A consortium composed of many different bacterial species is required to efficiently degrade polycyclic aromatic hydrocarbons (PAH) in oil-contaminated soil. We obtained six PAH-degrading microbial consortia from three oil-contaminated soils using two different isolation culture media. Denaturing gradient gel electrophoresis (DGGE) and sequence analyses of amplified 16s rRNA genes confirmed the bacterial community was greatly affected by both the culture medium and the soil from which the consortia were enriched. Three bacterial consortia enriched using malt yeast extract (MYE) medium showed higher degradation rates of PAHs than consortia enriched using Luria broth (LB) medium. Consortia obtained from a soil and then added back to that same soil was more effective in degrading PAHs than adding, to the same soil, consortia isolated from other, unrelated soils. This suggests that inoculum used for bioremediation should be from the same, or very similar nearby soils, as the soil that is actually being bioremediated.

Biochar produced from malt spent rootlets was employed for the removal of Hg(II) from pure aqueous solutions. Batch experiments were conducted at 25 °C. The optimum pH value for Hg(II) sorption onto biochar was 5. Biomass dose and contact time were examined to determine sorption kinetics and equilibrium capacity constants. The increase of biochar dose resulted in higher sorption efficiency. After a 24-h contact time at biochar concentrations of 0.3 and 1 g/L, the Hg(II) removal was 71 and 100 %, respectively. Based on the sorption kinetic data, the biochar sorption capacity for mercury reached its maximum after 2 h; 33 % of Hg(II) was removed within the first 5 min. Based on the isotherm data, the maximum biochar sorption capacity for Hg(II) was 103 mg/g. Finally, HCl, EDTA, NaCl, HNO₃, H₂SO₄, and distilled water leaching solutions were tested for Hg(II) desorption with HCl being the most effective.

The influence of inoculum preparation and cell density on the efficiency of Cr(VI) removal was assessed with two chromate-resistant yeasts, Pichia jadinii M9 and Pichia anomala M10, isolated from textile wastewaters. Batch cultures in yeast nitrogen base (YNB)′ liquid medium (YNB without amino acids and ammonium sulfate plus sucrose and ammonium sulfate) containing 1-mM initial Cr(VI) concentrations revealed that heavy metal removal in both isolates was substantially affected by the inoculation procedure. Inocula with high initial density or pregrown in a nutritionally rich medium (Malt Czapek) were found to be key factors in order to achieve successful Cr(VI) decontamination. In contrast, low-density inocula and/or synthetic media-precultured cells were shown to negatively influence Cr(VI) disappearance, either by increasing the time for complete degradation or by reducing the percentage of heavy metal removed. These results emphasized the relevance of the selection of an appropriate inoculum culture medium and the positive influence of increasing one order of magnitude inoculum cell density in order to achieve successful and rapid Cr(VI) removal. Under these considerations, the selected yeasts, P. jadinii M9 and P. anomala M10, exhibited a remarkable ability to tolerate and completely remove Cr(VI) concentrations up to 1 mM, thus being candidates for potential applications in bioremediation of Cr(VI)-contaminated environments.

The fixed-bed column biosorption process is the most widely used system, which aims to expand to industrial scale in wastewater treatment, and requires for its design thermodynamic equilibrium data. In this study, fixed-bed column experiments using malt bagasse, an industrial byproduct, were performed to quantitatively evaluate the dye biosorption capacity, as well as perform mathematical modeling of the breakthrough curves and obtain mass transfer parameters. The FTIR spectrum of malt bagasse was performed before and after the dye biosorption process. The best operating condition of the column occurred at the feed flow of 4mLmin⁻ ¹. The Langmuir isotherm (qₘₐₓ = 38.44mgg⁻ ¹; R² = 0.98) was used to represent the equilibrium data between the phases (fluid/solid) in column. The phenomenological mathematical model, which considered the resistance to internal diffusion as a limiting step of mass transfer, was able to adequately predict the dynamic behavior of the biosorption column operation, constituting a useful tool for analysis, description, and design of dye biosorption in fixed-bed column.

Phthalic acid esters (PAEs) are compounds that are used in the bottle as the main plasticizers. Therefore, the possibility of releasing phthalate esters into beverages is very high and there is a concern to consumer health and monitoring organizations. The aim of this research was to assess the phthalic acid esters (di-n-octyl phthalate (DNOP), butyl benzyl phthalate (BBP), dimethyl phthalate (DMP), diethyl phthalate (DEP) and dibutyl phthalate (DBP), bis(di-ethylhexyl) phthalate (DEHP), and total PAEs) in bottled non-alcoholic malt beverages (n = 120) by multi-walled carbon nanotubes were magnetized with iron (MWCNT-Fe₃O₄) using gaschromatography/mass spectrometry (GC-MS). The results showed that the highest and the lowest levels of total phthalate esters in samples were 9483.93 and 2412.50 ng/L, respectively. The mean of DEHP which has also been found to be carcinogenic in all samples was lower than 5944.73 ng/L. The highest concentration of DEHP in four samples was upper than 8957.87 ng/L. Perceived limit of detection (LOD) ranged from 13 to 30 ng/L and the limit of quantification (LOQ) ranged from 39 to 90 ng/L. Multivariate techniques and heat map visualization were used to assess the correlation among the type and levels of PAEs with the brand, color, product date, pH, sugar, volume, and gas pressure. Therefore, based on heat map and principal component analysis (PCA) results, the DEHP and total PAEs were the closest accessions, indicating that these variables had similar trends. Based on the results, it can be stated that due to the low average of total phthalate esters in non-alcoholic malt beverages, there is no serious health hazard of these compounds for humans.