Feidhlim Harty wrote:Hi Kat, what you're describing sounds like either a gravel reed bed system or a soil based constructed wetland system - or a combination of these approaches. (If you're interested in the main differences they're on www.wetlandsystems.ie/reedbedsystems.html) In Ireland, given our climate, average water consumption and water quality requirements - the typical size for a constructed wetland is about 100m2 (about 1000ft2) for a 3 bedroom house. A gravel reed bed will be about half that size. Here we use bulrush (or cattail in the US), common reed (the tall thatching reed), yellow flag Iris and a few others.
In arid climates such as the one you first read about, the system size would be a lot smaller and use a different range of plants, but the principle is identical. Basically the plants not only take up nutrients and provide evapotranspiration, but they also act like a creche for bacteria - providing just the right biological environment for them to thrive and party hard on the abundant supply of food (contaminants to you and me). And yes, the water can be really really clean at the outlet end - all for no electricity inputs and a wildlife habitat to boot!
I first heard of Constructed Wetlands in the early 1990s when our local town of about 10,000 people was planning to build a longer pipe (I kid you not!) as a solution to the sewage problem, and pump it further out into the local harbour. A group of local residents did a lot of research and organised the first Irish Constructed Wetland conference. My mother was one of those residents (chief protagonist actually) and so I got really interested in the whole area. What the book does is speaks to the sewage newbies about the whole range of options available: conventional systems, natural ones like I've described here, and hard-core eco such as willow systems and dry toilets. My ultimate aim is to get clean water back into every stream and river in the country - not unlike Paul's plans at world domination, but smaller scale.
At that conference, Dr. Don Hammer of the Tennessee Valley Authority spoke about soil based constructed wetlands, and how they helped to get a local lake back from the brink of extinction, so to speak. He outlined how maintenance free they were - and I was besotted. The rest, as they say apparently, is history.
Feidhlim Harty wrote:Hi Kat, thank you for the kind words, always happy to be of help!
If you're doing your research, check out my website for background information. It's at www.wetlandsystems.ie . Send off an email to me if you want me to send you on a copy of my constructed wetland information document.