05-04-2011, 09:55 AM
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1.INTRODUCTION
1.1 WHY REUSE WATER?
Sustainable water management is an important goal and a key element of sustainable urban development. Government authorities and the land development industry are increasingly seeking to use alternative sources, such as water reuse, to conserve drinking water supplies and minimize wastewater.
Water reuse must be considered in the context of the specific development and management of the entire water cycle. A Water Sensitive Urban Design (WSUD) strategy is the starting point for developments’ water management planning. Within such a strategy, reusing water may be deemed appropriate for a particular site after considering all other water streams and their interactions.
Water reuse describes the treatment of wastewater to a standard where it can be used within our community. Throughout the document the term “reused water” is used to describe recycled water, greywater reuse (wastewater from the household excluding toilet water), sewer mining or reclaimed effluent. References to particular water streams will be made where required. Reused water is used on a ‘fit-for-purpose’ basis – that is, of an appropriate quality for the intended use.
1.2 SUSTAINABLE AND INTEGRATED WATER CYCLE MANAGEMENT
The conventional urban water cycle consists of a large-scale centralized water supply and disposal system. Water is collected from catchments, treated and piped to customers. After use, wastewater flows through a second set of pipes (sewers) to sewage treatment plants. The treated water is then discharged to creeks, rivers, bays or oceans. Sustainable development aims to minimize water use and dependence on natural resources and maximize reuse within the built environment. In Figure 1, the dotted red line separates the natural and built environments. The general approach is to minimize water and pollutants crossing the boundary, and maximizing water reuse within the boundary. This can be achieved by:
• reducing drinking water demand (through demand management)
• using available water sources for the most appropriate purposes (‘fit-for-purpose’)
• identifying and maximzsing alternative water sources
• minimizing the impact of urban storm water on the receiving aquatic ecosystem.
2. SELECTION OF APPROPRIATE WATER TREATMENT TECHNOLOGIES
Conventional evaluation of treatment technologies compared technical viability and cost-effectiveness. But a simple cost-benefit analysis does not adequately assess the breadth of issues for water reuse. Site characteristics, an integrated water management perspective and ‘externalities’ such as downstream infrastructure interactions and the impact on the natural environment must be taken into account. The identification of water reuse as an alternative water source will occur before the evaluation of water treatment technologies. Typically a Water Sensitive Urban Design (WSUD) strategy is formulated to identify structural (eg. water treatment, storage and distribution infrastructure) and nonstructural (eg. policies, pricing, demand management) solutions for the provision of urban water services within the urban design. An integrated water cycle management strategy will then identify the opportunities for water reuse following which an evaluation and selection of appropriate water treatment technologies is undertaken.
The viability and suitability of technologies within an ecologically sustainable framework depend on criteria including:
• water end use and demand profile
• water quality and quantity
• available space for treatment and storage
• infrastructure near the site e.g. trunk sewers, proximity to local centralised treatment facility
• interaction with the environment e.g. greenhouse gas emissions, land capability, receiving waterbodies.
• social considerations e.g. community receptiveness to alternative water sources
• economic considerations
• climatic conditions
• operating and maintenance
• ongoing ownership of the treatment system
1.INTRODUCTION
1.1 WHY REUSE WATER?
Sustainable water management is an important goal and a key element of sustainable urban development. Government authorities and the land development industry are increasingly seeking to use alternative sources, such as water reuse, to conserve drinking water supplies and minimize wastewater.
Water reuse must be considered in the context of the specific development and management of the entire water cycle. A Water Sensitive Urban Design (WSUD) strategy is the starting point for developments’ water management planning. Within such a strategy, reusing water may be deemed appropriate for a particular site after considering all other water streams and their interactions.
Water reuse describes the treatment of wastewater to a standard where it can be used within our community. Throughout the document the term “reused water” is used to describe recycled water, greywater reuse (wastewater from the household excluding toilet water), sewer mining or reclaimed effluent. References to particular water streams will be made where required. Reused water is used on a ‘fit-for-purpose’ basis – that is, of an appropriate quality for the intended use.
1.2 SUSTAINABLE AND INTEGRATED WATER CYCLE MANAGEMENT
The conventional urban water cycle consists of a large-scale centralized water supply and disposal system. Water is collected from catchments, treated and piped to customers. After use, wastewater flows through a second set of pipes (sewers) to sewage treatment plants. The treated water is then discharged to creeks, rivers, bays or oceans. Sustainable development aims to minimize water use and dependence on natural resources and maximize reuse within the built environment. In Figure 1, the dotted red line separates the natural and built environments. The general approach is to minimize water and pollutants crossing the boundary, and maximizing water reuse within the boundary. This can be achieved by:
• reducing drinking water demand (through demand management)
• using available water sources for the most appropriate purposes (‘fit-for-purpose’)
• identifying and maximzsing alternative water sources
• minimizing the impact of urban storm water on the receiving aquatic ecosystem.
2. SELECTION OF APPROPRIATE WATER TREATMENT TECHNOLOGIES
Conventional evaluation of treatment technologies compared technical viability and cost-effectiveness. But a simple cost-benefit analysis does not adequately assess the breadth of issues for water reuse. Site characteristics, an integrated water management perspective and ‘externalities’ such as downstream infrastructure interactions and the impact on the natural environment must be taken into account. The identification of water reuse as an alternative water source will occur before the evaluation of water treatment technologies. Typically a Water Sensitive Urban Design (WSUD) strategy is formulated to identify structural (eg. water treatment, storage and distribution infrastructure) and nonstructural (eg. policies, pricing, demand management) solutions for the provision of urban water services within the urban design. An integrated water cycle management strategy will then identify the opportunities for water reuse following which an evaluation and selection of appropriate water treatment technologies is undertaken.
The viability and suitability of technologies within an ecologically sustainable framework depend on criteria including:
• water end use and demand profile
• water quality and quantity
• available space for treatment and storage
• infrastructure near the site e.g. trunk sewers, proximity to local centralised treatment facility
• interaction with the environment e.g. greenhouse gas emissions, land capability, receiving waterbodies.
• social considerations e.g. community receptiveness to alternative water sources
• economic considerations
• climatic conditions
• operating and maintenance
• ongoing ownership of the treatment system
