Glycerine from biodiesel: The perfect diesel fuel

Glycerine supply currently exceeds its demand by a significant margin as it is formed as by-product in biodiesel production. Different routes for its utilisation are currently being looked into, especially ones that would allow its use as a fuel addition. However these routes are not as energy efficient as its direct combustion.Previously glycerine and other very low cetane number calorific liquids were thought impossible to be used as fuels in compression ignition engines. We have developed a combustion cycle that permits the utilisation of glycerine as a fuel in a compression ignition engine without the need for pilot fuels or cetane improving additives. The paper discusses the results of glycerine combustion in standard unmodified Lister-Petter and Deutz compression ignition engines.     

Degradable polymers: The role of the degradation environment

The degradability of several degradable polymers was examined using three types of degradation environments. These include exposure in a laboratory-scale composting test system containing material representative of the organic fraction of municipal solid waste (MSW), exposure in a thermal hydrolytic environment consisting of water at 60‡C, and exposure in a thermal-oxidative, dry oven environment of 60‡C. The results of the investigation clearly indicate that, in addition to chemical and biological activity which can lead to polymer degradation, physical restructuring and reorganization of the macromolecular structure may also occur at temperatures typically found in a compost environment, resulting in changes in the mechanical properties of the polymer films. In the case of the polyethylene-modified polymers evaluated in this study, all behaved similarly, but differently from the other polymer types. The polyethylene-based films appeared to be susceptible to oxidative degradation and should degrade in a composting environment providing that there is sufficient air in contact with the film for a sufficient period of time. However, when exposed in a laboratory composter, it appears that although ideal temperature-time curves may be obtained, the test time period was insufficient in comparison to the induction period required to achieve the desired thermal oxidative degradation. Issued as NRCC No. 37620.     

Light scattering characteristics of aerosols as a function of relative humidity: Part I--A comparison of measured scattering and aerosol concentrations using the theoretical models

The Southeastern Aerosol and Visibility Study (SEAVS) was undertaken to characterize the size-dependent composition, thermodynamic properties, and optical characteristics of the ambient atmospheric particles in the southeastern United States. The field portion of the study was carried out from July 15 to August 25, 1995. As part of the study a relative humidity controlled inlet was built to raise or lower the relative humidity to predetermined levels before the aerosol was passed into an integrating nephelometer or particle-sizing device. Five other integrating nephelometers were operated in various configurations, two of which were fitted with a 2.5 microns inlet. Fine particle (< 2.5 microns) samplers were operated to measure concentrations of sulfate, nitrate, and ammonium ions, organic and elemental carbon, and fine soil. Mass size distributions were measured with an eight-stage, single orifice cascade impactor. Four different strategies for estimating scattering were used. First, an externally mixed model with constant specific scattering coefficients, sulfate ion mass interpreted as ammonium bisulfate, and ammonium bisulfate growth as a function of relative humidity, is assumed. Second, an externally mixed aerosol model, assuming constant dry specific scattering but with sulfate ammoniation and associated composition-dependent hygroscopicity explicitly accounted for, is used. Third, an externally mixed aerosol model, but with sulfate ammoniation, associated growth as a function of relative humidity, and sulfate size distributions, is applied. Fourth, an internally mixed aerosol model with measured sulfur size distributions and estimated size distributions for other species is used with the growth characteristics of the mixture being estimated using the Zdanovskii-Stokes-Robinson (ZSR) assumptions. Only ionic species were considered to be hygroscopic. The second, third, and fourth approaches yield similar results with reconstructed scattering comparing quite favorably with measured scattering. Accounting for sulfate ammoniation and associated water uptake was the most important detail in achieving closure between measurements and modeled scattering. In general, differences between estimated scattering, assuming internally or externally mixed models, was small. These same models were used to estimate wet to dry scattering ratios. The R2 for an ordinary least-squares regression between measured and predicted ratios was high (0.71-0.92), and in most cases the scattering ratio was insensitive to modeling assumptions. However, during some sample periods differences between predicted scattering ratios for the different modeling assumptions were as high as 30%.     

An Investigation of Odors and Volatile Organic Compounds Released during Composting

ABSTRACT

The emissions of odors and volatile organic compounds produced from a commercial composting operation have been studied using a laboratory-scale composting system. The composting activity of a typical commercial compost feed was followed by monitoring the composting temperature, as well as the respiratory rate. Using a controlled aeration system, the gaseous volatiles produced were tested for odors using the "dilution-to-threshold" method, as well as gas composition, as determined by gas chromatography-mass spectrometry.

The results indicated that while there may be a reasonable correlation between the release of volatile organic compounds (VOCs) and odors, care has to be taken when trying to identify offensive odors with specific chemical species. However, the data obtained suggests that offensive odors formed during commercial composting may be due to sulfurous and nitrogenous compounds, although their concentrations in the compost gases may not be very high.

The major release of VOCs occurred during the first two weeks of composting, after which the gaseous releases fell dramatically as the composting process proceeded and temperatures started to fall.     

The relationship between socio-economic indicators and air pollution in England and Wales: implications for environmental justice

This paper investigates the distribution of three common air pollutants, sulphur dioxide, nitrogen dioxide and fine particulates (PM₁₀), in England and Wales with respect to social class, ethnicity and population density. A multilevel model is used to demonstrate regional differences in the social distribution of pollution. The results show that, allowing for ethnicity and population density, there are different relationships between socio-economic status and exposure to air pollution within different regions in England and Wales. These differences suggest that national legislation introduced to reduce air pollution levels may give rise to environmental injustice, with geographical and social differences in the costs and benefits arising to the population due to such legislation. Received: 24 February 1999 / Accepted: 2 September 1999     

Evolutionary or fragmented environmental policy making? coal,power, and agriculture in the Hunter Valley,Australia

Intensified surface mining, power generation, and smelting operations in the Hunter River lowlands, NSW, Australia have posed numerous new environmental management problems. Legislative controls over water, soils, and land use management have been clearly insufficient and remain so. The complex range of environmental changes is challenging government agencies as well as coal developers. While water demands are increasing in the region the proportionally greatest competitors are power generation and irrigation. Comprehensive regional water quality assessment is inadequate and divided between a number of agencies with fragmentary interests. Coal development inquiries signal further controversy over appropriate management solutions and are an ongoing phenomenon in the region. The early 1980s resource boom has been followed by lower rates of economic growth, which have resulted in disparate agency responses to major ongoing environmental questions. While issue attention cycles are often remarkably short in environmental management, matters of water, land, and air quality require intensive and ongoing monitoring and policy development.