Sathasivan A.,Curtin University Australia |
Fisher I.,Watervale Systems Pty Ltd |
Kastl G.,MWH Australia
Journal / American Water Works Association | Year: 2010
Microbial acceleration of chloramine decay (including nitrification) exacerbates the difficulty of maintaining an adequate disinfectant residual in chloraminated systems with long retention times. An adaptive management strategy based on the microbial decay factor (Fn) was developed to improve chloramine residual in a service reservoir (tank). The reservoir studied has a capacity of 404 ML and is not mechanically mixed. It undergoes continuous chemical, physical, and microbial stratification in summer but in winter is only microbially stratified. At the end of summer 2002-03 (southern hemisphere), signs of severe nitrification were observed. After careful consideration of control options, serial dilution was adopted, particularly in winter. The F m value resulting from this serial dilution was predictable from previous measurement of Fm in the reservoir and its inflow. Subsequently, an adaptive control strategy to maintain low Fm ensured that the reservoir was clear of severe nitrification for the next two years of evaluation.
Findlay A.S.,MWH Australia |
Layson A.J.,Siemens AG
AWWA/AMTA Membrane Technology Conference and Exposition 2012 | Year: 2012
The use of polymer in pre-treatment steps to microfiltration and ultra-filtration membrane systems is typically avoided by engineers and membrane suppliers due to fears of excessive and potentially irreversible membrane fouling. The Gibson Island (GI) Advanced Water Treatment Plant (AWTP) has successfully demonstrated that a high rate clarification process (HRCP) utilising an anionic polymer can produce feed water of suitable quality to achieve 40 day intervals between membrane filtration (MF) chemical clean in place (CIP). The 100 ML/d (26 MGD) GI AWTP, located in Brisbane, Australia, treats secondary wastewater effluent to produce purified recycled water for reuse by industry and, under the original scheme plan, for indirect potable reuse through discharge to southeast Queensland's main drinking water supply, Wivenhoe Dam. Treatment processes at GI AWTP include phosphorus removal via chemical addition and HRCP, MF, reverse osmosis (RO), ultra-violet light advanced oxidation process (UV-AOP), and stabilisation. Several HRCP technologies were considered during preliminary design. The final design includes Actiflo® as the selected HRCP for phosphorus removal. The selected HRCP uses micro-sand and polymer to create rapidly settling floc particles which allows for significantly higher rise rates than traditional clarification. During initial operation of the plant, polymer and metal salt doses were set such that clarified effluent from the HRCP units was low in turbidity, typically less than 2 NTU, and phosphorus levels were very low. The MF units, however, were fouling much faster than desired resulting in excessive backwashing and chemical cleaning. Testing combined with analysis of operating data, indicated that polymer in the MF feed water was likely to be causing the fouling. Polymer dose was reduced until clarified effluent turbidity increased significantly, to about 5 NTU, at which point testing combined with analysis of operating data indicated no significant levels of polymer remaining in the MF feed. This change initially appeared to result in improved performance of the MF system. Over time, however, MF performance began to significantly deteriorate. Investigations revealed that the MF modules were retaining significant levels of solids and that retention of these solids was resulting in damage to the membranes and decreased membrane integrity. Further testing indicated that modifications to the backwash sequence and addition of low doses of metal salt to the HRCP effluent would significantly improve performance. These modifications were made to the plant and monitored over a 90 day proving period. The addition of metal salt to the HRCP effluent allowed the HRCP to be run at higher polymer doses, resulting in lower effluent turbidity (∼1.5 NTU), without the high fouling rates seen during the initial operation. MF performance during the 90 day proving period was good, with all units achieving 40 day CIP intervals. © 2012 American Water Works Association.
Zerihun A.,Curtin University Australia |
Mcclymont L.,Australian Department of Primary Industries and Fisheries |
Lanyon D.,MWH Australia |
Goodwin I.,Australian Department of Primary Industries and Fisheries |
Gibberd M.,Curtin University Australia
Journal of the Science of Food and Agriculture | Year: 2015
BACKGROUND: Grape berry composition is influenced by several factors including grapevine and soil properties and their interactions. Understanding how these factors interact to determine berry composition is integral to producing berries with desired composition. Here we used extensive spatio-temporal data to identify significant vine and soil features that influence Shiraz berry composition. RESULTS: The concentrations of berry flavonoids (anthocyanins, tannin and total phenolics), total soluble solids and pH were typically negatively associated with canopy, crop and berry size factors whereas titratable acidity was positively associated. The strengths of the associations, however, were generally greater with the crop and berry size factors than with the canopy size factor. The analyses also resolved separate influences of berry and crop size on berry composition. Soil properties had significant influences on berry composition; however, when influences of soil factors on vine-attributes were accounted for, the apparent effects of soil factors on berry composition were largely non-existent. CONCLUSION: At each site, variations in berry composition were more strongly associated with crop and berry size than with canopy size factors. Apparent influences of soil properties on berry composition are indirect, being mediated via their effects on vine attributes (canopy, crop and berry sizes). © 2014 Society of Chemical Industry.
Fisher I.,Watervale Systems Pty Ltd |
Kastl G.,MWH Australia |
Sathasivan A.,Curtin University Australia |
Jegatheesan V.,Deakin University
Critical Reviews in Environmental Science and Technology | Year: 2011
Effective disinfection planning and management in large, complex water distribution systems requires an accurate network water quality model. This model should be based on reaction kinetics, which describes disinfectant loss from bulk water over time, within experimental error. Models in the literature were reviewed for their ability to meet this requirement in real networks. Essential features were identified as accuracy, simplicity, computational efficiency, and ability to describe consistently the effects of initial chlorine dose, temperature variation, and successive rechlorinations. A reaction scheme of two organic constituents reacting with free chlorine was found to be necessary and sufficient to provide the required features. Recent release of the multispecies extension (MSX) to EPANET and MWH Soft's H2OMap Water MSX network software enables users to implement this and other multiple-reactant bulk decay models in real system simulations. © 2011 Taylor & Francis Group, LLC.
Brown V.,Melbourne Water Corporation |
Jackson D.W.,MWH Australia |
Khalife M.,MWH Australia
Water Science and Technology | Year: 2010
The bulk and retail water companies of the greater Melbourne area are developing the 2009 Metropolitan Sewerage Strategy to provide sustainable sewerage services to 2060. The objective of the strategy is to establish long term principles and near term actions to produce a robust sewage management system for Melbourne. Melbourne's existing sewerage system is largely centralised and discharges to two major treatment plants. Several small satellite treatment plants service local urban areas generally more distant from the centralised system. Decentralised and on-site wastewater systems are options for future sewage management and could play a role in local recycling. A portfolio of 18 on-site and decentralised concept designs was developed, applicable to the full range of urban development types in Melbourne. The concepts can be used in evaluation of metropolitan system configurations as part of future integrated water cycle planning. The options included secondary and tertiary treatment systems incorporating re-use of water for non potable uses, urine separation, black and greywater separation and composting toilets. On-site and cluster treatment systems were analysed. Each option is described by its indicative capital and operating costs, energy use and water and nutrient balances. This paper summarises and compares the portfolio mix of decentralized and on-site options in Melbourne's context. © IWA Publishing 2010.