Strategies for applying gray water effluent on ornamental sunflower crops

Environmental Science and Pollution Research - In a context of scarcity of good quality water, reuse is a mandatory practice to increase water availability, thus allowing the exploitation of more...     

Pesticide residues in river sediments from the Pantanal Wetland, Brazil

Sediment samples from 25 sites in 17 rivers of the Pantanal (Brazil) were analyzed with the objective of evaluating pesticide contamination in sediments. Samples were extracted with an acetone, ethylacetate, and water mixture 2:2:1 (v/v/v). The extract was purified by flash chromatography with aluminum oxide and florisil. A multiresidue gas chromatography-mass spectrometry method was applied to monitor 23 pesticides of different chemical classes (organochlorine, organophosphorus, triazines, anilides and pyrethroids) with some of their degradation products. Compounds identified in sediment samples included lambda -cyhalothrin (1.0 to 5.0 micro g kg(- 1)), p,p'-DDT (3.6 micro g kg(- 1)), deltamethrin (20.0 micro g kg(- 1)) and permethrin (1.0 to 7.0 micro g kg(- 1)).     

Distribution of Heavy Metals in Surface Sediments from an Antarctic Marine Ecosystem

The concentrations of lead, cadmium, copper,chromium, iron, manganese and zinc in surfacesediments collected from Potter Cove, in the 25de Mayo Island (King George Island), Antarctica, andits drainage basin, were measured by atomic absorptionspectroscopy. The obtained results were use todetermine the areal and vertical distribution of themetals of in the Cove and potential sources of thesemetals to this environment. The geochemical datasuggest that most of the metals found in Potter Coveconstitute a redistribution of autochthonous materialswithin the ecosystem. Therefore, the metalconcentrations can be considered to be present atnatural background levels in surface sediments.     

Performance and stability of an anaerobic fixed bed reactor subjected to progressive increasing concentrations of influent organic matter and organic shock loads

Data on the performance of a horizontal-flow anaerobic immobilized biomass (HAIB) reactor subjected to step increases of organic loading rates (OLR) and to organic shock loads (OSL) are presented and discussed. The tubular reactor (100 cm long and 5 cm diameter) with a useful volume of 1995 mL was filled with polyurethane foam cubic matrices holding immobilized biomass and fed with synthetic wastewater. The reactor was operated at the controlled temperature of 30+/-1 degrees C and hydraulic retention time of 7 h. After about 15 days, the HAIB reactor attained operating stability. Thereafter, it was subjected to step increases of the applied OLR that ranged from 6.8 to 18.8 kg COD/m(3)d. After steady state had been achieved at each step, OSL corresponding to approximately three times the operating OLR were applied for 7 h. No disturbance was observed due to the step increase in OLR. An increase in effluent chemical oxygen demand (COD) and volatile fatty acids (VFA) concentrations and a decrease in the percentage of methane in the biogas were observed due to OSL applications. However, stability of the monitoring parameters was always restored approximately 17 h after the application of OSL for all conditions tested.     

Magnetic properties of the microorganism Candidatus Magnetoglobus multicellularis

Magnetotactic microorganisms use the interaction of internal biomineralized nanoparticles with the geomagnetic field to orientate. The movement of the magnetotactic multicellular prokaryote Candidatus Magnetoglobus multicellularis under an applied magnetic field was observed. A method using digital image processing techniques was used to track the organism trajectory to simultaneously obtain its body radius, velocity, U-turn diameter, and the reorientation time. The magnetic moment was calculated using a self-consistent method. The distribution of magnetic moments and radii present two well-characterized peaks at (9 ± 2) × 10⁻¹⁵ and (20 ± 3) × 10⁻¹⁵ A m² and (3.6 ± 0.1) and (4.3 ± 0.1) μm, respectively. For the first time, simultaneous determination of the distribution of the organism radii and magnetic moment was obtained from the U-turn method by a new digital imaging processing. The bimodal distributions support an organism reproduction process model based on electron microscopy observations. These results corroborate the prokaryote multicellular hypothesis for Candidatus M. multicellularis.     

Evaluation of hexavalent chromium removal in a continuous biological filter with the use of central composite design (CCD)

Hexavalent chromium is frequently found in industrial effluents as a result of the industrial applications of this compound and its anti-corrosive features. However, hexavalent chromium is extremely toxic, and its discharge in water is regulated, with a maximum limit of 0.1 mg/L in accordance with legislation established by CONAMA-Brazil (no. 397, April 3, 2008). To achieve lower discharge values, it is necessary to reduce from Cr(VI) to Cr(III), which is less toxic, and an economic alternative involves biological removal of this compound. Residence time distributions (RTDs) were measured to evaluate the behavior of actual biofilter operation conditions in a biofilter flow. The medium residence time distributions used were 8 and 24 h (recommended by the legislation). To optimize this process, a central composite design was used, considering the initial chromium concentration and pH as the independent variables and the removal of hexavalent chromium as the response. The boundary curves and surface response showed optimal behavior at 3.94 mg/L [Cr(0)] and a pH of 6.2. The removal process of hexavalent chromium is mathematically described by the Michaelis-Menten kinetic model. This model appropriately represents the variation of chromium concentration along the bioreactor.     

An abiotic typology and reference conditions for nutrients and chlorophyll-a in subtropical reservoirs (São Paulo State,Brazil)

Environmental Science and Pollution Research - The establishment of reference conditions and typology are two important steps in water resources management. The reference conditions enable the...     

Use of fluff in a coking coal blend in a pilot scale

Journal of Material Cycles and Waste Management - Fluff is a shredder waste made up mostly of polymeric material generated in semi-integrated steel manufacturing plants, which is usually disposed...