A simple spectrophotometric method based on pH-indications for monitoring partial and total alkalinity in anaerobic processes

Partial alkalinity, as a measure of bicarbonate concentration, and total alkalinity, as a measure of the concentration of bicarbonate and volatile fatty acids, are useful parameters for monitoring anaerobic digestion processes. This paper reports a new method based on pH-indicators and spectrophotometric measurements for the monitoring of partial and total alkalinity. The method was used in an off-line procedure for monitoring of an anaerobic process and displayed less than 5% deviation from the traditional method of measuring partial and total alkalinity, as well as being rapid and reproducible. A flow injection analysis system based on the method was used on-line for monitoring overload in a UASB reactor, which demonstrated changes in alkalinity not easily registered using traditional methods.