Pilot study on the durability of optical fibre sensors for monitoring moisture in waste sewerage environment

Corrosion in infrastructure assets of waste water management is an important problem that results in large operational costs for mitigation and capital outlays for repair. In particular, bacteria causing wastage sewer concrete corrosion need a moist environment to grow and the high levels of humidity in sewer environments emphasizes the problem. Also, moisture acts as the dissolving medium for the gaseous hydrogen sulphide that comes in contact with both concrete and bacterial biofilms. The influence of humidity on the rate of corrosion of sewer concrete is over-looked, partly because it is difficult to measure. A main problem is that the corrosive sewer environment destroys the electronic sensors. City University London and Edinburgh Napier University have evaluated the feasibility of the utilization of optical fibre-based sensors for the purpose of long term monitoring of humidity and temperature in the highly corrosive sewer environment. This work details the feasibility tests conducted, the results obtained and the conclusions that could be reached, together with recommendations for further work, based on the research carried out.