Biodegradation of Nonionic Surfactants and Effects of Oxidative Pretreatment

Abstract

The aerobic biodegradability of nonionic, ethoxylated surfactants and model compounds, and the effect of advanced oxidation pretreatment on the biodegradability of the biorefractory surfactants were examined. Bioassays conducted using a mixed microbial seed showed that the linear primary alcohol ethoxylates, the fatty acid ethoxylates, and also polyethylene glycol were all degradable. The biomineralization of the linear secondary alcohol ethoxylate, ethylene oxide/propylene oxide block copolymer, and alkylphenol ethoxylate was observed to be inhibited to varying degrees. Additional bioassays were conducted on model compounds to examine the effect of specific structural components on biodegradability. Advanced oxidation pretreatment using hydrogen peroxide in combination with ozone was highly effective at enhancing the biodegradability of both the linear secondary alcohol ethoxylate and the ethylene oxide/propylene oxide surfactants. Advanced oxidation was not effective, however, at enhancing the biodegradability of alkylphenol ethoxylate with the oxidant dosages used.