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Grey Water and Azolla filiculoides in Tasmania
Continuing Grey Water small scale treatment
In my previous Hubs, I have described my experiments with mulch/gravel filtration, with a third-stage "polishing" through an Azolla pond. You may link back to that previous Hub by clicking the link immediately below this capsule.
I finished that Hub having deposited a small amount of Azolla filiculoides to the pond. I have now taken further photos of it, just few days later, to hopefully show how rapidly this inoculation can spread right over the surface of the pond.
Please check back at the end of this Hub occasionally. I will add sequelae in the form of further photos, just to show how the pond is progressing as the days go by.
There have also been areas of learning for myself. Certain hypotheses made by me turned out to be incorrect. A little editing of the Hub has been necessary as a result, but it all helps towards better comprehension.
This Entire Hub is Copyright!
Neither the text nor any of the photographs may be copied or plagiarized without express permission of, and direct reference to, the author.
Grey Water - Scientific Principles
- Grey Water - Scientific principles to clean up grey water using Azolla filiculoides
Small scale domestic treatment of grey water, keeping it simple, using nature as a teacher and resource. On-going experiment, basic science but without collegial input so far.
Latitude, approx. 43 degrees South.
Altitude, 450 metres above sea level.
Terrain, rocky, partly cleared native forest of Eucalyptus ssp, and shrubs
4 Feb 2013 around 3.30pm. Sunny day, little wind.
Air Temperature at time of photographs, 59 degrees F (14 degrees C)
Water temperature at the time was 69 F (20 C) - black walls of the pond warmed by the sun.
Water in the pond is filtered grey water, having passed first through a mulch filter (forest-floor debris of leaves, bark, twigs, leaf mould, worms, multiple species of fungi, insects, microbes), then through a gravel filter of particles <7.0mm dia.
In the bottom of the pond, depth 300mm approx., crushed recycled glass. This has imparted a slight brownish (rust, tannin, tea) colour to the water, which might increase solar absorption.
Reference for further understanding
The link to Wikipedia given below has some very useful information about the biology of Azolla.
That green layer of algae on the surface:
On searching with Google, I came across this Wikipedia site which explains everything! The early growth on the surface of the pond is not, after all, Azolla. It is in fact Spirogyra. I have altered the captions for the photos, which previously claimed the growth was Azolla, immediately following this capsule
Spirogyra is very common in relatively clean eutrophic water, developing slimy filamentous green masses. In spring Spirogyra grows under water, but when there is enough sunlight and warmth they produce large amounts of oxygen, adhering as bubbles between the tangled filaments. The filamentous masses come to the surface and become visible as slimy green mats.
Adding Azolla to the new pond
I obtained a small amount of Azolla florets from a friend and gently poured the Azolla onto the surface of my pond. ( If you spread your hands out wide and touch your thumbs to each other, the Azolla added to the pond would cover the area of your hands, approximately. )
Even after just 24 hours, this "seeding" had increased in size. The leaves at this stage are pink.
In full sunlight
Spreading across the pond surface
Ecosystem at Work
The cyanobacterium, Anabaena azollae, grows in symbiosis with the Azolla, fixing nitrogen from the air, which benefits the Azolla. As I understand it, this Anabaena azollae cannot be seen with the naked eye, because it grows within the leaf cavities.
This contributes to the value of Azolla as a food supplement for poultry and other farm animals.
Azolla is also able to extract phosphates from the grey water, helping to prevent eutrophication.
The Next Day !
The following day, 5 February, warm, sunny.
These next pictures were taken just 24 hours after the previous. It shows you the rate of growth and oxygen bubbles being given off.
Showing the speed of growth after 24 hours
A further 24 hours - Just 4 days growth in total
Photo at time of start, 4 days ago
7 Days After Start-up
The weather has cooled, wind has increased, and we have had a very light shower of rain.
The blanket of bright green Spirogyra, which occurred by the 4th day, broke up into small islands on the 5th and 6th days. I have since learned that the Spirogyra does in fact sink down below the surface at times when the water is colder and there is less UV light. Oxygen is produced as the water warms and the sun gets brighter, so the Spirogyra is able to float to the surface. Now, on the 7th day, the maturing florets of Azolla have multiplied from the initial small quantity added at the beginning of the experiment.
The water appears clear from the surface, but on taking a sample of the water in a jam jar, the water is pink/yellow/rust in colour. (The appearance might differ with each observer.... my eyesight is losing some of its red sensitivity.) I presume this colouring is from the crushed waste glass being used as the up-flowing filter in the pond.
Sample of water shows colouration from the waste glass filter medium
I had noticed some very tiny specks of green floating amongst the Azolla leaves and initially had various theories as to what they were.
After examining them under my digital microscope, and then searching via Google for more information, I discover that they are examples of Wolffia borealis, one of the world's tiniest flowering green plants.
Pond Surface study
Picture taken with a Kaiser Baas Digital Microscope
15 Days After Initiation of Project
Please notice the growth of Algae (Spirogyra), well established and providing oxygenation of the surface water presumably. The Azolla has multiplied well.
The weather has been warm, the water temperature likewise.
Duckweed - Lemna minor
In the middle zone of this photo, notice the small patch of Lemna minor.
In my ignorance, I initially thought these were young Azolla plants.
Conditions can change rapidly!
Yesterday, 18 Feb. was very hot here, around 30C most of the day. Overnight the temperature dropped rapidly and we had heavy rain/thunderstorm during the early hours of the morning.
As I write, 4.45pm on Tues. 19th, the air temperature is 58F (15C) and the water temperature 62F (17C).
The water sample taken in a jam jar is perfectly clear, with no obvious suspended particles, although the colour of the water remains like tea.
That covering of Spirogyra has completely covered the water surface between the Azolla. The Azolla has multiplied to cover approximately half the pond surface. The very tiny Wolffia are still there.
New information comes to light!
What a wonderful facility we have in the Internet and the World Wide Web!
I have been able to search for "Azolla filiculoides and symbiotic algae" and came up with this site: http://waynesword.palomar.edu/plnov98.htm.
Azolla and Anaebaena azollae have a fascinating symbiotic relationship. You can read all about it and other aspects within the site.
Thank you to that person or persons who have put so much work into their studies and made the information available to us here.
Further: Research from this site as well: http://bharatnamaskar.blogspot.com.au/2012/09/biogas-from-azolla-biomass-energy.html showing there are numerous potential applications for Azolla.
3 Weeks after Startup
30 Days after Start-up
Azolla has completely covered and dominated the pond surface. The leaves are standing up above the surface and flourishing well.
My finger in the smaller pictures give an indication of the size of leaves.
Two months since start-up - 8 April 2013
We. here in southern Tasmania, are into Autumn now. The days are shorter, air temperatures cooler. (62F, 18C at the time of writing), water temperature a couple of degrees lower.
Azolla is beginning to show a slight purple tinge.
In the photographs, note the small globules of water sitting on the fern surface. Interesting demonstration of water surface tension.
The 5-cent Australian coin is 19mm diameter to better demonstrate the depth of foliage.
The small jar of final effluent, taken immediately after taking sample, shows clarity at this stage. Absolutely no smell. Still the same colouring, presumed to be from the crushed glass (beer bottles, etc.).
Update 4 Months After Startup
29 May 2013. We are into winter here now, although it has been sunny and fair weather for the past couple of weeks.
Air temperature this morning is 12 degrees C. Water in the Azolla pond, 5 degrees C.
The Azolla has turned pink.
Wolffia borialis and Lemna (Duckweed) are surviving well.
There seem to be various explanations for the Azolla turning pink. I am assuming the combination of lower water temperature, less solar radiation and low phosphate levels are the cause.
Possible on-going experiments could be: 1) Increase the phosphate level, by using laundry powder which has a higher content. 2) Building a green house over the Azolla pond, to see if increased warmth is a benefit. 3) Harvesting the Azolla on a regular basis might produce a younger batch and this might show greener.
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.
Continuing Observations 18 November 2013
Three weeks ago, I removed some Azolla to use as fertilizer around my strawberries. Quantity was approximately 20 of fresh Azolla. The first picture below shows the portion moved from the pond.
Please note the wire netting over the pond. This has several purposes: To keep animals and birds of the surface, as they might think it's solid; and to prevent easy access to the water by children in particular.
Harvesting of Azolla for use as fertiliser.
3 weeks later, 18 November 2013
The weather has been varied: rain, warm, sunshine, wind..... springtime here in southern Tasmania. The pond's vacant space has been quickly covered over by 3 species of plant: Azolla, (aquatic fern); Spirogyra (algae); Wolffia borialis, (world's smallest flowering plants).
The Azolla will continue to cover the pond completely again and remain as the dominant species.
The Spirogyra on regaining access to sunlight is undergoing photosynthesis and producing oxygen, seen as numerous bubbles on the surface.
Wolffia has become prolific and also enjoys the sunshine
THESE PHOTOGRAPHS were taken with a Samsung Galaxy Express smart phone, GT-18730
Rapid growth of an ecosystem
Unexpected developments 2015
"Disappearance" of Azolla
In my grey water treatment pond and in various other man-made water bodies in the southeast of Tasmania ,(i.e. on the Tasman Peninsula in particular,) Azolla has been replaced by Duck Weed (Lemna minor). In my grey water pond there is also a profusion of Wolffia borialis.
So far, I have not been able to give a satisfactory reason for this. Up to the present time of writing, early April which is our early autumn period, the Azolla has not returned. I am hoping and trusting that this will happen around June or July.
© 2013 Alan