A drop in the ocean
Water: an odourless, tasteless, transparent liquid that is colourless in small amounts; the most abundant liquid on the planet covering 70 per cent of the Earth's surface; essential for life; consumption rising; recycling essential. Lora Lee Brown, marketing manager of Water Dynamics, reveals how grey water recycling and simple conservation techniques can save companies more than just the odd drop.
A nation of guzzlers
As a nation we have become great water guzzlers, and the demands that modern society makes upon the water supply mean the water issue will not go away. Between 1989 and 1991, no fewer than 178 drought orders were issued. Even without drought, there would be cause for worry. In the UK, water consumption in households has risen by 70 per cent since 1970. Yet we still regard water as a cheap and abundant commodity.
In January 1992, the United Nations held a world water conference in Dublin which tried to promote water conservation, prompting various governments, including ours to act.
The Water Supply Regulations in England and Wales and equivalent bylaws have put in place some very simple and practical water supply solutions. All newly installed WC's must use a six litre maximum flush compared with 7.5 litres and above previously. Sensible when you think that the 20 per cent water savings will benefit both the metered customer and the environment. Also, dual flush toilets are permitted with a smaller flush no more than two-thirds of the maximum.
It is certainly a start. However, if the government and water industries are serious about their stated objective of 'sustainable development' then there is still much work to be done in the water conservation department. It is the government's responsibility to educate society about water conservation.
For instance, in addition to the simple water conservation techniques already mentioned, there are two other sensible and easy ways in which those responsible for designing and building might consider conserving and managing water: harvesting rainwater from the roof, filtering and storing it for later use and recycling water that has already been used (commonly referred to as 'grey water recycling').
Unfortunately the government has left it to the vendors of such technologies to blow their own horns. And, unfortunately, UK businesses are traditionally sceptical of the salesman who comes knocking on the door with a piece of equipment guaranteed to save money.
Grey water recycling
Water Dynamics Ltd, one of the leaders in grey water recycling, is the only United Kingdom Accreditation Service-accredited manufacturer of water recovery systems.
Water Dynamics' marketing manager Lora Lee Brown, acknowledges the current situation, "Unfortunately we struggle with public perception of grey water recycling from communal sources," she says. The argument for using grey water for flushing toilets is strong when you consider that water from the mains used for flushing toilets is of drinking quality. It clearly does not have to be of such a high standard, although equally, it should not pose a health hazard.
The office of Water Reclamation of the City of Los Angeles completed a project on grey water re-use, which involved looking at eight test systems. Health worries centred on the use of water for garden watering rather than flushing the toilet, but the findings were that grey water does not raise the health risks so long as reasonable sanitary practices are followed.
Water Dynamics units are as simple as 'fit and forget'. Regardless of the size of your building, if it uses water - particularly in large quantities - Water Dynamics claims it can design a bespoke accredited system that will achieve a 40 per cent saving in water consumption: the greater the use, the greater the saving! Maintenance requirements are minimal and the units are claimed to have reasonable pay back periods.
The system makes no attempt to balance or synchronise grey water supply and demand; instead, it ensures that either grey water or mains water will always be available; continuity of supply to the toilet is maintained independently of grey water production, by the system automatically switching to mains water if there is not enough grey water. If there is excess grey water it is automatically discharged to the drain.
Water storage capacity in the recycling system is only what is needed for normal toilet operation, calculated at 180 litres (40 gallons) for a typical day. By storing only a limited amount of water, and by storing that water for only a short period of time, it has been possible to eliminate traditional engineering, hygiene and economic problems.
How does it work in practice? Grey water is pumped from a storage reservoir to a header tank, known as the 'Break Tank', which incorporates the mains water supply mechanism and also provides a gravity feed to toilets. The Break Tank has been designed so that the grey water cannot contaminate mains supply.
Water supplies from the storage reservoir are chemically treated before they enter the Break Tank by passing through a dispenser of slow dissolving bromine tablets. This process provides yearlong controlled dosage without adding more chemicals to the environment than is used for lavatory bowl cleaning. Under normal conditions, Water Dynamic's grey water recycling system is self-cleaning.
A high quality filter is used to purify the water to between 60 to 80 microns. After filtration, a brominator or disinfectant chamber will provide residual disinfectant to the system ensuring that Legionella, E. coli, organic growth and other bacterial attack are all catered for.
The filter elements receive a spray of disinfected water from the break tank after every pumping cycle. This keeps the filter chamber fresh and hygienic, prevents saponification in the filter pores and goes on to produce on-going disinfection of the water in the storage reservoir. These processes keep the filter elements effective for month after month of continuous, maintenance free use.
Water Dynamics have been fortunate enough to be involved in extensive water recycling trials and pilot schemes with water companies and developers resulting in WIMLAS/BRE accreditation. It is great mile stone because NHBC have now stipulated that they will not cover any non-accredited water recycling systems.
Brown: "In all honesty, with something as new as water recycling there are no text books with all the answers, but through extensive trials with BSRIA, CIRIA, BRE, Cranfield University, Wessex Water, Gleeson Homes, Crest Homes, Three Valleys Water to name but a few, we have inevitably learned and adapted our systems to overcome teething problems."
It also appears that public awareness and demand for water-efficient devices is growing. According to Peter Casey of Gleeson Homes, "Water efficiency was rated a very important factor among potential home-buyers in our latest survey - 62 per cent of potential house-buyers said they would pay more for a home with water saving features that offered long term cost savings."
With so many water saving devises and methods available to us, one has to wonder why the government and water companies aren't making it a necessary part of sustainability for our future. By offering significant incentives/grants to those companies willing to invest in the recycling technology, the government has it within their power to ensure that grey water recycling becomes an integral part of our society.
Grey and rain water systems are probably the easiest and most environmentally friendly systems; however, other choices are available:
- Composting, waterless WC's. There is a wide range available for a number of different applications. These are literally waterless, using no water at all. However problems include the high cost of installation, user acceptability and the perception of maintenance and cleaning as a 'dirty job'.
- A one-litre flush composting WC. The flush gives the user the impression that they are using a conventional lavatory.
- Urine-separating-style lavatories where the sterile and nutrient rich urine is never mixed with the potentially diseased and nutrient poor faecal material. The separated urine can be diluted and used directly as a fertiliser or passed through a carbon rich compost bed over the winter months.
- Waterless male urinal systems, using a urinal coating and a perfumed oil-filled trap with quarterly maintenance. Again, the urine can be taken for direct land use. There is also a range of systems that require a water flush as a transport mechanism but are more environmentally desirable than a conventional system.
- Reed beds which can treat sewage and grey wastewater. These require a large area of land and specialist maintenance and cropping for nutrient recycling.
- An aqua solar system that can treat sewage and grey water in a complete ecological system within a greenhouse. This system also requires specialist maintenance and cropping for nutrient recycling.
- Septic tank or small-scale package treatment plants can give nutrient recovery back to the land via leach fields, but may need tanker emptying.
- Anaerobic digesters treat sludge, recycle nutrients and produce methane,
which can be used as a power source but are expensive for small systems.