Degradation of high concentrations of nonionic surfactant (linear alcohol ethoxylate) in an anaerobic fluidized bed reactor

Microbial synergies drive simultaneous biodegradation of ethoxy and alkyl chains of Nonylphenol Ethoxylate in fluidized bed reactors

The widely-used surfactant Nonylphenol Ethoxylate (NPEO) produces endocrine-disrupting compounds during biodegradation, with these byproducts being more harmful than untreated NPEO. This study investigates the effectiveness of a Fluidized Bed Reactor (FBR) in reducing the production of 4-Nonylphenol (4-NP) during the biodegradation of NPEO. Two identical FBR filled with sand were used to assess the NPEO degradation and to enhance the microbial consortia capable of breaking down the complex byproducts, ethanol and fumarate were introduced as co-substrates. Our findings demonstrate the significant potential of the FBR, especially when coupled with fumarate, for enhancing the surfactant degradation. It outperforms the efficiency achieved with ethanol as the primary electron donor, albeit with a higher rate of byproduct production. Microbial community taxonomy and metabolic prediction revealed the high abundance of Geobacter (1.51-31.71%) and Methanobacterium (1.08-13.81%) in non-conductive sand. This may hint a new metabolic interaction and expand our understanding of Direct Interspecies Electron Transfer (DIET) in bioreactors applied to micropollutants degradation. Such an intricate relationship between facultative and anaerobes working together to simultaneously biodegrade the ethoxy and alkyl chains presents a new perspective on NPEO degradation and can potentially be extended to other micropollutants.

Transcriptomic changes in barley leaves induced by alcohol ethoxylates indicate potential pathways of surfactant detoxification

Hardly anything is known regarding the detoxification of surfactants in crop plants, although they are frequently treated with agrochemical formulations. Therefore, we studied transcriptomic changes in barley leaves induced in response to spraying leaf surfaces with two alcohol ethoxylates (AEs). As model surfactants, we selected the monodisperse tetraethylene glycol monododecyl (C12E4) ether and the polydisperse BrijL4. Barley plants were harvested 8 h after spraying with a 0.1% surfactant solution and changes in gene expression were analysed by RNA-sequencing (RNA-Seq). Gene expression was significantly altered in response to both surfactants. With BrijL4 more genes (9724) were differentially expressed compared to C12E4 (6197). Gene families showing pronounced up-regulation were cytochrome P450 enzymes, monooxygenases, ABC-transporters, acetyl- and methyl- transferases, glutathione-S-transferases and glycosyltransferases. These specific changes in gene expression and the postulated function of the corresponding enzymes allowed hypothesizing three potential metabolic pathways of AE detoxification in barley leaves. (i) Up-regulation of P450 cytochrome oxidoreductases suggested a degradation of the lipophilic alkyl residue (dodecyl chain) of the AEs by ω- and β- oxidation. (ii) Alternatively, the polar PEG-chain of AEs could be degraded. (iii) Instead of surfactant degradation, a further pathway of detoxification could be the sequestration of AEs into the vacuole or the apoplast (cell wall). Thus, our results show that AEs lead to pronounced changes in the expression of genes coding for proteins potentially being involved in the detoxification of surfactants.

Complete biodegradability assessment of polyoxyethylene glycerol ester non-ionic surfactant: Aerobic, anaerobic, combined biodegradation and inhibitory effects

Aerobic and anaerobic biodegradability have become one of the most relevant characteristics for all contaminants. This is especially important in case of surfactants, which are discharged in wastewater treatment plants or directly into the aquatic bodies. The aim of this study is the integral assessment of the biodegradability of the non-ionic surfactant polyoxyethylene glycerol ester PGE-OE17. The aerobic and anaerobic biodegradation of PGE-OE17 was evaluated at different initial surfactant concentrations, and the evolution of the toxicity of the surfactant and its by-products was followed during the aerobic and anaerobic processes using bacteria Vibrio fischeri. PGE-OE17 was not completely biodegradable neither aerobically nor anaerobically, and the increase in the initial surfactant concentration had a negative effect in the biodegradation. Toxicity of the surfactant solutions and degradation by-products had a first increase followed by a gradual decrease during both tests, revealing that toxic substances released can harm the microorganisms and therefore hinder the biodegradation. Additionally, combined aerobic-anaerobic biodegradation tests were performed, consisting in a first aerobic treatment of different duration and initial concentration, followed by a complete anaerobic treatment. Results showed that a balance between aerobic and anaerobic biodegradation duration can maximize the biodegradation rates in comparison with only aerobic or anaerobic tests.

Potential methanogenic and degradation of nonylphenol ethoxylate from domestic sewage: unravelling the essential roles of nutritional conditions and microbial community

Nonylphenol ethoxylathe (NPEO) is a non-ionic surfactant of increasing concern, used in the formulation of laundry detergents and is frequently found in aquatic environments. The purpose of this study was to evaluate the effects of yeast extract (YE) and sodium fumarate (SF) in NPEO removal from domestic sewage under anaerobic conditions via central composite rotatable design (CCRD) and response surface methodology (RSM). Experiments were designed by varying concentrations of NPEO (1.6-5.8 mg L^-1), YE (131.8-468.2 mg L^-1) and SF (97.7-602.3 mg L^-1) in batch reactors. SF and YE addition significantly influenced NPEO removal and CH₄ production. Optimal values of YE (400 mg L^-1) and SF (200 mg L^-1) result in removal efficiency of 97% for 5 mg L^-1 of NPEO, being mostly removed by biodegradation (86%). Meanwhile COD removal was 95% and methane yield was 134 ± 4 NmLCH₄ g^-¹COD_removed. The most abundant Bacteria genus identified were Macellibacteroides, Longilinea, Petrimonas and Proteiniphilum, while for Archaea, Methanosaeta and Methanoregula were the genera identified in higher relative abundances in optimized conditions.

Rapid determination of three textile surfactants in environmental samples by modeling excitation-emission second-order data with multi-way calibration methods

The textile industry is an important potential source of environmental pollution due to the use of chemical products. Dyes, hydrolyzed dyes, and surfactants, among others, are chemical compounds present in wastewater of textile plant. Moreover, the anionic surfactants have toxic effects for various aquatic organisms even in low concentrations. The methodologies investigated to quantify surfactants, in general, consume a lot of analysis time and frequently use toxic or environmentally objectionable reagents. For these reasons, the objective of this work was to develop a quick and simple method to quantify surfactants without the use of expensive reagents and equipment, avoiding extraction and preconcentration stages. The proposed method is based on fluorescent spectroscopy measurements for the acquisition of second-order data in excitation-emission matrices and multivariate calibration techniques applied to the data. The unfolded partial least squares combined to residual bilinearization (U-PLS/RBL) algorithm was better than parallel factor analysis (PARAFAC). U-PLS/RBL accurately quantified alkylnonylphenolethoxylated (APEO), dodecylbenzenesulfonic acid (ADBS), and 2-phenoxy-ethoxylated fatty alcohol (AGFE) surfactants. The chemometric model obtained good analytical figures of merit: REP% between 5 and 13 and LOQ between 0.45 and 2.77 μg mL^-1. This methodology had no significant difference compared with results obtained by a HPLC-FD reference technique, in addition with a considerable reduction in analysis time, reagent consumption, and therefore lower cost. For environmental applications, APEO, ADBS, and AGFE were quantify in textile wastewater treatment and in the receiving water body. The concentrations varied from 8.73 to 73.94 μg mL^-1 in the textile wastewater and were not detected in the receiving water body.

Water pathways through the ages: Integrated laundry wastewater treatment for pollution prevention

Rapid urbanization and the rising global population have led to the generation of substantial volumes of laundry wastewater. Accordingly, treatment of laundry wastewater has been advocated to curb water pollution and achieve water sustainability. However, technological limitations in treating (specifically) laundry wastewater and the lack of regulations governing the levels of contaminants for such discharges have been perennial problems. This review bridges the knowledge gap by delineating the feasibility of current technologies in laundry wastewater treatment and the experiences of various countries in adopting different approaches. Besides, the feasible methods for collecting laundry wastewater are elaborated. The development of the treatment technologies is highlighted, in which the integrated-treatment processes (physicochemical, biological, and combination of both) are critically discussed based on their functions and methods. A judicious selection of the technologies not only improves the energy efficiency and quality of the treated wastewater, but also mitigates capitals and operational costs. This is projected to enhance public acceptance towards the reuse of laundry wastewater. Thus, the comprehensive assessment herein is envisioned to insightfully guide national policymakers in exploring the viability of the technologies and water-recycling projects. Future research should focus on the techno-economic aspects of the treatment processes, especially their industrial scale-up.

4-Nonylphenol degradation changes microbial community of scale-up Anaerobic Fluidized Bed Reactor

Nonylphenol Ethoxylate (NPe) is a nonionic surfactant widely applied in domestic and industrial uses and its degradation generates the endocrine disruptor 4-Nonylphenol (4-NP). The effects of this compound in biological sewage treatment are uncertain, especially in anaerobic systems. The aim of this study was to assess the 4-NP removal and degradation in scale-up (20 L) Anaerobic Fluidized Bed Reactor (AFBR) filled with sand as support material, operated with Hydraulic Retention Time (HRT) of 18 h, fed with synthetic sewage plus 4-NP, performed in four phases named Phase I (894 mg COD L^-1), Phase II (878 mg COD L^-1, 127 μg 4-NP L^-1), Phase III (940 mg COD L^-1, 270 μg 4-NP L^-1) and Phase IV (568 mg COD L^-1, 376 μg 4-NP L^-1). 4-NP did not affect reactor stability and organic matter removal remained stable at 94%. Highest 4-NP removal (78%) occurred for highest 4-NP influent (Phase IV), which resulted from biomass adaptation in the presence of ethanol. Through the 4-NP total mass balance, about 70% was biodegraded and 1% adsorbed on the sand bed. 4-NP addition promoted selection of microbial consortium strongly linked to aromatic compounds and surfactants degradation such as Geothrix, Holophaga, Aeromonas, Pelobacter, Pseudomonas, Delftia.

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.

Alcohol ethoxylates significantly synergize pesticides than alkylphenol ethoxylates considering bioactivity against three pests and joint toxicity to Daphnia magna

Seeking alternatives for alkylphenol ethoxylates (APEOs) have been a heavily researched topic in the surfactant industry and agricultural systems. In this study, the combined effects of different ethoxylates and pesticides on the bioactivity against three pests and toxicological risks to Daphnia magna were investigated. Results showed that alcohol ethoxylates (AEOs) had higher synergistic effects on the bioactivity of pesticides against Spodoptera exigua, Agrotis ipsilon and Aphis citricola than did APEOs. In terms of the joint toxicity of the ethoxylates and pesticides to D. magna, additive index method, toxicity unit method, V value method and isobologram method were used in the tests. All of these methods indicated that the joint effects of APEOs + acetamiprid and APEOs + indoxacarb upon D. magna turned from synergism to antagonism with the increasing EO (ethylene oxide) numbers. Those of AEOs exhibited similar trends. Overall, AEOs may be potential alternatives for APEOs in agriculture as they synergize pesticides against three pests significantly more than do APEOs. However, further research should investigate the compounds' environmental risks to aquatic organisms because the AEOs were highly toxic to D. magna.

Metabolic routes involved in the removal of linear alkylbenzene sulfonate (LAS) employing linear alcohol ethoxylated and ethanol as co-substrates in enlarged scale fluidized bed reactor

In this study, the microbial community characterization and metabolic pathway identification involved in the linear alkylbenzene sulfonated (LAS) degradation from commercial laundry wastewater in a fluidized bed reactor (FBR) on an increased scale were performed using the Illumina MiSeq platform. Ethanol and non-ionic surfactant (LAE, Genapol C-100) were used as co-substrates. The FBR was operated in five operational phases: (I) synthetic substrate for inoculation; (II) 7.9 ± 4.7 mg/L LAS and 11.7 ± 6.9 mg/L LAE; (III) 19.4 ± 12.9 mg/L LAS, 19.6 ± 9.2 mg/L LAE and 205 mg/L ethanol; (IV) 25.9 ± 11 mg/L LAS, 19.5 ± 9.1 mg/L LAE and 205 mg/L ethanol and (V) 43.9 ± 18 mg/L LAS, 25 ± 9.8 mg/L LAE and 205 mg/L ethanol. At all operation phases, organic matter was removed from 40.4 to 85.1% and LAS removal was from 24.7 to 56%. Sulfate-reducing bacteria (SRB) were identified in the biofilm of FBR in all operational phases. Although the LAS promoted a toxic effect on the microbiota, this effect can be reduced when using biodegradable co-substrates, such as ethanol and LAE, which was observed in Phase IV. In this phase, there was a greater microbial diversity (Shannon index) and higher microorganism richness (Chao 1 index), both for the Domain Bacteria, and for the Domain Archaea.

Simultaneous determination of anionic and nonionic surfactants in commercial laundry wastewater and anaerobic fluidized bed reactor effluent by online column-switching liquid chromatography/tandem mass spectrometry

This study presents a new method developed for the simultaneous determination of anionic surfactant (linear alkylbenzene sulfonate - LAS, 4 homologs) and nonionic surfactant (linear alcohol ethoxylate - LAE) in commercial laundry wastewater. The surfactants were identified and quantified using online column-switching solid-phase extraction (SPE) coupled with liquid chromatography/tandem mass spectrometry (LC-MS/MS). Ten and three transitions (m/z) were identified for LAS and LAE, respectively. The detection and quantification limits were 75 and 200μg/L for LAS, respectively, and 75μg/L for LAE. This method was applied to the determination of the surfactants in the influent and effluent of an anaerobic fluidized bed reactor that was used for the treatment of commercial laundry wastewater. After 480days of operation with a hydraulic retention time (HRT) of 18h, the removal of 45.9±5.6% LAS and 99.2±4.3% LAE from an influent with surfactant concentrations of 26.1±12.9mg/L and 23.8±6.8mg/L, respectively, was obtained. Under these conditions, the breakage of longer-chain LAS homologs with the release of carbon units was observed with an increase in the number of shorter homolog chains. This SPE online sample treatment method is simple, fast and effective for the analysis of both surfactants. This technique is pioneering in its simultaneous measurement of two surfactant categories in anaerobic fluidized bed reactors.

Efficient methanogenic degradation of alcohol ethoxylates and microbial community acclimation in treatment of municipal wastewater using a submerged anaerobic membrane bioreactor

The effect of alcohol ethoxylates on the treatment of municipal wastewater by a submerged anaerobic membrane bioreactor was investigated by a 400days operation including the treatment efficiency, methanogenic activity of sludge and microbial community structure. The results indicated that alcohol ethoxylates (5.0-200mg/L) was efficiently degraded and converted into methane due to the similar COD removal 95.5-98.8% and rising biogas production rate (2.30-4.25L/d) compared with control (96.8% and 2.55L/d). The microbes in sludge could copy with the presence of alcohol ethoxylates in wastewater by releasing more SMP and EPS, which caused a higher membrane fouling rate. Moreover, via long term acclimation, the specific methanogenic activity of sludge was greatly enhanced due to the changes of microbial community structure. Hence, the sludge self-acclimation to alcohol ethoxylates was responsible to the efficient methane recovery in treatment of municipal wastewater.

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

This 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 (k₁^app) 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.

Micelles as Soil and Water Decontamination Agents

Contaminated soil and water pose a serious threat to human health and ecosystem. For the treatment of industrial effluents or minimizing their detrimental effects, preventive and remedial approaches must be adopted prior to the occurrence of any severe environmental, health, or safety hazard. Conventional treatment methods of wastewater are insufficient, complicated, and expensive. Therefore, a method that could use environmentally friendly surfactants for the simultaneous removal of both organic and inorganic contaminants from wastewater is deemed a smart approach. Surfactants containing potential donor ligands can coordinate with metal ions, and thus such compounds can be used for the removal of toxic metals and organometallic compounds from aqueous systems. Surfactants form host-guest complexes with the hydrophobic contaminants of water and soil by a mechanism involving the encapsulation of hydrophobes into the self-assembled aggregates (micelles) of surfactants. However, because undefined amounts of surfactants may be released into the aqueous systems, attention must be paid to their own environmental risks as well. Moreover, surfactant remediation methods must be carefully analyzed in the laboratory before field implementation. The use of biosurfactants is the best choice for the removal of water toxins as such surfactants are associated with the characteristics of biodegradability, versatility, recovery, and reuse. This Review is focused on the currently employed surfactant-based soil and wastewater treatment technologies owing to their critical role in the implementation of certain solutions for controlling pollution level, which is necessary to protect human health and ensure the quality standard of the aquatic environment.

Natural Gas Residual Fluids: Sources, Endpoints, and Organic Chemical Composition after Centralized Waste Treatment in Pennsylvania

Volumes of natural gas extraction-derived wastewaters have increased sharply over the past decade, but the ultimate fate of those waste streams is poorly characterized. Here, we sought to (a) quantify natural gas residual fluid sources and endpoints to bound the scope of potential waste stream impacts and (b) describe the organic pollutants discharged to surface waters following treatment, a route of likely ecological exposure. Our findings indicate that centralized waste treatment facilities (CWTF) received 9.5% (8.5 × 10(8) L) of natural gas residual fluids in 2013, with some facilities discharging all effluent to surface waters. In dry months, discharged water volumes were on the order of the receiving body flows for some plants, indicating that surface waters can become waste-dominated in summer. As disclosed organic compounds used in high volume hydraulic fracturing (HVHF) vary greatly in physicochemical properties, we deployed a suite of analytical techniques to characterize CWTF effluents, covering 90.5% of disclosed compounds. Results revealed that, of nearly 1000 disclosed organic compounds used in HVHF, only petroleum distillates and alcohol polyethoxylates were present. Few analytes targeted by regulatory agencies (e.g., benzene or toluene) were observed, highlighting the need for expanded and improved monitoring efforts at CWTFs.

Biological sulphide removal from anaerobically treated domestic sewage: reactor performance and microbial community dynamics

We developed a biological sulphide oxidation system and evaluated two reactors (shaped similar to the settler compartment of an up-flow anaerobic sludge blanket [UASB] reactor) with different support materials for biomass retention: polypropylene rings and polyurethane foam. The start-up reaction was achieved using microorganisms naturally occurring on the open surface of UASB reactors treating domestic wastewater. Sulphide removal efficiencies of 65% and 90% were achieved with hydraulic retention times (HRTs) of 24 and 12 h, respectively, in both reactors. However, a higher amount of elemental sulphur was formed and accumulated in the biomass from reactor 1 (20 mg S(0) g(-1) VTS) than in that from reactor 2 (2.9 mg S(0) g(-1) VTS) with an HRT of 24 h. Denaturing gradient gel electrophoresis (DGGE) results revealed that the the pink and green biomass that developed in both reactors comprised a diverse bacterial community and had sequences related to phototrophic green and purple-sulphur bacteria such as Chlorobium sp., Chloronema giganteum, and Chromatiaceae. DGGE band patterns also demonstrated that bacterial community was dynamic over time within the same reactor and that different support materials selected for distinct bacterial communities. Taken together, these results indicated that sulphide concentrations of 1-6 mg L(-1) could be efficiently removed from the effluent of a pilot-scale UASB reactor in two sulphide biological oxidation reactors at HRTs of 12 and 24 h, showing the potential for sulphur recovery from anaerobically treated domestic wastewater.

Microbial characterization and degradation of linear alkylbenzene sulfonate in an anaerobic reactor treating wastewater containing soap powder

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.