Comparing microbial risks from multiple sustainable waste streams applied for agricultural use: Biosolids, manure, and diverted urine

Despite the global push for a circular water and nutrient economy, the United States still lags in recycling and reusing valuable waste streams. The reuse of waste streams could result in more sustainable agricultural practices by reducing water withdrawals in stressed environments and nutrient inputs to eutrophication-impacted ecosystems. However, microbial risks are a key barrier to reuse. We identify research and regulatory gaps through a systematic review of quantitative microbial risk assessments (QMRAs) and regulations for biosolids, manure, and human source-separated urine. We propose a cohesive path forward to improve upon existing QMRA approaches, to combine QMRA with other risk frameworks, and to develop integrated monitoring and control strategies by incorporating molecular biology tools. The application of a farm-to-fork risk-based approach that considers the combined use of waste streams is needed to develop comprehensive best management practices, treatment recommendations, and microbial quality criteria that promote food safety while advancing agricultural sustainability.