Synthesis and Characterization of Low Volatile Content Polyurethane Dispersion from Depolymerised Polyethylene Terphthalate

In the past few decades, governments and international agencies have been placing more emphasis on the improvement of production technique, working conditions and reduction of the toxic emission to the atmosphere. In this context aqueous polyurethane dispersion was synthesized from depolymerised polyethylene terphthalate (PET) waste. 1,4-Butanediol was used in PET depolymerisation. Polyurethane dispersion films were characterized using differential scanning calorimeter, Fourier transform infrared spectroscopy, gel permeable chromatography, etc. Incorporation of PET waste in polyurethane dispersion was an added advantage in waste management and produced better quality polyurethane dispersion.     

Simultaneous carbon, nitrogen and phosphorous removal from municipal wastewater in a circulating fluidized bed bioreactor

In this study, the performance of the circulating fluidized bed bioreactor (CFBB) with anoxic and aerobic beds and employing lava rock as a carrier media for the simultaneous removal of carbon, nitrogen and phosphorus from municipal wastewater at an empty bed contact time (EBCT) of 0.82 h was discussed. The CFBB was operated without and with bioparticles' recirculation between the anoxic and aerobic bed for 260 and 110 d respectively. Without particles' recirculation, the CFBB was able to achieve carbon (C), total nitrogen (N) and phosphorous (P) removal efficiencies of 94%, 80% and 65% respectively, whereas with bioparticles' recirculation, 91%, 78% and 85% removals of C, N and P were achieved. The CFBB was operated at long sludge retention time (SRT) of 45-50 d, and achieved a sludge yield of 0.12-0.135 g VSS g COD(-1). A dynamic stress study of the CFBB was carried out at varying feed flow rates and influent ammonia concentrations to determine response to shock loadings. The CFBB responded favourably in terms of TSS and COD removal to quadrupling of the feed flow rate. However, nitrification was more sensitive to hydraulic shock loadings than to doubling of influent nitrogen loading.     

Pyrethrins and piperonyl butoxide adsorption to soil organic matter

The adsorption and mobility of pyrethrins (Pys), the major insecticidal components obtained from the pyrethrum daisy Tanacetum cinerariifolium, and piperonyl butoxide (PBO), a pyrethrum synergist, were determined in soil using batch-equilibrium and reverse-phase thin-layer chromatographic techniques. Two soil management practices were used, soil mixed with yard waste compost (COM) at 50 t acre(-1) on dry weight basis and no-mulch (NM) bare soil. Adsorption isotherm experiments were carried out using known concentrations of Pys (Py-I and Py-II) and PBO mixed with known amounts of COM or NM soil at constant temperature and pressure until equilibrium was attained. Pys and PBO in soil extracts were purified and concentrated using solid-phase extraction cartridges containing C18-octadecyl bonded silica. Pys and PBO residues were quantified using a high-performance liquid chromatograph equipped with a UV detector. Adsorption studies showed that compost amended soil adsorbed more Pys and PBO than native (NM) soil. Py-I adsorption was greater than Py-II and PBO. Adsorption of Pys and PBO to humic and fulvic acids was also studied by reverse-phase thin layer chromatography (RPTLC). Results indicated that humic acid, a significant component of organic matter, reduced Pys and PBO mobility. Pys and PBO mobility decreased as the concentration of humic acid in the mobile phase increased.     

Chromosomal abnormalities among welder trainees

Serial cytogenetic observations were made on a group of 273 military recruits who were being trained as welders at Aberdeen, MD. The trainees were being exposed to presumably increased levels of ozone in the course of their welding school experience, and it was the purpose of this study to determine whether or not ozone, at low-to-moderate doses, is capable of inducing chromosomal aberrations in peripheral blood lymphocytes.Previous exposures and the past medical experiences of the trainees were determined by questionnaire, enabling us to obtain a profile on the medical-social characteristics of the study sample. Each welder was to serve as his own control, having a blood sample drawn at the beginning of his twelve week training program, prior to ozone exposure, with two post-exposure bloods being obtained at 6 and 12 weeks after the start of the program.Ozone levels and the levels of the oxides of nitrogen were determined in the immediate area of the welding. The ozone levels were repeatedly found to be negligible, with the nitrogen oxides appearing to be the primary toxic agents involved. For those 165 subjects on whom two blood samples were obtained, and for those 86 on whom all three blood samples were obtained, no statistically significant increases in chromosomal aberrations were found.     

Environmental and Cost Assessment of a Polypropylene Nanocomposite

This paper describes a study on the use of a polypropylene (PP)/layered silicate nanocomposite as packaging film, agricultural film, and automotive panels. The study’s main question was “Are the environmental impacts and costs throughout the life cycle of nanocomposite products lower than those of products manufactured from conventional materials?” The conventional (benchmark) materials studied were pure polypropylene as packaging film, pure polyethylene as agricultural film, and glass fiber-reinforced polypropylene as automotive panels. In all three cases, the use of the PP nanocomposite resulted in a reduction of the amount of material used, while ensuring the same functionality. Material reduction was estimated using Ashby’s material indices and amounted to ?9% for packaging film, ?36.5% for agricultural film, and ?1.25% for automotive panels. It goes without saying that a product’s impact on the environment will decrease when less material is used. The production and incorporation of nanoparticles, however, may have additional impacts. We found clear environmental benefits throughout the entire life cycle when the PP nanocomposite is used in the manufacture of agricultural film. We noted some cost benefits when the nanocomposite is used in the production of agricultural film and automotive panels. If the price of nanoclay is at most €5,000 tonne then the cost of nanocomposite packaging film is also lower than that of the conventionally produced product.     

Analysis of barriers in e-waste management in developing economy: an integrated multiple-criteria decision-making approach

Environmental Science and Pollution Research - An increasing amount of electronic waste (e-waste) is not a new concern. It has been causing trouble globally. This waste comprises valuable metals...     

Forests and societal values: comparing scientific and public perception of forest health

This study examines the common ground between lay people and scientists regarding forest values and definitions of forest health. With the forest at Pinery Provincial Park, Ontario, as a case study, the authors compared six ecological indicators to determine which were sensitive to the multiple impacts of visitor use, deer browsing and fire suppression. Plant cover and proportion native species were sensitive to these impacts. Sapling height was greater in low deer density areas. The authors also conducted focused discussions with local interest groups, followed by qualitative data analysis. Overall, there was good convergence between scientific and public views of forests and forest health, although this may partly be due to the groups' interest in nature and the Pinery. Subjects saw a connection between their health and the state of the global and local environment, including forests. There is a need for increased awareness in the public to the necessity of managing high deer populations in parks to protect other forest components such as biodiversity. Forest managers must consider that people greatly value forests near them for mental well being. Group responses suggested that messages explicitly linking forest benefits to human health and well being may motivate people to protect forests.