Exploring the need for rainwater tank maintenance: survey, review and simulations

Rainwater tanks are a common feature of the urban landscape in Australia and globally. In Brisbane, Australia, provision of alternative water in new homes is mandatory and to meet this requirement rainwater tanks are considered an important option. The water savings of rainwater tanks can help defer investments in supply infrastructures. An emerging concern is that there is currently no mechanism in place for making sure that the household rainwater collection systems are maintained and in a good condition. In fact, in many locations, there is growing concern about whether the condition of this asset stock is adequate. The paper presents: a synthesis of required basic water tanks maintenance tasks; a short overview of published literature on householder motivations for maintenance; a synthesis of existing information about the condition of tanks, based on literature; simulation model results identifying the relationship between frequency of inspections and the (stationary) proportion of tanks with different types of problems; and the results of a survey to identify judgements about water tank maintenance in the region by professionals and plumbers. The paper concludes that there is a need for collecting more data and that mechanisms need to be in place to ensure the ongoing condition of tanks.</jats:p

Rethinking urban water systems - revisiting concepts in urban wastewater collection and treatment to ensure infrastructure sustainability

Technology and economic development has led to the growth of megacities and urban centres with populations in the millions. Such population expansion and densification increases the strain on wastewater collection and treatment infrastructure, which has been largely based on an end-of-line centralised model. However, in megacities new challenges arise, because provision of suitable sanitation is expensive and it requires infrastructure expansion through construction of extensive sewer networks and larger capacity wastewater treatment plants, which consume more energy. Alternative disposal techniques for solid and liquid waste generated during the treatment process are required, because disposal solutions are decreasing as landfill costs rise and environmental standards are tightened, the latter reducing opportunities for land reuse. Additionally, mass wastewater discharge can have a detrimental impact on the ecology of water bodies and on the health of downstream populations, and requires suitable treatment before disposal. These challenges have the potential to offset the savings that the economies of scale offered by the traditional wastewater collection and treatment systems can impart. The need for affordable and effective wastewater systems in megacities requires the re-evaluation of traditional systems and the re-engineering of water and wastewater transport and resource concepts. Alternative concepts in wastewater collection and treatment, such as decentralised treatment, allied with innovative solutions using current and new technology could play a role in providing affordable and sustainable solutions to deal with the wastewater issue. This paper investigates the scope that integrated wastewater treatment and localised water reuse (in-line treatment, sewer mining), resource recovery (biogas, biosolids), operational changes (timed discharge of sewers, vacuum sewers) and biotreatment (e.g. vermiculture, faecal coliform removal) can play to guarantee the longevity of wastewater infrastructure in megacities. These alternatives offer increased treatment efficiency, recovery of value-added products, and reduce infrastructure cost, whilst maintaining health standards and reducing environmental discharge.G. Tjandraatmadja, S. Burn, M. McLaughlin and T. Biswa

Headspace gas chromatography with flame ionization detection (HS-GC-FID) for the determination of dissolved methane in wastewater

There is currently a need for a simple, accurate and reproducible method that quantifies the amount of dissolved methane in wastewater in order to realize the potential methane that can be recovered and account for any emissions. This paper presents such a method, using gas chromatography with flame ionization detection fitted with a GS-Gas PRO column coupled with a headspace auto sampler. A practical limit of detection for methane of 0.9 mg L-1, with a retention time of 1.24 min, was obtained. It was found that the reproducibility and accuracy of the method increased significantly when samples were collected using an in-house constructed bailer sampling device and with the addition of 100 μL hydrochloric acid (HCl) and 25% sodium chloride (NaCl) and sonication for 30 min prior to analysis. Analysis of wastewater samples and wastewater sludge collected from a treatment facility were observed to range from 12.51 to 15.79 mg L-1(relative standard deviation (RSD) 8.1%) and 17.56 to 18.67 mg L-1(RSD 3.4%) respectively. The performance of this method was validated by repeatedly measuring a mid-level standard (n = 8; 10 mg L-1), with an observed RSD of 4.6%.</p

Evaluation of water needs index case studies

Adoption of a systems perspective by water planners responsible for infrastructure and supply can provide considerable benefits, even though analysis of water systems can be a very daunting task. Furthermore, actors in the system are often subject to individual biases, cognitive limitations, and often have limited timelines and resources. In addition, a paucity of pertinent information and spatial and temporal data limitations are problematic to water resource decision makers who are subject to bounded rationality. To overcome some limitations inherent in water resource management decisions, the authors have used exploratory techniques combining actor engagement with data collection and analysis using the Water Needs Index (WNI). The WNI methodology is a structured approach to assess multiple dimensions of water needs of particular spatial environments. The WNI has been previously applied at different scales (national, regional, catchment and urban) and has been found to be of most use at catchment and urban scales. The WNI methodology applies a mix of qualitative and quantitative approaches in case study settings. The process involves a review of several data sources (quantitative records and grey literature) for selection and compilation to calculate a WNI for a range of spatial locations. Qualitative research methods, such as workshops, have been used to investigate subjective opinions and incorporate local contextual knowledge. Workshops with key actors from urban water management case study areas have been found to be useful in facilitating dialogue and establishing dimensions, identifying useful and reliable data sources and adding insights and confirmation of appropriateness of data selection. This research reports on several case studies using the WNI methodology, in the Philippines, Viet Nam and Indonesia. The WNI methodology has been used to inform development of preliminary information embedded in Integrated Urban Water Management (IUWM) approaches and Integrated Water Resource Management (IWRM) which take a more holistic systems\u27 perspective when planning for urban water management. The WNI index is a relatively straightforward multi-criteria assessment (using weights) forming a two-level hierarchy of dimensions and data sources, with systems analysis. The key task is the definition of dimensions, and the choice of data sources, as either observations or proxies of the dimensions. Selection of dimensions and subsequent ranking of water needs become an integral part of the development of the IUWM and IWRM. These approaches provide a means to manage water resources more sustainably by accounting for natural flows, water quality, water extraction, and balancing environmental and community needs. By taking a systems perspective and using index methodology, the views of stakeholders can be considered in the decision-making process and inform planning for more efficient use of resources. The research shows that the WNI is useful in informing urban water management planning and for provision of information essential to more holistic water resource outcomes. Activities have been designed to achieve a number of objectives for each case study city. Activities were designed to collectively frame the enquiry by taking a systems\u27 perspective and using an observational framework by identifying data sources and integrating diverse knowledge sources. Engaging with a mix of stakeholders with often conflicting goals required a process for dialogue between actors and between institutions and enable conflict resolution to take place if required. The primary research outcome was development of a preliminary systems analysis. This research explores whether workshop interactions and data gathering activities achieved each project\u27s stated objectives. This paper reports on the success or otherwise in meeting project objectives by introducing an evaluation process, based on the Protocol of Canberra

Australian examples of residential integrated water cycle planning: accepted current practice and a suggested alternative

Australian examples of Integrated Water Cycle Planning (IWCP) for residential development demonstrate that providing multiple household-water connections is a generally accepted practice. These connections typically include a potable mains supply, a separate non-potable supply utilising reclaimed water and/or a household roofwater tank for non-potable uses. Stormwater is not fully exploited as a potential urban water source. The advent of national guidelines for using recycled water for drinking purposes is expected to simplify IWCP towards a single-line household-water supply reclaimed from a range of different sources. An IWCP approach is suggested in this paper based on a single household supply complemented by: 1) potential separation of blackwater to reduce human health risk and to enhance community acceptance of recycled water, 2) the use of water sensitive urban design requirements of storing and slowly releasing urban stormwater, and 3) taking advantage of economies of scale by integrating communal roofwater tanks into the urban stormwater system