I want to carry out remediation in a screen house using different macrophytes to test their remediation potential on 5 different industrial effluents. How do I design the experiment?
Hi
We've been doing some phytoremediation experiments of late, but not yet published (though my student's PhD has now been successfully defended). I'd suggest a two factor random block design with three replicates:
Factor 1: macrophyte species: (n = 5 levels)
level 1 species A
level 2 species B
level 3 species C
level 4 species D
level 5 species E
Factor 2: effluent (n = 3 levels)
level 1 no pollution (clean water: control)
level 2 intermediate: 50% effluent: 50 % clean water
level 3: 100% effluent
Blocks I, II, III (n = 3 blocks)
So you would need 5 x 3 x 3 treatment units to do the experiment = 45 units (tanks, buckets, or whatever you want to use to hold your plants, but each one must be independent of the others, don't start putting different plants in the same treatment unit or you'll end up with a pseudoreplicated design which is useless and can't show you the effects of your treatments (which of course is what you are interested in).
Each block will occupy one discrete area of your screening house and will contain 15 treatment units, arranged at random within the block, representing a full set of treatment-combinations (species A clean, species A intermediate, species A polluted; species B clean etc).
The advantage of the block design is that it takes out an element of the error (due to "spatial position" of your treatments) and hence makes it easier to find significance in your results (if there is any) because the error term is reduced in the ANOVA.
If you are pushed for resources you could eliminate the intermediate treatment, thereby losing one third of the treatment units needed, but don't reduce the number of blocks; 3 reps is essential to have any chance of getting a good statistical outcome.
There are thousands of examples of this simple but effective design in the literature.
Cheers
Kevin
There are a few other methods to use too. How many species do you want to test? Can species live in the same habitat? Are you able to create different levels of macrophytes? like say 0 macrophytes, 100 macrophytes, 200 macrophytes, etc.
If so, you can create optimal factorial or optimal response surfaces. These will allow you to test different combinations of species and effluents.
THANKS PROF KELVIN AM REALLY HAPPY WITH YOUR ANSWER @ANDREW THANKS TOO
- Badges
- Science topic