|On-site waste water management
As part of the planning process the Centre for Sustainable Living has pursued water conservation opportunities. The aim is the reduction in per capita water use and therefore reduce wastewater generated.
The Water Corporation's Water Forever strategy aims to reduce water consumption per head from 155 litres/day to 135 litres/day. We already achieve that target and believe we all need to do much better than that! Water saving appliances have been installed, including water conserving shower roses, waterless urinals, and dry composting toilets. These appliances are part of the introductory tour and education program for all users of the centre, where the use of water saving behaviour and technologies is explained, demonstrated and finally used!
Specifics of Centre Daily Flows:
A total combined flow of 9860 litres/day at 145 litres/person for a population of 68 has been used to design the wastewater systems. Greywater (showers and handbasins) conributes to 60% of the flow (a total of 5916 litres/day) and blackwater 40% of the flow (3944 litres/day). Although the 145 litres/day (standard water reduction figure) has been used this figure is very conservative, because all laundry (linen, clothes etc), apart from that used within the caretaker's cottage (two people maximum), will be processed offsite.
Biolytix aerobic treatment unit
A Biolytix BF-STP (3) system takes the wastewater from the kitchen, male toilets and showers and disabled toilets and showers. The Biolytix incorporates a geotextile filter system and biological treatment organisms such as microbes, worms and compost beetles to break down solids and remove nutrients. This is an innovative system which has been approved by health departments and demonstrated in Queensland, New South Wales, South Australia and Victoria.
The BF6 model has received Department of Health approval in Western Australia according to AS/NZS 1547:2001, with the BF2 model approval being processed. The centre provides a demonstration system with information collation for Western Australian government departments (for example the Departments of Health and Environment) and educational centres (schools, universities and TAFEs).
The biolytix system (BF-STP) designed for the Denmark Sustainability Centre has been rated to cope with loadings of 6,600 litres/day and incorporates a parallel design of three filters. The BF-STP includes a BF2 pre-filtration unit and two BF6 filters, one gravity-fed the other with a pump for irrigation, to maximise effluent treatment. At a maximum loading of 6600 litres/day the system provides effluent to a high secondary standard appropriate for subsurface irrigation in the gardens on site.
Biomax aerobic treatment unit
The Biomax C30 takes wastewater from the women's toilet and shower block, the caretaker unit and the laundry. The Biomax system has been used extensively in Western Australia for decentralised wastewater reuse/disposal. A further modification to the system for this project will include periodic aeration to enhance denitrification.This modification has been requested for the unit to be located at the centre, as a result of research at Murdoch University's Environmental Technology Centre, which found that two hour on-off aeration enhanced denitrification by up to 30%.
The Biomax system used for the Denmark Sustainability Centre is a C30 model that treats wastewater to a high secondary standard for subsurface irrigation in the gardens on site.
The Rota-loo 950 is located at the Sanctuary. These toilets can handle continuous use by up to eight people. Principally the composting toilet demonstrates technologies for water conservation and human waste reuse techniques.