Novel biotreatment process for glycol waters

Propylene oxide (PO), propylene glycol (PG), and polyols are produced from propylene via propylene chlorohydrin. Effluents from these plants contain biological oxygen demand/chemical oxygen demand (BOD/COD) loads besides high chloride concentrations. The high salinity poses severe problem to adopt conventional methods like activated sludge processes. Presently, a simple, economically viable and versatile microbiological process has been developed to get more than 90% biodegradation in terms of BOD/COD, utilizing specially developed Pseudomonas and Aerobacter. The process can tolerate high salinity up to 10 wt% NaCl or 5 wt% CaCl2 and can withstand wide variations in pH (5.5-11.0) and temperature (15-45 degrees C). The biodegradation of glycols involves two steps. The enzymatic conversion of glycols to carboxylic and hydroxycarboxylic acids is aided by Pseudomonas. Further degradation to CO2 and H2O by carboxylic acid utilizing Aerobacter, and possible metabolic degradative pathway of glycols are discussed. Various process parameters obtained in the lab scale (50 L bioreactor) and pilot scale (20 m3 bioreactor), and unique features of our process are also discussed.