Corrosion Monitoring and Control in Concrete Sewer Pipes

A crown flushing technique for reducing the low pH caused on concrete sewer pipes by Thiobacillus bacteria has been evaluated using a corrosion monitoring system consisting of bare steel electrodes, steel electrodes embedded in concrete, and pH electrodes. Data for these sensors have been taken simultaneously every 10 min for several months in a corrosion chamber fed with sewer gas. In addition, laboratory experiments have been performed with this sensor system in the absence of intentionally added bacteria. Impedance data serve as a very sensitive indicator of the initiation of corrosion on steel in concrete.