Mollison Filter Brainstorming

Hi,
can ou guys help me out a bit?

Really looking forward to this discussion!

Btw, here is his lecture on the topic:

What do you need help with?

Well i personally need to filter out water that runs from the Highway to my garden/farm under construction,
so i need to start building a Mollison filter, and  need to get the details figured out.

It is difficult for me to source freshwater mussel shells, can i also use saltwater mussel shells?

Thanks for sharing Bill Mollison's Water Filter and Sewer Treatment system.

I don't know if adding something salty to the filter would make a difference.

It seems the important item is a medium through which the water goes through.  Rocks or shells either would work.

Here are some threads that might be of interest to you and to others:

https://permies.com/t/147427/Wastewater-Pond-thoughts#1151589

https://permies.com/t/43424/system-restrictions#341479

I have seen some really great threads on these kinds of topics of how to clean water using plant filters, mulch basins, lagoons, or settling ponds.  People interested in these might check the building forum for greywater systems.

Most native freshwater mussels are very endangered and ought be left to live and reproduce where they are still around  in my (and most jurisdictions’) opinion. It may be possible to help the population by providing them habitat like this, but i’d be very careful and research how to acquire them ethically and keep them happy. The loss of these mussels across much of the Earth makes me wonder about how much they might have helped make water drinkable for people right from a stream they lived in.

Ben, Bill's suggestion as you can see in the diagram uses Mussel shells not live mussels.

One reason I mentioned using rock is that mussel shells of any kind may be hard to come by.  Maybe where Bill lived in Australia things are different than they are in our country.

And may be even different in the part of the country where you live.

Good point Anne, thanks for catching that mistake. I didn’t mean to imply the OP would be going out digging up endangered mussels, just wanted to help others understand doing so could be problematic. I saw every strain of obliviousness as a park ranger and now have to assume people may not know better.

I thought I remembered the diagram from the BBB and was surprised and concerned when looking at the picture above on my phone because  “shells” was cut off of “fresh water mussel shells”. The species we have nearby only persists in old-growth surrounded streams, which is why they are now so rare. They are very cool to watch do their work of filter feeding, and this was one of students’ favorite parts of wetland/stream environmental ed classes I taught. It was also nice to see how careful most kids would be once they knew what they might accidentally step on, and they’d go into their best effort at the “fox walk” I taught every class.

I think the main benefit of shells in Mollison’s filtration and water systems, besides being a substrate for filtering microbes, is their calcium. I’ve seen and used oyster shell as an alternative. I’d bet limestone or decomposed granite would be similarly beneficial.

Ben Zumeta wrote:I think the main benefit of shells in Mollison’s filtration and water systems, besides being a substrate for filtering microbes, is their calcium. I’ve seen and used oyster shell as an alternative. I’d bet limestone or decomposed granite would be similarly beneficial.

Ben, you may be right about the calcium.

I was going to mention oyster shells as a possible medium.  When we lived on the coast, the shells were so plentiful they were used on driveways and parking lots instead of rocks.

Plenty of restaurants would probably be glad for someone to haul them off.

Anne Miller wrote:Thanks for sharing Bill Mollison's Water Filter and Sewer Treatment system.

Thanks for replying.

Anne Miller wrote:Ben, Bill's suggestion as you can see in the diagram uses Mussel shells not live mussels.

Actually it uses both. There are live freshwater mussels in the filter. So it is providing for its own mussel shells and allows replicating the filter after some time.
The mussels probably also trap nasty stuff in their shell, and they dont degrade as fast as limestone rock etc.
As for the initial batch of mussels i can probably work out something with the local authorities to source exaclty
the species that used to live here, to introduce them to my ecosystem, and hopefully later reintroduce them to their former habitat.

My thougth was whether the initial batch of mussel shells is allowed to be from saltwater mussels,
as they are so easy to come by. It is just one detail of many.

Miles Flansburg wrote:What do you need help with?

Also i am not shure how to make the basins for the filter.
It would definetly need to be half-watercylce and not full-watercycle,
to prevent contamination of the ground.

If i use gley, the gley layer might accumulate some heavy metals and radioactives over time,
but the glay layer can be taken out and its organic matter then separated from the the toxins.
So by using gley, regular maintenance is a must.

However plastic/concrete/metal might be safer from seepage,
but became an pollutant at the end of its lifetime plus those materials
could also pollute the environment during their lifetime.

Probably best would be basins made of monolithic rocks that had been carved out,
but aquiring them in the desired volume would make me sad about the mountain it used to be.