Early Warning System for Hazardous Substances in Sewage
This report was produced for the Urban Water Research Association of Australia, a now discontinued research program.
Report no. UWRAA 50
Illegal or toxic discharges to the sewerage system can compromise the safety of sewer workers, may result in damage to biological treatment processes and can possibly cause serious environmental pollution. Sewer discharge points are sampled and analysed regularly, but it is unlikely that a harmful discharge, be it accidental or deliberate, will coincide with the time at which these samples are taken.
In an attempt to provide an improved level of sewer surveillance, Melbourne Water obtained a research grant from the Urban Water Research Association of Australia to assist in funding an investigation into the feasibility of continuously monitoring sewers for hazardous conditions.
Consequently, CSIRO was contracted by Melbourne Water and the Urban Water Research Association of Australia to develop an automated on-line sewer monitoring system. The “Sewer Sentinel” is based on a package of physico-chemical sensors which are immersed in a fast flowing side stream of macerated raw sewage. The sensor package is controlled and results logged using customised PC-based software. The system is able to detect discharge events, and can be configured to command an automatic sampler to collect a sample for subsequent examination and laboratory analysis.
The “Sewer Sentinel” system has been successfully demonstrated in sewers connected to industrial estates (CSIRO site, Clayton and Levanswell Rd, Moordialloc), in a domestic sewer (Lower Plenty), and at a regional sewage treatment plant(Brushy Creek). Results are most promising, with the system being able to operate reliably for at least a month with little attention.