Fluorescence spectroscopy can monitor changes in wastewater quality in real-time. By installing portable fluorimeters at a treatment plant, researchers found that organic matter levels in wastewater vary throughout the day and are influenced by flow rate and rainfall. High fluorescence and ammonia levels are linked to sewage sludge liquor, while process failures can be detected by increased fluorescence intensity. This technique can detect even minor changes in effluent quality and identify issues with treatment plant performance.