Effects of activated sludge and UV disinfection processes on the bacterial community and antibiotic resistance profile in a municipal wastewater treatment plant

Environmental Science and Pollution Research - Wastewater tertiary treatment has been pointed out as an effective alternative for reducing the concentration of antibiotic resistant bacteria and...     

Biomarker responses as indication of contaminant effects in Oreochromis niloticus

The current study investigated oxidative stress parameters (enzymes activities, metallothionein content and lipid peroxidation) in freshwater fish, Oreochromis niloticus, tilapia exposure to Monjolinho River (in 4 months of year: January, April, July and November). One critical site in Monjolinho River (site B) was assessed in comparison to a reference site (site A). Water pH and oxygen concentration was lower than that recommended by CONAMA (Brazilian National Environmental Committee), resolution 357/2005 for protection of aquatic communities, and ammonium and the metals Cu, Zn, Mn and Fe (on all months) concentrations were higher than the maximum concentration recommended. Glutathione peroxidase (GPx) and superoxide dismutase (SOD) activities were significantly decreased in liver and muscle in tilapia from Monjolinho River, throughout the year, in relation to reference except in gills that SOD activity increased. Glutathione S-transferase (GST) activity was significantly increased in liver of the tilapia from Monjolinho River in all sites, in relation to reference except in gills that GST activity increased in July and decreased in November, suggesting that GST activity could be induced to neutralize the pollutants toxicity. On the other hand, GST activity was significantly decreased in white muscle indicating a toxic effect of pollutants, resulting in a decreased ability of tilapia to perform defense reactions associated to GSTs. The decrease of catalase (CAT) activity in gills of the O. niloticus together with the increase of SOD activity, could explain the increased lipid peroxidation (LPO) level in this organ. Metallothionein levels in liver and gills were significantly high in all sites. Results indicate that the exposure to metals caused severe damage to tissues; despite the consensually assumed antioxidant induction as a sign of exposure to contaminants the effects seem in part to be mediated by suppression of antioxidant system with SOD, CAT and GPx as potential candidates for tissues toxicity biomarkers of pollutants.     

Effect of glyphosate on the microbial activity of two Brazilian soils

Glyphosate [N-(phosphonomethyl)-glycine] is a broad-spectrum, non-selective, post-emergence herbicide that is widely used in agricultural. We studied, in vitro, changes in the microbial activity of typical Hapludult and Hapludox Brazilian soils, with and without applied glyphosate. Glyphosate was applied at a rate of 2.16 mg glyphosate kg(-1) of soil and microbial activity was measured by soil respiration (evolution of CO(2)) and fluorescein diacetate (FDA) hydrolysis over a period of 32 days. We found an increase of 10-15% in the CO(2) evolved and a 9-19% increase in FDA hydrolyses in the presence of glyphosate compared with the same type of soil which had never received glyphosate. Soil which had been exposed to glyphosate for several years had the strongest response in microbial activity. Most probable number (MPN) counts showed that after 32 days incubation the number of actinomycetes and fungi had increased while the number of bacteria showed a slight reduction. After the incubation period, high pressure liquid chromatography (HPLC) detected the glyphosate metabolite aminomethyl phosphonic acid (AMPA), indicating glyphosate degradation by soil microorganisms.     

The Impact of the Macaíba Components Addition on the Biodegradation Acceleration of Poly (Ɛ-Caprolactone) (PCL)

Journal of Polymers and the Environment - Nowadays, there is a need to obtain eco-friendly materials, especially plastics that are responsible for most of the environmental pollution. In this...     

Decontamination of produced water containing petroleum hydrocarbons by electrochemical methods: a minireview

Produced water (PW) is the largest waste stream generated in oil and gas industries. The drilling and extraction operations that are aimed to maximize the production of oil may be counterbalanced by the huge production of contaminated water (called PW) with pollutants, such as heavy metals, dissolved/suspended solids, and organic compounds. PW is conventionally treated through different physical, chemical, and biological methods. In offshore platforms, because of space constraints, compact physical and chemical systems are used. However, major research efforts are being developed with innovative technologies for treating PW in order to comply with reuse and discharge limits. Among them, electrochemical technologies have been proposed as a promising alternative for the treatment of this kind of wastewaters. Then, this paper presents a minireview of efficient electrochemical technologies used until now for treating PW generated by petrochemical industry.     

Experimental investigation and characterization of nano-scale dry electro-machining

This paper presents an experimental investigation and characterization of a novel technique of nanoscale electro-machining (EM) in atmospheric air, named dry nano-EM, by using scanning tunneling microscopy (STM) as the platform for nanomachining. The electro-machining has been conducted in near field by maintaining a gap distance of 1–2 nm between the Platinum–Iridium [Pt–Ir (80:20)] tool electrode and atomically flat gold substrate with the air as dielectric medium. An in situ process of evaluating the tool quality before and after machining has been used by monitoring the current–displacement (I–Z) spectroscopy curves. The mechanism of dry nano-EM has been presented as well as the machining performance of the process has been evaluated. Based on the observations, it has been established that field induced evaporation due to intense heat generated at the gap width is the primary mechanism of material removal in dry nano-EM. The experimental results show that dry nano-EM is capable of fabricating consistent nano-features with good repeatability. The volume of material removal increases almost linearly with increasing number of features machined and machining time, indicating the consistency in the dimensions of the nano-features. Finally, dry nano-EM is established as a technique capable of machining 50–100 features in a pre-defined manner with average feature size of 7.5–10 nm in a single pass, thus suitable for nano-patterning in atomically flat electrically conducting surfaces.     

Surfactant-mediated complex formation for determination of traces amounts of zinc, cadmium, and lead with 4-(2-thiazolylazo) resorcinol and chemometric methods

The partial least squares modeling is a powerful multivariate statistical tool applied to the spectrophotometric simultaneous determination of the divalent ions of zinc, cadmium, and lead based on the formation of their complexes with 4-(2-thiazolylazo) resorcinol in surfactant media. The linear concentration range for zinc, cadmium, and lead were 0.10-1.31, 0.148-1.92, and 0.148-3.70 mg L(?-1), respectively. The experimental calibration set was composed of 36 sample solutions using a mixture design for three component mixtures. The absorption spectra were recorded from 380 through 650 nm. The effect of pH on the sensitivity in determination of zinc, cadmium, and lead was studied in order to choose the optimum pH (pH = 8) for determination. The root-mean-square errors of predictions for zinc, cadmium, and lead were 0.0466, 0.0282, and 0.050, respectively. The proposed method was successfully applied for the determination of zinc, cadmium, and lead in water samples.     

Physical,chemical, and mechanical properties of landfilled waste from Campina Grande,Brazil

Environmental Science and Pollution Research - The properties of municipal solid waste (MSW) in landfills vary considerably, depending on the waste’s composition, time, and density. This...     

Effects of exposure to the UV-filter 4-MBC during Solea senegalensis metamorphosis

Environmental Science and Pollution Research - Many personal care products integrate UV-filters, such as 4-methylbenzylidene camphor (4-MBC), a compound frequently detected in aquatic habitats,...     

Arsenic and lead in the indoor residential settings of different socio-economic status; assessment of human health risk via dust exposure

Environmental Science and Pollution Research - In the present study, occurrence of arsenic (As) and lead (Pb) is reported in rural and urban household dust (floor and AC filter dust) of the Kingdom...