Juliana Kawanishi Braga

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

The removal and degradation of the nonionic surfactant linear alcohol ethoxylate (LAE)Genapol® C-100 in an anaerobic fluidized bed reactor were evaluated with 4.7 mg LAE/L to 107.4 mg LAE/L added to the synthetic substrate (535 ± 121 mg/L to 882 ± 126 mg/L of organic matter). High removal efficiencies of the COD (chemical oxygen demand) (88%) and LAE (98%) were observed even at high surfactant concentrations during the 492 days of operation. The absence of sucrose in the synthetic substrate modified the microbial community. Similarity coefficients between the phases with sucrose and without sucrose were 74% and 59% for the Archaea and Bacteria domains, respectively. The higher LAE removal (98%) was obtained for the 97.9 mg LAE/L influent in the absence of the co-substrate, as well as the greater diversity of volatile fatty acid. At the end of the reactor operation 2.05 mg of LAE was adsorbed in the biomass and 98.5% was biodegraded.

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.

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

ABSTRACT 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 (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.

Design and optimization of hydrogen production from hydrothermally pretreated sugarcane bagasse using response surface methodology

Hydrogen production from hydrothermally pretreated (200 °C for 10 min at 16 bar) sugarcane bagasse was analyzed using response surface methodology. The yeast extract concentration and the temperature had a significant influence for hydrogen production (p-value 0.027 and 0.009, respectively). Maximum hydrogen production (17.7 mmol/L) was observed with 3 g/L yeast extract at 60 °C (C10). In this conditions were produced acetic acid (50.44 mg/L), butyric acid (209.71 mg/L), ethanol (38.4 mg/L), and methane (6.27 mmol/L). Lower hydrogen productions (3.5 mmol/L and 3.9 mmol/L) were observed under the conditions C7 (2 g/L of yeast extract, 35.8 °C) and C9 (1 g/L of yeast extract, 40 °C), respectively. The low yeast extract concentration and low temperature caused a negative effect on the hydrogen production. By means of denaturing gradient gel electrophoresis 20% of similarity was observed between the archaeal population of mesophilic (35 and 40 °C) and thermophilic (50, 60 and 64 °C) reactors. Likewise, similarity of 22% was noted between the bacterial population for the reactors with the lowest hydrogen production (3.5 mmol/L), at 35.8 °C and with the highest hydrogen production (17.7 mmol/L) at 60 °C demonstrating that microbial population modification was a function of incubation temperature variation.

Robustness and Microbial Diversity of a Fluidized Bed Reactor Employed for the Removal and Degradation of an Anionic Surfactant from Laundry Wastewater

AbstractA fluidized bed reactor (FBR) was employed to evaluate the removal and degradation of linear alkylbenzene sulfonate (LAS) from laundry wastewater without supplementary feeding. After immobi...

Bacterial and archaeal community structure involved in biofuels production using hydrothermal and enzymatic pretreated sugarcane bagasse for hydrogen and methane improvement

Sugarcane bagasse (SCB) was used as a lignocellulosic substrate, combining the co-production of H2 (Stage I) and CH4 (Stage II) by a dark fermentation process in batch reactors. Hydrothermally- and enzymatic (Aspergillus niger)-pretreated SCB were applied as substrate sources. Two fermentative inocula (In1 and In2) were used in Stage I and a methanogenic inoculum in Stage II (In3), comprising in total three experimental series in relation to Stage I: A (In1), B (In1 plus In2), and C (In2). The final metabolites (solid, liquid, and gaseous fractions) from Stage I were used for CH4 production (Stage II). The SCB pretreatment employed was favorable for biogas and organic acids production. Higher H2 and CH4 yields were obtained in C (4.3 and 6.3 mmol g−1 SCB, respectively). For all conditions, the H2 production occurred primarily via an acetic acid route. The predominance of cellulolytic enzyme producers (Enterococcus and Clostridium) may have favored the H2 and subsequent CH4 production; this last was produced mainly from members of the Methanoregulaceae and Methanosaetaceae families. Furthermore, homoacetogenic bacteria (Acetobacterium, Clostridium, Eubacterium, Holophaga) were also identified in both stages. The synergistic action of these microbial groups promoted the hydrolysis of SCB as well as hydrogen and methane production.

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.