mib-geomin-1200x300MIB and Geosmin

The main cause of taste and odor in drinking water can be attributed to the microbial production of (−)-geosmin [(−)-(4S,4aS,8aR)-4,8a-dimethyloctahydronaphthalen-4a-ol] and MIB ( (−)-2-methylisoborneol) {(1R-exo)-1,2,7,7-tetramethylbicyclo[2.2.1]heptan-2-ol}. The concentration of these compounds in parts per trillion will cause an earthy musty odor.

Geosmin and MIB are tertiary alcohols produced by members of certain groups of benthic and pelagic aquatic microorganisms found in source waters such as lakes, reservoirs, and running waters. Cyanobacteria also termed as “blue-green algae” are some of the major producers of these compounds.

Cyanobacteria are a photosynthetic nitrogen-fixing type that survives in a wide variety of habitats, soils, and water. In this group, photosynthetic pigments are cyanophycin, allophycocyanine and erythrophycocyanine. Their thalli vary from unicellular to filamentous and filamentous heterocystous. They fix atmospheric nitrogen in aerobic conditions by heterocyst, specialized cells, and in anaerobic conditions.

It has also been documented that post-treatment production of geosmin, due to biological activities, can result in odor issues downstream of water treatment and throughout the distribution system. Geosmin and 2-MIB are stable to compounds and persist in the open water in a dissolved form for extended periods of time. The stability of these compounds makes it difficult for conventional filtration to oxidize and eliminate the problem. Early detection can allow treatment and intake modification to eliminate or reduce the intensity of the problem.