Abstract
Alkalinity or buffering in anaerobic digesters may be chiefly attributed to bicarbonate and should be at least 1000 mg CaCO3/l for successful operation. A simple on-line instrument for the direct determination of bicarbonate concentration, especially for automatic control of anaerobic digesters, is described. The proposed method is based on a continuous measurement of the carbon dioxide flow rate evolved from a stream of sampled solution after saturation with gaseous CO2 and subsequent acidification with excess acid. This eliminates the need for a pH probe which is subject to fouling. The device was calibrated using sodium bicarbonate solutions (0.01-0.065 M) and the calibration showed an accuracy of ±5%. The device was tested on effluent from anaerobic digesters operating on ice-cream waste supplemented with sodium bicarbonate within a range of 0.02-0.04 mol/l. The results compared favourably with titrimetric measurements, extensively used to determine bicarbonate alkalinity with an accuracy of ±5%. The response of the instrument to variation in alkalinity concentration is sufficiently rapid for most industrial applications.
Original language | English |
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Pages (from-to) | 167-170 |
Number of pages | 4 |
Journal | Water Research |
Volume | 27 |
Issue number | 1 |
DOIs | |
Publication status | Published - Jan 1993 |
Keywords
- alkalinity
- anaerobic digestion
- bicarbonate
- on-line monitoring