Silver in the product stream: From consumer goods to sludge and water ecosystems with focus on stakeholder positions

One of Sweden’s 16 national environmental objectives includes a sub-objective that 60% of phosphorus will be recycled from wastewater to agriculture by 2015. The use of sludge as a medium in which to return phosphorus to agriculture is seen as the best solution. There is however a societal and regulatory demand that the sludge be of a certain quality and silver is one toxin of focus. Until recently, many Swedish wastewater treatment plants have seen a rapid decrease in silver concentrations. Why the decrease has halted is unknown but emerging consumer products is considered to be a potential source. The Swedish Water and Wastewater Association (Svenskt Vatten) oversees the sludge certification system (REVAQ) and is interested in the use of silver and stakeholder positions and activities. This study documents niche markets, current research and regulatory trends and stakeholder positions surrounding this issue. Literature review was conducted, interviews and correspondence with stakeholders were executed and a consumer survey was administered to gather information. Silver-treated (anti-odor) textiles and hygiene products, which have received some attention in Sweden and are of most focus for this study, are shown by research to represent a minor but diffuse portion of total silver pollution. Research regarding degree of risk associated with silver is not conclusive but regulatory action is oncoming with the EU Biocide Directive, for which the Swedish Chemical Agency (KemI) is responsible for silver-related recommendations. Some non-industry stakeholders are concerned about dispersive use of silver, accumulation in soils, and market expansion. Consumers appear to value the anti-odor function to a certain degree and are willing to pay for it, at least when not specifically made aware of potential risks. When aware of potential risks, reception to the function is considerably less favorable. Pro-silver industry stakeholders see silver treatments as the best available technology, as representing a miniscule amount of silver, and as something environmentally beneficial from the life-cycle point of view. Fashion industry stakeholders do not see such treatments as relevant. Other industry stakeholders appear generally cautious and almost all industry stakeholders report looking for improvements and alternatives, of which there are a few. This precaution and search for alternatives, along with cost limitations and past changes in the anti-odor market indicate rapid evolution and a silver-treated product market that is limited in time and scope.