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Llado S.,University of Barcelona | Gracia E.,University of Barcelona | Solanas A.M.,University of Barcelona | Vinas M.,GIRO Joint Research Unit IRTA UPC
Soil Biology and Biochemistry | Year: 2013

The application of bioremediation technologies to polycyclic aromatic hydrocarbon (PAH)-contaminated soils does not remove the excess of the high-molecular-weight fraction (HMW-PAHs), as has been widely reported. Taking into account the metabolic capacities of white-rot fungi, their bioaugmentation has been extensively assayed on polluted soils, but with controversial results.The aim of this study is to gain insight into how fungal bioaugmentation assays affect both PAH degradation and autochthonous microbial populations in a previously biotreated aged creosote-polluted soil contaminated with HMW-PAHs. To this end, we performed a set of slurry bioassays encompassing different biostimulation and bioaugmentation strategies.The results show that the autochthonous microbial populations degraded PAHs the most; specifically, the 4-ring PAHs under carbon-limiting conditions (26% and 28% degradation for benzo(a)anthracene and chrysene respectively). Although Trametes versicolor amendment produced the highest depletion of benzo(b+. k)fluoranthene and benzo(a)pyrene concentrations in an autoclaved soil, it did not improve either the 4-ring or the 5-ring PAH degradation, when active native PAH-degrading microbiota was present. Microbial community analysis of fungal and eubacterial populations, based on the 16SrRNA gene and ITS1 region respectively, revealed that the ribotypes closely related to the eubacterial genera Chryseobacterium, Pusillimonas and Sphingobium, that are concomitant with the autochthonous fungal genus Fusarium, could be important in HMW-PAH degradation processes in polluted soils.Antagonistic effects or resource competition resulting from the effects of active native soil microbiota on augmented white-rot fungi should be evaluated in polluted soil before scaling up the remediation process to field scale. © 2013 Elsevier Ltd. Source

Llado S.,University of Barcelona | Solanas A.M.,University of Barcelona | de Lapuente J.,Unitat de Toxicologia Experimental i Ecotoxicologia | Borras M.,Unitat de Toxicologia Experimental i Ecotoxicologia | Vinas M.,GIRO Joint Research Unit IRTA UPC
Science of the Total Environment | Year: 2012

A diversified approach involving chemical, microbiological and ecotoxicity assessment of soil polluted by heavy mineral oil was adopted, in order to improve our understanding of the biodegradability of pollutants, microbial community dynamics and ecotoxicological effects of various bioremediation strategies. With the aim of improving hydrocarbon degradation, the following bioremediation treatments were assayed: i) addition of inorganic nutrients; ii) addition of the rhamnolipid-based biosurfactant MAT10; iii) inoculation of an aliphatic hydrocarbon-degrading microbial consortium (TD); and iv) inoculation of a known hydrocarbon-degrading white-rot fungus strain of Trametes versicolor. After 200. days, all the bioremediation assays achieved between 30% and 50% total petroleum hydrocarbon (TPH) biodegradation, with the T. versicolor inoculation degrading it the most. Biostimulation and T. versicolor inoculation promoted the Brevundimonas genus concurrently with other α-proteobacteria, β-proteobacteria and Cytophaga-Flexibacter-Bacteroides (CFB) as well as Actinobacteria groups. However, T. versicolor inoculation, which produced the highest hydrocarbon degradation in soil, also promoted autochthonous Gram-positive bacterial groups, such as Firmicutes and Actinobacteria. An acute toxicity test using Eisenia fetida confirmed the improvement in the quality of the soil after all biostimulation and bioaugmentation strategies. © 2012 Elsevier B.V. Source

Pitk P.,Tallinn University of Technology | Kaparaju P.,University of Jyvaskyla | Palatsi J.,GIRO Joint Research Unit IRTA UPC | Affes R.,GIRO Joint Research Unit IRTA UPC | Vilu R.,Tallinn University of Technology
Bioresource Technology | Year: 2013

The rendering product of Category 2 and 3 Animal By-Products is known as sterilized mass (SM) and it is mainly composed of fat and proteins, making it interesting substrate for anaerobic digestion. Batch and semi-continuous laboratory experiments were carried out to investigate the effect of SM addition in co-digestion with sewage sludge on methane production and possible process limitations. Results showed that SM addition in the feed mixture up to 5%(w/w), corresponding to 68.1% of the organic loading, increased methane production 5.7 times, without any indication of process inhibition. Further increase of SM addition at 7.5%(w/w) caused methane production decrease and volatile solids removal reduction, that was mainly related to remarkably increased free ammonia concentration in the digester of 596.5±68.6gNH3L-1. Sterilized mass addition of 10%(w/w) caused intensive foaming, LCFA accumulation of 9172±701.2mgCOD-LCFAg-1 sample and termination of the experiment. © 2013 Elsevier Ltd. Source

Zonta T.,GIRO Joint Research Unit IRTA UPC | Zonta T.,Polytechnic University of Catalonia | Alves M.M.,IBB Institute for Biotechnology And Bioengineering | Flotats X.,GIRO Joint Research Unit IRTA UPC | And 2 more authors.
Water Research | Year: 2013

Mathematical modelling of anaerobic digestion process has been used to give new insights regarding dynamics of the long chain fatty acids (LCFA) inhibition. Previously published experimental data, including batch tests with clay mineral bentonite additions, were used for parameter identification. New kinetics were considered to describe the bio-physics of the inhibitory process, including: i) adsorption of LCFA over granular biomass and ii) specific LCFA substrate (saturated/unsaturated) and LCFA-degrading populations. Furthermore, iii) a new variable was introduced to describe the state of damage of the acetoclastic methanogens in order to account for the loss of cell-functionality (inhibition) induced by the adsorbed LCFAs. The proposed model modifications are state compatible and easy to be integrated into the International Water Association's Anaerobic Digestion Model N°1 (ADM1) framework. Practical identifiability of model parameters was assessed with a global sensitivity analysis, while calibration and model structure validation were performed on independent data sets. A reliable simulation of the LCFA-inhibition process can be achieved, if the model includes the description of the adsorptive nature of the LCFAs and the LCFA-damage over specific biomass. The importance of microbial population structure (saturated/unsaturated LCFA-degraders) and the high sensitivity of acetoclastic population to LCFA are evidenced, providing a plausible explanation of experimental based hypothesis. © 2012 Elsevier Ltd. Source

Silvestre G.,GIRO Joint Research Unit IRTA UPC | Illa J.,University of Lleida | Fernandez B.,GIRO Joint Research Unit IRTA UPC | Bonmati A.,GIRO Joint Research Unit IRTA UPC
Applied Energy | Year: 2014

Thermophilic co-digestion of sewage sludge with three different doses of trapped grease waste (GW) from the pre-treatment of a WWTP has been assessed in a CSTR bench-scale reactor. After adding 12% and 27% of grease waste (on COD basis), the organic loading rate increased from 2.2 to 2.3 and 2.8kgCODm-3d-1 respectively, and the methane yield increased 1.2 and 2.2 times. Further GW increase (37% on COD basis) resulted in an unstable methane yield and in long chain fatty acids (LCFA) accumulation. Although this inestability, the presence of volatile fatty acids in the effluent was negligible, showing good adaptation to fats of the thermophilic biomass. Nevertheless, the presence of LCFA in the effluent worsens its dewatering properties. Specific methanogenic activity tests showed that the addition of grease waste ameliorates the acetoclastic activity in detriment of the hydrogenotrophic activity, and suggests that the tolerance to LCFA can be further enhanced by slowly increasing the addition of lipid-rich materials. © 2013 Elsevier Ltd. Source

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