Biodegradation Of Linear Alkylbenzene Sulfonate Research Articles

Dissolved oxygen dependence of Microbe-Derived dissolved organic nitrogen dynamics during membrane biofilm-based linear alkylbenzene sulfonate mineralization

Oxygen-based membrane biofilm reactor (O2-MBfR) can achieve bubble-free efficient linear alkylbenzene sulfonate (LAS) mineralization. However, effluent microbially derived dissolved organic nitrogen (mDON) reduces recycled water quality and induces water eutrophication. How dissolved oxygen (DO) impacts the dynamics of mDON during LAS biodegradation is unknown. Here, we explored the fate of mDON releasing, molecular characteristics and formation metabolisms in the O2-MBfR responding to DO dynamics using Fourier transform ion cyclotron resonance mass spectrometry and metagenomic analyses. Results showed that DO presents a negative impact (λ = -0.242, P < 0.001) on mDON production, but can positively influence mDON reduction through influencing total organic nitrogen (TDN) removal. DO of 0.3 mg/L led to the lowest concentration of mDON with the least number of organic molecular formulas and high proportion of stable N2– and N3-containing organics. Much lower (0.0 mg/L) or higher (0.6 mg/L) DO concentrations favored dissimilatory-based ammonia formation and assimilatory nitrogen fixation that enhancing mDON formation. Firmocutes were the dominant bacteria that contributing to mDON formation. TDN (λ = 0.844, P < 0.001) and pH (λ = 0.248, P < 0.01) directly affected the effluent mDON concentration. The relatively low effluent mDON under anoxic condition suggested that DO controlling can be an effective strategy to minimize bioavailable mDON discharges in the O2-MBfR, which showed great implication potential for high-quality reclaimed water production and eutrophication control.

Use of nitrate, sulphate, and iron (III) as electron acceptors to improve the anaerobic degradation of linear alkylbenzene sulfonate: effects on removal potential and microbiota diversification.

Linear alkylbenzene sulfonate (LAS) is a synthetic anionic surfactant that is found in certain amounts in wastewaters and even in water bodies, despite its known biodegradability. This study aimed to assess the influence of nitrate, sulphate, and iron (III) on LAS anaerobic degradation and biomass microbial diversity. Batch reactors were inoculated with anaerobic biomass, nutrients, LAS (20mg L-1), one of the three electron acceptors, and ethanol (40mg L-1) as a co-substrate. The control treatments, with and without co-substrate, showed limited LAS biodegradation efficiencies of 10 ± 2% and 0%, respectively. However, when nitrate and iron (III) were present without co-substrate, biodegradation efficiencies of 53 ± 4% and 75 ± 3% were achieved, respectively, which were the highest levels observed. Clostridium spp. was prominent in all treatments, while Alkaliphilus spp. and Bacillus spp. thrived in the presence of iron, which had the most significant effect on LAS biodegradation. Those microorganisms were identified as crucial in affecting the LAS anaerobic degradation. The experiments revealed that the presence of electron acceptors fostered the development of a more specialised microbiota, especially those involved in the LAS biodegradation. A mutual interaction between the processes of degradation and adsorption was also shown.

Microbial niches and dynamics of antibiotic resistance genes in a bio-enhanced granular-activated carbon biofilm treating greywater

Accumulation and transmission of antibiotic resistance genes (ARGs) in greywater treatment systems present risks for its reuse. In this study, a gravity flow self-supplying oxygen (O2) bio-enhanced granular activated carbon dynamic biofilm reactor (BhGAC-DBfR) was developed to treat greywater. Maximum removal efficiencies were achieved at saturated/unsaturated ratios (RSt/Ust) of 1:1.1 for chemical oxygen demand (97.6 ± 1.5%), linear alkylbenzene sulfonates (LAS) (99.2 ± 0.5%), NH4+-N (99.3 ± 0.7%) and total nitrogen (85.3 ± 3.2%). Microbial communities were significantly different at various RSt/Ust and reactor positions (P < 0.05). The unsaturated zone with low RSt/Ust showed more abundant microorganisms than the saturated zone with high RSt/Ust. The reactor-top community was predominant by aerobic nitrification (Nitrospira) and LAS biodegradation (Pseudomonas, Rhodobacter and Hydrogenophaga) related genera; but reactor-bottom community was predominant by anaerobic denitrification and organics removal related genera (Dechloromonas and Desulfovibrio). Most of the ARGs (e.g., intI-1, sul1, sul2 and korB) were accumulated in the biofilm, which were closely associated with microbial communities at reactor top and stratification. The saturated zone can achieve over 80% removal of the tested ARGs at all operation Phases. Results suggested that BhGAC-DBfR can provide assistance in blocking the environment dissemination of ARGs during greywater treatment.

Degradation and transformation of linear alkyl-benzene sulfonates (LAS) in integrated constructed wetland–microbial fuel cell systems

Linear alkylbenzene sulfonates (LAS) are the most commonly-used anionic surfactants in cleaning agents and detergents. Taking sodium dodecyl benzene sulfonate (SDBS) as the target LAS, this study investigated the degradation and transformation of LAS in integrated constructed wetland–microbial fuel cell (CW–MFC) systems. Results showed that, SDBS was able to improve the power output and reduce the internal resistance of CW–MFCs by reducing transmembrane transfer resistance of organics and electrons because of the amphiphilicity and solubilization, however, SDBS with relatively high concentration had a great potential to inhibit electricity generation and organics biodegradation of CW–MFCs because of the toxic effects on microorganisms. C atoms on alkyl group and O atoms on sulfonic acid group of SDBS had greater electronegativity and were prone to oxidation reaction. The biodegradation of SDBS in CW–MFCs was a process of alkyl chain degradation, desulfonation and benzene ring cleavage in sequence via ω, β and/or α-oxidations and radical attacks under the action of coenzymes and oxygen, in which 19 intermediates were produced, including four anaerobic degradation products (toluene, phenol, cyclohexanone and acetic acid). Especially, for the first time cyclohexanone was detected during the biodegradation of LAS. The bioaccumulation potential of SDBS was greatly reduced through the degradation by CW–MFCs, and thus the environmental risk of SDBS was effectively reduced.

Biodegradation of Linear Alkylbenzene sulfonate-Anthracene Mixture by a Microbial Consortium isolated from Sediment

Linear alkylbenzene sulfonate and anthracene are chemical compounds which form pollutant mixtures with high toxic potential, causing damage to ecosystems. The process known as biodegradation is an effective, low-cost process carried out by microbial populations that reduces the toxic effect of linear alkylbenzene sulfonate and anthracene. In the present study, biodegradation was determined at different concentrations of linear alkylbenzene sulfonate, anthracene and the mixture of both compounds. The resulting reduction in toxicity produced by the mixture, the compounds separately and their biodegradation intermediaries was assessed using a microbial model. The ISO 9439 system was used to assess the biodegradation effect of a microbial consortium isolated from polluted sediment on 5, 10 and 20 mg/l of linear alkylbenzene sulfonate and the same concentrations of anthracene. Toxicity was determined by measuring inhibition of Bacillus cereus dehydrogenase activity produced by 0.25 ml aliquots of the linear alkylbenzene sulfonate, anthracene and the mixture of both compounds before and after they had been subjected to the biodegradation test. After 11 days, the linear alkylbenzene sulfonate -anthracene mixture was biodegraded to a greater degree than the compounds individually (3057.36 μmol CO2), but at a concentration of 20 mg/l of both compounds, a marked inhibition of biodegradation was observed. A reduction in toxicity produced by the biodegradation of linear alkylbenzene sulfonate and its mixture with anthracene at 5 and 10 mg/l respectively was observed.

The influent COD/N ratio controlled the linear alkylbenzene sulfonate biodegradation and extracellular polymeric substances accumulation in an oxygen-based membrane biofilm reactor

This work evaluated the fates of linear alkylbenzene sulfonate (LAS), chemical oxygen demand (COD), ammonia nitrogen (NH4+−N), and total nitrogen (TN) when treating greywater (GW) in an oxygen-based membrane biofilm reactor (O2-MBfR). An influent ratio of chemical oxygen demand to total nitrogen (COD/TN) of 20 g COD/g N gave the best removals of LAS, COD, NH4+−N and TN, and it also had the greatest EPS accumulation in the biofilm. Higher EPS and improved performance were linked to increases in the relative abundances of bacteria able to biodegrade LAS (Zoogloea, Pseudomonas, Parvibaculum, Magnetospirillum and Mycobacterium) and to nitrify (Nitrosomonas and Nitrospira), as well as to ammonia oxidation related enzyme (ammonia monooxygenase). The EPS was dominated by protein, which played a key role in adsorbing LAS, achieving short-time protection from LAS toxicity and allowed LAS biodegradation. Continuous high-efficiency removal of LAS alleviated LAS toxicity to microbial physiological functions, including nitrification, nitrate respiration, the tricarboxylic acid (TCA) cycle, and adenosine triphosphate (ATP) production, achieving the stable high-efficient simultaneous removal of organics and nitrogen in the O2-MBfR.

Anaerobic reactor applied to laundry wastewater treatment: Unveiling the microbial community by gene and genome-centric approaches

Gene and genome-centric approaches were applied to investigate the microbial taxonomic and metabolic diversity profiles from a lab-scale anaerobic reactor applied to laundry wastewater treatment with increasing concentrations of linear alkylbenzene sulfonate (LAS). Therefore, metagenomic analysis was carried out with reactor samples collected under three conditions, (i) Stage I, the reactor was fed with synthetic medium, (ii) Stage II, synthetic medium was replaced by diluted laundry wastewater with specific LAS loading rates (SLLRs) of 1.0 ± 0.3 mgLASgTVS−1d−1 and (iii) Stage III, SLLRs increased to 2.7 ± 0.7 mgLASgTVS−1d−1. Shotgun metagenomic sequencing was performed on an Illumina HiSeq 2 × 150 bp platform. Gene-centric analysis of each step of the metabolic pathway (fumarate addition, β-oxidation, ring cleavage and desulfonation) for anaerobic aromatic degradation showed eight over-representative genera (Achromobacter, Pelodictyon, Pseudomonas, Psychrobacter, Rhodococcus, Stenotrophomonas, Sulfurovum and Syntrophobacter), suggesting a microbial core with an important role in LAS biodegradation. Some of these genera were also recovered through a differential binning method, representing fifteen bacterial and one archaeal metagenome-assembled genomes (MAGs). Biodegradation pathway reconstruction of LAS using six MAGs unveiled the syntrophism for complete degradation of the LAS molecule. Only the MAGs with taxonomic annotation for Syntrophobacter showed genetic potential for fumarate addition, whereas in the ring cleavage, there was a predominance of genes in MAGs with taxonomic annotation for Pseudomonas fragi and Rhodococcus. This work represents the first report of genome-centric approach to study biological reactors applied in anionic surfactant degradation, contributing with detailed metabolic information of the key microbial actors in LAS degradation and opening perspectives for future biotechnological strategies aiming at bioaugmentation and/or biostimulation of indigenous microbial populations.

Optimal conditions, kinetic model and Packed Bed Reactor system for biodegradation of Linear Alkylbenzene Sulfonate by AOS-15 microorganism

Optimal conditions, kinetic model and Packed Bed Reactor system for biodegradation of Linear Alkylbenzene Sulfonate by AOS-15 microorganism

Kinetics of methane production and biodegradation of linear alkylbenzene sulfonate from laundry wastewater

ABSTRACTThis study evaluates the kinetics of methane production and degradation of standard linear alkylbenzene sulfonate (LAS) (50 ± 3.5 mg/L) and LAS from laundry wastewater (85 ± 2.1 mg/L) in anaerobic batch reactors at 30°C with different sources of inoculum. The inocula were obtained by auto-fermentation (AFM) and UASB reactors from wastewater treatment of poultry slaughterhouse (SGH), swine production (SWT) and wastewater treatment thermophilic of sugarcane industry (THR). The study was divided into three phases: synthetic substrate (Phase I), standard LAS (Phase II) and LAS from laundry wastewater (Phase III). For SGH, the highest values for cumulative methane productions (1,844.8 ± 149 µmol—Phase II), methane production rate (70.8 ± 88 µmol/h—Phase II and 4.01 ± 07 µmol/h—Phase III) were observed. The use of thermophilic biomass (THR) incubated at 30°C was not favorable for methane production and LAS biodegradation, but the highest kinetic coefficient degradation (k1app) was obtained for LAS (0.33 ± 0.3 h) compared with mesophilic biomass (SGH and SWT) (0.13 ± 0.02 h). Therefore, both LAS sources influenced the kinetics of methane production and organic matter degradation. For SGH, inoculum obtained the highest LAS degradation. In the SGH inoculum sequenced by MiSeq-Illumina was identified genera (VadinCA02, Candidatus Cloacamonas, VadinHB04, PD-UASB-13) related to degrade toxic compounds. Therefore, it recommended the reactor mesophilic inoculum UASB (SGH) for the LAS degradation.

Methanogenic activity inhibition by increasing the linear alkylbenzene sulfonate (LAS) concentration

ABSTRACTThe effect of the initial concentration of linear alkylbenzene sulfonate (LAS) on specific methanogenic activity (SMA) was investigated in this work. Six anaerobic flasks reactors with 1 L of total volume were inoculated with anaerobic sludge (2 g VSS L−1). The reactors were assayed for 42 days, and fed with volatile fatty acids, nutrients, and LAS. The initial LAS concentrations were 0, 10, 30, 50, 75, and 100 mg L−1 for the treatment flasks T1 (control), T2, T3, T4, T5, and T6, respectively. When compared with T1, T2 exhibited a 30% reduction in maximum SMA and total methane production (TMP). In treatment T3 through T6, the reductions were 44–97% (T3–T6) for SMA, and 30–90% (T3–T6) for TMP. Total LAS removal increased following the increase in the initial LAS concentration (from 36% at T1 to 76% at T6), primarily due to the high degree of sludge adsorption. LAS biodegradation also occurred (32% in all treatments), although this was most likely associated with the formation of non-methane intermediates. Greater removal by adsorption was observed in long-chain homologues, when compared to short-chain homologues (C13 > C10), whereas the opposite occurred for biodegradation (C10 > C13). The C13 homologue was adsorbed to a great extent (in mass) in T4, T5 and T6, and may also have inhibited methane formation in these treatments.

Biodegradation of linear alkylbenzene sulfonate in commercial laundry wastewater by an anaerobic fluidized bed reactor

The biodegradation of linear alkylbenzene sulfonate (LAS) from commercial laundry wastewater was evaluated in an anaerobic fluidized bed reactor (FBR) fed with synthetic substrate (598 mg L−1 to 723 mg L−1 of organic matter) supplemented with 9.5 ± 3.1 mg L−1 to 27.9 ± 9.6 mg L−1 of LAS. The average chemical oxygen demand (COD) removal efficiency was 89% and the biodegradation of LAS was 57% during the 489 days of anaerobic FBR. Higher levels of volatile fatty acids (VFA) were observed in the effluent at the stage with the best LAS removal performance. Increasing the surfactant concentration did not increase the VFA production in the effluent. The predominant VFAs after the addition of LAS were as follows: isovaleric acid and valeric acid, followed by propionic acid, caproic acid and formic acid. The similarities of 64% and 45% to Archaea and Bacteria domains were observed in the samples taken in the operating period of anaerobic FBR fed with 23.6 ± 10 mg L−1 and 27.9 ± 10 mg L−1 of LAS. During the operation stages in the reactor, Gemmatimonas, Desulfobulbus and Zoogloea were determined as the most abundant genera related to surfactant degradation using 454-Pyrosequencing.

Effect of nitrogen supplementation on aerobic degradation of linear alkylbenzene sulfonate by consortia of bacteria

Untreated detergent bearing wastes discharged into the environment are sources of linear alkylbenzene sulfonate (LAS). Detergent wastes usually do not contain nitrogen or contain very low amounts. Biostimulation by introducing limiting nutrient element can be useful in biotreatment of such waste. The effect of inorganic and organic nitrogen supplements on aerobic degradation of LAS by LAS-utilizing bacteria was examined. Phosphate-buffered LAS mineral media were prepared and supplemented with different nitrogen sources: NPK fertilizer (inorganic) and urea fertilizer (organic). Individual and various consortia of pure cultures of &lt;em&gt;Alcaligenes odorans&lt;/em&gt;, &lt;em&gt;Citrobacter diversus&lt;/em&gt;, &lt;em&gt;Micrococcus luteus&lt;/em&gt; and &lt;em&gt;Pseudomonas putida&lt;/em&gt;, previously isolated from a detergent effluent polluted stream, were used. Biodegradation of LAS was monitored in terms of half-life (t&amp;frac12;) of the surfactant. The rates of biodegradation by the consortia can be ranked as: 4-membered (t&amp;frac12;=8-12 days) &amp;gt;3-membered (t&amp;frac12;=8-13 days) &amp;gt;2-membered consortia (t&amp;frac12;=10-15 days) &amp;gt;individuals (t&amp;frac12;=9-16 days). The inorganic nitrogen source enhanced utilization of the surfactant, while organic nitrogen supplementation generally slowed degradation of the surfactant. In undertaking biotreatment of detergent bearing effluent, inorganic nitrogen should be used as biostimulant.

Effect of additional carbon source on biodegradation of linear alkylbenzene sulfonate by las-utilizing bacteria

Aerobic biodegradation of linear alkylbenzene sulfonate (LAS) by LAS-utilizing bacteria (LUB) in the presence of other sources of carbon (glucose and soluble starch) was examined. Biodegradation of LAS was monitored as primary degradation in terms of half-life (t&amp;frac12;) of the surfactant. Biodegradation of LAS by the individual LUB was slower in the presence of Glucose. Biodegradation of the surfactant by the various consortia of LUB was slower in the presence of the carbon sources: t&amp;frac12; increased to 3 days. The rates of biodegradation by the consortia can be ranked as: four-membered (t&amp;frac12;=9 days) &amp;gt; three-membered (t&amp;frac12;=9 to 13 days) &amp;gt; two-membered consortia (t&amp;frac12;=10 to 15 days). Generally, degradation in the presence of the carbon sources was faster with the consortia than the individual species. Degradation of the surfactant by the LUB was generally fastest in the absence of additional carbon sources. The possible role of additional carbon sources in persistence of surfactant in water bodies and the application of the observation in management of LAS-containing-effluent is suggested.

Linear alkylbenzene sulfonate (LAS) in water of Lake Dianchi—spatial and seasonal variation, and kinetics of biodegradation

For the purpose of elucidating the environmental characteristics of anion surfactants [linear alkylbenzene sulfonates (LAS)] in the water of Lake Dianchi, a sampling investigation in the field from October 2006 to July 2007 and a batch of biodegradation experiments in the laboratory were carried out. The results showed that concentrations of LAS ranged from 18.6 to 260.1 μg L(-1), and the average concentration was 52.6 μg L(-1) in Lake Dianchi. The highest concentrations of LAS were found in the Northwest region, and the distribution of LAS varied through seasons, with much lower concentrations in fall than in any other seasons. LAS can be primarily biodegraded by microorganisms in the lake water, and the percentage of degradation was >97% after 28 days. Biodegradation of LAS was well-fitted with the kinetic model presented in this paper, and the half-lives ranged from 3.2 to 16.3 days. Temperature, pH, and initial concentrations could affect the biodegradation of LAS, among which temperature was the major factor influencing on biodegradation of LAS in water of Lake Dianchi.

Aerobic biodegradation of linear alkylbenzene sulfonates and sulfophenylcarboxylic acids for different salinity values by means of continuous assays

Aerobic biodegradation of linear alkylbenzene sulfonates (LAS) and sulfophenylcarboxylic acids (SPCs) in water, at different salinity values, has been studied. Three experiments have been carried out employing a staircase model system with continuous dosage of LAS to the system and using concentrations of LAS of the same order as those detected in littoral waters receiving urban wastewater discharges. LAS biodegradation was observed to be almost complete (showing a great extent), and in all cases exceeds 98.4%. At the very low concentration values of LAS utilized in the experiments, no significant variations in the biodegradation of LAS due to the effect of the different salinity values assayed were observed. The biodegradation intermediates detected for all the cases were sulfophenylcarboxylic acids with carboxylic chains of between five and 13 carbon atoms. The detection of C13-SPC (which is only produced by C13-LAS) confirms the existence of omega-oxidation. The total disappearance of SPCs in all cases indicates that mineralization of LAS at the concentrations tested was complete.

Use of dynamic simulation to assess the behaviour of linear alkyl benzene sulfonates and their biodegradation intermediates (sulfophenylcarboxylic acids) in estuaries

Dynamic laboratory simulation of processes affecting chemical species in their transit through estuaries is a very useful tool to characterize these littoral systems. To date, laboratory studies concerning biodegradation and sorption (onto suspended particulate matter) of LAS in an estuary are scarce. For this reason, a dynamic automated estuarine simulator has been employed to carry out different experiments in order to assess the biodegradability of linear alkyl benzene sulfonates (LAS) and their biodegradation intermediates (sulfophenylcarboxylic acids, SPCs) using environmentally representative LAS concentrations in estuaries by a continuous injection of LAS into the system. During the experiments, a great affinity of LAS for the solid phase has been found, as well as an increased adsorption in line with increased chain length. On the other hand, the presence of SPCs with chain length between 6 and 13 carbon atoms was detected. Accumulation and persistence of medium chain length SPCs (C 6–C 8) along the experiments show that their degradation constitutes the limiting step for the process of LAS mineralization. In the final zone of the simulated estuarine system, the levels of SPCs were below the limits of detection. Thus, the disappearance of SPCs indicated that LAS biodegradation had been completed along the estuary. Similar results have been described for different Iberian littoral ecosystems. Therefore, the simulator employed in this research appears to be a useful tool to anticipate the behaviour of a xenobiotic chemical in its transit through littoral systems with different salinity gradients.

Determination of Sulfophenyl Carboxylic Acids in Agricultural Groundwater Samples by Liquid Chromatography with Fluorescence Detection

We have developed an analytical method to determine six sulfophenyl carboxylic acids (SPC) in agricultural groundwater samples. It involves a solid-phase extraction (SPE) procedure and subsequent separation and determination using liquid chromatography with fluorescence detection (LC–FD).The quantification limits ranged between 0.7 and 1.2 ng ml−1. The proposed method was proved satisfactorily for the detection and determination of these compounds in groundwater samples during a study into the biodegradation of linear alkylbenzene sulfonates (LAS) in an agricultural soil sampled from the irrigated plain to the west of Granada (Spain).

Degradation of linear alkylbenzene sulfonate by a bacterial consortium isolated from the aquatic environment of Argentina

To isolate and identify linear alkylbenzene sulfonate (LAS)-degrading bacteria from Río de la Plata and adjacent waters, and to assay their degradation capability as a consortium and as single organisms. A consortium consisting of four bacterial strains: Aeromonas caviae (two strains), Pseudomonas alcaliphila and Vibrio sp. was identified by 16S rRNA analysis. Isolates grown as a consortium produced higher biomass from LAS and CO(2) release (mineralization) than individual cultures, and degraded 86% of LAS (20 mg l(-1)), whereas pure strains degraded between 21% and 60%. Bacterial desulfonation from LAS was evidenced in the consortium and A. caviae strains. A complete disappearance of LAS (10 mg l(-1)) was accomplished, and LAS levels of 50 and 100 mg l(-1) led to a pronounced decrease in the biodegradation extent and inhibition of culture growth. A bacterial consortium capable of complete LAS degradation was isolated from the Río de la Plata and adjacent waters. This consortium was more efficient for LAS degradation than individual cultures, and was sensitive to high LAS concentrations. The autochthonous consortium with high effectiveness on LAS biodegradation is a useful tool for LAS depletion from these polluted ecosystems.

Determination of sulfophenyl carboxylic acids in agricultural groundwater samples by CE with ultraviolet absorption detection

An analytical method for the determination of six sulfophenyl carboxylic acids, namely (p-sulfophenyl)acetic, 2-(p-sulfophenyl)propionic, 2-(p-sulfophenyl)butyric, 3-(p-sulfophenyl)butyric, 4-(p-sulfophenyl)butyric, and 5-(p-sulfophenyl)valerianic acid, in agricultural irrigation water samples was developed. It involves an SPE procedure, an on-line preconcentration normal stacking mode and subsequent separation and determination using CE with UV detection (CE-UV). p-Sulfobenzoic acid was used as internal standard. The compounds were separated with an uncoated capillary and a 25 mM ammonium acetate/acetic acid buffer solution (pH 5.5) with 2-propanol (30% v/v) and 0.75 mM CTAB. Analyses were run at -25 kV, 25 degrees C, and 100 s of hydrodynamic injection with UV detection at 225 nm. Quantification limits found ranged between 4 and 6 ng/mL. The proposed method was validated using a recovery assay. It was satisfactorily used for the determination of these compounds in groundwater samples to track down the biodegradation of linear alkylbenzene sulfonates in an agricultural soil from the fertile plain of Granada (Spain).

On the complete aerobic microbial mineralization of linear alkylbenzene sulfonate

The xenobiotic organic compounds linear alkylbenzene sulfonates (LAS) are among the most thoroughly investigated with respect to biodegradability. Previous studies have shown that LAS are relatively rapidly degraded under aerobic conditions, but only very slowly or not at all degraded under anaerobic conditions. In the present work, the degree of primary and ultimate biodegradation of LAS by consortia of aerobic microorganisms was examined. The quantification of primary biodegradation was conducted via analysis of the LAS content inthe mixed liquor, which was based on microwave-assisted-extraction (MAE) followed by solid phase extraction with liquid chromatography coupled with a fluorescence detector (HPLC-FD). The ultimate biodegradability of LAS was examined by measuring both the disappearance of the test compound and the formation of carbon dioxide using the OECD method 301B or the sulphate. It was found that the established enriched mixed microbial population was capable for complete mineralization of all LAS, as verified by the sulfate production as well as the application of the OECD method and the carbon mass balances carried out throughout the course of the conducted experiments. In particular, any intermediate compound formed during LAS biodegradation was rapidly decomposed, making any intermediate accumulation temporal.