FluoroFlo: A Semi-Autonomous System for Detecting Optical Brighteners in Urban Streams

860 billion gallons of sewage escapes into the environment every year, which has caused 3.5 million Americans to contract viruses and diseases. While fecal indicator bacteria, human-associated indicator bacteria, and other viral indicators are used to detect sewage leaks, these methods are sometimes unreliable. This project proposes the use of optical brighteners (OBs) to identify wastewater discharge. OBs are fluorescent whitening agents often found in laundry detergents, cleaning agents, and toilet paper. They contain a special property where they emit a visible blue light at 440nm when exposed to UV light at 360nm. The design will utilize this characteristic in order to detect sewage contamination in the Hans Groot Kill. The overall goal is to develop a semi-autonomous system to record OBs in stream water while also reducing the need for frequent manual sampling. It combines an automated water collection system, a customized fluorometer that uses UV light and a 400nm longpass filter, and a microcontroller-based control system with wireless data transmission. The device performs fluorescence measurements on site and uploads the data for remote monitoring. The overall design emphasizes durability, low maintenance, and sustainability for long term environmental water quality monitoring. Results showed that the system's battery life depends largely on the sampling time input. If the user desires a faster sampling time of 1 hour, the system can last for 2 days and 7 hours. If the user enters a slower sampling time of 4 hours, the device will be able to operate for 9 days and 4 hours. Additionally, calibration experiments achieved a minimum detection limit of 10ppm of Tide laundry detergent (which contains OBs), with a baseline curve producing a linear fit of 0.951 R2. Field deployment of the system identified fluorescence signals consistent with potential wastewater contamination in the Hans Groot Kill, demonstrating the device's potential as a practical tool for continuous environmental monitoring.