Crestone Eagle, April 2004:
The alchemy of plant-treated sewage
A visit with David Austin and his Living Machines
story & photos by Roni S. Chernin
Austin is an unusual blend of balanced and gentle male energy.
With advanced degrees in aquatic ecology and environmental
engineering, he is one of an elite group of practicing ecological
engineers worldwide. As director of R&D for Living Machines,
Inc. (a division of Dharma Living Systems) in Taos, he has
developed a process where plants digest sewage, producing
clean, usable water.
How the wetland environment is created for microbes
to clean the water
In a Living Machine®, plants are carefully matched to
the right “soil” (an engineered aggregate) to
best support their roots and ecology. Most soils have a slightly
negative electrical charge, so the positive ions in water
adhere to the soils. In wastewater key nutrients like ammonia
have positive ions. Ammonia “sticks” to the soil
when the wetland is flooded. When drained, the ammonia remains
“stuck” in thin films of water. When exposed to
air, oxidation happens very quickly—accelerated by the
plants and soil. With oxygen, one type of bacteria quickly
converts ammonia to nitrate, which other bacteria use in the
next flood cycle to consume other pollutants. The plants,
roots and aggregate together support the community of healthy,
sewage digesting microorganisms.
Solid materials get digested in place by the microbe community
living in the plant’s roots. This process simply asks
plants to do what they already do well, and provides the support
where needed. The human engineering includes a programmed
controller governing the pre-treatment and pumps that circulate
water through the system. The system processes about the last
2/3 of the treatment. Flooding and draining by pumps allow
these man-made wetlands to be much smaller than conventional
treatment wetlands, because they are better aerated. Aeration
by pumping and draining is more energy efficient than traditional
aeration techniques. Energy consumption is estimated to be
25% of that used by the advanced treatment in an activated
sludge system. The trade-off is that this system occupies
a bigger area than conventional wastewater treatment.
Other Living Machine® systems have plants with roots
growing in aerated water. The first stage happens in a tank
partially filled with an artificial media he calls “plastic
rigatoni” in a low aeration mix. Above that tank, a
biofilter with compost and more “rigatoni” controls
odors. Removing many of the pollutants in sewage, this initiates
the process for the plants to finish. Aeration uses more energy
than the wetlands, but allows Living Machines to be small
enough to fit into greenhouses. Coincidentally, plants that
thrive in aerated tanks also thrive in greenhouses. The wetlands
system grows almost any plant that likes wet roots.
A miniature jungle in hot tubs
The R&D facility hides on the road into Taos in a nondescript
unlabeled building. When you walk in, it is warm, moist, and
smells like a greenhouse. The R&D facility contains “high
rate wetlands in bathtubs”. The tropical plants include
healthy specimens of umbrella plants, Calla and canna lillies,
elephant ear, purple taro and black willow. A septic tank
contains a blend of sewage made to duplicate the typically
generated kind composed of horse manure, cheese whey, urea
pellets and well water. (That did smell like sewage!) Detergents,
papers and other solids typically found in sewage were not
included because they normally drop out of this process before
the reactions start. To keep the sewage “fresh”,
he adds about 5 gallons of horse manure per month.
A programmed controller orchestrates pumps in the septic
tanks and tubs. Water from the septic tank alternates flooding
and draining through the large planter tubs which contain
an aggregate of expanded shale, similar to a road base. It
is a geotechnical fill made to construction standard. For
David, determining the most effective material was the most
difficult part. The pollutants in the water are broken down
as it gets pumped through the series of planter tubs.
In this prototype, the end product gets a “non detect”
for key pollutants, which means that usable water is being
created from wastewater. After a final disinfection process
it passes EPA and state standards for application on landscapes.
There are five US and several international patents pending
on this and other Living Machine® Systems.
Another simpler version of this technology can run by solar
panels. First developed for a World Bank project in Africa,
it has good potential for remote areas. Requiring more space
than the parent system, it is still a significant improvement
in wastewater treatment technology.
Living in balance with biology – the Biolarium.
The El Monte Sagrado in Taos showcases a Living Machine under
real life conditions and treats the wastewater for the facility.
The large greenhouse structure contains swimming pools, the
plants, a waterfall, and photovoltaics. El Monte is one of
Travel & Leisure’s top 25 hotels in the world, and
prides itself on its commitment to sustainable practices.
The spa water is not part of the system; Federal regulations
require a disinfectant, so Curoxin, a less harsh chlorine
dioxide product, is added.
Plants do their waste metamorphosis magic
Wastewater from the lodge circulates through the biolarium
plants for cleaning, then is re-used for grounds irrigation.
The waterfall aerates and displays the finished clear water
from the Living Machine. Large koi eat algae off the rocks.
The outdoor heated soaking pond has fish and plants on a
separate treatment system. Storm water collected in the lower
storage pond is also used for irrigation, “keeping the
local water local”.
A sewer or septic alternative
Living Machines are designed to treat wastewater from neighborhoods
and small towns and to fit into local sewage collection systems.
Advanced treatment and reuse is cost competitive, around $10,000
per home in a medium size development. Traditional septic
costs $3-5,000, but requires larger lots to prevent groundwater
contamination. A home sized advanced treatment system in an
area with poor soils might cost $20,000 or more. Conventional
sewers, treatment and reuse can cost $15,000 per home or more.
Living Machine systems are appropriate for developments of
about 300 homes, and can realize substantial savings against
the infrastructure of typical gravity sewer systems.
Where water is scarce, technologies that can create clean
water from wastewater are increasingly attractive. David believes
these systems are good science, good engineering and good
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