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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