Challenges and solutions of municipal biosolids market creation: A critical review

As a result of a 9 billion global population by 2050 and the associated increased demand for food, future crop productivity will need to expand by 70% to 100% above the current production level. As biosolids are abundant in nitrogen and phosphorus, land application practices have significantly contributed to the recovery of nutrients as renewable fertilizers for agricultural intensification since the 1990s. However, at the time, the consensus on the benefits of biosolids application to land focused on the recovery of one single resource - nitrogen - while the fate of other biosolids components was not clearly identified; as such, some of the potential environmental and health risks associated with biosolids land application were overlooked. The emergence of new contaminants such as per and polyfluoroalkyl substances or microplastics are putting these current practices into question. Biosolids management requires a balance of achieving sustainable production and consumption through transition to a more circular economy - centered around valuable resource recovery - and the need to protect human health and the environment. However, due to a lack of systematically documented practices, there remain knowledge gaps that need to be addressed on approaches when trying to create a new market for biosolids from wastewater. Uncertain regulations on emerging contaminants in biosolids question land application practices but also the efficacy of innovative technologies to destroy these contaminants for safe consumers’ use. Biosolids testing and quality demonstration are insufficient to mitigate risks for intended applications. Branding of biosolids to match emerging contaminants and new treatment technologies risk assessment with environmental benefits of circularity is lacking. Poor market research fails to identify appropriate stakeholders. Uncomprehensive pricing mechanisms hinder the true value of biosolids to the economy by omitting externalities and environmental benefits of circularity. All these in turn contribute to a perceived negative risk to end-users and customers about the potential benefits from biosolids to the economy, communities and the environment, thereby hindering biosolids market creation. This paper provides a critical review of the current practices for recovered biosolids market creation and suggestions for future improvements in creating effective biosolids markets, where biosolids are regarded as products or feedstocks to other processes rather than waste. • A critical review of current biosolids management practices was performed • The emergence of PFAS and microplastics now question such practices • Some knowledge gaps remain on approaches to create markets for biosolids • A systems-thinking staged approach is required to promote new adaptive practices