Optical microscopy as a new approach for characterising dust particulates in urban environment.

In urban environments airborne particulates (dust) must be managed to ensure that industry and community coexist in a mutually beneficial and sustainable manner. The composition of the dust is a function of the local environment and industry. In general, there is a view by many community members that a significant proportion of inhalable (PM10) and respirable (PM2.5) dust in these environments could be coal. Thus there is a need to have an analytical method that provides a quantitative analysis of the amount and size distribution of the different particulates that can be present in air samples. Australia's national research body, the Commonwealth Scientific and Industrial Research Organisation (CSIRO) has developed a Coal Grain Analysis (CGA) system that uses reflected light optical microscopy to provide a unique visual perspective, a qualitative feeling of the sample and quantitative information on the composition and size of the individual particles greater than 1 µm. Furthermore, semi-automated Optical Dust Marker software uses each individual particle's colour reflectance fingerprint to classify that particle. These markers can currently identify coal, combustion chars, iron, quartz/dark minerals, pyrite/bright materials and particulates of organic origin. This paper presents a case study performed using CGA to evaluate the dust composition and proportion of coal and other particulates and also their size distribution in samples collected in an urban area along a coal rail corridor in Newcastle (Australia). In coastal environments a significant proportion of dust can be water soluble (salt) particulates; the proportion of soluble particulates in those samples varied from 46% to 52.3%. The concentration of insoluble particles in samples varied from 5.9 to 15.5 µg m-3 in the PM2.5-10 fraction and from 0.4 to 0.9 µg m-3 in the PM1-2.5 fraction. All samples consisted predominantly of particles of organic origin (mostly plant and insect remains) - 55.3%-85.3% by mass. Dark material particles of mainly inorganic origin (low reflecting material, mainly stone dust, clay, soot, rubber and soil), combustion char and metal particles (rust and iron oxides) were present in lower concentrations - 0.0% to 19.9% by mass. The amount of coal in the water insoluble fraction of the samples ranged from 5.3% to 19.7% by mass with 2.9%-13.5% by mass of coal particles in the thoracic (2.5-10 µm) and 0.3%-1.2% by mass in the respirable (1-2.5 µm) size fraction.

Possibilities of the utilization of char from the pyrolysis of tetrapak.

Since the cellulose used in the production of tetrapak is of very high quality, the char generated during pyrolysis should be influenced mainly by the pyrolysis temperature. This article aims to determine the chemical composition of biochar prepared at the temperatures of 400, 500, 600 and 700 °C and its environmental properties determined by the presence of organic compounds with toxicity and relatively high mobility in the environment. The analytical pyrolysis of char was used to identify the following groups of organic compounds: alkanes, cycloalkanes, alkenes, cycloalkenes, alkynes, alkadiens, ethers, alcohols, nitrogen compounds, nitrils, ketones and aldehydes, compounds containing phenols, furans, benzofurans, PAHs (polycyclic aromatic hydrocarbons), carboxylic acids, compounds containing benzenes and markers indicative of the presence of synthetic polymers (polyethylene layers, a part of dyes, antioxidants, stabilizers), and fragments of cellulose. Concerning the use of char as a soil conditioner, its ecotoxicity was monitored (Folsomia candida) by monitoring its addition to the artificial soil (char addition: 0.5, 1, 2.5, 5, 10, 15, 20, 50 and 100%). The lowest reproduction inhibition of Folsomia candida is caused by biochar prepared at the temperature of 400 °C and 700 °C, but it is not suitable for the agricultural application, the concentration of PAHs is three times higher than the EBC limit. Low-density polyethylene which is present in the aseptic box in concentration of 6%, can degrade biochar so that it cannot be used as a soil amendment. The results of the char analyses show that the pyrolysis temperature is a decisive factor in the applicability of biochar.

Enrichment and distribution of 24 elements within the sub-sieve particle size distribution ranges of fly ash from wastes incinerator plants.

The management of an increasing amount of municipal waste via incineration has been gaining traction. Fly ash as a by-product of incineration of municipal solid waste is considered a hazardous waste due to the elevated content of various elements. The enrichment and distribution of 24 elements in fly ash from three wastes incinerators were evaluated. Two coarse (>100 µm and <100 µm) and five sub-sieve (12-16, 16-23, 23-34, 34-49, and 49-100 µm) particle size fractions separated on a cyclosizer system were analyzed. An enhancement in the enrichment factor was observed in all samples for the majority of elements in >100 µm range compared with <100 µm range. The enrichment factor of individual elements varied considerably within the samples as well as the sub-sieve particle size ranges. These variations were attributed primarily to: (i) the vaporization and condensation mechanisms, (ii) the different design of incineration plants, (iii) incineration properties, (iv) the type of material being incinerated, and (v) the affinity of elements.