Assessment of two thermally treated drill mud wastes for landfill containment applications.

Offshore oil and gas drilling operations generate significant amounts of drill mud waste, some of which is transported onshore for subsequent thermal treatment (i.e. via thermal remediation). This treatment process results in a mineral waste by-product (referred to as thermally treated drill mud waste; TTDMW). Bentonites are originally present in many of the drill mud products and it is hypothesized that TTDMW can be utilized in landfill containment applications (i.e. cover or base liner). The objective of this paper is to examine the feasibility of this application by performing various physical and chemical tests on two TTDMW samples. It is shown that the two TTDMW samples contained relatively small amounts of clay-sized minerals although hydraulic conductivity values are found to be less than 10(-8) m/s. Organic carbon contents of the samples were approximately 2%. Mineralogy characterization of the samples confirmed varying amounts of smectite, however, peak friction angles for a TTDMW sample was greater than 36 degrees. Chemical characterization of the TTDMW samples show potential leaching of barium and small amounts of other heavy metals. Discussion is provided in the paper on suggestions to assist in overcoming regulatory issues associated with utilization of TTDMW in landfill containment applications.     

Preparation of effective TiO<Subscript>2</Subscript>/Bi<Subscript>2</Subscript>O<Subscript>3</Subscript> photocatalysts for water treatment

Photocatalytic oxidation using semiconductors is one of the advanced oxidation processes for degradation of organic pollutants in water and air. TiO₂ is an excellent photocatalyst that can mineralize a large range of organic pollutants such as pesticides and dyes. The main challenge is to improve the efficiency of the TiO₂ photocatalyst and to extend TiO₂ light absorption spectra to the visible region. A potential solution is to couple TiO₂ with a narrow band gap semiconductor possessing a higher conduction band such as bismuth oxide. Therefore, here we prepared Bi₂O₃/TiO₂ heterojunctions by the impregnation method with different Bi/Ti ratio. The prepared composites have been characterized by UV–Vis diffused reflectance spectra and X-ray diffraction. The photocatalytic activity of the heterojunction has been determined from the degradation of orange II under visible and UV light. Results show that Bi₂O₃/TiO₂ heterojunctions are more effective than pure TiO₂-anatase under UV-A irradiation, with an optimum for the Bi/Ti ratio of 5 %, for the photocatalytic degradation of Orange II. However, the photocatalytic activity under irradiation at λ higher than 420 nm is not much improved. Under UV–visible radiation, the two semiconductors are activated. We propose a mechanism explaining why our products are more effective under UV–visible irradiation. In this case the charge separation is enhanced because a part of photogenerated electrons from the conduction band of TiO₂ will go to the conduction band of bismuth oxide. In this composite, titanium dioxide is the main photocatalyst, while bismuth oxide acts as adsorbent photosensitizer under visible light.     

Influence of the Concentrations of Chitosan and Glycerol on Edible Film Properties Showed by Response Surface Methodology

The individual and interactive effects of glycerol and chitosan concentrations on edible film properties were investigated using response surface methodology. The results of ANOVA indicated that all the independent variables exhibited significant effect on the film properties. Chitosan concentration had a positive effect on CO₂ permeability and negative effect on O₂ while the glycerol concentration had a positive effect on permeability to both gases. Regarding water vapor permeability, the chitosan concentration had a negative effect, whereas the glycerol had no influence. Moreover, both chitosan and glycerol concentration influenced the elongation at break point (%A), and only glycerol concentration had a significant effect on tensile strength. Optimization by desirability approach was carried out on the independent variables to get the optimum levels within the experimental conditions. It was found that 1.5 % of chitosan and 25 % of glycerol (wt/wt of chitosan) retarded respiration and showed a strong permeability to water vapor.     

Photocatalytic degradation of the diuron pesticide

The occurrence of chlorinated pesticides in wellwaters is a major problem of public health in Ivory Coast and other African countries. Here, we studied the photocatalytic degradation of the pesticide diuron in aqueous solution in presence of two commercial TiO₂ catalysts, P25 and PC500. The capacity of diuron adsorption at the TiO₂ surface is lower for both photocatalysts. The efficiency of photocatalytic degradation of diuron, it is higher using P25 Degussa than PC500 Millenium TiO₂ catalyst.     

First approach of the selective treatment of water by heterogeneous photocatalysis

Photocatalytic reactions using titanium dioxide are of great interest due to their possible applications to solar energy storage and detoxification of wastewater. However, TiO₂ has usually given a very poor selectivity. Here we show that, using binary mixtures, it is possible to selectively degrade one molecular substance without any concentration change of another substance. We have studied the influence of the pH and TiO₂ concentration on the selectivity of the degradation of benzamide and 4-hydroxybenzoic acid. With appropriate modifications of both parameters, the selectivity can be improved.     

Landscape and Agricultural Patterns in Rural Areas: a Case Study in the Brionne Basin, Normandy, France

Landscape changes over a period of 25 years were assessed for a catchment basin in Normandy, France. Landscape attributes, i.e. land use, land cover and natural habitat, were obtained from aerial photographs (1964, 1989) and soil maps, to define a landscape typology. Data were aggregated on a 500 m×500 m grid system and treated by multivariate analysis. Results of these analysis show that this rural landscape has undergone changes in landcover (mainly grassland receding to crop) as well as changes in spatial structure (mainly increase of plot size and uniformisation). These changes were related to a typology of farms (realised by multivariate analysis of a field survey on the 38 registered farms of the site). Results suggest that (i) farms with a narrow range of production, i.e. specialised farms, are located on a narrow range of environmental conditions and are associated with stable landscapes, while (ii) farms with a broader range of production (i.e. polyculture) are distributed more widely throughout the landscape, and are mostly associated with the landscape changes.     

How to uncoil your partner—“mating songs” in giant pill-millipedes (Diplopoda: Sphaerotheriida)

The stridulation of the giant pill-millipede genus Sphaerotherium from South Africa, one of only three groups of millipedes that produce sounds, was studied. One hundred one stridulation series of a total of nine different species (Sphaerotherium dorsaloide, Sphaerotherium hanstroemi, Sphaerotherium mahaium, Sphaerotherium similare, Sphaerotherium punctulatum, Sphaerotherium convexitarsum, Sphaerotherium dorsale, Sphaerotherium rotundatum, and Sphaerotherium perbrincki) were analyzed. Stridulation sounds are produced only with a special field of ribs on the posterior surface of the posterior telopod, which is actively moved over a field of sclerotized nubs on the inner margin of the anal shield. The Sphaerotherium male usually stridulates only when in contact with a female to initiate mating. This seems to prevent the female from volvating into a ball or stimulate the female to uncoil when already rolled in. The sound analyzes revealed a broad frequency spectrum in all stridulation sounds produced, without obvious differences in frequency distribution among species. However, the temporal pattern of the stridulation varies greatly between species and seems to be species-specific, arguing for a species recognition function of the stridulation during courtship behavior. A single species (S. punctulatum) was found to stridulate during mating while three species also show postcopulatory stridulation. Apparently, pill-millipedes are not capable of acoustic perception, as no hearing organs are known, indicating that the communication is mainly based on perception of temporal vibration patterns, and not of the acoustic signal itself. The need to overcome the rolling-in reflex of the female is developed as a hypothesis why stridulation exists only in millipedes able to coil into a ball, and apparently evolved four times independently in the superorder Oniscomorpha.     

Exposure to four chemical UV filters through contaminated sediment: impact on survival,hatching success,cardiac frequency,and aerobic metabolic scope in embryo-larval stage of zebrafish

Environmental Science and Pollution Research - UV filters are widely used in many pharmaceutical and personal care products such as sunscreen and cosmetics to protect from UV irradiation. Due to...