In Ireland we spend a lot of time thinking about water. Or at least, we spend a lot of time having it falling out of the sky onto our heads, and this in turn means that we think (and talk!) a lot about water. As part of a long term project to reduce our resource usage and waste output this winter the Perfumery will upgrade it's waste water treatment with the goal of returning water to the environment at the same or better quality than we extract it.

The Burren Perfumery uses 300,000 litres (75,252 US gallons, 65,991 Imperial gallons) per year. The Environmental Protection Agency in Ireland estimates that each person in Ireland uses approximately 180 litres per day. (By comparison, figures on the web for the United States vary between 260 and 380 litres per person per day). So the Burren Perfumery uses the same volume of water as a household of 4.5 people. As we are "off mains" we have to pump all of our water ourselves. Our source is the turlough (seasonal lake) that lies behind the Perfumery (see the map below, the Perfumery is in the upper right, turlough area is to the south). Immediately after heavy rain this lake can fill to an average depth of say 0.5 metres and cover an area of 1.6 square kilometres, that is: 800,000,000 litres of water, or enough to supply our annual needs more than 2500 times over! Unfortunately because the Burren is full of holes, most of this water will usually disappear within a few days, unless there is continuous rain (like this summer for example...).

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So even though there is a lot of water around us, we still have to be careful about what we use. Not only because the supply may be limited, but also because the water needs to be pumped and treated, processes requiring energy, another resource we need to conserve. On the plus side, unlike municipal supplies, we use nearly all of what we extract and purify. In Ireland it is estimated that between 50% and 70% of all water treated by city and county councils for public consumption is lost through wastage, predominantly through leaks in mains piping. In some cases this is known to be as high as 90%. [And it's not just that Ireland is plumbed badly - many urban water supplies would have similar levels of wastage.]

On the incoming side our water goes through four stages of treatment. First, a centrifugal sediment separator extracts 90% of particles larger than 70 microns (a human hair is between 40 and 120 microns thick). This first stage extracts the heavy sediments, particles of soil and clay, that are suspended in the water as a result of it washing down from hills into the valley. Next comes a high volume 30 micron particle filter, followed by another high volume filter, this time of 10 microns. This filters extract most of the remaining suspended particles. Finally the water is pumped past an ultra violet light which sterilises any remaining biological contaminants.

Our purification system doesn't include any chemical treatments so the taste of the water is unaltered. When we have the water tested (both before and after treatment) no chemical or metal pollutants show up, which is good, but also in line with what one would expect. There are no sources of chemical pollutants in the watersheds around us; rainfall predominantly comes in from the West over 3000 miles of uninterrupted Atlantic Ocean; and air pollution over the Burren is virtually unknown. [Incidentally lichens are known to be extremely sensitive to air pollution hence their luxurious growth in the Burren is a good sign of the purity of the air here.]

Having to pump and purify your own water makes you very conscious of your water usage. Acutely so when anything goes wrong with your supply. The pump which supplies us is located near the centre of our seasonal lake. During dry spells the lake dwindles to a very small spring a few metres across and one can walk out to the pump house to check that everything is working correctly. When something breaks down in the winter it is a different story, and I often have to row or kayak across the lake with a handful of spanners, in the middle of the night or the teeth of a gale, to apply the miniscule amount of plumbing know-how I possess to try and get things working again. In fact, over the last few years I've learned far more about plumbing than I ever wished to, and I guess this article is prompted in part by an eagerness to share this new found knowledge!

Where the story of water gets really interesting though is what happens to it afterwards. After what? After it is consumed in some way. Most of the water the Perfumery consumes does not go into products. We distill water to use in perfumes, floral waters and creams. Water is also used in soap making. However all of the water that goes into products doesn't amount to more than a few thousand litres, if even that.

Most of the rest goes down the toilet, and that is where this article is going now.

The majority of water used by first world households is used to flush toilets. How much depends on how new the toilet is and where it is. In Europe, especially in countries with water supply problems, low flush toilets are required under building regulations and have been for years. There are also dual flush toilets - a small flush option for urine and a full flush for excrement. Since 1994 in US, toilets are required to use a maximum of 1.6 gallons per flush (6 litres). Prior to that toilets could use between 3.5 and 7 gallons per flush.

However, despite these improvements, the basic problem is that a large proportion of the water that is extracted and purified (whether by a home owner or by the state) to be fit for drinking is then used to flush away human waste, and thus polluted. This water must then be treated again before it can re-enter the environment.

There are a few of problems with this. The first is that for, shall we delicately say: 'non-liquid' human waste, at least 6 litres of water gets polluted in order to transport 200-300 grammes of waste to the sewerage system. Secondly, 'liquid' waste could pretty much transport itself away, however in most cases another 6 or more litres of water gets polluted for this (except for dual flush systems). Both liquid and non-liquid waste are then mixed together are carried away along with the polluted water to be treated either locally (for off-mains households) or municipally. The problem here is that the constituents of liquid and non-liquid waste are different and ideally they would be treated differently and independently. For example, there are specially designed toilets that separate urine from solids, allowing the former to be stored in tanks and evaporated down to (mostly) ammonia, which can be used for fertiliser, and the latter to be composted under controlled conditions which ensure sterilisation of the bacteria in the waste and again all the resultant compost to be returned to the ground.

At the Perfumery we have spent two years looking at our options for improving the treatment of the waste water we produce. I have read and learned more about sewage treatment than I ever wished to! We've learned about reed beds, septic tanks, percolation areas, polishing filters - all manner of things which absolutely don't concern you if you live 'on mains'. I read through 250 pages of EPA guidelines. I engaged an engineer, we dug holes (or at least tried to!), we discussed options, we schemed schemes.

In the end however, what I learned is that there ideas about what can be done and then there is legislation that dictates what you actually can (and in some cases must) do. The legislation tends to lag somewhat behind the technical possibilities, but it's hard to see how this could be otherwise. When reviewing the possibilities available to us I quickly realised that there can be a gap between the benefits that advocates (and manufacturers!) claim for their systems and what may be achievable in reality.

To cut along story short, in consultation with our engineer and our county council's environmental officer, we have decided to replace our existing waste water treatment system with a new system that will combine four separate treatments. Since each treatment has it's own advantages and disadvantages, we hope to achieve a high overall level of treatment as well as avoiding putting all our eggs in one basket. We have also agreed to use conventional, i.e. mandated treatment options first, to treat a worst case scenario of the expected current volume of waste water plus fifty percent contingency, and then to add in elements which should reduce the overall volume of water polluted (such as ultra low flush- , composting- and urine only- toilets).

The four treatment stages are:

• separation and aerated digestion (package treatment plant)
• peat filtration
• reed bed filtration
• raised bed polishing

In the first stage, sewage is gathered in a large underground tank which is chambered in a way that separate solids from liquids. Solids settle to the bottom and are removed annual by tanker to be treated by the municipal authority. Within the upper part of the tank a series of large rotating disks, half submerged in the waste water, continually lift the water into the air. Bacteria growing on these disks, combined with the constant aeration, digest the biological waste material suspended in the water.

The waste water is then pumped into a series of large tanks each filled with a compressed mixture of peat (from Irish bogs) and crushed sea shells. As the water slowly percolates through this mixture, further suspended solids are trapped and digested by bacteria living in the peat.

When the waste water exits the peat filters it then enters a series of reed bed modules. These are basically shallow troughs filled with a growing medium (washed gravel) and planted with local reeds. The reeds extract nutrients (ammonia and nitrates) from the water, further purifying it.

From there the waste water flows into pipe distribution system that is buried within a raise mound of soil. This is the final polishing stage. The pipework has a special 'fluffy' exterior that creates big surface area for more bacteria to grow on. The water is evenly distributed throughout the soil mound and further cleaned by bacteria growing on the pipework and in the soil as the water percolates down. This final also slows the release of the water back to the environment, evening out the rate of release.

Our target for this system is to return the water to the environment at the same level of quality (or better) than we extract. In other words to have either no impact, or a positive impact, on the environment in this area. To monitor this we will install sampling points between each stage in the process, so that we can assess whether the treatment is having the effect we expect and, if it proves necessary, increase level of treatment at a given stage.

Installation will begin this winter and the systems should be complete and commissioned by early spring. I hope we will be able to report back to you then on how it is working. The reed bed suppliers claim that you can drink the water that comes out of them. I'll get back to you on that one...

Ralph Doyle

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