Treatment of linear alkylbenzene sulfonate in a horizontal anaerobic immobilized biomass reactor (original) (raw)
Related papers
2010
An anaerobic fluidized bed reactor was used to assess the degradation of the surfactant linear alkylbenzene sulfonate (LAS). The reactor was inoculated with sludge from an UASB reactor treating swine wastewater and was fed with a synthetic substrate supplemented with LAS. Sand was used as support material for biomass immobilization. The reactor was kept in a controlled temperature chamber (30±1 ºC) and operated with a hydraulic retention time (HRT) of 18 h. The LAS concentration was gradually increased from 8.2±1.3 to 45.8±5.4 mg.L -1 . The COD removal was 91%, on average, when the influent COD was 645±49 mg.L -1 . The results obtained by chromatographic analysis showed that the reactor removed 93% of the LAS after 270 days of operation.
2003
The anaerobic biodegradation of Linear Alkylbenzene Sulfonate (LAS) was studied in Upflow Anaerobic Sludge Blanket Reactors (UASB). One reactor was fed with easily degradable substrates and commercial LAS solution during a period of 3 months (Reactor 1), meanwhile a second reactor was fed with a commercial LAS solution without co-substrate (Reactor 2) during 4 months. Both reactors were operated with an organic loading rate of 4-5 mg-LAS/l * day and a hydraulic retention time of one day. The LAS biodegradation was determined by full mass balance. LAS was analysed by HPLC in the liquid phase (influent and effluent streams of the reactors) as well as in the solid phase (granular sludge used as biomass). The results indicate a high level of removal (primary biodegradation: 64-85%). Biodegradation was higher in the absence of external co-substrates than in the presence of additional sources of carbon. This indicates that the surfactant can be partially used as carbon and energy source by anaerobic bacteria. Under the operating conditions used, inhibition of the methanogenic activity or any other negative effects on the biomass due to the presence of LAS were not observed. The methanogenic activity remained high and stable throughout the experiment.
Journal of Environmental Management, 2009
Two horizontal-flow anaerobic immobilized biomass reactors (HAIB) were used to study the degradation of the LAS surfactant: one filled with charcoal (HAIB1) and the other with a mixed bed of expanded clay and polyurethane foam (HAIB2). The reactors were fed with synthetic substrate supplemented with 14 mg l−1of LAS, kept at 30 ± 2 °C and operated with a hydraulic retention time (HRT) of 12 h. The surfactant was quantified by HPLC. Spatial variation analyses were done to quantify organic matter and LAS consumption along the reactor length. The presence of the surfactant in the load did not affect the removal of organic matter (COD), which was close to 90% in both reactors for an influent COD of 550 mg l−1. The results of a mass balance indicated that 28% of all LAS added to HAIB1 was removed by degradation. HAIB2 presented 27% degradation. Molecular biology techniques revealed microorganisms belonging the uncultured Holophaga sp., uncultured delta Proteobacterium, uncultured Verrucomicrobium sp., Bacteroides sp. and uncultured gamma Proteobacterium sp. The reactor with biomass immobilized on charcoal presented lower adsorption and a higher kinetic degradation coefficient. So, it was the most suitable support for LAS anaerobic treatment.
Bioresource technology, 2014
The aim of this study was to evaluate the removal of linear alkylbenzene sulfonate (LAS) in an anaerobic fluidized bed reactor (AFBR) treating wastewater containing soap powder as LAS source. At Stage I, the AFBR was fed with a synthetic substrate containing yeast extract and ethanol as carbon sources, and without LAS; at Stage II, soap powder was added to this synthetic substrate obtaining an LAS concentration of 14 ± 3 mg L(-1). The compounds of soap powder probably inhibited some groups of microorganisms, increasing the concentration of volatile fatty acids (VFA) from 91 to 143 mg HAc L(-1). Consequently, the LAS removal rate was 48 ± 10% after the 156 days of operation. By sequencing, 16S rRNA clones belonging to the phyla Proteobacteria and Synergistetes were identified in the samples taken at the end of the experiment, with a remarkable presence of Dechloromonas sp. and Geobacter sp.
In this study, 454-pyrosequencing technique was employed to investigate the bacterial communities from a fluidized bed reactor (FBR) with sand as support material. This reactor was used for linear alkylbenzene sulfonate (LAS) removal from laundry wastewater. The FBR was inoculated with sludge from a UASB (upflow anaerobic sludge blanket) reactor used in the treatment of swine manure and was operated in two stages: I (23.6 10 mg/L of LAS and 691 103 mg/L of COD) and II (28 10 mg/L of LAS and 666 161 mg/L and COD), for hydraulic retention times (HRT) of 18 and 23 h, respectively. The biomass from the support material (S) and phase separator (PS) were analysed in both stages, with sucrose (S-I and PS-I) and without sucrose (S-II and PS-II) as co-substrate. Proteobacteria followed by Bacteroidetes was found to be the dominant phylum (higher relative abundance) in the samples from Stage I, and Proteobacteria and Gemmatimonadetes predominated in the samples from Stage II. The sucrose removal of synthetic substrate changed the microbial community since the similarity between that of Stages I and II was low. In the FBR biomass 22 genera related to LAS degradation were identified. The differences found between the samples indicated that it is likely that the treatment process had effects on the microbial structure.
Journal of Xenobiotics, 2011
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 (t½) 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: t½ increased to 3 days. The rates of biodegradation by the consortia can be ranked as: four-membered (t½=9 days) > three-membered (t½=9 to 13 days) > two-membered consortia (t½=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 pe...
Journal of Environmental Management, 2013
Linear alkylbenzene sulfonate (LAS) is an anionic surfactant used in cleaning products, which is usually found in wastewaters. Despite the greater LAS removal rate related to a lower concentrations of volatile fatty acids (VFA), the influence of different ranges of VFA on LAS degradation is not known. LAS degradation was evaluated in upflow anaerobic sludge blanket (UASB) and expanded granular sludge bed (EGSB) reactors at different ranges of VFA concentrations. The reactors were fed with a synthetic wastewater containing LAS (14 mg/L). A greater LAS removal rate (40e80%) was related to the lower and narrower range of acetic acid concentration (1e22 mg/L) in the EGSB reactor. In the UASB reactor, the acetic acid concentrations presented a wider range (2e45 mg/L), and some low LAS removal rates (around 20e25%) were observed even at low acetic acid concentrations (<10 mg/L). The high recirculation rate in the EGSB reactor improved substrate-biomass contact, which resulted in a narrower range of VFA and greater LAS removal rate.
DESALINATION AND WATER TREATMENT, 2017
Linear alkylbenzene sulphonate (LAS) is widely used for household and industrial purposes while influencing negatively on the environment. Present paper aimed to study LAS biodegradation among different loading rates and fate of LAS in integrated fixed-film activated sludge (IFAS) using synthetic media. A synthetic wastewater among three LAS loading rates with LAS concentrations of 5, 12 and 20 mg/L was investigated within an operative period of 111 d. In doing so, a kinetic model was developed to explain the biodegradation rate of LAS. Finally, the obtained data were analyzed by analysis of variance statistical test. The mean removal efficiency of LAS among three LAS loading rates were 92.32% ± 2.81%, 95.55% ± 2.74% and 96.22% ± 2.74%, respectively. Nevertheless, in terms of total removal efficiency of LAS, the contributions of LAS biosorption in sludge among the three LAS loading rates were 21.3%, 34.2% and 48.5%. The mean removal efficiency of chemical oxygen demand (COD) in among three LAS loading rates were 92.17% ± 4.32%, 91.53% ± 3.34% and 90.91% ± 2.98%, respectively. Moreover, the higher LAS loading rate, the higher removal efficiency of LAS (p ≤ 0.001) and the lower COD removal efficiency (p ≤ 0.001). The results of Michaelis-Menten model for biodegradation kinetics showed that the LAS biodegradation follows the first-order reaction kinetics (R 2 = 0.9949). In addition, biodegradation kinetic and removal efficiency of LAS showed that following the increased concentration of LAS among different loading rates, the LAS biodegradation rate was increased. Therefore, IFAS system is argued to be applicable for wastewater treatment in low and high concentrations of LAS up to 20 mg/L.
Anionic surfactants, the earliest and the most common surfactants in detergent and cosmetic product formulations contribute significantly to the pollution profile of the ecosystem. Linear alkylbenzene sulfonates (LAS), a major chemical constituent of detergents, forms an imperative group of anionic surfactants. Bioremediation of LAS by conventional processes such as activated sludge is ineffective due to the low kinetics of degradation by unsuitable organisms and foam production. Hence this study was focused on isolating and characterizing indigenous LASdegrading bacteria from soil. Twenty different LASdegrading bacteria were isolated from detergentcontaminated soil by enrichment culture technique and degradation efficiency was assessed by Methylene Blue Active Substances (MBAS) assay and by reverse-phase high-performance liquid chromatography (HPLC) analysis. The most efficient LASdegrading isolates, L9 (81.33±0.7) and L12 (81.81± 0.8), were selected and identified as Pseudomonas nitroreducens (MTCC 10463) and Pseudomonas aeruginosa (MTCC 10462). The 16S rDNA sequences of the isolates were deposited in NCBI GenBank under the accession numbers HQ 271083 (L9) and HQ 271084 (L12). The isolates were capable of degrading 0.05 g/l LAS at 25 °C and pH 7.0–7.5. Presence of a solid support caused biofilm formation which in turn enhanced LAS degradation. The isolates tend to display diauxic growth with alternate carbon source such as dextrose. These isolates also have the capability to degrade other xenobiotics like hydrocarbons and pesticides. Since xenobiotic pollutants in nature occur as a mixture of compounds rather than single pollutants, the potential of these two indigenous LAS-degrading isolates to degrade multiple xenobiotics gains relevance. Keywords Biodegradation . Methylene Blue Active
Chemosphere, 2006
The degradation of linear alkylbenzene sulfonates and their degradation intermediates (sulfophenylcarboxylic acids) has been characterized at 9°C in an activated sludge pilot plant. After an adequate adaptation period (20 days), LAS primary degradation exceeds 99% and takes place preferentially for long alkyl chain homologues and external isomers. LAS homologues in the reactor are preferentially sorbed onto particulate matter, while sulfophenylcarboxylic acids (SPCs) are present predominantly in solution, due to their lower hydrophobicity. During the adaptation period the most abundant LAS biodegradation intermediates were long chain sulfophenylcarboxylic acids (SPCs) (C 9 -C 13 SPC). However once this system is fully adapted, the microorganisms are capable of degrading SPCs efficiently. SPCs with 7-9 carbon atoms in the carboxylic chain predominate due to their degradation being slower than for the rest of the SPCs. The presence of C 13 SPC confirms that LAS degradation in wastewater starts with a x-oxidation on the alkylic chain. A preferential degradation of SPC isomers of the types 2/C n SPC to 6/C n SPC was also detected, as shown by the relatively higher SPC concentrations of the remaining ones.