Performance and bacterial community shifts during phosphogypsum biotransformation

Phosphogypsum (PG) is an industrial waste composed mainly by sulfate, turning it a suitable sulfate source for sulfate-reducing bacteria (SRB). In the present work, the capability of two SRB communities, one enriched from Portuguese PG (culture PG) and the other from sludge from a wastewater treatment plant (culture WWT-1), to use sulfate from PG was compared. In addition, the impact of this sulfate-rich waste in the microbial community was assessed. The highest efficiency in terms of sulfate reduction was observed with culture WWT-1. The bacterial composition of this culture was not significantly affected when sodium sulfate from the nutrient medium was replaced by PG as a sulfate source. Next generation sequencing (NGS) showed that this community was phylogenetically diverse, composed by bacteria affiliated to Clostridium, Arcobacter, and Sulfurospirillum genera and by SRB belonging to Desulfovibrio, Desulfomicrobium, and Desulfobulbus genera. In contrast, the bacterial structure of the community enriched from PG was modified when sodium sulfate was replaced by PG as the sulfate source. This culture, which showed the poorest performance in the use of sulfate from PG, was mainly composed by SRB related to Desulfosporosinus genus. The present work provides new information regarding the phylogenetic characterization of anaerobic bacterial communities with the ability to use PG as sulfate donor, thus, contributing to improve the knowledge of microorganisms suitable to be used in PG bioremediation. Additionally, this paper demonstrates that an alternative to lactate and low-cost carbon source (wine wastes) can be used efficiently for that purpose

Structural characterization of mechanically alloyed nanocrystalline Cu-Fe: Strain broadening due to dislocations

Nanocrystalline Cu(Fe) solid solution was successfully synthesized by using high-energy mechanical milling. The structural and morphological changes during mechanical milling were investigated by X-ray diffraction and scanning electron microscopy. The patterns so obtained were analyzed using the X’Pert High Score Plus program. The final product of the mechanical alloying process was nanocrystalline FCC Cu(Fe) solid solution with a mean crystallite size in the range of few nanometers. The final microstructure, especially the high levels of lattice strains was explained by the presence of dislocations, with a dislocation density of about 7.4×1016 m−2. The identified steady-state saturation values of these parameters can be related to accumulate strain hardening of the powder material during longer milling times

Structural characterization of mechanically alloyed nanocrystalline Cu-Fe: Strain broadening due to dislocations

Nanocrystalline Cu(Fe) solid solution was successfully synthesized by using high-energy mechanical milling. The structural and morphological changes during mechanical milling were investigated by X-ray diffraction and scanning electron microscopy. The patterns so obtained were analyzed using the X’Pert High Score Plus program. The final product of the mechanical alloying process was nanocrystalline FCC Cu(Fe) solid solution with a mean crystallite size in the range of few nanometers. The final microstructure, especially the high levels of lattice strains was explained by the presence of dislocations, with a dislocation density of about 7.4×1016 m−2. The identified steady-state saturation values of these parameters can be related to accumulate strain hardening of the powder material during longer milling times

Structural characterization and Mössbauer studies of nanocrystalline Fe60Ni20Cr10B10 alloy prepared by high energy ball milling

International audienceNanostructured Fe(Ni,Cr) and NiFe solid state powders were elaborated from elemental powders of Fe, Ni, Cr and B using planetary high-energy ball mill. Scanning electron microscopy (SEM) was employed to examine the morphology of the powdered samples as a function of milling time. The transformations occurring in the material during milling were studied at the atomic scale with the use of X-ray diffraction and 57Fe Mössbauer spectrometry. The thermal behavior of the milled powders was examined by differential scanning calorimetry (DSC). The results, as well as dissimilarity between calorimetric curves of the powders after 10 and 50 h of milling, indicated the formation of a nanostructured Fe(Ni,Cr) and NiFe solid solutions

Study of the nanocrystalline bulk Al alloys synthesized by high energy mechanical milling followed by room temperature high pressing consolidation

AbstractIn the present study high energy mechanical milling followed by high-pressing consolidation has been used to obtain bulk nanocrystalline Al-Fe-Si alloy. Quantitative XRD analysis and scanning electron microscopy were used to characterize the material evolution during thermal treatments in the temperature range 25–500∘C. The cold-worked structure have been synthesized with microstructure showing a mixture of a significant low size of crystallite (70 nm) and a high level of lattice strains (0.85%). Starting from the nanocrystalline specimens, isochronal experiments were carried out to monitor the reserve microstructure and transformations. The high temperature annealing is required for ameliorating the quality of room temperature consolidated materials by removing all porosity and obtaining good interparticle bonding. The thermal conductivity and the thermal diffusivity are investigated with the Photothermal deflection technique. These thermal parameters increase with the annealing temperatures. This behavior is attributed to the increase in the rate of diffusion coefficient of added elements inside the aluminum matrix

A comparative study of the biodegradability of oleic acid by sludge from a reactor fed with olive mill wastewater and sludge from a reactor fed with oleic acid

In the present study, we investigate the biodegradability of oleic acid by sludge from anaerobic filter reactor fed with olive mill wastewater (sludge T). A comparative study was conducted using a second sludge from an expanded granular bed reactor exposed to oleic acid (sludge P). The performance of treating oleic acid and the influence of the composition of the culture media were investigated and compared. Methane production by sludge T started after a lag phase of 150 hours. However no lag phase was observed with sludge P. In contrast a higher methane production was obtained with the sludge T. The addition of nutrients (minerals and yeast extract) to culture medium reduced the lag phase of methane production by 40 hours

Catalytic wet air oxidation of olive oil mill effluents 4. Treatment and detoxification of real effluents

Minh, Doan Pharn Gallezot, Pierre Azabou, Samia Sayadi, Sami Besson, MicweOlive oil mill wastewater (OMW) generated by the olive oil extraction industry constitutes a major pollutant, posing severe environmental threats. It contains a high organic load and phytotoxic and antibacterial phenolic compounds which resist biological degradation. Platinum and ruthenium supported titania or zirconia were studied in the catalytic wet air oxidation (CWAO) of OMWs in a batch reactor and in a continuous trickle-bed reactor. CWAO experiments at 190 degrees C and 70 bar total air pressure confirmed the effective elimination of the TOC(total organic carbon) and of the phenolic content of actual diluted OMW. Simultaneously, toxicity towards Vibrio fischeri was reduced and a decrease in phytotoxicity occurred. The ruthenium catalysts were found stable over a long period of operation in a trickle-bed reactor. The biodegradability of the oxidized waste has been enhanced and this study also examined the feasibility of coupling CWAO and an anaerobic digestion treatment. The pretreatment of the OMW in the presence of a ruthenium catalyst reduced considerably the total phenolic contents of the wastewater, and produced an effluent suitable to be treated by anaerobic treatment with increased biomethane production compared to the untreated effluent. (C) 2008 Elsevier B.V. All rights reserved