Performance of constructed evaporation ponds for disposal of smelter waster water: a case study at Portland Aluminum, Victoria, Australia

The construction of evaporative ponds and wetlands for the disposal of waste water high in ionic concentrations is a waste disposal strategy currently considered by many industries. However, the design, construction and management of these ponds and wetlands are not straightforward as complex chemical interactions result in both spatial and temporal changes in water quality. The effects of evaporation and drainage on the water quality in two constructed ponds, an adjacent man-made wetland and local groundwater at Portland Aluminium were investigated. The minimum volume of water entering the ponds during the study period was 0.96±0.16 ML per month. The predicted theoretical evaporative capacity of the two ponds was calculated to be 0.30±0.07 ML per month. More water enters the ponds than it is theoretically possible to evaporate under the ambient weather conditions at Portland, yet the ponds do not overflow, suggesting percolation through the pond lining. No spatial differences in solute concentrations (fluoride, sulphate, bicarbonate, carbonate, sodium, potassium, calcium, and magnesium ions) were found within the waters of either pond, although temporal differences were apparent. The results support the conclusion that the ponds are not impermeable, and that much of the waste water entering the ponds is being lost through seepage. The impacts on local groundwater chemistry of this seepage are addressed. Significant correlations exist between solute presence within and between the ponds, wetland and groundwater. Fluoride and sulphate concentrations were significantly higher in pond waters throughout the duration of the experiment. Pond sediments revealed a high degree of spatial and temporal heterogeneity in the concentration of all monitored ions resulting from the chemical heterogeneity of the material making up the pond linings. Adsorption isotherms for fluoride indicate that the adsorption capacity of the pond linings remains high for this ion. Implications for the management of waste water by this strategy are discussed.

Irrigation with reclaimed water at Portland Aluminium

Through extensive laboratory and field based analysis of soil chemical and physical processes, this research identified and addressed key management issues associated with the sustainable irrigation of municipal wastewater onto sandy water repellent soils, overlaying a shallow aquifer, in an environmentally significant coastal system.

Hydrodynamics, nutrients and algae of Fitzroy and Merri River estuaries

Various physical, biological and chemical attributes were investigated for the Fitzroy and Merri River estuaries. This research found algal communities were most influenced by high nitrogen concentrations at times of low flow. Mangement of nutrients within each catchment is therefore of high importance to reduce the possibility of future blooms.

Drip irrigation of treated municipal effluent in vineyards

Vine-row soil chemical and physical properties were significantly and detrimentally altered by drip irrigation of treated municipal effluent. Hydraulic gradients under the drip-emitter fostered strong chemical gradients and high variability of vine-row soil parameters, complicating soil management. Gypsum improves soil properties without impacting vine production when applied in small quantities.

Palinurid lobster aquaculture: nutritional progress and considerations for successful larval rearing

The closed-cycle rearing of palinurid lobsters in commercially relevant quantities currently represents one of the most difficult challenges facing modern-day aquaculture. The length and complexity of the larval life cycle exacerbate the problem, comprising the major bottleneck to their successful aquaculture. The general consensus is that developments in the key research area of nutrition will provide the necessary breakthroughs to make the closed-cycle rearing of lobster a reality. Due to the cryptic nature of feeding preferences and complex larval morphology, a commercially formulated feed for their culture does currently not exist. Nevertheless, there has been a wealth of research conducted to elucidate many of the unknowns concerning larval nutritional requirements. This review presents a synthesis of this information, ranging from investigations of larval morphology and feeding behaviour, hatchery nutrition practices, the elucidation of wild prey items and the nutritional content of wild-caught larval species. Based on the information available, this review culminates with a ‘best guess’ formulation for a larval spiny lobster diet, taking aspects concerning both the physical and chemical attributes of formulation into consideration. It is concluded that larval spiny lobsters are likely comparatively low in relation to other larval species with respect to their quantitative dietary requirements. Ultimately, the overall success of the larval cycle appears to be dictated by the stockpiling of lipids to fuel an energy-demanding metamorphosis and a subsequent nonfeeding puerulus phase. These insights provide valuable direction for the formulation of nutritionally complete feeds to permit the closed-loop culture of spiny lobster species.

Variability of soil chemistry following irrigation with recycled municipal effluent: a Great Western vineyard case study

In areas of Australia where viticultural operations have been limited by lack of an acceptable irrigation water source, considerable expansion has occurred through the use of recycled wastewater. Despite this rapid expansion, little is known of the potential impacts of the water’s chemical constituents on soil properties, or the long-term sustainability of the vineyards using the water. In order to establish the impacts of drip irrigated recycled wastewater on a vineyard in Great Western, Australia, a study comparing the soils from the vineyard inter-row and row area was undertaken. Chemical and physical properties of the soil with varying distances from the drip emitter were also investigated. During the irrigation season, significant differences between the inter-row and row area were found for several chemical parameters including pH(1:5soil/water) (P<0.001), electrical conductivity (EC1:5) (P<0.001), water-soluble sodium (WS Na+) (P<0.001), and water-soluble chloride (WS Cl-) (P<0.001). This paper will discuss differences observed between soil properties of the inter-row and vine row area, as well as the spatial distribution of solutes under the drip emitter.

Modelling the fate of chromated copper arsenate in a sandy soil

A pulse of chromated copper arsenate (CCA, a timber preservative) was applied in irrigation water to an undisturbed field soil in a laboratory column. Concentrations of various elements in the leachate from the column were measured during the experiment. Also, the remnants within the soil were measured at the end of the experiment. The geochemical modelling package, PHREEQC-2, was used to simulate the experimental data. Processes included in the CCA transport modelling were advection, dispersion, non-specific adsorption (cation exchange) and specific adsorption by clay minerals and organic matter, as well as other possible chemical reactions such as precipitation/dissolution. The modelling effort highlighted the possible complexities in CCA transport and reaction experiments. For example, the uneven dosing of CCA as well as incomplete knowledge of the soil properties resulted in simulations that gave only partial, although reasonable, agreement with the experimental data. Both the experimental data and simulations show that As and Cu are strongly adsorbed and therefore, will mostly remain at the top of the soil profile, with a small proportion appearing in leachate. On the other hand, Cr is more mobile and thus it is present in the soil column leachate. Further simulations show that both the quantity of CCA added to the soil and the pH of the irrigation water will influence CCA transport. Simulations suggest that application of larger doses of CCA to the soil will result in higher leachate concentrations, especially for Cu and As. Irrigation water with a lower pH will dramatically increase leaching of Cu. These results indicate that acidic rainfall or significant accidental spillage of CCA will increase the risk of groundwater pollution.

Degradation of phenanthrene and pyrene in soil slurry reactors with immobilized bacteria Zoogloea sp.

The environmental fate of polycyclic aromatic hydrocarbons (PAHs) in soils is motivated by their wide distribution, high persistence, and potentially deleterious effect on human health. Polycyclic aromatic hydrocarbons constitute the largest group of environmental contaminants released in the environment. Therefore, the potential biodegradation of these compounds is of vital importance. A biocarrier suitable for the colonization by micro-organisms for the purpose of purifying soil contaminated by polycyclic aromatic hydrocarbons was developed. The optimized composition of the biocarrier was polyvinyl alcohol (PVA) 10%, sodium alginate (SA) 0.5%, and powdered activated carbon (PAC) 5%. There was no observable cytotoxicity of biocarriers on immobilized cells and a viable cell population of 1.86 × 10¹⁰ g^–1 was maintained for immobilized bacterium. Biocarriers made from chemical methods had a higher biodegradation but lower mechanical strengths. Immobilized bacterium Zoogloea sp. had an ideal capability of biodegradation for phenanthrene and pyrene over a relative wide concentration range. The study results showed that the biodegradation of phenanthrene and pyrene reached 87.0 and 75.4%, respectively, by using the optimal immobilized method of Zoogloea sp. cultivated in a sterilized soil. Immobilized Zoogloea sp. was found to be effective for biodegrading the soil contaminated with phenanthrene and pyrene. Even in "natural" (unsterilized) soil, the biodegradation of phenanthrene and pyrene using immobilized Zoogloea sp. reached 85.0 and 67.1%, respectively, after 168 h of cultivation, more than twice that achieved if the cells were not immobilized on the biocarrier. Therefore, the immobilization technology enhanced the competitive ability of introduced micro-organisms and represents an effective method for the biotreatment of soil contaminated with phenanthrene and pyrene.

Eri silk fibre attributes and sliver preparation

Eri silk produced by Philosamia cynthia ricini silkworm is a fibre not well-known to the silk industry, in spite of the fact that Eri silk is finer, softer, and has better mechanical and thermal properties than most animal fibres. Eri silk has a high commercial potential, as the host plants of Eri silk worms are widespread in diverse geographical locations, and the worms also have a higher degree of disease resistance than most other silk worms. Mills are often not aware of the properties of Eri for designing appropriate end products. Thus, Eri silk yarn is traditionally produced by hand spinning, and Eri silk usually ends up as material for handwoven shawls. The potential for bulk fibre processing and the development of soft luxurious novel Eri silk products is yet to be discovered. To better understand the material and its processing behaviour, Eri silk was characterised and cocoons were processed into tops through degumming, opening, and cutting filaments into different lengths, followed by a worsted spun silk processing route. Fibre properties such as fineness, crimp, strength and length at different processing stages up to combed tops were measured. The results indicate that staple Eri silk can be processed via the worsted topmaking route, using a cut length of 200 mm or 150 mm for filament sheets prepared from degummed cocoons.

Attributes for Australian mechanical engineers through proximal and distance education

The 1996 Johnson stakeholder review of Australian engineering education recommended the development of a number of broadly defined attributes in all engineering graduates. The Institution of Engineers, Australia (now Engineers Australia) responded swiftly by switching the focus of its engineering course accreditation requirements from course content to graduate attribute outcomes. To maximise the effectiveness of this approach to the mechanical engineering discipline a clear understanding of the relative significance of a more detailed range of attributes to Australian industry is essential, yet the scope of the mechanical engineering profession is broad and views of individual practitioners contributing to debate on attribute requirements are largely influenced by their own often unique professional formation. The research presented in this thesis is unique in using a role based analysis of the relative significance of an extensive range of attributes considered relevant to Australian mechanical engineers. The study covers the six industries found to employ the greatest number of Australian mechanical engineers. The significance of these attributes in the core mechanical engineering roles of each industry are weighted according to the numbers of mechanical engineers employed in those roles. These attribute significance profiles are considered in the context of a study of the formative development of the profession under the extensive influence of 19th and 20th century UK and US practices and recent momentous changes in engineering employment and formation. A wide range of appropriate teaching strategies to develop the most significant attributes through proximal and distance learning are explored and a brief account of the candidate’s work in developing and assessing the use of technology to enhance flexible learning in the field of engineering education is also included in this thesis. Whilst major areas of the mechanical engineers knowledge base are considered as part of the main study, further case study based research is presented to assess in more detail the knowledge base requirements for Australia’s best performing manufacturing industry by ‘industry value added’ - Food, Beverage and Pharmaceuticals and as such provides an indication of the relevance of the content base of Australian mechanical (as well as chemical and electrical) engineering degree programs to an Australian industry sector.

Sorption and Fractionation of Copper in soil at a sewage irrigation farm in Australia

Copper (Cu) is an important heavy metal to be considered in soil contamination, because high concentrations of copper in soil produce toxic effects and may accumulate in plant tissues. In Australia's oldest sewage irrigation farm, located in Werribee, Victoria, soil in the land filtration area is contaminated by Cu. However, Cu content in herbage tissues is in the normal range and has been trending downward since 1979. Therefore, studies on the sorption capacity and sequential extraction of Cu in soil at the Werribee Farm is of significance, not only for better understanding the mechanism of transport, chemical processes, and plant uptake of Cu, but also in providing information for the practical management of sewage farm soils. Methods of combining sorption isotherms with sequential extraction procedures were adopted, and the results showed that the soil in the land filtration area at Werribee Farm has a high sorption capacity for Cu, and distribution coefficients, K_f of Cu, were 629 L kg^-1 in surface soils (0-20 cm) and 335 L kg^-1 in subsurface soils (20-40 cm). The sequential extraction fractions demonstrate that exchangeable and carbonate fractions are very low, only comprising 3.49 to 5.49% of total copper. The other fractions are also discussed. This characteristic of Cu in soil is related to the low concentration of Cu in plant tissues.

The effect of concentrations and properties of phenanthrene, pyrene, and benzo(a)pyrene on desorption in contaminated soil aged for 1 year

Purpose : The choice and timing of microorganisms added to soils for bioremediation is affected by the dominant bioavailable contaminants in the soil. However, changes to the concentration of bioavailable PAHs in soil are not clear, especially when several PAHs coexist. This study investigated the effects of PAH concentration and chemical properties on desorption in meadow brown soil after a 1-year aging period, which could reflect changes of PAH bioavailability during bioremediation. Materials and methods : Based on the percentage of different molecular weights in a field investigation, high-level contaminated soil (HCS) and low-level contaminated soil (LCS) were prepared by adding phenanthrene (PHE), pyrene (PYR) and benzo(a)pyrene (BaP) to uncontaminated meadow brown soil. The concentrations of HCS and LCS were 250 mg kg−1 (PHE, PYR, and BaP: 100, 100, and 50 mg kg−1) and 50 mg kg−1 (PHE, PYR, and BaP: 20, 20, and 10 mg kg−1) respectively. The soils were aged for 1 year, after which desorption was induced by means of a XAD-2 adsorption technique over a 96-h period. Results and discussion : The range of the rapidly desorbing fraction (F rap) for PHE, PYR, and BaP in HCS and LCS was from 1.9 to 27.8 %. In HCS, desorption of PYR was most difficult, and the rate constant of very slow desorption (K vs) of PYR was 8 orders of magnitude lower than that of BaP, which had similar very slow desorbing fractions (49.8 and 50.5 %, respectively). However, in LCS, desorption of PYR was the easiest; the Kvs of PYR was 8–10 orders of magnitude higher than those of PHE and BaP. In HCS, the time scale for release of 50 % of the PAHs was ranked as BaP > PYR > PHE, while in LCS this was BaP > PHE > PYR. Conclusions : The combined effect of PAH concentrations and properties should be taken into account during desorption. The desorption of PAH did not always decrease with increasing molecular weight, and the desorption of four-ring PAHs might be special. These results are useful for screening biodegrading microbes and determining when they should be added to soils based on the dominant contaminants present during different periods, thus improving the efficiency of soil bioremediation.

TMI for urban resilience : measuring and mapping long-term climate change effects on soil moisture

The effect of climate change on the shallow expansive foundation conditions of resident dwellings is costing several hundred billion dollars worldwide. The design and costs of constructing or repairing residential footings is greatly influenced by the degree of ground movement, which is driven by the magnitude of change in soil moisture. The impacts of climate change on urban infrastructure are expected to include accelerated degradation of materials and foundations of buildings and facilities, increased ground movement, changes in ground water affecting the chemical structure of foundations, and fatigue of structures from extreme storm events. Previous research found that residential houses that were built less than five years ago have suffered major cracks and other damage caused by slab movement after record rainfall. The Thornthwaite Moisture Index (TMI) categorises climate on the basis of rainfall, temperature, potential evapotranspiration and the water holding capacity of the soil. Originally TMI was mainly used to map soil moisture conditions for agriculture but soon became a method to predict pavement and foundation changes. Few researchers have developed TMI maps for Australia, but generally, their accuracy is low or unknown, and their use is limited. The aims of this paper are: (1) To produce accurate maps of TMI for the state of Victoria for 100 years (1913 to 2012) in 20 year periods using long-term historical climatic data and advanced spatial statistics methods in GIS, and (2) Analyse the spatial and temporal changes of TMI in Victoria. Preliminary results suggest that a better understanding of climate change through long-term TMI mapping can assist urban planning and guide construction regulations towards the development of cities which are more resilient.

Riparian reforestation: are there changes in soil carbon and soil microbial communities?

Reforestation of pastures in riparian zones has the potential to decrease nutrient runoff into waterways, provide both terrestrial and aquatic habitat, and help mitigate climate change by sequestering carbon (C). Soil microbes can play an important role in the soil C cycle, but are rarely investigated in studies on C sequestration. We surveyed a chronosequence (0-23years) of mixed-species plantings in riparian zones to investigate belowground (chemical and biological) responses to reforestation. For each planting, an adjacent pasture was surveyed to account for differences in soil type and land-use history among plantings. Two remnant woodlands were included in the survey as indicators of future potential of plantings. Both remnant woodlands had significantly higher soil organic C (SOC) content compared with their adjacent pastures. However, there was no clear trend in SOC content among plantings with time since reforestation. The substantial variability in SOC sequestration among plantings was possibly driven by differences in soil moisture among plantings and the inherent variability of SOC content among reference pastures adjacent to plantings. Soil microbial phospholipid fatty acids (PLFA, an indicator of microbial biomass) and activities of decomposition enzymes (β-glucosidase and polyphenol oxidase) did not show a clear trend with increasing planting age. Despite this, there were positive correlations between total SOC concentration and microbial indicators (total PLFA, fungal PLFA, bacterial PLFA and activities of decomposition enzymes) across all sites. The soil microbial community compositions (explored using PLFA markers) of older plantings were similar to those of remnant woodlands. There was a positive correlation between the soil carbon:nitrogen (C:N) and fungal:bacterial (F:B) ratios. These data indicate that in order to maximise SOC sequestration, we need to take into account not only C inputs, but the microbial processes that regulate SOC cycling as well.