In "Permaculture Guide to Reed Beds," Feidhlim Harty goes into significant detail on designing, building, and planting wetland treatment systems. The book is largely focused on constructed wetlands, horizontal flow reed beds, and vertical flow reed beds for treating household effluent. The author makes an effort to encourage environmentally friendly options while still maintaining system and operator safety. Included in this book are plenty of details for meeting code requirements in Ireland and the UK.
I have to admit that going into reading this book I was pretty nervous. I hadn't done much research into reed beds before I read this book and based off of what I had read before I was worried that this book was going to be all about how big of a massive concrete reed bed you needed and how you needed all sorts of fancy pumps and whatnot to make it work.
I was pleasantly surprised! Very early on in the book there was a strong encouragement to use as little energy as possible and make it as natural as possible while still functional given the site conditions.
When I picked up this book I thought it was about treating greywater. While that is true, the main focus of the book is actually on treating blackwater. So a bit more advanced than what I thought I was getting into.
Something that I really appreciated about this book is that the author was extremely serious about safety and taking appropriate precautions when dealing with effluent. He hammered that point home pretty hard, which I think is important because a lot of people seem to not think about it.
You can tell that Feidhlim knows what he's talking about. This book is dense with details. Specific mentions are made throughout this book on how to meet planning requirements in Ireland and the UK, which must be awesome if you live in Ireland or the UK.
I don't live in Ireland or the UK. I live in Canada. And I live in a flat part of Canada where the frost can go down as deep as 8 ft... so these solutions on their own don't quite work for me. To be fair, the author explicitly mentioned in the opening that the systems presented in this book would not fit climates such as mine. He covered himself... so no points off there.
Despite the very wet nature of the conversation, I found the book to be a little dry at times. But seriously, it's a book about effluent treatment. I think he made it about as interesting as it can get.
In general I thought he covered nearly all of my questions at some point in the book. I would like to have seen more discussion about low cost techniques for greywater that avoid the need for a septic tank. Maybe a section more focused on greywater-specific things. Or maybe that's another book?
Otherwise I'm glad I read it. I feel like I understand both septic systems and reed beds much better now. I recommend this book for anyone who is considering installing a reed bed treatment system, especially if you live in Ireland or the UK.
Many thanks for your thorough (and generous) review.
With regards to cold weather, I know that there is a constructed wetland system in Minot, North Dakota, performance of which "…declines with lower water temperatures, but has performed very well for normal wastewater discharge parameters" Hammer DA and DL Burckhard (2002) Low temperature effects on pollutant removals at Minot's wetland. In:Mander,U and P.Jenssen (2002) Natural Wetlands for Wastewater Treatment in Cold Climates. WIT Press, Billerica, MA, USA. I'm not sure if you're a lot colder than North Dakota, but I'm sure adaptations could be made for colder climates than that if needed.
Your comments indicated a greater interest in grey water options than I had covered. Essentially the gunk in grey water is usually trickier to treat than black water. The chemicals we put down the sink (well, those of our species who hunt their food in supermarkets, of which I am all too often one) are harder on the environment than simple straightforward faeces and urine (which, for the record, our surrounding environment has evolved to recycle to the generous tune of about 100%). Thus for grey water, I propose a wetland of 50-60% the size of a standard black water reed bed or constructed wetland, based on the overall flow volumes reaching it.
Anna Eday (solviva.com) is another excellent source of information for setting up a grey water system, if you're interested. Unfortunately in the regulatory context in Ireland and the UK (as in Eday's Massachusetts), woodchip filter systems have yet to receive the research and legislative blessing needed to adopt them as part of your main planning permission process. Doesn't mean they're not effective - just that they're not yet a legal option for new houses.
Anyway, thanks again - and do let me know if you have specific grey water questions or with to play option-volley.
I think colder winter weather is always a gotcha when I've read about such systems, which is annoying when I ponder my options for the future homestead in zone 6 which currently has nothing in place and with as little waste that I currently produce I consider a septic tank an over-engineered waste.
On the contrary, constructed wetland systems should be absolutely fine for Zone 6. They've been used successfully in North Dakota, which is Zone 2/3, so 6 should be positively balmy. Certainly you'll need to design with care, but it shouldn't cause too much trouble for the effectiveness of the system. (Here's a brief overview of the different treatment wetland types. The ones best suited to northern latitudes are probably soil based constructed wetlands: http://www.engineersjournal.ie/2017/11/07/reed-beds-natural-solution-irelands-waste-treatment-problems/, but horizontal flow gravel reed beds will also be good. Vertical flow reed beds will probably just freeze up on you.)
Certainly if you're aiming for the ideal scenario, then septic tanks leave a lot to be desired - whether you use a treatment wetland or not. Ultimately you're much better off recirculating biomass and nutrients rather than flushing them down to an anoxic tank... This can be achieve with a dry toilet, Aquatron separator, woodchip filter and/or urine diversion toilet. After that you can use a reed bed or wetland to minimise local groundwater impacts of any residual contaminants, or route the effluent through a willow plantation to harvest firewood from the remaining nutrients.
For folks that live in colder areas, I wonder if it would be practical to have the wetlands inside a solargreenhouse? Or perhaps even inside the house?
I had though of something similar for treating grey water, having the reed bed as a decorative feature inside the house, possibly even as part of the bathroom. In the end I decided against it mainly because it would be to complicated and time consuming to retrofit my house. But if it was designed in from the beginning...
My opinions are barely worth the paper they are written on here, but hopefully they can spark some new ideas, or at least a different train of thought
Hi Peter, Good thought, but my fear around the in-house version is that you'd essentially be investing more cash and carbon into building the house bigger in order to install something that works perfectly well outside.
The greenhouse version may be good though. Particularly if you route the grey water (only) through a bed of edible greens such as cat-tail, water chestnut or watercress. You'd need to be very careful of inputs in the house though, so that you could eat your greens then afterwards. This has the double advantage of keeping the greenhouse a little above zero as well.
My preferred option is to build the system deep enough to tie in with the local building codes in order to prevent damage or stoppage by frosts. What happens in very northern latitudes? Any knowledge of this here on the forum? Due to the warmer water coming in from underneath (for a base-fed system to counteract the cold) the base will likely stay free of ice for all of the year except perhaps in extreme cases.
Just finished reading the book. It was very helpful, and I would definitely recommend it. I did have some question, for you though, Mr. Harty. You mentioned that it's best for the reeds to have a about a year to get established before using it for the effluent. How quickly could this process be sped up? Planting denser could help, but it sounded like the roots needed time to establish and at lower water levels. Can they still establish with low levels of effluent, or are they just not able to work their cleaning magic until they have a little time to grow?
The other questions I have are concerning the final disposal of effluent. Originally, I was hoping to clean up the effluent enough to use for irrigation, but that sounds like it might be a little intensive. Our drainfield is failing, right now (16 yr. old dome system, which apparently, all dome systems fail after about 15 yrs.......so they found out), and I was hoping for a permaculture alternative, and avoiding the 10k to put in a new drainfield. But, I'm a bit stuck as to what to do after a wetland, besides the willow option. Are there other ways to discharge into the ground?
Hi Andrea, I'm glad you found it helpful. Thanks for the kind words.
Plant establishment is a flexible feast. In reality you can build your system, flush the loo and then don wellies and full protective clothing and wade in to do the planting if you wish. The drawbacks are the potential for contamination (if you get the wrong bacteria entering your body via a cut from one of your reeds it can actually kill you, so it's not something to recommend); it's a smelly, unpleasant sort of job; the soil (free water constructed wetland) or effluent in the gravel (horizontal flow gravel reed bed) will be anaerobic (due to the low dissolved oxygen levels in the effluent) and thus more of your plants will fail than if you plant into more suitable conditions. Also, the treatment effectiveness will be reduced until the plants thicken up.
It's not uncommon though for systems to be planted on the same day that effluent is introduced. If you have a problem site with existing pollution going to a stream - you're much better off putting it into a less-than-100%-effective reed bed than continuing to dump it in the stream for the year. In this case I often use straw, barley straw if possible, scattered in rows across the flow of the system (soil based constructed wetlands only) to provide a biomat layer for microbes to adhere to from the get-go.
Vis a vis your site: Do you know why your dome system is failing? Microfibre caking on the soil base; sludge overload; soil ingress? Is there a chance that a load of willows planted over the top of the system would provide enough preferential flow pathways to reignite the drainage again? See the next Permaculture Magazine (spring 2019) for layout details if you're interested in a design.
If you put in a reed bed, you'll still need to dispose of it. Section 7.2 "Permaculture Percolation" offers some thoughts on this, but no hard and fast designs. Have a read of that and let me know if that approach (a reduced dome system really, with cleaner effluent going into it and then planted with willows) would work.