Application of novel technologies in water reclamation, reuse and recycle

Water reuse has become an integral element of the "total water resources planning and management" along with the other elements such as water conservation, water use efficiency and management of the allocation of existing water sources. Researchers are working actively on the following aspects of water reuse: identification and characterization of different wastewaters that could be reclaimed, development of treatment technologies and effluent standards, quantification of potential gains due to recycling and risk management. The wastewaters that can be reclaimed are domestic and industrial wastewaters, grey water, black water, stormwater and rain water and their potential reuse lies in agriculture, aquaculture, industries, non-potable use in residential and community fronts and indirect and direct potable use. The treatment of wastewater ranges from secondary treatment to advanced treatment, which produces different "Classes" of reclaimed water. This paper evaluates the current status of the research on the above-mentioned important aspects of water reuse with relevant case studies and the future demand for reuse water. The direction in which the future-reuse schemes should be formulated so that they are safe, environmentally sustainable and cost effective are also discussed.

Performance evaluation of different ultrafiltration membranes for the reclamation and reuse of secondary effluent

This study investigates and compares the performance of two different types of ultrafiltration (UF) membranes in the recovery of water from secondary treated wastewater. Filtration experiments were carried out on a pilot scale cross-flow unit using synthetic wastewater similar to the quality of secondary treated wastewater by varying the operating parameters such as transmembrane pressure (TMP), feed composition and membrane configuration. The filtration experiments demonstrated that the flux recovery through spiral polymeric UF membrane was more sensitive to the variation in TMP compared to the tubular ceramic UF membrane over the range of TMP studied. The resistance in series model was used for the evaluation of the resistance to the permeate flux. The fouling resistance, particularly irreversible resistance compared to reversible resistance plays a major role in the total resistance for the tubular ceramic membrane. In contrast clean membrane resistance is the major contributor for the total resistance of the spiral polymeric membrane. Finally, the effectiveness of the filtration treatment was determined by evaluating the rejection coefficients for various pollution indices of the wastewater. Significant differences in the performance of the membrane types were observed which are likely to impact on the selection, operation and maintenance of the membrane system.

Comparison of the performance of ceramic microfiltration and ultrafiltration membranes in the reclamation and reuse of secondary wastewater

Advanced treatment of secondary wastewater generally has been achieved using polymeric microfiltration and ultrafiltration membranes. Newly developed ceramic membranes offer distinctive advantages over the currently employed membranes and were recently introduced for the purpose. This paper presents results of a pilot study designed to investigate the application of ceramic microfiltration (MF) and ultrafiltration (UF) membranes in the recovery of water from secondary wastewater. Synthetic wastewater similar to the quality of secondary treated wastewater was fed to ceramic MF and UF system in a cross-flow mode. The filtration experiments revealed that the flux recovery through tubular ceramic MF membrane was more sensitive to the variation in TMP compared with the tubular ceramic UF membrane over the range of TMP studied. The resistance in series model was used for the evaluation of the resistance to the permeate flux. The results revealed that for ceramic UF membrane, the contribution to the total resistance of fouling was higher than the inherent of the clean membrane resistance. However, both the clean membrane resistance and the fouling resistance contribute equally in the case of MF membrane. Various wastewater indices were measured to evaluate the effectiveness of the filtration treatment. The ceramic UF membrane consistently met water quality in the permeate in terms of colour, turbidity, chemical oxygen demand and absorbance, suggesting that the permeate water could be made to be reused or recycled for suitable purposes. However, MF membrane appeared to be incompetent with respect to the removal of colour. The unified membrane fouling index (UMFI) was used to measure the fouling potential of both the membranes. The result showed that for UF membrane, the value of UMFI is one order of magnitude higher than MF membrane. The overall results suggest that there were significant differences in the performance of both the ceramic UF and MF membranes that are likely to impact on the operation and maintenance of the membrane system.

Monoethanolamine reclamation using electrodialysis

Monoethanolamine (MEA) is the benchmark solvent for the capture of carbon dioxide from both natural gas and flue gas streams. Despite its effectiveness in absorbing CO2, this solvent can react with impurities in the gas stream to form heat stable salts and other degradation products. These impurities can cause problems such as an increase in solvent viscosity and corrosion of the operating units. Thus, a number of approaches have been considered to mitigate the occurrence of these problems. In this paper, the use of electrodialysis as an online MEA reclamation process in a postcombustion CO2 capture facility is investigated. The study shows that high heat stable salts removal can be achieved with a high MEA recovery. However, it is necessary to limit the current density, particularly at lower salt concentrations, to reduce water splitting. The stability of the commercial ion-exchange membranes in the highly alkaline solvent is also investigated. The results show that the membranes are stable upon exposure to 30 wt % MEA for at least 4.5 months.

Nanofiltration for the concentration of heat stable salts prior to MEA reclamation

While monethanolamine has shown great potential as a solvent for the capture of carbon dioxide, impurities can build within the solution over time, leading to increased viscosity and corrosivity. Classically, these impurities are removed by a combination of neutralization and either thermal reclamation, ion exchange or electrodialysis. In this work, we evaluate the use of nanofiltration to concentrate the heat stable salts within the solution prior to such reclamation. This allows the recirculating solvent to operate with low concentrations of these impurities, while providing a low volume, concentrated solution for reclamation. Results show that nanofiltration can reject greater than 80% of the heat stable anions, while allowing the monoethanolamine to permeate through the membrane, for return to the process. Rejection of the MEA itself is less than 7%. The nanofiltration operation is only effective on lean solvent with CO2 loadings of less than 0.2 and neutralization would be required upstream to deprotonate the amine. The two membranes tested (Koch MPF-34 and MPF-36) appeared stable to exposure to the solvent for over four months.

Wastewater reuse and treatment options for the dairy industry

Milk-processing plants generate significant quantities of wastewater with relatively high organic matter concentrations on a daily basis. In addition to environmental damage that can result from the discharge of these wastewaters into the natural waterways, the presence of products such as milk solids into wastewater streams represents a loss of valuable product for the plants. This paper presents a review of wastewater management practices employed by six milk-processing plants in Victoria, Australia. In all six plants investigated, milk powder represents a major product. During the milk powder production, water is evaporated, condensed and can be reused for various purposes with a significant impact on water usage. Other major products are anhydrous milk fat, cheese, butter, and UHT milk. The effectiveness of the practices was assessed through two main criteria: first through the water to milk intake ratio, and the waste volume coefficient. Both parameters characterise the plant efficiency in regard of water consumption and water reuse, Information on cleaning chemical usage and recovery was also assessed as part of the review. Significant discrepancies emerge between the plants first due to the products manufacturad and water reuse possibilities available in each plant. Second the type of treatment technologies used for condensate and cleaning solution influences the figures. One of the investigated plants is almost self-sufficient for water, emphasising the benefits gained from the use of technologies like membrane separations for condensate and cleaning solution treatment. In some cases, less cost-intensive technologies such as a clarifier are successful to improve cleaning agent recovery.

Is the risk of illness through consuming vegetables irrigated with reclaimed wastewater different for different population groups?

The use of reclaimed wastewater for irrigation of horticultural crops is commonplace in many parts of the world and is likely to increase. Concerns about risks to human health arising from such practice, especially with respect to infection with microbial pathogens, are common. Several factors need to be considered when attempting to quantify the risk posed to a population, such as the concentration of pathogens in the source water, water treatment efficiency, the volume of water coming into contact with the crop, and the die-off rate of pathogens in the environment. Another factor, which has received relatively less attention, is the amount of food consumed. Plainly, higher consumption rates place one at greater risk of becoming infected. The amount of vegetables consumed is known to vary among ethic groups. We use Quantitative Microbial Risk Assessment Modelling (QMRA) to see if certain ethnic groups are exposed to higher risks by virtue of their consumption behaviour. The results suggest that despite the disparities in consumption rates by different ethnic groups they generally all faced comparable levels of risks. We conclude by suggesting that QMRA should be used to assess the relative levels of risk faced by groups based on divisions other than ethnicity, such as those with compromised immune systems.

Improving contaminated land remediation practices for service station sites in Queensland

The research aims to provide improvements to remediation practices for land contaminated by service station activities in the period 1988-2004 by assessing previous methods of remediation. Thirty-four such Queensland sites were examined. The resultes will be useful to government, developers, land holders, consultants and the community.

From estrangement to a sense of place …

Maggie MacKellar in her book Core of my Heart, my Country writes 'What is sense of place? Why is relationship with place so fundamental to our identity as individuals and as communities?' MacKellar rightly acknowledges that 'A sense of place is a complex connection between land and self. Place is both inside and outside; it takes us beyond ourselves, yet allows us to make sense of ourselves. Attachments to place are born into us, but they are also formed through movement, through labour, through words.' My mother Maria Radzimirski-Herzog considered herself truly Swiss and thoroughly Australian. Through one migrant's story this paper explores something of the complex intertwining of place, memory and identity. It grapples with the notion of belonging to one's country of birth and one's adopted country via a rich understanding of place. In Maria's case, place becomes inextricably bound with who she became as a person. In the early 1940s, Maria explored Switzerland on bike and on foot during war-time restrictions on cars and she came to know it intimately. She photographed the land and the mountains; she documented her journeys. Spirn writes perceptively that 'Significance does not depend on human perception or imagination alone.' For Maria significance was, to use Spirn's words, 'there to be discovered, inherent and ascribed, shaped by what senses perceive, what instinct and experience read as significant, what minds know'. For Maria, Landscape was not 'mere scenery'. The ability to see, to listen, to be present in place, stood her in good stead in her adopted country, Australia. Maria called place into being for her children: through her lived experiences, her memories, her story telling, through language, traditions and history, Maria shared her Swiss identity with her children. But imperceptibly she also taught them how to understand her new homeland Australia, their birth country. How did Maria become Australian? Was that her creative response to exile from Switzerland? How did she come to feel at home in both countries, to understand both places? How did they seep into her and she into them? Through my own research on place I have discovered that assessing 'sense of place' is not an exact science but a creative analysis of the attributes of a place. The methodology I have adopted to explore the complex interrelationships between place, memory and identity allows recovery and reclamation, rediscovery, juxtaposing the subjective and the objective, the co-presence of different evidence. This paper draws on place research, on personal papers, letters and photographs, and the author's own experiences and memories. Through story and narrative it interweaves autobiography and biography with theoretical scholarship, to illuminate one migrant's journey from estrangement to a sense of place in her adopted country, Australia.

Comparison of fouling mechanisms in low-pressure membrane (MF/UF) filtration of secondary effluent

Membrane filtration in municipal wastewater treatment is being increasingly used to improve the quality of water and increase the productivity of existing plants. However, membrane fouling encountered in reclamation of municipal wastewater represents serious design and operational concern. There are several fouling models which are being developed and used as a powerful tool to increase the understanding of the fouling mechanisms and its key characteristics that influence the design of optimal process and operating conditions. This study investigates and compares the fouling mechanisms of three different types of polymeric and ceramic ultrafiltration (UF) and microfiltration (MF) membranes in the recovery of water from secondary effluent. The result demonstrated that ceramic UF membrane produced very high quality of water compared to polymeric UF and ceramic MF membranes. Out of four fouling models used to fit the experimental flux data, cake filtration and pore narrowing and complete pore blocking models predicted the initial fluxes of polymeric UF membrane more accurately. On the other hand, the cake filtration and pore narrowing models predicted the performance of ceramic UF membrane. Whereas, pore narrowing model predicted the performance of ceramic MF membrane more precisely compared to other three models. Further, the application of unified membrane fouling index (UMFI) was used to assess the fouling potential of the membranes. Good agreement between UMFI and other models was found. © 2013 Copyright Balaban Desalination Publications.

A history of wastewater irrigation in Melbourne, Australia

Reclamation of wastewater for irrigation has had an important role to play in Melbourne’s struggle to manage water resources as effectively as possible. Rapid growth within the first few years of the founding of the city led to a sanitary crisis, which provided the impetus for the construction of a large sewerage system. Interest in using the effluent from sewage treatment plants for irrigation gained attention in the late 1970s, but despite some activity in the early 1980s, it was not until 2005 that large-scale wastewater irrigation schemes became a reality. Successful to a degree, there have also been problems, and the future viability of one large irrigation scheme for commercial vegetable production is threatened by high salt concentrations in the treated wastewater. Greywater irrigation at the household level has also become commonplace in Melbourne over the last decade, but it is difficult to regulate and the health risks urgently need to be quantified. More recently, several third-pipe schemes, where treated wastewater is reticulated to households, have been commissioned with plans for many more, and treated stormwater is growing in popularity, particularly for irrigation of public open spaces.

High internal phase emulsion (HIPE) xerogels for enhanced oil spill recovery

Oil spills cause serious damage to the aquatic ecosystem and require quick cleanup. Herein we report high internal phase emulsion (HIPE) xerogels for the first time as oil absorbents for enhanced oil spill recovery. The HIPE xerogels absorb diesel from the water-oil mixture in 20-30 seconds. The absorption capacity of the HIPE xerogels ranges from 20 to 32 times for different kinds of oils, and the oils can be recovered simply by being squeezed out, with a recovery rate around 80%. They can be reused at least 40 times without obvious deterioration in oil separation properties from 0 to 45 °C. These novel xerogels are suitable for practical use in oil spill reclamation and wastewater treatment.

Potential for water-resource infrastructure to act as refuge habitat

Permanent sources of natural water are expected to decline in Mediterranean-climate regions under future climate change. Therefore, stable water bodies that act as refuge habitats will become increasingly important to the maintenance of freshwater biodiversity. Man-made water bodies such as those associated with water-resource infrastructure could contribute to the available refuge habitat but little is known about fish, zooplankton and frog assemblages in such water bodies. We quantified the diversity and abundance of fish, zooplankton and frogs that reside within raw water storages and water reclamation plants and compared them to assemblages from nearby natural water bodies over a total of 19 water bodies.Overall, the faunal assemblages within the man-made water bodies showed similarities to the nearby natural water bodies with very few differences found among the three water body types. Diversity of available substrates and of submerged and emergent macrophytes were the habitat variables best correlated with diverse faunal assemblages. This study suggests that the faunal assemblages within raw water storages and water reclamation plants resemble those found within nearby natural water bodies and that there is therefore potential for water-resource infrastructure to act as an important refuge habitat during drought. Furthermore, small changes in the management of these storages to maximise habitat diversity could increase the value of the refuge, complementing their role in water-resource delivery.