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Short abstract

This paper examines the role of microplastics in Austria’s 2024 decision to ban the re-use of sewage sludge in agriculture. We conceptualize microplastics as “disturbances” – elements that trouble and open existing practices and infrastructures for managing and redistributing residues to scrutiny.

Long abstract

Sewage sludge occupies an ambiguous position between waste and resource. As by-product of wastewater treatment, it acts as a sink for many residues of contemporary life, including pharmaceuticals, heavy metals, PFAS, or microplastics. At the same time, sludge contains valuable nutrients like nitrogen and phosphorus, and is thus widely re-used as fertilizer in agriculture, thereby reintroducing pollutants previously removed from wastewater into soils.

This paper examines Austria’s 2024 decision to ban the agricultural re-use of sewage sludge, mandating incineration instead. Notably, the ban was largely framed as an intervention to keep microplastics out of soils – a contaminant that, in contrast to many of the other substances present in sludge, does not (yet) show clear evidence of harm. In the Austrian context, microplastics thus acquired political agency, becoming a catalyst accelerating longstanding controversies around sludge re-use.

Drawing on interviews with policymakers, microplastics researchers, wastewater engineers, and composters, we trace how different actors problematize microplastics in sludge and how these perspectives relate to competing visions of environmental good, including efficient wastewater treatment, circular nutrient reuse, and incineration.

We conceptualize microplastics as “disturbances” – elements that trouble existing practices and infrastructures for managing and redistributing residues. By rendering visible the arrangements through which innovation societies contain and distribute environmental externalities, microplastics open space to question technosolutionist responses and reconsider alternative ways of living and dealing with residues.

This research is done together with Ulrike Felt (PI) as part of the ERC project Innovation Residues (GA 101054580).