Surfactant-enhanced solubilization and subsequent biodegradation of phenanthrene and pyrene from aqueous solutions by Arthrobacter strain Sphe3 was investigated. The results show that growth of Arthrobacter strain Sphe3 was increased upon increase in concentration of Tween 20 and Tween 80. Inhibition of bacterial growth was observed with increasing Triton X-100 concentrations, whereas sodium dodecyl sulfate (SDS) totally inhibited this bacterial growth. Phenanthrene and pyrene solubilization was enhanced in the presence of surfactants and found to be linearly proportional to their concentrations, above the critical micelle concentration (CMC). In addition, Tween 20 and Tween 80 enhanced the biodegradation of phenanthrene and pyrene. The high correlation coefficient (R ²) values obtained at all the concentrations studied, suggest that biodegradation kinetics of both phenanthrene and pyrene in the presence of Tween 20 and Tween 80 follow first-order kinetic equation model. Experimental results suggest that Tween 20 and Tween 80 may have great potential for applications in bioremediation of these polycyclic aromatic hydrocarbon (PAH) compounds using Arthrobacter strain Sphe3.

The purpose of this study was to determine the effect of soil contamination with tri- and hexavalent chromium and soil application of compost, zeolite, and CaO on the mass of oats and content of nitrogen compounds in different organs of oats. The oats mass and content of nitrogen compounds in the crop depended on the type and dose of chromium and alleviating substances incorporated to soil. In the series without neutralizing substances, Cr(VI), unlike Cr(III), had a negative effect on the growth and development of oats. The highest doses of Cr(VI) and Cr(III) stimulated the accumulation of total nitrogen but depressed the content of N-NO₃ ⁻ in most of organs of oats. Among the substances added to soil in order to alleviate the negative impact of Cr (VI) on the mass of plants, compost had a particularly beneficial effect on the growth and development of oats. The application of compost, zeolite, and CaO to soil had a stronger effect on the content of nitrogen compounds in grain and straw than in roots. Soil enrichment with either of the above substances usually raised the content of nitrogen compounds in oats grain and straw, but decreased it in roots.

The impact of three commercially available nanoparticles (NPs) on trichloroethylene (TCE) adsorption onto granular activated carbon (GAC) was investigated. TCE adsorption isotherm and column breakthrough experiments were conducted in the presence and absence of silicon dioxide, titanium dioxide, and iron oxide nanoparticles. A rapid small-scale column test (RSSCT) was assessed for its ability to predict TCE adsorption in pilot-scale GAC in the presence and absence of NPs. Zeta potential of the three NPs and the GAC were measured. Particle size distribution of the NP dispersions was analyzed as a function of time. The surface area and the pore size distribution of the virgin and the exhausted GAC were obtained along with transmission electron microscopy and Fourier transform infrared spectroscopy analysis. The effect of NPs was found to be a function of their zeta potential, concentration, and particle size distribution. Due to their electrical charge, NPs attached to the GAC and blocked the pores and thus reduced the access to the internal pore structure. However, due to the fast adsorption kinetics of TCE, no effect from the three NPs was observed in the isotherm and kinetic studies. The RSSCT, on the other hand, accurately predicted the pilot-column TCE breakthrough in the presence of NPs.

Textile industries use large amounts of water in dyeing processes and a wide variety of synthetic dyes. A small concentration of these dyes in the environment can generate highly visible pollution and changes in aquatic ecosystems. Adsorption, biosorption, and biodegradation are the most advantageous dye removal processes. Biodegradation occurs when enzymes produced by certain microorganisms are capable of breaking down the dye molecule. To increase the efficiency of these processes, cell immobilization enables the reuse of the immobilized cells and offers a high degree of mechanical strength, allowing metabolic processes to take place under adverse conditions. The aim of the present study was to investigate the use of Saccharomyces cerevisiae immobilized in activated sugarcane bagasse for the degradation of Acid Black 48 dye in aqueous solutions. For such, sugarcane bagasse was treated with polyethyleneimine (PEI). Concentrations of a 1 % S. cerevisiae suspension were evaluated to determine cell immobilization rates. Once immobilization was established, biodegradation assays for 240 h with free and immobilized yeast in PEI-treated sugarcane bagasse were evaluated by Fourier transform infrared spectrophotometry. The results indicated a probable change in the dye molecule and the possible formation of new metabolites. Thus, S. cerevisiae immobilized in sugarcane bagasse is very attractive for biodegradation processes in the treatment of textile effluents. © 2013 Springer Science+Business Media Dordrecht.

The presence of macrolide antibiotics in aquatic environments causes serious antibiotic resistance propagation in microorganisms. In this study, the use of porous resins as adsorbents for the removal of tylosin from aqueous solutions was evaluated. The effectiveness of the resins (macroporous resin XAD-4, hypercross-linked resin MN-202, and aminated polystyrene resin MN-150) was compared with commercial hydroxylated multiwall carbon nanotubes (H-MWCNTs). Similar patterns of pH-dependent adsorption were observed despite the different surface properties and pore structures of the three resins, implying the importance of the tylosin molecular form in the adsorption process. Tylosin adsorption onto the four adsorbents showed different ionic strengths and temperature dependence consistent with the tylosin speciation and corresponding adsorption mechanism. The adsorption of tylosin onto the XAD-4 and MN-202 is mainly controlled by the intermolecular interactions between the matrix of the adsorbents and the tylosin molecule, whereas specific bonds among multiple surface functional groups are the predominant contributors to MN-150 and H-MWCNTs. The pore size is the key parameter in tylosin adsorption onto the surface of the adsorbents. The adsorption kinetics of the four adsorbents followed the pseudo-second-order model. The adsorption isotherm data well fit the Langmuir models, indicating surface coverage by a monomolecular layer.

A pot experiment was conducted in order to study the relationships of soil pollution indices to maize (Zea mays L.) growth characteristics and soil and plant heavy metal content, as well as the metal plant uptake. A completely randomized block design was used, including 11 treatments in three replications. The treatments applied were control (freshwater), four levels of inorganic NPK fertilizer combined with treated municipal wastewater and freshwater and three sludge levels (5, 25 and 50 %, respectively) in the presence of treated wastewater and freshwater, respectively. The mean effect of the applied sludge levels independent of the presence of the freshwater or wastewater contributed to the accumulation of heavy metals Cr, Cu, Zn and Mn in soil and in leaves. The soil pollution indices, i.e., pollution load index (PLI), elemental pollution index (EPI), total concentration factor and heavy metal load, showed that the soil had been polluted with heavy metals to a great extent. The application of sludge treatment affected positively the maize plant height, leaf number and the indices PLI and EPI. All pollution indices studied were positively related to plant leaf number and plant height, as well to heavy metal soil content.

N-Nitrosodimethylamine (NDMA) is recently defined as one of nitrogenous disinfection by-products with high carcinogenicity and can be frequently detected in finished water. The decomposition of NDMA in water using nanoscale zero-valent iron (NZVI) in the presence of aluminum and iron salts was investigated in this paper. The results showed that some salts can enhance the removal of NDMA by commercial NZVI in the order of Al(SO) >> AlCl > FeSO > NaSO ≈ NZVI alone, and the highest NDMA removal was 87.3 % in the presence of Al(SO). NDMA removal varied with the addition of Al(SO), NZVI dosage, initial NDMA concentration, solution pH, and temperature. The reduction of NDMA increased with the dosage of Al(SO) and NZVI, which follows a pseudo-first-order kinetics model. The removal of NDMA by NZVI was higher in acidic pHs than in alkaline ones, and the highest removal was found at pH 5. Higher reaction temperature can improve the removal of NDMA and reduce the reaction time. Based on the total nitrogen balance, most nitrogen of NDMA was converted to ammonium and dimethylamine.

Sepiolite reveals as a low-cost and efficient adsorbent for the adsorption of caffeine from aqueous solutions. The characterization of this material was carried out by N₂ adsorption–desorption at 77 K, Fourier transform infrared spectroscopy, thermogravimetric analysis, and electronic microscopy. Initially, batch adsorption experiments were developed in order to determine the equilibrium time and the adsorption isotherm of the system. Pseudo–first-order, Elovich equation, pseudo–second-order, and intra-particle diffusion models were applied to the experimental data to determine the adsorption kinetics. In continuous adsorption, the influence of several operation conditions (initial caffeine concentration, volumetric flow rate, and mass of adsorbent) on the shape of breakthrough curves and the mass transfer resistance was evaluated. Experimental data were fitted to the bed-depth service-time model bed-depth service-time (BDST). Through the calculation of the adsorption, parameters as breakthrough time or caffeine removal percentage can be concluded that the removal of this compound from aqueous solutions by adsorption in sepiolite beds is an alternative technique to the current methods, in order to eliminate this micropollutant.

A comparative long-term study of three subsurface horizontal-flow (HF) constructed wetlands (CW) treating winery wastewater was carried out. The water depth for HF1 was 0.3 m, while the depth for HF2 and HF3 was 0.6 m, respectively. Hydraulic loading rate ranged from 7 to 93 mm/d, while surface loading rates fell into the following ranges: 4–85 g COD/m²·d, 2–49 g BOD₅/m²·d and 0.5–6 g TSS/m²·d. The percentage of biological oxygen demand (BOD₅) removal clearly decreased when influent concentration increased, while surface removal rate increased and reached a maximum of approximately 8 g BOD₅/m²·d removed in the range of 10–20 g BOD₅/m²·d fed, depending on the CW depth. HF1 showed a worse performance than the other units, appearing to be more affected by high influent concentrations. Solids accumulation on gravel media, hydraulic conductivity and gas emissions were monitored over the 2.8 years of operation.

In this study, chemical oxidation was applied to treat three contaminated sediments. All the sediments were contaminated with mineral oil, polycyclic aromatic hydrocarbons and heavy metals and had an organic matter content ranging from 2.4 to 7.6 %. The natural oxidant demand of the sediments was determined during treatment with two different types of oxidants (potassium permanganate and sodium persulfate), and the effect of these oxidants on the heavy metal release and on the microbial community was investigated. The natural oxidant demands of the sediments under persulfate treatment were lower (30–100 g kg⁻¹) than the ones treated with permanganate (50–450 g kg⁻¹). Cr was released during the application of permanganate whereas Zn and Pb were released under persulfate treatment. qPCR results showed that permanganate and persulfate, both at a concentration of 150 g kg⁻¹, caused a decrease (2 log units) in the number of 16S rRNA gene of total bacteria in the sediment having the lowest organic matter content. However, the total ATP, considered as a biomarker for microbial activity, was below detection limit in all sediments in the presence of at least 150 g kg⁻¹ oxidant. Only permanganate induced a shift in the structure of the microbial community.