skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Nondegraded metabolites arising from the biodegradation of commercial linear alkylbenzenesulfonate (LAS) surfactants in a laboratory trickling filter

Abstract

The degradation of a commercial linear alkylbenzenesulfonate (LAS) surfactant was examined kinetically in a trickling filter, which allowed simultaneous chemical determinations in the aqueous phase (e.g., DOC) and in the gas phase (CO{sub 2}). About 60% of the carbon applied as LAS was released as CO{sub 2}, whereas 15% remained as DOC in the eluate of acclimated trickling filters. The biomass was analyzed after the experiment, and it was found to have sorbed about 23 mg LAS/g of dry biomass; this represented about 3% of the LAS applied to the filter. The LAS and the eluates from the trickling filter were further analyzed by HPLC and UV and IR spectrometry. The residual carbon from acclimated filters contained no LAS-like material (HPLC), which was obviously subject to quantitative biotransformation. The residual material comprised > 50 polar metabolites, some of whose UV spectra differed from that of LAS, and most or all of which were sulfonated. These nondegraded metabolites included carboxylated dialkyltetralinesulfonates and sulfophenylcarboxylates. These residual materials showed no detectable toxicity to algae or Daphnia, and did not significantly lower the surface tension of water.

Authors:
;  [1];  [2];  [3]
  1. Swiss Federal Inst. for Materials Testing and Research, St. Gallen (Switzerland)
  2. ETH-Zentrum, Zuerich (Switzerland). Inst. of Microbiology
  3. ETH-Zentrum, Zuerich (Switzerland). Inst. of Microbiology|[Univ. of Konstanz (Germany). Faculty of Biology
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
42918
Resource Type:
Journal Article
Resource Relation:
Journal Name: Environmental Toxicology and Chemistry; Journal Volume: 14; Journal Issue: 4; Other Information: PBD: Apr 1995
Country of Publication:
United States
Language:
English
Subject:
56 BIOLOGY AND MEDICINE, APPLIED STUDIES; SURFACTANTS; BIODEGRADATION; TOXICITY; METABOLITES; CHEMICAL ANALYSIS; DAPHNIA; SENSITIVITY

Citation Formats

Koelbener, P., Baumann, U., Leisinger, T., and Cook, A.M. Nondegraded metabolites arising from the biodegradation of commercial linear alkylbenzenesulfonate (LAS) surfactants in a laboratory trickling filter. United States: N. p., 1995. Web. doi:10.1002/etc.5620140403.
Koelbener, P., Baumann, U., Leisinger, T., & Cook, A.M. Nondegraded metabolites arising from the biodegradation of commercial linear alkylbenzenesulfonate (LAS) surfactants in a laboratory trickling filter. United States. doi:10.1002/etc.5620140403.
Koelbener, P., Baumann, U., Leisinger, T., and Cook, A.M. 1995. "Nondegraded metabolites arising from the biodegradation of commercial linear alkylbenzenesulfonate (LAS) surfactants in a laboratory trickling filter". United States. doi:10.1002/etc.5620140403.
@article{osti_42918,
title = {Nondegraded metabolites arising from the biodegradation of commercial linear alkylbenzenesulfonate (LAS) surfactants in a laboratory trickling filter},
author = {Koelbener, P. and Baumann, U. and Leisinger, T. and Cook, A.M.},
abstractNote = {The degradation of a commercial linear alkylbenzenesulfonate (LAS) surfactant was examined kinetically in a trickling filter, which allowed simultaneous chemical determinations in the aqueous phase (e.g., DOC) and in the gas phase (CO{sub 2}). About 60% of the carbon applied as LAS was released as CO{sub 2}, whereas 15% remained as DOC in the eluate of acclimated trickling filters. The biomass was analyzed after the experiment, and it was found to have sorbed about 23 mg LAS/g of dry biomass; this represented about 3% of the LAS applied to the filter. The LAS and the eluates from the trickling filter were further analyzed by HPLC and UV and IR spectrometry. The residual carbon from acclimated filters contained no LAS-like material (HPLC), which was obviously subject to quantitative biotransformation. The residual material comprised > 50 polar metabolites, some of whose UV spectra differed from that of LAS, and most or all of which were sulfonated. These nondegraded metabolites included carboxylated dialkyltetralinesulfonates and sulfophenylcarboxylates. These residual materials showed no detectable toxicity to algae or Daphnia, and did not significantly lower the surface tension of water.},
doi = {10.1002/etc.5620140403},
journal = {Environmental Toxicology and Chemistry},
number = 4,
volume = 14,
place = {United States},
year = 1995,
month = 4
}
  • Linear alkanesulfonates and linear alkylbenzenesulfonates constitute a large fraction of the surfactants used in commercial detergents and cleansers. Despite the industrial significance and the possible environmental impact of these compounds, very little in known regarding the molecular properties of these compounds and how they relate to macroscopic properties desired in applications. This study employs vibrational sum frequency spectroscopy (VSFS) to examine and compare the molecular structure of surfactants in these two classes as they adsorb at organic/water and air/water interfaces. The linear alkane- and alkylbenzenesulfonates studied are, respectively, dodecanesulfonate and dodecylbenzenesulfonate. By measurement and comparison of the vibrational spectra ofmore » these adsorbed surfactants, changes in the orientation of the aromatic ring and the conformation of the alkyl chains are examined as a function on the number density of surfactant molecules at the interface. The change in aromatic ring orientation as a function of surface concentration is quite different for the dodecylbenzenesulfonate at the air/water interface relative to that at the organic/water interface (CCl{sub 4}/water). The alkyl chains of the dodecylbenzenesulfonate are highly disordered at both interfaces as a function of interfacial concentration, in stark contrast to what is observed for the dodecanesulfonate. The results are discussed in terms of the disruptive nature of the benzene ring and the higher degree of hydrophobicity of the alkyl chain relative to the benzene ring near the ionic sulfonate group.« less
  • The standard procedure to examine the biodegradability of a (group of) compound(s) in a trickling filter is a continuous-flow system. In this test, nondegraded metabolites from a commercial linear alkylbenzenesulfonate (LAS) surfactant are detected. This procedure has now been augmented by two phases in closed cycle to give a test for refractory organic carbon (ROC test). First, the concentration of nondegraded metabolites was increased by readdition of LAS to the solution being cycled through the filter. Second, the concentrated residues were further recycled till the net dissolved organic carbon (DOC) stabilized at a finite value and the net released CO{submore » 2} stabilized at about zero. The organic compounds remaining at this phase of the experiment were considered recalcitrant and could be examined by global (e.g., DOC) and specific (e.g., HPLC) assays. Four different commercial preparations of LAS were examined, as were the (4-sulfophenyl)undecane homologue (C{sub 11}-LAS), the (4-sulfophenyl)dodecane homologue (C{sub 12}-LAS), and some related compounds. The four commercial LAS preparations contained different levels if impurities which were largely dialkyltetralinesulfonates (DATS) and branched-chain alkylbenzenesulfonates (bABS). The refractory organic carbon (ROC) remaining after biodegradation varied from 3 to 14%. The results were a characteristic of the LAS under study and were independent of the source of the biomass used in the experiment. Residues were examined by HPLC, and 50 to 100 peaks were observed, which were usually characteristic of the LAS studied. No peak has been conclusively identified. The authors consider the recalcitrants to represent carboxylated DATS and carboxylated bABS.« less
  • Apparent water solubilities of 1,1-bis(p-chlorophenyl)-2,2,2-trichloroethane (DDT), 2,4,5,2{prime},5{prime}-pentachlorobiphenyl (PCB), and 1,2,3-trichlorobenzene (TCB) were determined at room temperature in aqueous solutions of commercial linear alkylbenzenesulfonate (LAS), oil-free (solvent-extracted) LAS, and single-molecular 4-dodecyl-benzenesulfonate. The extent of solute solubility enhancement by commercial LAS is markedly greater than that by other ionic surfactants below the measured critical micelle concentration (CMC); above the CMC, the enhancement data with LAS are comparable with other surfactants as micelles. The small amount of neutral oils in commercial LAS (1.7%), comprising linear alkyl-benzenes (LABs) and bis(alkylphenyl) sulfones, contributes significantly to the enhanced solubility of DDT and PCB below the CMC;more » the effect is ascribed to formation of oil-surfactant emulsions. The oil-surfactant emulsion formed corresponds to {approximately}9-10% of the commercial LAS below the CMC. The data suggest that discharge of wastewater containing a significant level of oils and surface-active agents could lead to potential mobilization of organic pollutants and LABs in aquatic environments.« less
  • The behavior of linear alkylbenzenesulfonate (LAS) in soils (i.e., degradation, percolation, and sorption) was investigated in field and laboratory tests. For this purpose sorption studies were carried out using Freundlich's method in order to obtain sorption constants. A prediction of sorption constants in characterized soils was possible using multiple regression and correlation methods. Degradation under laboratory conditions can faithfully be used for the interpretation of degradation times under field conditions. In laboratory tests LAS has reacted immobilely as in field tests. The uptake of LAS in plants is very high; however, it is slowly metabolized.
  • An aquatic hazard assessment was conducted for branched and linear nonionic surfactants using toxicity and biodegradation measurements. Four nonionic alcohol ethoxylate surfactants with different degrees of branching were evaluated for neat surfactant toxicity, degradation in laboratory sewage treatment units, and aquatic toxicity of treated effluents. Acute testing with neat surfactants showed ranges for EC50s of 1.3 to 11.6 mg/L for Daphnia, 1.6 to 6.1 mg/L for Pimephales promelas (fathead minnow), and 1.5 to 11.4 mg/L for Microtox[reg sign]. Chronic testing of algae showed NOECs of 1 to 10 mg/L and maximum acceptable toxicant concentrations (MATCs) of 0.8 to 14.2 mg/L.more » Seven-day chronic estimation tests showed MATCs of 0.6 to 41.4 mg/L for Pimephales promelas and 1 to 14 mg/L for Daphnia. Effluents collected from treatment units receiving a 50-mg/L surfactant feed at 25 C showed no acute toxicity to either Daphnia or fathead minnows, with the exception of a unit containing nonylphenol ethoxylate. Chronic effluent toxicity was greatest in effluent from the nonylphenol ethoxylate unit and least in the effluent from the linear alcohol ethoxylate unit. Chronic toxicity of the highly branched C[sub 13] alcohol ethoxylate effluent was greater than that for the linear alcohol ethoxylate unit effluent.« less