An automated spectrophotometric system for monitoring buffer capacity in anaerobic digestion processes.

Anaerobic digestion is a suitable method for the treatment of wastewater and organic wastes, yielding biogas as a useful by-product. A common way of preventing instability problems and avoiding acidification in anaerobic digesters is to keep the organic load to the digester far below its maximum capacity. An improved way of operating digesters would be to use monitoring and control systems for increased organic load under controlled conditions such that the digester performance is improved. The partial alkalinity, which indicates the bicarbonate concentration, has in many cases been found to be a suitable parameter to monitor. Here, an automated monitoring system for alkalinity measurements is described. It is shown to be applicable for measuring a wide range of bicarbonate concentrations. The system shows potential for monitoring anaerobic digesters as it responds to the alkalinity of digester effluent, as well as being stable over a relatively long time span with few maintenance requirements.