ORP MEASUREMENT IN ANAEROBIC SYSTEMS USING FLOW-THROUGH CELL

A new method was developed using a flow-through cell for the measureme nt of oxidation-reduction potential (ORP) for anaerobic microbial cult ures. The method involves passing the reactor effluent through a recyc le line equipped with an ORP probe. Stable ORP values were obtained fo r two different anaerobic reactors, operating under steady-state condi tions, for more than 2 months. One of the reactors was strictly methan ogenic and the other was sulfate-reducing. A comparison of ORP measure ments by this method with conventional measurement techniques showed t his method minimizes uncertainty in the measurement as a result of hyd rodynamic limitations, temperature changes, and oxygen contamination o f the sample. It prevents fouling of the ORP probe by allowing for eas y cleaning of the probe and checking for calibration before use. The m ethod can also be used for both batch reactors and chemostats (CSTR).