Rethinking Alternative Water Resources-In Research The Feasibility Of Adopting Rainwater And Greywater In Residential Developments

Water resources such as rainwater and treated greywater have attracted increasing interest in recent years around the world due to water crisis. The water crisis is chiefly resulted from excessive consumption of raw water, climate change, groundwater and surface water pollution, and unsustainable water resource consumption. The application of these alternative water services not only contributes to diminish surface water and ground water resources but also, eases the pressure of reliance on wastewater treatment plants and reduces energy consumption.This thesis introduced water conservation and put rainwater use and greywater recycling into the context of a water conservation strategy with adoption of the new conception of Integrated Urban Water Management (IUWM). The integration of water, stormwater and wastewater services and systems are considered in the integrated water management approach.The performance of alternative water use/reuse systems were monitored at the Burwood site experimental study in the south east of Central Business District (CBD) of Melbourne, Australia. This site consists of 2 residential units with the occupancy of 42 for Building 1 (3 levels) and 80 for Building 2 (5 levels). A dual water supply system (rainwater/greywater and mains water) was used to supplement mains water supplies for toilet and/or garden irrigation on the urban water cycle which was examined in residential developments.Water balance and contaminants balance were simulated based on the model of UVQ (Urban Volumes and Quality). The investigation of water balance for residential buildings of Burwood site was developed in terms of alternative water usage, the average annual volumetric reliability (VR), as well as stormwater and wastewater discharge reduction. Storage dimensions were determined by VR which is the proportion of the demand supplied and is defined as the volume of supplied water divided by the total water requirement (i.e. demand) during the entire simulation period.In light of tank capacities of rainwater use schemes, the tank dimensions for irrigation use options were significantly larger than those for toilet purpose options. The tank sizes of rainwater supplying irrigation for Building 1 were about twice of Building 2, which was resulted from that Building 1 covered larger garden area (1409m2) than Building 2 (783m2). Whilst for the end use of toilet schemes, the conditions were on the opponent way due to Building 2 occupied 80 residents while Building 1 occupied 42 persons. It has been found that the required tank values for end uses of irrigation coupling with toilets were significantly larger than irrigation or toilet considered alone.The significant difference of tank sizes occurred between greywater for irrigation and toilet considered alone, which was due to the unsteady water demand for irrigation whilst the regular water supply and constant water demand for the end use of toilet.In case of the conservation of imported water supply, which was determined by the connected fixtures and their types, end uses of irrigation plus toilets outperformed end use of irrigation or toilet considered alone. Water efficient domestic facilities reduced drinking water supply dramatically, as well as the wastewater disposal.The contaminants removal in mass was evaluated based on the percentage removal values and alternative water usage volumes. The greatly difference of contaminant loads between 'Reference Option' and alternative water services options was TSS, which was the basis of that the highest removal for TSS comparing with others. The water efficient appliances installed offered low water consumption, which resulted in low potable water substituted. Thus, the high demand management (6 stars appliances used) produced less contaminants discharge in comparison to usual demand management (3 stars appliances installed). From the results and analysis of the contaminants balance it could be concluded that alternative water using for irrigation service integration with toilet flushing outranked other considered end uses in terms of reducing contaminants to receiving waters.An economic analysis was performed in order to evaluate the benefits of utilizing rainwater or greywater strategy. Life cycle costing (LCC) is the technique for the estimation of total cost over the life of the service provision. LCC of water supply, stormwater and wastewater services over an analysis period of 50 years was calculated by applying the Net Present Value (NPV) method in this study. This thesis assessed the financial cost for all modeled scenarios for both rainwater harvesting system and greywater reuse system with regards to the cost of conveyance, pump, tank cost and installation, maintenance, greywater treatment plant, savings, as well as the total cost. For the scenarios of the combination of garden irrigating and flushing purpose, it was found that these cases accounted the largest financial cost either within the condition of single buildings investigated or the whole area evaluated.This study simulated the rainwater use and greywater recycling options by incorporating the multi-criteria of water quantity, VR, water quality, financial cost, social and PW (Potable Water) reduction impact. These associated results were obtained by adopting the software 'DecisionLab 2000'. This investigation provided an assessment of potential preferences of alternative water serving options. Twelve cases were modeled for each single building and six for the study area. These schemes were plotted by using methodologies of profile (performance) analysis, GAIA (Geometrical Analysis for Interactive Assistance) Analysis, and PROMETHEE (Preference Ranking Organization Method for Enrichment Evaluations) Ranking. It has been seen that economy was the most significant impact factor due to the highest weight value. The criteria of water quantity and water quality were agreed with each other, as well as VR and PW reduction (bar Building 2). Theâ–³values of both individual buildings and the study area were over 90%, which identified the high quality of simulation reliability. The options of alternative water to flush toilets ranked the first for either individual buildings or the study area. In light of the whole study area, recycled greywater supplying irrigation conducted the most preferred option than others if 3 stars rating domestic facilities installed.