vyEPA
United States
Environmental Protection
Agency
Wastewater Technology Fact Sheet
The Living Machine®
DESCRIPTION
The Living Machine® is an emerging wastewater
treatment technology that utilizes a series of tanks,
which support vegetation and a variety of other
organisms. The Living Machine® was conceived by
Dr. John Todd, President of the non-profit
organization Ocean Arks International, and gets its
name from the ecologically-based components that
are incorporated within its treatment processes
(microorganisms, protozoa, higher animals such as
snails, and plants). The Living Machine® has
sometimes been referred to as the "Advanced
Ecologically Engineered System" or AEES. The
Living Machine® is now designed and marketed by
Living Machines, Inc. of Taos, New Mexico.
The Living Machine® is a second generation design.
Dr. Todd developed the Living Machine™ design
concept after working on a number of similar small
pilot-scale facilities, now referred to as Solar
Aquatics™ and marketed by Ecological
Engineering Associates of Marion, Massachusetts.
The Living Machine® incorporates many of the
same basic processes (e.g., sedimentation, filtration,
clarification, adsorption, nitrification and
Source: U.S. EPA., 2001.
FIGURE 1 THE OPEN AEROBIC TANKS
OF THE LIVING MACHINE® IN SOUTH
BURLINGTON, VT
denitrification, volatilization, and anaerobic and
aerobic decomposition) that are used in
conventional biological treatment systems. What
makes the Living Machine® different from other
systems is its use of plants and animals in its
treatment process, and its unique aesthetic
appearance. While these systems are aesthetic
appealing, the extent to which the plants and
animals contribute to the treatment process in
current Living Machine® designs is still being
verified (U.S. EPA, 2001). In temperate climates,
the process is typically housed within a large
greenhouse, which protects the process from colder
temperatures.
Living Machines, Inc. describes the Living
Machine® as being a wastewater treatment system
that:
Is capable of achieving tertiary treatment;
Costs less to operate than conventional
systems when used to achieve a tertiary
level of treatment; and
Doesn't typically require chemicals that are
harmful to the environment" as a part of its
treatment process (Living Machines, Inc.,
2001).
Several federally-funded Living Machine®
demonstration systems have been constructed, the
largest of which handled design flows of up to
80,000 gpd. As configured for these
demonstrations, these systems treated municipal
wastewaters at various strengths, and reliably
produced effluents with five-day biochemical
oxygen demand (BOD5), total suspended solids
(TSS), and Total Nitrogen < 10 mg/L, Nitrate
< 5 mg/L, and Ammonia < 1 mg/L (U.S. EPA, 2001
and see Table 1). With regard to phosphorus
removal, the Living Machine® process is capable of
about 50 percent removal with influents within the
5-11 mg/L range (U.S. EPA, 2001). In addition to
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the demonstration projects, the Living Machine®
technology is being used by a variety of municipal
and industrial clients, where similar performance
has been reported.
Treatment Process
A typical Living Machine® comprises six principle
treatment components, after influent screening. In
process order (see Figure 1), these are (1) an
anaerobic reactor, (2) an anoxic tank, (3) a closed
aerobic reactor, (4) aerobic reactors, (5) a clarifier,
and (6) "ecological fluidized beds" (EFBs). While
the open aerobic reactors and EFBs are found in
almost all Living Machines®, the other components
are not always utilized in the treatment process.
The specific components used are selected by the
designers depending upon the characteristics of the
wastewater to be treated and the treatment
objectives. Sometimes additional process
components may be added if considered necessary
by the designers. For example, the demonstration
system in Frederick, Maryland utilized a "Final
Clarifier" and a high-rate subsurface flow (SF)
wetland as the last two components of its treatment
train.
Anaerobic Reactor (Step 1)
When it is employed, the anaerobic reactor serves
as the initial step of the process. The reactor is
similar in appearance and operation to a septic tank,
and it is usually covered and buried below grade.
The main purpose of the anaerobic reactor is to
reduce the concentrations of BOD5 and solids in the
wastewater prior to treatment by the other
components of the process. When necessary, gases
are passed through an activated carbon filter to
control odor.
Raw influent enters the reactor, which acts as a
primary sedimentation basin. Some of the
anaerobic reactors used have an initial sludge
blanket zone, followed by a second zone for
clarification. Additionally, strips of plastic mesh
netting are sometimes used in the clarification zone
to assist with the trapping and settling of solids, and
to provide surface area for the colonization of
anaerobic bacteria, which help to digest the solids.
Sludge is typically removed periodically via
perforated pipes on the bottom of the reactor, and
wasted to a reed bed or other biosolids treatment
processes. Gasses produced are passed through an
activated carbon filter or biofilter for odor control.
Anoxic Reactor (Step 2)
The anoxic reactor is mixed and has controlled
aeration to prevent anaerobic conditions, and to
encourage floe-forming and denitrifying
microorganisms. The primary purpose of the anoxic
reactor is to promote growth of floe-forming
microorganisms, which will remove a significant
portion of the incoming BOD5.
Mixing is accomplished through aeration by a
coarse bubble diffuser. These diffusers are typically
operated so that dissolved oxygen is maintained
Source: Living Machines Inc., 2001.
FIGURE 1 THE COMPONENTS OF THE LIVING MACHINE®: (1) ANAEROBIC REACTOR,
(2) ANOXIC REACTOR, (3) CLOSED AEROBIC REACTOR, (4) OPEN AEROBIC
REACTORS, (5) CLARIFIER, AND (6) "ECOLOGICAL FLUID BED"
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below 0.4 mg/L. The space over the reactor is
vented through an odor control device, which is
usually a planted biofilter. Additionally, an
attached growth medium can be placed in the
compartment to facilitate growth of bacteria and
microorganisms.
Settled biosolids from the clarifier (Step 5), and
nitrified process water from the final open aerobic
reactor (Step 4) are recycled back into this reactor.
The purpose of these recycles is to provide
sufficient carbon sources to the anoxic reactor to
support denitrification without using supplemental
chemicals, such as methanol.
Closed Aerobic Reactor (Step 3)
The purpose of the closed aerobic reactor is to
reduce the dissolved wastewater BOD5 to low
levels, to remove further odorous gases, and to
stimulate nitrification.
Aeration and mixing in this reactor are provided by
fine bubble diffusers. Odor control is again
achieved by using a planted biofilter. This biofilter
typically sits directly over the reactor and is planted
with vegetation intended to control moisture levels
in the filter material.
Open Aerobic Reactors (Step 4)
Next in the process train are the open aerobic
reactors, or aerated tanks. They are similar to the
closed aerobic reactor in design and mechanics (i.e.,
aeration is provided by fine bubble diffusers);
however, instead of being covered with a biofilter,
the surfaces of these reactors are covered with
vegetation supported by racks. These plants serve
to provide surface area for microbial growth,
perform nutrient uptake, and can serve as a habitat
for beneficial insects and microorganisms. To what
extent the plants enhance the performance treatment
process in the Living Machine® is still being
verified (U.S. EPA, 2001). However, with the
variety of vegetation present in these reactors, these
units (along with the Ecological Fluidized Beds -
Step 6) set the Living Machine® apart from other
treatment systems in terms of their unique
appearance and aesthetic appeal.
The aerobic reactors are designed to reduce BOD5 to
better than secondary levels and to complete the
process of nitrification. The size and number of
these reactors used in a Living Machine® design are
determined by influent characteristics, effluent
requirements, flow conditions, and the design water
and air temperatures.
Clarifier (Step 5)
The clarifier is basically a settling tank that allows
remaining solids to separate from the treated
wastewater. The settled solids are pumped back to
the closed aerobic reactor (Step 3), or they are
transferred to a holding tank, and then removed for
disposal. The surface of the clarifier is often
covered with duckweed, which prevents algae from
growing in the reactor.
Ecological Fluidized Beds (Step 6)
The final step in the typical Living Machine®
process are the "ecological fluidized beds" (EFBs).
These are polishing filters that perform final
treatment of the wastewater, and one to three are
used in series to reduce BOD5, TSS and nutrients
meet final effluent requirements.
An EFB consists of both an inner and outer tank.
The inner tank contains an attached growth medium,
such as crushed rock, lava rock, or shaped plastic
pieces. The wastewater flows into the EFB in the
annular space between the inner and outer tanks and
is raised by air lift pipes to the top of the inner ring
that contains the media. The bottom of the inner
tank is not sealed, so the wastewater percolates
through the gravel media and returns to the outer
annular space, from where it is again moved back to
the top of the gravel bed. The air lifts also serve to
aerate the water and maintain aerobic conditions.
The unit serves as a fixed bed, downflow, granular
media filter and separates particulate matter from
the water. Additionally, the microorganisms that
occupy the granular media surfaces provide any
final nitrification reactions.
As sludge collects on the EFB, it reduces its ability
to filter. This would eventually clog the bed
completely. Therefore, additional aeration diffusers
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beneath the gravel bed are periodically turned on to
create an upflow airlift, reversing the flow
direction. This aeration is intended to "fluidize" the
bed and release the trapped sludge (hence the name
of this unit). This sludge is washed over and
accumulated at the bottom of the outer annular
space where it can be collected manually, and
wasted along with the biosolids from the anaerobic
reactor. Consequently, the name "ecological
fluidized bed" is somewhat misleading for this unit
since, in its treatment mode, it acts like a typical,
conventional, downflow coarse media contact filter
unit. Only during backwash cleaning does the bed
become partially fluidized.
After this last step, the wastewater should be
suitable for discharge to surface waters or a
subsurface disposal system, or reused for landscape
irrigation, toilet flushing, vehicle washing, etc.
(Living Machines, Inc., 2001).
APPLICABILITY
The Living Machine® is well suited for treating
both municipal and some industrial wastewaters.
As with most treatment systems using plants, it can
require a larger footprint than more conventional
systems, and its requirement for a greenhouse in
more temperate climates can impact costs.
However, its unique and aesthetically pleasing
appearance make it an ideal system in areas that
oppose traditional treatment operations based on
aesthetics (i.e., smell and appearance). The
designers also stress the educational benefits of the
Living Machine®
(http://www.livingmachines.com/htm/planet2.htm)
in raising awareness of wastewater treatment
methods and benefits.
ADVANTAGES/DISADVANTAGES
Advantages
Capable of treating wastewaters to BOD5,
TSS, and Total Nitrogen < 10 mg/L, Nitrate
< 5 mg/L, and Ammonia < 1 mg/L.
Offers a unique, aesthetically pleasing
environment for treating and recycling
wastewater. This may be helpful when
attempting to locate the treatment system in
areas where the public opposes traditional
wastewater treatment operations for
aesthetic reasons.
Disadvantages
• The Living Machine® has only been shown
to remove about 50 percent of influent
phosphorous (with influents in the range of
5-11 mg/L). The removed phosphorus
appears to be primarily associated with the
incoming solids.
• The process requires a greenhouse for
reliable operation in the cold weather of
more temperate climates, adding to system
costs.
DESIGN CRITERIA
Every Living Machine® system is designed by
Living Machines, Inc. based upon the expected
wastewater volume and content, as well as the
treatment requirements and local climate. Once
these factors are known, the designers then
determine whether a greenhouse is necessary, what
types of reactors are needed, how many of each type
of reactor are required, and what capacity is required
to achieve the suitable residence times.
PERFORMANCE
The Living Machine® has reliably achieved
treatment goals of BOD5, TSS, and Total Nitrogen
< 10 mg/L, Nitrate < 5 mg/L, and Ammonia <
1 mg/L. Table 1 shows the results of independent
evaluations of two demonstration systems. The
Living Machine® demonstration project in
Frederick, Maryland was designed to treat
40,000 gpd of screened and degritted wastewater.
It employed a single anaerobic reactor for primary
solids digestion, then three parallel treatment trains,
each comprised of two open aerobic reactors, a
clarifier, three "ecological fluidized beds," a final
clarifier, and a small, high-rate subsurface flow
wetland. The demonstration project located in
South Burlington, Vermont was designed to treat
80,000 gpd of screened and degritted wastewater,
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TABLE 1 PERFORMANCE OF THE FREDERICK AND BURLINGTON LIVING
MACHINES®
Parameter
BOD5
COD
TSS
NH3
NO3
TN (total
nitrogen)
TP (total
phos-
phorus)
FREDERICK
Influent . ,GH .
mg/L lnflu??
u mg/La
230 156
944 378
381 70
22
20.8
44
11 7.7
Effluent
mg/L
4
21
2
1.2
10
11
6
%
Removal
97
94
97
94
52
75
45
BURLINGTON
Influent Effluent %
mg/L mg/L Removal
227
556
213
16.3
15.9b
29.3
6.0
5.9
35.9
5.3
0.4
4.9
5.6
2.0
97
94
98
98
69
81
67
Effluent
Goal
<10
-
<10
<1
<5
<10
<3
a Effluent from the anaerobic reactor at Frederick into the reactors contained within the greenhouse.
b Assumes that all removed ammonia is converted to nitrate.
Source: U.S. EPA, 2001.
and employed five open aerobic reactors (though
one of these was later converted to an anoxic
reactor), a clarifier, and three "ecological fluidized
beds."
In these instances, the Living Machine® was
capable of BOD5 and TSS removal in excess of
95 percent. While the Frederick system did not
consistently achieve its goal of < 5 mg/L for
Nitrate, the Burlington Living Machine® did. The
Living Machine® reliably demonstrated about
50 percent removal of Total Phosphorous (TP),
although the Burlington system had a low influent
TP concentration (U.S. EPA, 2001).
While the Frederick Living Machine® achieved
quite good coliform removal (< 200 MPN/lOOmL),
the Burlington system's effluent was above
1,000 MPN/lOOmL. Consequently, disinfection
may be required as an additional step depending
upon system configuration and effluent
requirements.
OPERATION AND MAINTENANCE
Routine Activities
The routine operation and maintenance (O&M)
requirements for Living Machines® are similar to
the requirements for a conventional wastewater
treatment plant, with a few additional requirements.
These additional requirements include cleaning the
inlet/outlet structure; cleaning the screen and tank;
removing and disposing sludge; and maintaining
and repairing machinery. Other requirements are
vegetation management, including routine
harvesting to promote plant growth, and removal of
accumulated plant litter. Additionally, it may be
necessary to manage fish and snail populations, and
control mosquitoes and flies (if applicable).
Residuals Management
The Living Machine® produces residuals
comparable in quantity to conventional treatment
systems. However, some of these residuals are
biosolids, while others are in the form of plant
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TABLE 2 PRESENT WORTH COMPARISON OF "LIVING MACHINES®" AND CONVENTIONAL
SYSTEMS
Process
40,000 gpd
(1) Cost difference is less than 20 percent
(2) Cost difference is greater than 20 percent
Source: U.S. EPA, 2001.
80,000 gpd
1 million gpd
"Living Machine" with
greenhouse
"Living Machine" without
greenhouse
Conventional System
$1,077,7771
$985,391
$1,207,0361
$1,710,2801
$1,570,246
$1,903,7511
$10,457,5422
$9,232,257
$8,579,9782
material. Analyses at the Frederick demonstration
system showed that plant residuals could be
composted and used for many agricultural or
horticultural purposes. The biosolids would likely
require stabilization and treatment to reduce
pathogens and indicator organisms before they
would meetPart 503 limits for sewage sludge (U.S.
EPA, 2001).
COSTS
Since the Living Machine® is designed, marketed
and trademarked by Living Machines, Inc., precise
cost data are proprietary. However, a cost
comparison with "conventional" treatment systems
was performed as a part of an independent U.S.
EPA evaluation of the Living Machines® (U.S.
EPA, 2001). Table 2 summarizes the results of this
cost comparison.
This analysis concluded that Living Machines® are
typically cost competitive with more conventional
wastewater treatment systems at flow volumes up to
1,000,000 gpd, if they are located in a warm climate
where a greenhouse is not necessary. However, if
the climate cannot support the plants year-round
and a greenhouse must be constructed, construction
costs will increase. Addition of a greenhouse
structure makes the Living Machine® cost
competitive with more conventional systems up to
flow rates of around 600,000 gpd.
REFERENCES
Other Related Fact Sheets
Other EPA Fact Sheets can be found at the
following web address:
http://www.epa.gov/owm/mtb/mtbfact.htm
1. Living Machines, Inc., 2001. Web Site:
http://www.livingmachines.com/
2. Massachusetts Foundation for Excellence in
Marine and Polymer Sciences, Inc., Boston,
MA, Ocean Arks International, Living
Technologies, Inc., 1997. Advanced
Ecologically Engineered System, South
Burlington, Vermont.
3. U.S. EPA, 2001. The "LivingMachine"
Wastewater Treatment Technology: An
Evaluation of Performance and System
Cost. EPA 832-R-01-004.
ADDITIONAL INFORMATION
Living Machines, Inc.
125 La Posta Road
8018NDCBU
Taos, New Mexico 87571
http://www.livingmachines.com/
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The mention of trade names or commercial
products does not constitute endorsement or
recommendation for use by the U. S. Environmental
Protection Agency.
Office of Water
EPA 832-F-02-025
October 2002
For more information contact:
Municipal Technology Branch
U.S. EPA
ICC Building
1200 Pennsylvania Ave., NW
7th Floor, Mail Code 4201M
Washington, D.C. 20460
" 2002 -•'
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CLEAN WATER
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