I know this is only of general interest for those of you gardening at home, but it’s fascinating to me how quickly the mainstream world is moving in the direction of environmental awareness and behaviour.
As I may have mentioned before, I spent most of the last winter interviewing professional growers about their workforce practices. You can find out the details of that here if it interests you. One of the companies I interviewed was Lowaters. One of their directors, Charles Carr was also carrying out a project – this one on water recycling.
You see the water industry has woken up to the fact that we are likely to start seeing difficulties with water supply – and countries where food is grown for us such as Spain and Italy are very much in the front line. Already it’s nearly impossible to get a new water abstraction licence in the South East as a commercial grower. So there is some real interest in water recycling – and until it’s abolished SEEDA is offering 40% grants for water recycling projects. Since we have about 2 acres of glass here it’s clearly of more than academic interest – in fact we’re at the grant submission stage ourselves having already jumped through the planning permission hoops.
Anyway Lowaters have created a really interesting set up – 7000 cu meter reservoir (we would get through about 600 cu meter here in months like July and August) which is purified by oxyenation via a venturi pump and an iris bed. More about that in a minute.
The water is collected from the glasshouse roof and goes through a gravel bed after a silt trap to do a first stage purification. The water ends up in a pit from which it’s pumped up to the main reservoir. The water is purified by a combation of filtration and running through the Iris bed. As permaculture enthusiasts will know this is a key trick in the reservoir – but it’s amazing to see it installed in a mainstream nursery. What’s particularly surprising is how small it is relative to the amount of purification of pathogens like phytophora that it removes. But analysis of the water demonstrates that it does. It passes 4 cu metres per hour or around 100 cu metres per day – five times what we would use here at our irrigation peak. Here’s a couple of pictures.
As you can see, the roots of the Irises which sit in a floating polystyrene island are able to clean the water that passes through them.
If you would like a copy of Charles’ report you can download it free from this page which also has a slideshow of the whole project