Microbial degradation of diethanolamine and related compounds

Thirteen diethanolamine compounds were tested for their biodegradability employing 1) a bacterium selectively isolated from an industrial cutting fluid and 2) an acclimated sewage population obtained from a domestic waste treatment plant. Pure culture growth and biochemical oxygen demand studies with the isolate showed that only diethanolamine, methyl-diethanolamine, triethanolamine, and laurylsulfate-diethanolamine were degradable. Biochemical oxygen demand techniques using the acclimated sewage microorganisms as seed yielded similar results with only diethanolamine, methyl-diethanolamine, triethanolamine, and laurylsulfate- diethanolamine being oxidized to any meaningful extent. Cyclohexyldiethanolamine, phenyl-diethanolamine, and m-tolyl-diethanolamine had oxygen demands of less than 1% of their theoretically calculated values, while ethyl-diethanolamine and benzyl-diethanolamine accounted for 3.6 and 2.3% of their theoretical values, respectively. In both systems, substitution of the tertiary hydrogen of the amine group with isopropyl, 3-aminopropyl, n-butyl, or t-butyl resulted in biologically recalcitrant compounds.