Economic feasibility and sustainability assessment of residual municipal solid waste management scenarios in NSW, Australia

This study evaluates the economic cost and sustainability of treating residual municipal solid waste (MSW) through five waste management scenarios. In the baseline scenario (Bsc), all waste was managed through landfilling, while in scenario 1 (Sc1) all waste was treated by incineration. Sc2 employed anaerobic digestion (AD) for food waste and landfilling, and Sc3 treated the waste through AD for food waste, incineration of combustible and plastic wastes, and landfilling. Sc4 treated the waste using AD, incineration, landfilling, and recycling of the plastic waste. The economic cost of waste management scenarios was estimated by calculating different economic variables, such as gate fees, including capital and operating costs, governmental incentives and levies, and also the potential of employed waste treatment technologies for resource recovery. The results revealed that Sc3 has the lowest economic cost of 238.1 mAUD/year, followed by Sc1 (261.9 mAUD/year), while Bsc proved to be the highest cost at 476.1 mAUD/year for MSW treatment. It was noticed that scenarios employing incineration had lower economic costs compared to Bsc and Sc2, mainly because incineration resulted in higher electricity generation and reduced greenhouse gas emissions. The sustainability assessment results confirmed that Sc3 had the lowest and Bcs the highest total economic cost and environmental damage

Slow pyrolysis of metal(loid)-rich biomass from phytoextraction: characterisation of biomass, biochar and bio-oil

Plants have successfully been used for phytoextraction of metal contaminated soils, however the use of these plants for energy production has been a subject of debates due to the potential conversion of the metals in the plants into airborne respirable particles. The aim of this study was to investigate the deportment of metal(loid)s during pyrolysis of a biomass cultivated in a highly contaminated soil in order to engineer best practice environmental approach for utilization of this biomass. A heavy metal(loid) contaminated mangrove (Avicennia marina var. australasica) biomass was used as a feedstock in this study. The biomass was subjected to slow pyrolysis under the heating rate of 60 ℃/min and different pyrolysis temperatures. Inductively coupled plasma mass spectrometry, thermogravimetric analysis, Fourier-transform infrared spectroscopy, X-ray fluorescence spectroscopy and gas chromatography–mass spectrometry were introduced to characterise the biomass, biochar and bio-oil samples. Results showed that biochar yield decreased from 57.4 % to 35.3 % with the increase in pyrolysis temperature from 300 to 700 ℃. Heavy metal(loid)s (chromium, manganese, iron, copper, zinc, arsenic and lead) were mainly bound in the biochar produced at 300 ℃, while the recovery decreased substantially with the increase of pyrolysis temperature. Phenols, carboxylic acids and alcohols were the dominant compounds in all bio-oil samples. This study suggested further requirements of biochar quality and environmental risk assessment to provide a safe and value-added way of phytoextraction residual applications

Life cycle analysis of energy production from food waste through anaerobic digestion, pyrolysis and integrated energy system

The environmental performance of industrial anaerobic digestion (AD), pyrolysis, and integrated system (AD sequence with pyrolysis) on food waste treatment were evaluated using life cycle assessment. The integrated treatment system indicated similar environmental benefits to AD with the highest benefits in climate change and water depletion in addition to the increased energy generation potential and the production of valuable products (biochar and bio-oil). Pyrolysis results illustrated higher impact across water, fossil fuel, and mineral depletion, although still providing a better option than conventional landfilling of food waste. The dewatering phase in the AD process accounted for 70% of the treatment impact while the pre-treatment of the food waste was responsible for the main burden in the pyrolysis process. The study indicated that the three treatment options of food waste management are environmentally more favorable than the conventional landfilling of the wastes

Investigating the effect of Cu/zeolite on deoxygenation of bio-oil from pyrolysis of pine wood

Pyrolysis is one of the significant technologies that can utilize lignocellulose biomass to produce different bioenergy fuels, such as bio-oil, pyrolytic gases and bio-char. The application of pyrolysis has been extensively studied to produce bio-oil, which is foreseen as the potential transportation fuel in the near future. However, the presence of oxygenated compounds, such as phenols and alcohols in bio-oil makes it highly acidic and unstable for a suitable transportation fuel. These oxygenated compounds can be converted to refinable hydrocarbons by using different catalysts. Therefore, this study aimed to prepare a catalyst that is Cu10%-zeolite and investigated its deoxygenation activity for bio-oil produced from pyrolysis of pine wood sawdust. The catalyst was prepared by a wet-impregnation method. Subsequently, the catalyst was characterized by X-ray diffraction and transmission electron microscopy. Furthermore, the catalyst was applied for in-situ (catalyst: biomass=5) and ex-situ catalytic pyrolysis (catalyst: biomass=3) and the results were compared with those from sole zeolite support. The pyrolysis process was carried out at a heating rate of 100 °C/min to a final temperature of 700 °C and the composition of bio-oil was examined by gas chromatography-mass spectroscopy. The results revealed that Cu-zeolite showed significant deoxygenation activity for bio-oil as compared to zeolite or without any catalyst. Evidently, Cu-zeolite after in-situ pyrolysis produced bio-oil with 20.9% aromatic hydrocarbons and 7.5% aliphatic hydrocarbons, which were approximately 80% and several times higher than with only zeolite, respectively. Meanwhile the concentration of alcohols was reduced from 47.5% to 5%. On the other hand, bio-oil produced from ex-situ catalytic pyrolysis was enriched with 41.6% aromatic hydrocarbons while only 1% alcohols were present in bio-oil. This promising deoxygenation activity can be ascribed to Cu-zeolite’s catalytic activity that converted phenol and alcohols to refinable hydrocarbons via various reactions, such as dehydration, decarboxylation and decarbonylation

Preliminary screening for microplastic concentrations in the surface water of the Ob and Tom Rivers in Siberia, Russia

This study characterizes the abundance and morphology of microplastics in surface water of the Ob River and its large tributary, the Tom River, in western Siberia. The average number of particles for two rivers ranged from 44.2 to 51.2 items per m3 or from 79.4 to 87.5 μg per m3 in the Tom River and in the Ob River, correspondingly. 93.5% of recovered microplastics were less than 1 mm in their largest dimension, the largest group (45.5% of total counts) consisted of particles with sizes range 0.30-1.00 mm

Iron ore reduction using sawdust : experimental analysis and kinetic modelling

Iron and steel making are two of the largest energy intensive industries with the highest growth rate in energy consumption of all energy utilisation sectors. In order to meet the growing greenhouse challenges, incorporation of renewable energy sources to the existing and emerging metallurgical operations is desirable. In this respect, biomass can potentially be applied as fuel for minerals processing to stabilise the greenhouse gas emissions as it is renewable and CO₂ neutral. The work presented here investigates the fundamental mechanisms of iron ore reduction with biomass wood waste. Several mixtures with different ratios of biomass and iron ore were subjected to thermal, gaseous and X-ray Diffraction analysis. The iron ore was successfully reduced to predominantly metallic iron phase when up to 30% by weight of biomass was introduced into the mixture. Reduction commenced at approximately 670°C and was almost completed at 1200°C. Thermal analysis data identified the individual thermal reaction regions associated with developments of individual iron phases during the heating and were used to calculate the corresponding kinetics of the reduction process.14 page(s

System approach to biomass pyrolysis : product characterisation

Engineering a system solution of the biomass pyrolysis process requires thorough investigation of the possible end-use applications of the biomass pyrolysis products (bio-oils and bio-char) in order to determine the most feasible and greenhouse gas abating options for their use. This work investigates the biomass pyrolysis process of three potentially applicable energy crop species and provides characterization of the biooil and biochar products of pyrolysis. The analysis suggests that the biochar contains the OH, aromatic C=C and inorganic Si-O-Si bonds. The biooil samples exhibited much more complex structure and were highly variable in composition suggesting requirement for their further upgrading.5 page(s

Measurements of the heats of coal devolatilisation

Research Doctorate - Doctor of Philosophy (PhD)An experimental investigation of coal thermal behaviour at elevated temperatures is presented. The aim of the experimental study was to develop a technique for continuous measurement of the thermal properties of coals in order to determine the heats of reactions during devolatilisation. A new experimental apparatus was designed for measuring the apparent volumetric specific heat, thermal conductivity and diffusivity of five Australian coal samples

Pyrolysis of biomass

31 page(s

Thermal decomposition of wheat straw and mallee residue under pyrolysis conditions

The pyrolysis behavior of wheat straw and mallee residue and resulting gases, liquids, and chars were examined. The specific heat and thermal conductivity of both species were measured using computer-aided thermal analysis at heating rates of 10 and 100 °C/min to a temperature of 1000 °C. The sample decomposition was also measured by thermogravimetry. Gas chromatography detected evolved gases, and the bio-oils were characterized using GC-MS. Chars were examined using FTIR, proximate, and ultimate analysis. Both species initially displayed endothermic behavior, followed by rapid decomposition and fluctuating specific heat and thermal conductivity between 250 and 500 °C. Oxides of carbon were the primary gases evolved, with small amounts of hydrocarbons and hydrogen. The bio-oils predominantly contained oxygenated aromatics and organic acids, and the chars had high fixed carbon and low sulfur. In all instances approximately half of the product output was liquid. Straw produced 14% gas and 32% solid at 500 °C, whereas mallee produced 13% gas and 36% solid. At 1000 °C the proportions of solid decreased and gas increased. The efficiency of pyrolysis to 500 °C, assuming no losses, was around 96% for both species. At 1000 °C the efficiency decreased, with pyrolysis of mallee slightly more efficient than for straw.7 page(s