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Primary and ultimate biodegradation of anionic surfactants under realistic discharge conditions in river water

Conference ·
OSTI ID:367489
;  [1]
  1. Procter and Gamble Co., Cincinnati, OH (United States)
Some levels of even the most highly biodegradable compounds escape sewage treatment and enter rivers and streams as components of effluent. Rapid biodegradation in the stream lowers a chemical`s concentration, prevents its dispersion through the environment, limits exposure of aquatic organisms downstream, and minimizes any potential for bioaccumulation. The biodegradation kinetics of representative anionic surfactants were determined under conditions simulating the mixing zone below a treatment plant outfall. {sup 14}C-1 C{sub 14} alkyl sulfate (AS), {sup 14}C-(ethoxylate) C{sub 14}E{sub 3} alkyl ethoxylate (AE), {sup 14}C (ethoxylate) C{sub 14}E{sub 3}S alkyl ethoxylate sulfate (AES) and {sup 14}C-(ring) C{sub 12} linear benzenesulfonate (LAS) were dosed at 75 {micro}g/l into river water amended with 1% activated sludge liquor to approximate a mixing zone. Evolution of {sup 14}CO{sub 2} was monitored over time, and periodically samples were flash frozen, lyophilized, extracted, filtered and analyzed by Rad-TLC. Incorporation into biomass was determined by quantifying the radioactivity associated with the extracted solids on the filter. Primary degradation of all four surfactants exhibited first-order kinetics, and half-lives ranged from 0.4 to 11.0 hrs. The time needed for ultimate degradation, defined as mineralization or incorporation into biomass, to reach 50% ranged from 0.7 to 19 hrs. These data demonstrate the power of this approach for understanding the fate of chemicals in river water. Furthermore, this work shows that loss of parent and consequently loss of toxicity can occur very rapidly under realistic conditions generating kinetic data, which can be used directly with few assumptions to model exposure concentrations downstream.
OSTI ID:
367489
Report Number(s):
CONF-9511137--; ISBN 1-880611-03-1
Country of Publication:
United States
Language:
English