Transformation and biodegradation of 1,2,3-trichloropropane (TCP)

PURPOSE: 1,2,3-Trichloropropane (TCP) is a persistent groundwater pollutant and a suspected human carcinogen. It is also is an industrial chemical waste that has been formed in large amounts during epichlorohydrin manufacture. In view of the spread of TCP via groundwater and its toxicity, there is a need for cheap and efficient technologies for the cleanup of TCP-contaminated sites. In situ or on-site bioremediation of TCP is an option if biodegradation can be achieved and stimulated. This paper presents an overview of methods for the remediation of TCP-contaminated water with an emphasis on the possibilities of biodegradation. CONCLUSIONS: Although TCP is a xenobiotic chlorinated compound of high chemical stability, a number of abiotic and biotic conversions have been demonstrated, including abiotic oxidative conversion in the presence of a strong oxidant and reductive conversion by zero-valent zinc. Biotransformations that have been observed include reductive dechlorination, monooxygenase-mediated cometabolism, and enzymatic hydrolysis. No natural organisms are known that can use TCP as a carbon source for growth under aerobic conditions, but anaerobically TCP may serve as electron acceptor. The application of biodegradation is hindered by low degradation rates and incomplete mineralization. Protein engineering and genetic modification can be used to obtain microorganisms with enhanced TCP degradation potential.     

Degradation of Phenolic Resin by Tremetes versicolor

A phenolic resin that is used as syntan in leather manufacturing was degraded using Tremetes versicolor. On degradation of this resin for eight days, the reduction in biochemical oxygen demand (BOD), chemical oxygen demand (COD) and total organic carbon (TOC) were 65.11, 76.66 and 72.94% respectively. It was found from the infra red (IR) spectra of the samples that up to seven days the aromaticity was not perturbed however there were reductions in BOD and COD. Addition of co-substrate starch, brought about reduction in BOD, COD and TOC by 85.36, 91.93 and 89.98% respectively. After eight days, there observed a disturbance in the aromatic ring. The enzyme was extracted and assayed for polyphenol oxidase and laccase. Polyphenol oxidase activity and laccase activity of the crude enzyme were found to be 31.4 and 1.67 U/mL. On ammonium sulfate precipitation and dialysis, the polyphenol oxidase activity and laccase activity were enhanced by 1.5- and 3.2-folds respectively.     

Synthesis of Soy-Polyol by Two Step Continuous Route and Development of Soy-Based Polyurethane Foam

Soy-polyol has been synthesized via a low energy two-step continuous route thus avoiding intermediate steps and chemicals. The functional groups of soy-polyol thus produced were identified by Fourier transform infrared (FTIR) spectroscopy which confirmed the cleavage of the double bonds, the formation of new epoxy linkages and the presence of hydroxyl groups. The change in chemical structure and physical properties of the soy polyol was further characterized and the results indicated a successful conversion with reduced unsaturation, increased hydroxyl number and increased viscosity. Polyurethane foam was prepared from soy-polyol using isocyanate and thermogravimetric analysis was used to study its thermal decomposition behaviour. Multiple transitions were identified in relation to depolymerization and bond dissociation. Density and compressive strength of the soy-foam were found to be satisfactory. An investigation of microstructure of soy foam by scanning electron microscope and X-ray computed tomography revealed the internal cell morphology and cell structure.     

Development of Thixotropic Coatings Using Dimerized Soybean Oil Fatty Acids: The Case of Polyamide of 1,2-Phenylene Diamine

Soybean oil (SBO) was dimerized and the crude dimer acid product reacted with 1,2-phenylene diamine at 210 ± 5 °C under inert atmosphere to obtain fatty polyamide (FPA). The FPA was used to modify a commercial alkyd resin by reacting a mixture of the alkyd resin with 5 wt% of FPA at 120 °C for 80 min under inert atmosphere. The FTIR spectrum of the FPA modified resin showed evidence of higher degree of H-bonding than was found for the unmodified alkyd. White gloss coatings of 15, 20, 25, and 30% solids were formulated from the modified and unmodified resins and examined for performance with respect to: leveling, sag resistance, drying time, pigment settling, skinning tendency and film hardness. Results showed that the unmodified alkyd coatings exhibited good leveling but poor sag resistance at all solid contents. In contrast, FPA modified alkyd coatings combined good leveling with high sag resistance indicating their thixotropic nature. A strong tendency to pigment settling was observed for unmodified alkyd coatings but was not observed in the FPA modified alkyd coatings. The modified alkyd coatings showed skinning while the unmodified alkyd coatings did not skin. A 30% solids coating formulation of the FPA modified resin showed shorter surface dry time but longer hard dry time than the unmodified alkyd resin coating.     

Assessing computer waste generation in Chile using material flow analysis

The quantities of e-waste are expected to increase sharply in Chile. The purpose of this paper is to provide a quantitative data basis on generated e-waste quantities. A material flow analysis was carried out assessing the generation of e-waste from computer equipment (desktop and laptop PCs as well as CRT and LCD-monitors). Import and sales data were collected from the Chilean Customs database as well as from publications by the International Data Corporation. A survey was conducted to determine consumers’ choices with respect to storage, re-use and disposal of computer equipment. The generation of e-waste was assessed in a baseline as well as upper and lower scenarios until 2020.The results for the baseline scenario show that about 10,000 and 20,000 tons of computer waste may be generated in the years 2010 and 2020, respectively. The cumulative e-waste generation will be four to five times higher in the upcoming decade (2010–2019) than during the current decade (2000–2009). By 2020, the shares of LCD-monitors and laptops will increase more rapidly replacing other e-waste including the CRT-monitors. The model also shows the principal flows of computer equipment from production and sale to recycling and disposal. The re-use of computer equipment plays an important role in Chile. An appropriate recycling scheme will have to be introduced to provide adequate solutions for the growing rate of e-waste generation.     

Food Aid and the Famine Relief Argument (Brief Return)

Recent publications by Pogge (Global ethics: seminal essays. St. Paul: Paragon House 2008) and by Singer (The life you can save: acting now to end world poverty. New York: Random House 2009) have resuscitated a debate over the justifiability of famine relief between Singer and ecologist Garrett Hardin in the 1970s. Yet that debate concluded with a general recognition that (a) general considerations of development ethics presented more compelling ethical problems than famine relief; and (b) some form of development would be essential to avoiding the problems of growth noted by Hardin. Better than renewing the debate, we should recognize two points. First, food needs do indeed evoke a moral response that is more direct and compelling than the philosophical positions often generated to rationalize a duty to bring aid. As such the argument for feeding hungry people cannot be generalized into a paradigm for development ethics without distortions that undercut the morally valid elements in Singer’s original argument. Second, contrary to prevailing assumptions in present day development ethics, food aid and famine relief continue to be important priorities for international agencies, notably the World Food Program. Emergency food assistance, the nominal topic of Singer’s original article, thus is an important issue for agricultural as well as development ethics, though one that should indeed be seen as distinct from more complex duties to address the conditions of chronic poverty and underdevelopment.     

Accumulation and biological cycling of heavy metal in four salt marsh species, from Tagus estuary (Portugal)

Pools of Zn, Cu, Cd and Co in leaf, stem and root tissues of Sarcocornia fruticosa, Sarcocornia perennis, Halimione portulacoides and Spartina maritima were analyzed on a bimonthly basis, in a Tagus estuary salt marsh. All the major concentrations were found in the root tissues, being the concentrations in the aboveground organs neglectable for sediment budget proposes, as seen by the low root-aboveground translocation. Metal annual accumulation, root turnovers and cycling coefficients were also assessed. S. maritima showed the higher root turnovers and cycling coefficients for most of the analyzed metals, making this a phytostabilizer specie. By contrast the low root turnover, cycling coefficient and low root necromass generation makes S. perennis the most suitable specie for phytoremediation processes. Although the high amounts of metal return to the sediments, due to root senescence, salt marshes can still be considered sinks of heavy metals, cycling heavy metals mostly between sediment and root.     

Bio-immobilization of Cu and Zn in recirculated bioreactor landfill

Purpose  

To protect the environmental quality of soil, groundwater, and surface water near the landfill site, it is necessary to make an accurate assessment of the heavy metal mobility. This study aims to present the bio-immobilization behavior of heavy metals in landfill and provide some reference suggestion for the manipulation of heavy metal pollution control after closure.     

Why ozonolysis may not increase the hydrophilicity of particles

It is commonly assumed that atmospheric oxidation of hydrocarbon particles or hydrocarbon coatings on particles leads to polar products and increased water uptake, altering atmospheric visibility and increasing the likelihood they will act as cloud condensation nuclei (CCN). We show here through laboratory experiments that increased water uptake depends on the 3-dimensional structure of the particles. Laboratory studies of particles formed during ozonolysis of surface-bound alkenes, present as terminally unsaturated self-assembled monolayers (C8= SAM) on a silica substrate, were carried out at room temperature and 1 atm pressure. SAMs were exposed to ～10¹³ O₃ molecules cm^?3 for 40 min and resultant particles were analyzed using single particle Fourier transform infrared micro-spectroscopy (micro-FTIR) and secondary ion mass spectroscopy (SIMS). Spectroscopy results show that –COOH and other polar groups are formed but are buried inside a hydrophobic shell, consistent with earlier observations (McIntire et al., 2005, Moussa et al., 2009) that water uptake does not increase after reaction of the terminal alkene with O₃. These insights into the 3-D structure of particles formed on oxidation have important implications for the ability of secondary organic aerosols to act as CCN. In addition, the nature of the surface of the particles is expected to determine their uptake into biological systems such as the surface of the lungs.