety of using various organic resources (often waste products from agricultural products, production and processes) as fertilizer in agriculture. Due to possible contaminants in the organic resources, those resources must be judged as "fit for purpose", that is: long-term safety for man and the environment, when used as fertilizer, e.g. the use of the waste material that remains after production of green gas. In this context, RIVM addresses both benefits (green gas) as well as risks (e.g., via contaminant transport to soil), in the context of sustainable development.