What is combined sewer overflow?
Combined sewer overflow (CSO) is the discharge of a combination of storm water and domestic sewage waste water caused by sewer capacity being exceeded during heavy storms. When waste water exceeds the sewage system's capacity, storm and sewage water is directed into CSOs which flow into streams, rivers and the sea, through outfall pipes. CSOs provide a failsafe during heavy storms to stop household domestic sewage waste and storm water backing up through the system and flooding peoples' homes and streets.
The CTG BACTI-Wader and the BOD-Wader enable in situ real-time reporting of Bacteria within natural water systems and are effective tools for monitoring transitional and coastal waters to detect outflow events from waste water treatment works (such as Combined Sewage Overflows) and farm slurry.
The sensors detects fluorescent proteins that are inherent within sewage and slurry. The principle behind the measurement is the excitation of Tryptophan-like fluorescence within UV wavelength band, which is highly sensitive and has been shown to correlate with bacterial contamination.
The National Water Quality Instrumentation Service (NWQIS) has been working with local environment officers and Chelsea Technologies deploying and trialling the Chelsea BACTI-Wader to help detect high levels of sewage pollution in bathing waters off the UK coast.
Applications for the BACTI-Wader & BOD-Wader include:
- Combined Sewage Overflow (CSO) event detection
- Bathing water quality monitoring
- Faecal Indicator (FI) monitoring
- Assessment of bathing & shellfish waters
- River pollution surveillance and investigative monitoring
- Point source pollution surveys