In the clip, Folke K Larsson, chief secretary of the investigation, explains that it will be a major change for the sewage treatment plants that produce the sludge, and the contractors who help spread and store it.

- In Germany, for example, which has come a long way in this, a conversion period of ten, fifteen years is expected, he says.

100 kilos per person per year

Sewage sludge is a residual product from wastewater treatment plants that needs to be taken care of. According to Folke K Larsson, we Swedes produce about 100 kg of sludge per person per year.

In addition to phosphorus, the sewage sludge contains additional plant nutrients and carbon, where there is much talk about utilizing valuable resources for the natural cycle. Today, about one third of the sludge is used for agricultural manure, another is deposited on landfills or used in, for example, soil preparation.

But at the same time, the sludge can also contain many harmful toxins such as chemicals, drug residues and heavy metals.

To quality assure and sanitize the sewage sludge, it must often be stored, even before use. One such, two football pitches large "storage plate" is currently causing concern among residents in Tränsta between Hallstahammar and Köping.

Can be tightened

Today, the treatment plants work a lot with what comes into the systems in order for the sludge produced to be of good quality. For example, toxic waste - as from industries - can be shut out.

Contractors in the industry also use special certification to ensure the quality of the sludge. The poison content in the sludge is thus often well below the permissible limit values.

But the regulations governing the handling of sewage sludge are both old and outdated. Within a couple of months, the state investigation will present its proposal on how this should be handled in the future and how it should also be possible to recover phosphorus from the sludge.

- The investigation is likely to find that the regulations need to be tightened properly and that the social actors, which central authorities need to have a much more active and supportive approach to this, says Folke K Larsson.