Grey Water Clean Up With Azolla Update
Developments 1 Year after Start 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 Duck Weed.
In mid-December I travelled overseas for 6 weeks, during which time no grey water flowed into the filter. The weather during that time was fairly hot, with little or no rain.
The water level dropped about 100mm in total. Azolla was presumably getting too little nutrients. Spirogyra became dominant, with some Duck Weed.
Please click on the Link below for a very impressive account of Duck Weed: with many thanks to that author!
When Grey Water Flow Ceases
Smothering Mat Removed
6 Days Later
One Week More
Three Weeks After Rejuvenation
Just three weeks after removing that thick mat of algae and decaying Azolla, the surface of the pond is covered in an ecosystem of Duckweed, Spirogyra, Azolla and Wolffia. The water under this growth is not smelly. It has been oxygenated well by photosynthesis of the algae and two species of flowering plant.
The colour of the water is now a light brown, caused probably by tannins from the mulch filter upstream from the pond.
Conclusions so far
It would be useful now to get a test done on the water, to see if the BOD, e.coli and nitrogen levels have changed with the dominant species.
More by this Author
A small-scale biological method of treating grey water, using a symbiotic mixture of Azolla filiculoides, Wollfia borealis, Lemna minor and Spirogyra.
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.
Local biological materials for filtration of grey water