Open access publications in the SLU publication database

In order to move towards a more sustainable agriculture, plant nutrients from food crops and other
crops need to be recycled back to agriculture. This is stressed by the Swedish Environmental Quality
Goal for good built environment, which contains the target that "by 2015, at least 60 percent of the
phosphorus compounds in wastewater should be recycled to productive land, of which at least half
should be recycled to arable land." One quarter of the on-site wastewater systems in Stockholm
County has a collection tank for blackwater. Blackwater needs to be adequately hygienized for farmers
to accept it as a fertilizer. Hygienization can be achieved through liquid composting, ammonia
hygienization or long term storage. Agriculture has a key role as recipient and user of wastewater
derived fertilizing products and needs to be involved at an early stage of the process.
The municipality has a central role in the planning and establishment of recycling systems for waste
and wastewater fractions. The fact that these systems are areas where new knowledge and new
structures evolve make it important to compile and spread knowledge and experiences. This report
describes recycling initiatives for urine and blackwater in the Stockholm region. Some conclusions
are:
• The literature review indicates that there is a good potential to use source-separated waste fractions
as fertilizers. They have low levels of contamination, contain large amounts of nutrients and the
Environmental Protection Agency (2006) states that local authorities should have systems for the
recycling of source-separated waste fractions as fertilizers. The reported case studies show large
activity in the Stockholm region, in projects where municipalities, LRF - the Federation of Swedish
Farmers, Stockholm County Council through its Environmental Grant, the County Administrative
Board and the residents have been involved.
• Several of the systems presented in the report raise institutional questions. Systems for recycling of
sewage fractions do not organize themselves, on the contrary, they mean that more actors need to
interact in a way that they do not have any experience of and which the existing framework, in the
form of municipal structure, policy documents and legislation etc. are not developed for. Efforts to
develop and adapt frameworks are in progress, for example, it has now been made clear that urine and
blackwater are waste fractions, which means that the municipal waste organization has the overall
responsibility and they have also begun to address this responsibility.
• The projects presented in the report illustrates that one of the key questions to get source-separated
waste fractions into the nutrient cycle is how to design the municipal water and waste fee systems so
that they steer towards practices that are environmentally and economically best.
• Finally - motivated and responsible stakeholders are needed throughout the process. There are
motivated organizations in the region which pushes the evolution of recycling systems, slowly but
surely. Municipalities step in and initiate activities and LRF - the Federation of Swedish Farmers,
meets up with expertise and solutions, and last but not least Stockholm County Council Environmental
Grant and the County Board have the foresight to finance development projects. Together these
stakeholders mean a clear potential for success.