Biodegradabilities of chelating agents were tested with activated sludge. Ethylenediaminetetraacetic acid (EDTA) remained intact in the effuent even after acclimation for 100 days, but propanediamine-N, N'-disuccinic acid (PDDS) and nitrilotriacetic acid (NTA) were biodegraded after acclimation for 5 and 23 days, respectively. Optical isomers of ethylenediamine-N, N'-disuccinic acid (EDDS) had different biodegradabilitibs: SS- and RS-isomers were susceptible to biodegradation, but the RR-isomer was resistant. SS-isomer was degraded even by activated sludge without acclimation.
Japan Society for Bioscience, Biotechnology, and Agrochemistry