Living Machine

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The Living Machine is the wastewater treatment plant for our central campus. The Living Machine uses helpful bacteria, invertebrates and other small critters that love to eat waste in the water. Many of the buildings at IslandWood send their wastewater to the Living Machine, where it is cleaned.

See the lesson: Systems and Stewardship at the Living Machine

Why Have a Living Machine?

1. Fresh water for human consumption is really scarce and expensive. By processing our wastewater to the level where it can be reused, every gallon we reuse, we don't have to buy from the city (And they don't have to treat it to drinking standards!) We use the reclaimed water to water landscape plants around campus, and we will soon reuse the water in our toilets!

2. To demonstrate the biological processes by which nature cleans water.

How does it Work?

The general theory is:

Organic Material & Nutrients (what we flush) becomes Cell biomass, Energy, Gases and Water

Macroinvertebratess and bacteria uptake the organic matter and convert it into cell matter as a normal function of their metabolism.  Through respiration and predation, this biomatter is converted into carbon dioxide, water, minerals and organic residuals - all benign (or even helpful) to the environment.


The diagram above shows the cyclical process - this is part of the water cycle!

1. The Flush

And the drain. The input to our Living Machine system is the toilets and sinks in our Administrative office complex (Admin Building, Dining Hall, Ichthyology Inn, the Art Studio and the Learning Studio) Facilities, Laundry and the Garden.  Most of that "water" is from Island Utility (our water purveyor), but some is also brought in to the system inside the bodies of our guests.

2. Primary Settling Tanks

As with traditional septic systems, the dining has a grease trap and a primary settling tank to remove solids and grease (easily separated out) near the beginning.  These tanks are cleaned (pumped) as often as quarterly. 

3. Settling & Equalization Tanks

Data shows there are three peaks of wastewater flowing to our Living Machine - 7-9 am, 11-1pm and 5-7 pm.  The large, underground equalization tank acts as a way to regulate the flow into the rest of the machine.  From here on, water flows through the system at a maximum of 2.4 gallons per minute - rate flow rate of a typical bathroom sink faucet.  Normally we average about 1.5 gallons per minute.

4. Tidal Flow Wetlands

These two outside tanks provide huge amounts of surface area for bacteria - the main organisms for removing unused chemical energy (food)  from the wastewater.  They are about 16 feet across and 8 feet deep - each with a capacity of 8000 gallons. These tanks are filled and drained 16-24 times a day (hence the "tidal" name) which gives the bacteria food and oxygen needed to do their thing.

5. Aerated Wetlands

Aerated wetlands (inside the greenhouse) are another way of allowing bacteria to continue to remove impurities and unused energy from the water.

6. Vertical Flow Wetlands

The final biological stage, again, uses bacteria to add a final cleaning and finishing of the water.

7. Filter and Disinfect

We run the water to a few filters at the end:

  1. Sand Filter - to remove any particles that may be left.
  2. Textile Cartidge Filters
  3. UV - to kill any living organisms
  4. Chlorine Tablets - to make the water clear. (If the water even has a slight tinge of color, studies show that it would increase the number of times folks would flush the toilets...)

8. End Product Water Storage

We have a final storage tank to hold the cleaned water as it waits to be re used as...

9. Reuse it!

  • Up to 1000 gallons a day for flushing toilets

Possible Activity: Systems and Stewardship in the Living Machine