Alcohol ethoxylate degradation of activated sludge is enhanced by bioaugmentation with Pseudomonas sp. LZ-B

An effective bioaugmentation strategy was developed for the removal of alcohol ethoxylates (AEs) from municipal wastewater. An AE-degrading strain, Pseudomonas sp. LZ-B, was isolated from an activated sludge. Strain LZ-B was able to degrade 96.8% of 200 mg/L C₁₂E₄ (Brij 30) within 24 h and showed significant biomass increase and removal of total oxygen concentration (TOC). The optimal degradation temperature and pH value were 37 °C and 6.0, respectively. The strain demonstrated greater potential to degrade five different molecular weight AEs within 5 days. HPLC-MS/MS analysis demonstrated that the major metabolites obtained were polyethylene glycol (PEG) and carboxylated AE chains. Activated sludge has a low ability to remove AEs. After inoculation of strain LZ-B into the activated sludge reactor, Strain LZ-B successfully colonized the activated sludge, and AE removal efficiency increased to more than 95% when the hydraulic retention time (HRT) was 10 h. After strain LZ-B cleaved the AE chains, the sludge microbial communities easily removed PEG fragments to facilitate complete biodegradation of AEs. This is the first report describing bioaugmentation to increase AE degradation in an activated sludge system.

Determination of dodecanol and ethoxylated fatty alcohols from environmental samples using diatomaceous earth as a green sorbent for solid-phase extraction

This study describes the use of diatomaceous earth during solid-phase extraction as an efficient sorbent for separation and concentration of dodecanol and ethoxylated dodecanol containing 1-9 ethoxyl groups. The efficiency of different eluents was evaluated for model samples which allowed to select methanol and chloroform for tests with river water samples. During model experiments, it was observed that the recovery rates of specific compounds in the studied mixture were influenced by the character of the solvent used for desorption. Hydrophobic compounds, such as dodecanol and ethoxylated dodecanol with 1-3 ethoxyl groups, were eluted by chloroform with 100% efficiency. In case of the remaining compounds, which were more hydrophilic, a 97% recovery rate was achieved during elution with methanol. Such dependencies were not observed in case of river water samples, as the results obtained for both studied sorbent-eluent systems were comparable. In both variants the recovery of dodecanol and ethoxylated dodecanol containing 1-9 ethoxyl groups ranged from 33 to 99%.

Biodegradation of Oxyethylated Fatty Alcohols by Bacterium Pseudomonas alcaligenes; AE Biodegradation by Pseudomonas alcaligenes

Pseudomanas alcaligenes is a Gram-negative soil bacteria which has the potential to degrade hydrocarbons including aromatic compounds. The biodegradation of a representative oxyethylated fatty alcohol by the PA strain under static model conditions with a surfactant as a sole source of organic carbon was investigated. Polydispersal oxyethylated dodecanol C12E10 is biodegraded by the bacterial P. alcaligenes strain of following two alternative pathways: central fission with formation of poly(ethylene glycols) or ω-oxidation of an oxyethylene chain with the formation of carboxyl end group and intermediate aldehyde group. Shorter homologues of polydispersal mixture C12E10 are faster biodegraded and the mixture is enriched with longer homologues.

Parallel pathways of ethoxylated alcohol biodegradation under aerobic conditions

Non-ionic surfactants (NS) are a major component of the surfactant flux discharged into surface water, and alcohol ethoxylates (AE) are the major component of this flux. Therefore, biodegradation pathways of AE deserve more thorough investigation. The aim of this work was to investigate the stages of biodegradation of homogeneous oxyethylated dodecanol C12E9 having 9 oxyethylene subunits, under aerobic conditions. Enterobacter strain Z3 bacteria were chosen as biodegrading organisms under conditions with C12E9 as the sole source of organic carbon. Bacterial consortia of river water were used in a parallel test as an inoculum for comparison. The LC-MS technique was used to identify the products of biodegradation. Liquid-liquid extraction with ethyl acetate was selected for the isolation of C12E9 and metabolites from the biodegradation broth. The LC-MS/MS technique operating in the multiple reaction monitoring (MRM) mode was used for quantitative determination of C12E9, C12E8, C12E7 and C12E6. Apart from the substrate, the homologues C12E8, C12E7 and C12E6, being metabolites of C12E9 biodegradation by shortening of the oxyethylene chain, as well as intermediate metabolites having a carboxyl end group in the oxyethylene chain (C12E8COOH, C12E7COOH, C12E6COOH and C12E5COOH), were identified. Poly(ethylene glycols) (E) having 9, 8 and 7 oxyethylene subunits were also identified, indicating parallel central fission of C12E9 and its metabolites. Similar results were obtained with river water as inoculum. It is concluded that AE, under aerobic conditions, are biodegraded via two parallel pathways: by central fission with the formation of PEG, and by Ω-oxidation of the oxyethylene chain with the formation of carboxylated AE and subsequent shortening of the oxyethylene chain by a single unit.

Bacterial strains isolated from river water having the ability to split alcohol ethoxylates by central fission

Alcohol ethoxylates (AE) are a major component of the surfactant stream discharged into surface water. The "central fission" of AE with the formation of poly(ethylene glycols) (PEG) is considered to be the dominant biodegradation pathway. However, information as to which bacterial strains are able to perform this reaction is very limited. The aim of this work was to establish whether such an ability is unique or common, and which bacterial strains are able to split AE used as a sole source of organic carbon. Four bacterial strains were isolated from river water and were identified on the basis of phylogenetic trees as Enterobacter strain Z2, Enterobacter strain Z3, Citrobacter freundii strain Z4, and Stenotrophomonas strain Z5. Sterilized river water and "artificial sewage" were used for augmentation of the isolated bacteria. The test was performed in bottles filled with a mineral salt medium spiked with surfactant C12E10 (10 mg L(-1)) and an inoculating suspension of the investigated bacterial strain. Sequential extraction of the tested samples by ethyl acetate and chloroform was used for separation of PEG from the water matrix. LC-MS was used for PEG determination on the basis of single-ion chromatograms. All four selected and investigated bacterial strains exhibit the ability to split fatty alcohol ethoxylates with the production of PEG, which is evidence that this property is a common one rather than specific to certain bacterial strains. However, this ability increases in the sequence: Stenotrophomonas strain Z5 < Enterobacter strain Z2 < Enterobacter strain Z3 = Citrobacter freundii strain Z4. Graphical Abstract Biodegradation by central fission of alcohol ethoxylates by bacterial strains isolated from river water.

Monitoring of selected non-ionic surfactants in river water by liquid chromatography-tandem mass spectrometry

Alcohol ethoxylates (AEs) are a significant component of the non-ionic surfactant (NS) flux discharged into surface water. Due to the polydispersity of the majority of NS, they are easily recognizable by their 'fingerprints', i.e. a series of mass peaks which differ by m/z = 44, namely the m/z of a single oxyethylene subunit. Dodecanol ethoxylates (C12EOx) represent AEs from both renewable and petrochemical sources. Therefore, C12Ex are suitable fingerprints of NS in the aquatic environment. The aim of this work was to develop an LC-MS/MS method suitable for AE monitoring in river water. River water samples taken from the River Warta in Poznan (Poland) were extracted with ethyl acetate, evaporated, reconstituted in the mobile phase and processed by the LC - Multistage MS procedure (LC-MS/MS) using optimum multiple reaction monitoring (MRM). The method of multiple standard additions was used for the evaluation of each AE fingerprint concentration. The concentration of C12EOx having 2-9 oxyethylene subunits was determined. Standards for higher C12EOx are not yet available. The developed method offers an LOD of between 1 and 9 ng L(-1), and is suitable for the monitoring of NS fingerprints in river water. The range of C12EO2-9 concentrations determined in the River Warta varied within two orders of magnitude in all cases. The lowest determined concentration was 17 ± 1 ng L(-1), while the highest was 2.6 ± 0.14 μg L(-1). The total concentration of C12EO2-C12EO9 homologues varied between 1.4 and 11.2 μg L(-1). A relatively high concentration of short-chained homologues (2-5 oxyethylene subunits) was observed in the investigated river water. This provides evidence of a biodegradation pathway involving the gradual shortening of the AE oxyethylene chain. Distinct evidence was also obtained of unregulated NS discharges into the river.

Identification of Non-ionic Surfactants in Elements of the Aquatic Environment

Information concerning the use of non-ionic surfactants (NS) in household products is very scanty. Therefore, a qualitative determination of NS in raw sewage is an alternative source of information concerning the presence and manufacture of NS. The aim of this work was to identify NS in raw sewage (in Poznan and Blonie, both Poland) and treated sewage (in Blonie) and to compare the results with those obtained for river water (Warta in Poznan, Poland). LC-MS/MS was used for this purpose. The presence of 116 ethoxamers, being exclusively polydispersal alcohol ethoxylates (AE) containing alkyl moieties from C10 to C16 and C18, as well as 20 poly(ethylene glycols), was confirmed in the raw sewage, while 68 ethoxamers were found in the treated sewage, including 12 octylphenol ethoxylates. No nonylphenol ethoxylates were identified in the raw or treated sewage.