Grey Water - Scientific principles to clean up grey water using Azolla filiculoides
I have given extra attention to Azolla filiculoides in a separate Hub, also listed under Grey Water. Grey Water and Azolla filiculoides in Tasmania . My earlier set-up, as illustrated here in this hub, has been revised and is working much better. (Please see Link immediately following this capsule).This is an area under continuing investigation.
I would be most interested in communicating with others who might be taking up any, or some, of the point raised in this Hub.
The concepts devised by me are freely given to the world of Alternative and Appropriate Technology. I have no wish to take up a commercial interest at this point in time. If you know of any further experiments or investigation into the biological mulch filtration of grey water by anyone, but especially if you are involved personally, I would be most interested to hear about it.
My only reward will be the joy of knowing that others are indeed interested, and that my ideas either work, or don't work for you. Sharing information of a technical nature, for me, brings its own rewards.
I am hoping to visit India in the next few months, during the middle of 2013. Primary objective will be in the deep south, Kerala and Tamil Nadu. If anyone visiting this Hub would like me to visit your project, I would honoured if you like to contact me via email.
Link to other Hub specifically relating to Azolla
- Azolla Update with Grey Water Clean Up
The final filtration of my grey water through an Azolla pond has been functioning extremely well for a little under a year. The Azolla had grown profusely over the entire surface, dominating over the Spirogyra, Wolffia borialis and Duckweed. In...
My ideas for this experiment have come from several years of interest and involvement in dealing with grey water in the domestic environment.
The first book I came across, about 12 years ago, was "Sewage Solutions," by Nick Grant, Mark Moodie and Chris Weedon. published by The Centre for Alternative Technology, Machynlleth, Powys, SY20 9AZ, UK. Web Page: http://www.foe.co.uk/CAT. I am most grateful to these people, and to C.A.T., for a most enlightening and helpful book.
This book is devoted to the treatment of the complete sewage stream, including toilet effluent ("Black Water"). Although my system does not include Black Water (I use a Humanure composting toilet), chapter 4 deals extensively and very informatively with the biological breakdown of various chemical elements found in Grey Water. I gleened from that chapter that one needs to incorporate an aerobic phase at the beginning at the process (oxygen supply being vital), this being referred to as nitrification, (i.e. the formation of nitrate from ammonia); then a final stage requiring an-aerobic conditions for the de-nitrification. The latter is to prevent eutrification in the environment (an excess of nitrogen nutrients where they would not normally occur in the natural environment).
Observing the Mulch Filter after One Year's Use
28 March 2013.
This is an important observation, especially since several people have asked me how often the mulch in the first Filter should be changed.
I have up to now replied that all one needs to do, once or twice per year, is remove a shovel load of the broken down mulch, (resembling soil), and replace it with some fresh mulch. This has been working fine, however now I notice that the grey water does not pass through the mulch so quickly as it did previously. This part of the filtration becomes partially blocked. My conclusion is that the mulch needs to be spread over a greater area and it needs to be "rested" on a regular basis.
Install a larger mulch bed, maybe 2-or-more meters diameter. Split the bed surface into 7 equal segments.
Arrange for the grey water to fall on the surface of each segment sequentially, one for each day of the week. When the appropriate time comes to empty one of the segments, this would be an easy procedure, provided there is good design applied to the system.
Water Quality in the Azolla Pond 18 July 2013
I have noticed that there is a very slight anaerobic smell. Having referenced some of the Websites concerning Azolla, I suspect this anaerobic condition is actually caused by the smothering effect of the Azolla.
One possible solution is to aerate the water after it has left the Azolla pond, because I feel that it's important to keep the water level in the Azolla pond constant.
With the current colder weather (southern hemisphere, wintertime, lower light level,) the Azolla is fairly pink, little growth taking place and I am not harvesting it. Maybe removing some and putting it into compost will help to revitalize the pond.
As at 17 August, I have taken samples of the final effluent and sent them to a Laboratory for analysis. Results will be published here.
Sample of Final Effluent water was taken on 8 August 2013, with the following results:
Total Coliforms: >24196/100ml
BOD: 22,2 mg/lt BOD holding time <48 hrs
Total N: 1.62 mg N/L
Total P: 0.64 mg P/L
My NON-Expert view regarding the Total Coliforms would be that they derive from the mulch filter, which contains all manner of biota, such as worms, etc.
E.Coli are to be expected, from use of the shower and bidet.
B.O.D. might be as a result of Azolla decay particles retained above the surface of the crushed glass gravel. Very little light reaches this region because of dense Azolla coverage. I also suspect there is little oxygenation of the water below the Azolla.
1. My objective of reclaiming treated grey water to be stored for later garden watering, without having to disinfect it has scored a NEGATIVE. The presence of that many E.coli indicates the water WILL need to be disinfected before storage.
2. Dispersal of the effluent into topsoil will continue to be adequate, provided it is over a large enough area.
3. When removing Azolla for any other purpose, it must be done with proper hygiene protection.
4. Regular harvesting is desirable to encourage fresh growth and thereby continued removal of phosphates. I add the harvested Azolla into the Humanure compost pile.
5. Use of Azolla for chicken feed, when the Azolla is taken from a grey water treatment plant would not be appropriate. However, Azolla from another safer source would be good for the chickens.
Latest photo showing growth after one week
The water with which we wash our bodies, our clothes, our floors, our pots and pans, is discarded, usually down the drain. This waste water is termed "Grey Water." Water which comes from the toilet, containing faeces and urine, is called "Black Water."
This article deals only with Grey Water. I use the Humanure system of composting toilet and will describe that more fully another time. Meanwhile you can access Joe Jenkins' Website for more information. ( http://humanurehandbook.com/instructions.html )
If you store Grey Water for more than 24 hours, it will begin to smell and become putrid. It can also be dangerous to health if it is not dealt with in a safe manner.
If you want to store it for some time, in order to use it again for, say, watering the garden when needed, then the Grey Water must be treated in such a way as to render it safe and to prevent it from becoming smelly.
The reason the water may become smelly if not treated is that foreign matter in suspension in the water will be attacked by bacteria. The foreign matter, such as skin and hair particles, food particles, various kinds of dirt, gets broken down into simpler chemical substances and some of these resulting substances, such as ammonia and hydrogen sulphide, are the chemicals which give rise to the bad smell. All this happens in conditions called an-aerobic., i.e., most if not all of the free oxygen in the water has been used up. The bacteria left in the water then have to split up water molecules (2 atoms of Hydrogen with 1 atom of Oxygen) in order to obtain their oxygen. The Hydrogen then gets combined with other molecules to make the smelly stuff.
There have been various ways devised to remove the foreign matter. Some methods are industrial, highly technical and complicated. Some methods are expensive. Some methods are unnecessarily complex and difficult.
My method, the subject of this Hub, is still in the experimental stage but so far it has worked well for me. I share my experiment and experiences with you so that others might wish to contribute further information and ideas.
I make no claims regarding the effectiveness or efficiency of this method, nor do I claim that it is absolutely safe to do, because I have no formal qualifications.
OBSERVING NATURE'S WAY
If you take a look at the floor of any healthy forest, you will see the surface of an Ecosystem. Litter falls onto this surface. This litter we call Mulch. That Mulch may comprise leaves in various stages of decay; twigs; seed pods; pieces of peeled-off bark; bird and animal droppings; broken off bits of fungus, flowers, feathers, etc., etc. If it has rained recently, the surface will be moist and alive with numerous little creatures like beetles, slaters, spiders, worms. Even with no recent rain, if you dig down a short way it will most likely be still moist, allowing the biological populations to thrive.
If you dug down below about 10cm (4 inches) you would find a change. You will find soil. This soil will be made up of all those bits on the surface which have been broken down by living organisms, in the process called Decomposition. You might find more worms of various sizes. There might be sand or gravel. Chalk or limestone and some clay will be mixed in with the organic matter. This is termed the Topsoil. It's a living organism in itself, performing a beautiful job of recycling organic matter into new food so that other living things can benefit from a feast.
The rain that falls onto the forest floor passes down through the Mulch and the Top Soil. Although the rain will appear as a muddy mess whilst on the surface, by the time it has dropped down a short way, it has lost that muddiness. If you went to a point some distance away, where the water reappears from a spring or a stream, the water will be quite clear and clean.
WE CAN COPY NATURE! The process described above can be replicated and applied in a controlled manner to clean the grey water which we create in our homes. This is the subject of the Hub which you are reading here.
THE PROCESS EXPLAINED
If a natural process can be used to clean up the Grey Water, this should be fairly simple and effective. It copies Nature, using bacteria and other micro-organisms, and mimics the process which happens on and within the floor of a forest. My method ensures that the water is treated in an oxygen-rich environment, known as Aerobic.
First the Grey Water passes through a Mulch filter bed. This Mulch consists of leaves, small twigs, and leaf mould, together with various fungi, bacteria, microbes, worms, beetles, etc. This diversity of natural life forms devour many of the solid particles found in the Grey Water; particularly waste water from the kitchen benefits from this Mulch filter. Fats, organic oils, food particles, all get dealt with by the microbes. There are some "dos" and "don'ts" applicable here which I will deal with as an appendix.
Secondly, the Grey Water passes down through a deep bed of gravel, specifically blue stone chips, with an average dimension of 7.0mm. A very fine layer of slime gradually forms on the surfaces of these gravel chips. The slime consists of more bacteria, which continue the biological attack on impurities still remaining in the Grey Water.
Thirdly, the Grey Water, (which by this time is hardly Grey Water as such, because it's fairly clear to look at), passes into the bottom of a small tank, approximately 500mm long, 400mm wide and 400mm deep. This tank is filled to within 100mm of the top with course sand. The sand is again the habitat for bacteria (in this case, an-aerobic), and other organisms, which further clean the water. The water passes upwards, slowly, through this final sand filter.
On the surface of the water above the sand is an aquatic fern species called Azolla filiculoides. This species is endemic around the Pacific Basin. It grows prolifically in the summer, but dies back considerably during cooler, winter temperatures. It can remove phosphates and other nutrients from the water. Small florets of the Azolla spread over onto the surface of the pond and will eventually totally cover the surface.
(April 14 2012) I have just read an account at this URL: http://davesgarden.com/guides/articles/view/1150/ where I have reason to believe the Azolla species I am using is in fact Azolla pinnata. If any expert out there needs to enlighten me on this, please feel free to comment.
Water finally trickles over the edge of the pond into surrounding top soil, and will be absorbed by natural vegetation in the forest.
The Azolla can be harvested for various uses, e.g., composted and used as a fertiliser; fed into a methane gas digester; dried and used for poultry feed supplement. Others have experimented with these and other uses, but my experiments have not extended beyond this point so far. From what I have read about Azolla, it lives symbiotically with Cyano-bacteria which are able to "fix" nitrogen from the air. A very informative Website is this: http://visual.ly/azolla-superplant
It is also hoped to show that this final effluent water could be stored for later use in the garden.
The success of a process such as that described above depends largely on how it is understood and operated. A major factor is your lifestyle, and what you put into the system.
First, how aware are you about what goes down the plug hole? Do you use a lot of soap? Or a lot of detergent when washing dishes? The soap or detergent are NOT the cleaner! Does this surprise you? The WATER is the cleaner. That soap or detergent is only there to help the water come into contact with the dirt and grime, so that the water can then carry the dirt away.
If there is minimal dirt, or no grease/fat/oil on the plates, then you hardly need any detergent at all. From the amount you normally use, just try reducing it gradually to see if you still get an adequate wash. Then use just the amount required and no more. This way you will be helping to protect the natural biological processes in the grey water treatment. I personally use Laundry Balls (http://www.laundryball.com.au/). They have worked well for me over two years now. Subsequently I have taken to using "Aware" laundry powder, as this is apparently environmentally friendly. I use the balls as well because they help in the rinse, right through to spin dry.
Next, how long do you spend in the shower? The amount of water you use, if it's too much, will likely overload the grey water treatment system. Just be aware of actual quantities: If there is, say, 10 litres of water coming out of your shower head every minute, then if you shower for 10 minutes you have used 100 litres of water. Simple arithmetic, right? Check out the tall white plastic bottles that hold 25 litres (5 galls approx.). Four of those in a 10-minute shower!
No one, Yours Truly included, can tell you what to do, but with this sort of information you can make your own informed choices, hopefully for the better. This is just one more way of ensuring your grey water treatment system works well for you without any problems.
Finally, you will be well aware by now that "garbage" stuff, like washing paint brushes, motor oil, chlorine and other bleach-based products, insecticides, etc., must NOT, NEVER be put down the drain when you have a natural process working for you.
I am experimenting with the addition of commercial washing detergent ("Aware"), adding just one desert spoonful to each wash load. This then shows up in the extra green Azolla growth, i.e., more nutrients available, presumably phosphates (I am guessing here, might be wrong).
I have harvested some of the growth from this pond surface and added it to a small methane gas digester. I have read that the most productive methanogenic bacteria work best at around 30 degrees Celsius. A small experiment is underway now to see if solar energy can be trapped to raise the temperature of my digester.
This experiment has been abandoned for the time being.... I am too busy with other things, and much more energy would be need to make a successful conclusion to the experiment.
It is my hope that someone will come forward to get involved with me in this research.
With my limited background knowledge; my lack of scientific discipline; my age - causing a slow-down of the mental processes; also a reduction in my physical energy reserves - it would be wonderful if there were a university undergraduate, or post-graduate student, anywhere in the world, who is interested in expanding and furthering these experiments. I would be happy to travel, in order to learn from you. Likewise, you would be most welcome here.
PHASE 4 - Upgrade - Jan/Feb 2013
The Azolla pond was a temporary affair, dished into the ground about 400mm deep, rocks placed around the edges and lined with black builder's plastic for leak-proofing.
There were two reasons for wanting to change the pond. First, the plastic was leaking and the pond drained, leaving the Azolla to die right out.
The second reason was that I felt the original pond was un-necessarily large. Much of the Azolla was remaining pink, signifying that virtually all the nutrients had been dealt with.
THE LARGEST "POND" available was a black plastic trough for livestock, 1.4 metres diameter at the base, at a cost of around AU$200.00.
Having some flat surfaces where the input valve would normally be allowed for easy insertion of inlet and outlet pipe flanges.
New Filter Medium
A local quarry company is crushing recycled glass. I decided to try this, instead of coarse washed river sand which had been used before. The crushed glass has a particle size of 5-7 mm and smaller, with approximately 60% being less than 2mm. The particles are not sharp, and therefore present no danger of causing injury.
Inlet Pipe arrangement
Inlet pipe goes across the bottom of the trough, and opens under a plastic device with geo-fabric covering it. I obtained this for AU$1.00 at the local recycling shop.
A piece of shade cloth across the outlet is to prevent Azolla florets from blocking the outlet pipe.
Innoculation with Azolla filiculoides
Just a very small amount of Azolla has been added to the surface of the pond. This will grow fairly quickly and cover the entire surface in about 3-4 weeks.
I am continuing to use "Aware" laundry powder, made by Planet Ark. It remains to be seen how green the Azolla grows.
The water in the pond is initially quite cloudy with particles washed up out of the crushed glass. I predict that when the Azolla has become well established, the water will become much more clear. I believe there is some kind of electrical charge caused by the biomass, this causing the suspended solids to precipitate out and fall to the bottom.. (Organic solids from the waste water have already been filtered out by mulch in the earlier part of the system.)
Ongoing Studies - Subsequent Hub
I have opened another Hub, dealing more closely with the Azolla filiculoides and other plant species in the pond. You might care to look through that Hub if it interests you. The Link is given below.
© 2011 Alan
More by this Author
The art of using unusual bits and pieces to do the job you need, without spending a lot of money in the process. This art form can transcend national boundaries and cultures.
A small-scale biological method of treating grey water, using a symbiotic mixture of Azolla filiculoides, Wollfia borealis, Lemna minor and Spirogyra.
Local biological materials for filtration of grey water