Sustainable Engineering at The University of Edinburgh

1. Sustainable Engineering at University of Edinburgh Water RecyclingBy: Bruce Callan (0679027); Kevin Heneghan (0840462); Aaron McClatchey (0094415); Rory Sinclair (0675441)IMS3 Sustainability Module, March 2009 Introduction With continuous population growth throughout the world, water is becoming an increasingly valuable commodity. This has widespread implications in terms of politics, economics, environment, technology and social issues. The importance of water as a resource means the best possible use must be made of it. Recycling, reuse and reclamation are becoming necessary to meet a growing demand. Recycling Methods at Home Toilet flushing accounts for a third of household water use. The water used need not be of drinking water quality yet it comes from the same source. ‘Grey water’ is waste water from bathroom sinks, baths and showers which requires only basic (disinfectant or microbiological) treatment to make it reusable. A concept that is gaining much publicity is pumping treated sewage back into the supply network to be used as potable drinking water. Even though this would be of a higher standard than most run-off, the idea is unpopular due to intrinsic public perception. However, it is already successfully employed in areas where supply is short e.g. Australia and California. In the UK around 17 billion cubic metres of water is consumed every year. Non-domestic usage accounts for the majority of it at 13.5 billion (80%), while 3.3 billion is drawn by households (20%) from the public water supply network. Electricity/gas production and fishing accounted for Reed bed sewage treatment systems provide higher quality effluent while being aesthetically pleasing, low maintenance and ecologically beneficial. Care must be taken as the chemicals in grey water from kitchen sinks, washing machines and dishwashers has the potential to destroy soil structure and poison plants. Rainwater collection involves large over or underground tanks, equipped with filters and pumps, to supply non-potable usage, cutting down on flood risks and water bills. A ‘header’ tank system provides low pressure at low cost whilst ‘direct pump’ systems offer better pressure at greater expense. These tanks are designed to top up the supply from the mains when running low and ensure no backflow contaminates it. the bulk of water removed directly by industry (57%). The public water supply network under our pavements annually produces around 7.2 billion cubic metres out of the total 17 billion consumed, of which roughly 1.8 million is lost through leakage. There are many possible ways of reducing our demand on the supply network, with some of the most economic and palatable presented here. Recycling Processes & Technologies Case Study: The GGSS Existing water recycling practices are both diverse and complex in nature. Each one requires a level of technical detail which cannot be included here. Examples of mainstream methods include: BioDenipho Process, Chlorination, Clarifiers/Continuous Backwash Filters, Microfiltration, Ozonation/BAC Filtration and Ultra-Violet Disinfection PROBLEM - The Gerringong and Gerroa areas of the Australian coast are very environmentally sensitive regions due to the beaches in addition to the diverse flora and fauna found there. The existing sewage strategy used a septic tank system with absorption trenches and was inadequate to satisfy demand. The community envisioned a scheme that would be ecologically, economically and socially sustainable. SOLUTION - The Gerroa sewage treatment plant was designed to produce advanced tertiary quality effluent using a sequence of systems including BioDenipho processes, clarifiers, continuous backwash, ozonation, microfiltration and UV disinfection. The Future References ENVIRONMENTAL BENEFITS •Eliminating the discharge from previous facility into the environment. •Eliminating overflows associated with on-site systems, improving the quality of local waterways. The UK has underinvested in water infrastructure for decades, and as a result has enjoyed a relatively cheap price for a high quality of water. This lack of investment however has resulted in an aging and crumbling network that will require huge investment to modernise and continue current supply. However, it is perhaps in a privileged position compared to sub-equatorial countries where the prospect of water wars is realistic. Not only is huge and creative investment required in the world-wide water infrastructure, but also a change in social attitude as to how we freely use such an invaluable resource. http://www.aquatekltd.co.uk/ http://www.therenewableenergycentre.co.uk/ Asano, Takashi et al., Water Reuse: Issues, Technology & Applications (McGraw-Hill, New York, 2007) Hartley, Troy W., Water Reuse: Understanding Public Perception & Participation (Water Environment Research Foundation, Alexandria, VA, 2003) Khan, S.J. & M.H. Muston & A.I. Schafer, Integrated Concepts In Water Recycling 2005 (University of Wollongong, Wollongong, NSW, 2005) COMMUNITY BENEFITS •Reusing at least 80% effluent and 100% bio-solids for agricultural purposes •Reducing potential health hazards Reducing odours and truck movements associated with tank pump-outs Water Recycling By: Bruce Callan (0679027); Kevin Heneghan (0840462); Aaron McClatchey (0094415); Rory Sinclair (0675441) IMS3 Sustainability Module, March 2009 Water Recycling By: Bruce Callan (0679027); Kevin Heneghan (0840462); Aaron McClatchey (0094415); Rory Sinclair (0675441) IMS3 Sustainability Module, March 2009 Water Recycling By: Bruce Callan (0679027); Kevin Heneghan (0840462); Aaron McClatchey (0094415); Rory Sinclair (0675441) IMS3 Sustainability Module, March 2009 Sustainable Engineering at The University of Edinburgh Recycling Methods INTRODUCTION With continuous population growth throughout the world, water is becoming an increasingly valuable commodity. This has widespread implications in terms of politics, economics, environment, technology and social issues. The importance of water as a resource means the best possible use must be made of it. Recycling, reuse and reclamation are becoming necessary to meet a growing demand. In the UK around 17 billion cubic metres of water is consumed every year. Non-domestic usage accounts for the majority of it at 13.5 billion (80%), while 3.3 billion are drawn by households (20%) from the public water supply network. The electricity and gas production and fishing industries accounted for the bulk of the water removed directly by industries (57%). The public water supply network under our pavements annually produces around 7.2 billion cubic metres out of the total 17 billion consumed, of which roughly 1.8 million are lost through leakage. There are many possible ways of reducing our demand on the supply network, and the most economic and palatable are presented in this display. A concept that is gaining much publicity is pumping treated sewage back into the supply network, to be used as potable drinking water. It is a very unpopular idea even though the water would be of a standard higher than most runoff. It is already successfully being employed in areas where supply is short (e.g. Australia and California). Toilet flushing accounts for a third of household wastewater. The water used need not be of drinking water quality yet it comes from the same source. The waste from bathroom sinks, showers etc (gray water) can - after basic treatment - be suitable for toilet flushing. • Reed bed sewage treatment may be used in conjunction with settlement tanks to achieve a high quality of effluent discharge that can be re-used. • Benefits: • Low maintenance. • Aesthetically pleasing. • Ecologically beneficial. • Care must be taken as the chemicals in the gray water waste water from kitchen sinks or washing machines, has the potential to destroy the soil structure and plants. • Rainwater collection involves placing large tanks equipped with filters and pumps above or underground, storing water to later supplement non-potable mains supply when running low. • Benefits: • Serves to reduce the risk of flood. • Reduces water bills, providing low pressure at low cost (a ‘direct pump’ system can provide a greater pressure at greater expense). • Better for garden as lower Ph due to lack of chemicals. Figure showing UK water use by industry Case Study—The GGSS The Problem – The Gerringong and Gerroa areas of the Australian coast is a very environmentally sensitive region due to the beaches and diverse flora and fauna that are found there. The existing sewage strategy used a septic tank system with absorption trenches and was inadequate to satisfy demand. The community envisioned a scheme that would be ecologically, economically and socially sustainable. The Solution – The Gerroa sewage treatment plant was designed to produce advanced tertiary quality effluent using a sequence of systems including BioDenipho processes, clarifiers, continuous backwash, ozonation, microfiltration and UV disinfection. The Benefits…to the environment •Eliminating the discharge from previous facility into the environment. •Eliminating overflows associated with on-site systems, improving the quality of local waterways. …to the local community •Reusing at least 80% effluent and 100% bio-solids for agricultural purposes. •Reducing potential health hazards. •Reducing odours and truck movements associated with tank pump-outs. The Future…. In the UK we have underinvested in our water infrastructure for decades, and as a result have enjoyed a relatively cheap price for our high quality of water. This lack of investment however has resulted in an aging and crumbling network that will require huge investment to modernise and carry on supplying us with that precious commodity. We are perhaps in a privileged position compared to sub equatorial countries where the prospect of ‘water wars’ is realistic. Huge and creative investment is required in the world-wide water infrastructure, but also a change in our social attitude to how we freely use this precious resource. References Figure showing rolling average of reuse water divided by inflow.