EPA 832-R-97-002
RESPONSE TO CONGRESS ON THE AEES
"LIVING MACHINE" WASTEWATER TREATMENT
TECHNOLOGY
OFFICE OF WATER
U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, DC
April 1997
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RESPONSE TO CONGRESS ON THE AEES "LIVING MACHINE"
WASTEWATER TREATMENT TECHNOLOGY
TABLE OF CONTENTS
EXECUTIVE SUMMARY . . . ES-1
INTRODUCTION . , . . i-i
1.1 Background , . 1-1
1.2 Scope and Purpose . , 1-2
1.3 Organization of the Report : 1-2
DESCRIPTION OF THE AEES "LIVING MACHINE" PROCESS DEMONSTRATIONS 2-1
2.1 Introduction f 2-1
2.2 Frederick Co., MD, AEES "Living Machine" . .2-1
2.2.1 Anaerobic Bio-Reactor ..; 2-4
2.2.2 Aerated Tanks, . ...;., 2-5
2.2.3 Ecological Fluidized Beds \ '. 2-6
" 2.2.4 Final Clarifier 2-7
2.2.5 High-Rate Marsh . . 2-7
2.3 South Burlington, VT, AEES "Living Machine" 2-8
2.3.1 Aeration Tanks '.' . 2-9
2.3.2 Ecological Fluidized Beds ., 2-9
2.4 San Francisco, CA, AEES "Living Machine" . 2-10
2.5 Harwich, MA AEES "Lake Restorer" 2-12
PROCESS EVALUATION OF THE AEES "LIVING MACHINE" !'...._ ......'. 3-1
3.1 Introduction . . :. ; 3-1
3.2 AEES, Frederick, MD . 3-1
3.3 AEES, South Burlington, VT 3-9
3.4 Process Residuals 3-11
3.5 Role of Plants.in the AEES "Living Machine" Process .'. . 3-11
3.6 Chemical Additions to the AEES "Living Machine" Process . 3-13
3.7 AEES "Living Machine" System Costs 3-13
3.8 AEES, San Francisco, CA 3-16
3.9 AEES, Harwich, MA 3-16
3.10 Summary '.-.,'. 3-18
CONCLUSIONS -.....;...... : . ... ... 4-1
REFERENCES , ." '. 5-1
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LIST OF TABLES
Table 2.1 Treatment Goals for the Frederick AEES "Living Machine" 2-2
Table 2.2 Oceanside WWTP Effluent and San Francisco AEES Process Goals 2-11
Table 3.1 EPA Water Quality Data Summary for Frederick, MD AEES 3-2
Table 3.2 Effluent Quality, Burlington, VT, and Frederick, MD 3-9
Table 3.3 Present Worth Comparison, AEES and Alternative Systems 3-14
Table 3.4 San Francisco AEES "Living Machine" Performance Results
for September 1996 , 3-16
LIST OF FIGURES
Figure 2-1 Schematic Diagram of the AEES "Living Machine" at Frederick, MD ........ 2-3
Figure 3-1 Frederick, MD, BOD5 Input Versus Output, March 1995-March 1996 ....... 3-3
Figure 3-2 Frederick, MD, COD Input Versus Output, March 1995-March 1996 ........ 3-4
Figure 3-3 Frederick, MD, TSS Input Versus Output, March 1995-March 1996 ........ 3-5
Figure 3-4 Frederick, MD, Ammonia Nitrogen Input Versus Output,
March 1995-March 1996 3-6
Figure 3-5 Frederick, MD, Total Nitrogen, Input Versus Output,
March 1995-March 1996 3-7
Figure 3-6 Frederick, MD, Phosphorus Input Versus Output,
March 1995-March 1996 .3-8
Figure 3-7 Cost Comparison, "Living Machine" Versus Conventional Technology ..... 3-15
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EXECUTIVE SUMMARY
The Advanced Ecologically Engineered System (AEES) "Living Machine" wastewater
treatment technology is intended to provide water quality improvements for a variety of water
sources. The process was conceived by Dr. John Todd, the President of Ocean Arks
International (OAI), a non-profit institution based in Falmouth, MA, and is termed a "Living
Machine" owing to the ecologically-based components of the treatment system. The
components of the AEES contain various microorganisms, protozoa, higher animals, and plants
which are intended to provide "natural" water treatment, as opposed to conventional wastewater
treatment processes. The "Living Machine" has been claimed by its developers to clean
wastewater to advanced treatment standards using "natural solar powered greenhouse based
technology without the use of chemicals."
, Four AEES demonstration projects, funded in part with special appropriations by the
US Congress, were designed to show the ways in which this technology could be employed in
various wastewater treatment applications. The demonstration projects were located in
Frederick County, MD, South Burlington, VT, Harwich, MA and San Francisco, CA. The
Frederick facility was intended to provide advanced levels of wastewater treatment for untreated
raw sewage. The project in South Burlington uses basically the same technology and has the
same goals as the system in Frederick but is designed to operate at higher flow rates and in a
colder climate. The demonstration project in Harwich (the "Lake Restorer") uses the AEES
technology to provide in-situ water quality improvements in Flax Pond. Finally, the project in San
Francisco used an aspect of the "Living Machine" process with the aim of providing final polishing
of secondary effluent which would allow unrestricted irrigation reuse of the water in accordance
with California "Title 22" requirements. All of these facilities were designed and constructed for
the grantee, the Massachusetts Foundation for Excellence in Marine and Polymer Sciences
(MFEMPS), by OAI and Living Technologies, Inc (LTI) of Burlington, VT.
These demonstration systems have been operated by OAI and LTI personnel who have
also routinely collected process performance data. However, the grantee decided that it would
be desirable for USEPA to conduct an independent evaluation of these systems, to assess the
extent to which the "Living Machines" have achieved their goals and in what ways they provide
an alternative to "conventional" water treatment processes. While all of the demonstration
projects were included in this evaluation, an independent sampling and data collection effort was
undertaken at the Frederick site since it was expected to be operating at "steady state"
conditions when the study commenced. This performance assessment examined the ability of
the Frederick "Living Machine" to meet its process goals and also looked at the contribution of
the macrophytic plants to the treatment process. In addition to process performance, the
evaluation also looked at the economics of the AEES technology, comparing costs for
construction and operation with conventional wastewater treatment technologies for a range of
design flow rates (40,000 gpd to 1,000,000 gpd).
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The evaluation of the "Living Machine" in Frederick indicated that the system is capable
of reliable performance with respect to removal of biochemical oxygen demand, suspended
solids, and ammonia. It was also considered that the process has the potential to achieve the
target removal requirements for nitrate and total nitrogen although this has not been
demonstrated conclusively to date. The system does not appear to be capable of achieving its
phosphorus removal goal as presently configured. An assessment of the role of the floating
macrophytic plants in the treatment process suggested that their contribution to treatment was
minimal and that the same process goals could be achieved whether or not they were present.
Additionally, without the plants present the "Living Machine" closely resembles a conventional
treatment process. However, the plants within the "Living Machine" do provide a very pleasing
aesthetic environment which is not typically found with conventional processes.
With respect to an initial economic evaluation, the AEES process is comparable in cost to
conventional treatment technologies at flow rates of 100,000 gpd or less. However, at flow rates
higher than 100,000 gpd, conventional wastewater treatment processes would be expected to be
more cost effective wastewater treatment systems. OAI and LTI have suggested that there may
be ways to reduce the system costs but this still remains to be demonstrated. Consequently, the
AEES "Living Machine" appears to be well suited to applications in small subdivisions, schools, '
condominiums and commercial developments, and where the enhanced aesthetics of the
process will encourage public acceptance. Comparable conclusions for both process .
performance and cost would be expected to apply to the pilot facility in South Burlington which
has a similar process configuration to the Frederick "Living Machine." However, until further data
are available from the South Burlington facility while operated under steady state conditions at
design flows over and extended period, these conclusions regarding process performance are
only tentative.
As operated, the San Francisco AEES "Living Machine" proved to be unable to meet its
treatment goals for bacteria which would have permitted unrestricted irrigation reuse of the water
in accordance with State requirements. Since this process was operating at about 30 percent of
the design flow rate, it is questionable whether the process would be cost effective in this
application. With the present level of testing of the AEES "Lake Restorer" in Flax Pond at
Harwich, it was not possible to evaluate the capabilities of the system, since local factors at its
location may be responsible, at least in part, for the apparent water quality improvements in Flax
Pond.
Based on the evaluations to date, it can be concluded that the AEES "Living Machine"
has not yet demonstrated reliable attainment of all of its process goals. While the use of a
greenhouse and the plants within the AEES "Living Machine" is unique, the floating macrophytes
appear to contribute more to the aesthetics of the system than to the treatment performance.
Also, the "Living Machine" concept does not appear to offer any economic advantages over
conventional technologies, and appears to be clearly more costly than conventional processes
at flow rates more than 100,000 gpd. In-view of these conclusions, the continuation of Federal
funding support for these demonstration projects is not warranted.
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CHAPTER 1
INTRODUCTION
1.1 Background
The Advanced Ecologically Engineered System (AEES) "Living Machine" technology is
intended to provide water quality improvements for a variety of water sources. The concept is
called a "Living Machine" because of the ecologically based components in the treatment
process. It was conceived by Dr John Todd, the President of Ocean Arks International (OAI), a
non-profit institution in Falmouth, MA. The "Living Machine" includes microorganisms, protozoa,
higher animals, and plants in an "ecologically balanced" treatment system which has been
claimed by its developers to be based on solar energy and "natural" treatment responses as
compared to mechanical energy and chemicals in conventional wastewater treatment processes.
-.'',' - - * '
The AEES demonstration systems were located in Frederick Co., MD, South Burlington,
VT, Harwich, MA, and San Francisco, CA. The Frederick facility (decommissioned in June 1996
due to a lack of funds for continued operations) was intended to provide advanced levels of
treatment for untreated raw sewage. The Buriington project uses essentially the same basic
technology, and has the same purpose as the Frederick facility but is designed to operate at a
higher flow rate arid in a colder climate. The project in Harwich, MA (inactivated in October >
1996) used a floating raft incorporating a portion of the AEES technology to provide in-situ water
quality improvements of Flax Pond. The project in San Francisco (inactivated in December
1996) also used part of the AEES technology to provide final high flow rate polishing of
secondary effluent; the intent was to produce a water quality which would allow unrestricted
irrigation reuse of the water in accordance with State of California "Title 22" requirements.
Process details on each of these systems can be found in subsequent chapters. These AEES
"Living Machine" facilities were designed and constructed by Living Technologies, Inc. of
Buriington, VT.
The four AEES demonstration projects were funded, in part, with special appropriations
by the U.S. Congress, awarded by EPA to the Massachusetts Foundation for Excellence in
Marine and Polymer Sciences (MFEMPS) through a cooperative agreement (grant). The
demonstration facilities were designed and operated by either OAI or LTV under contract to the
MFEMPS, and these operating personnel routinely collected performance data. However, the
grantee, MFEMPS decided that an independent evaluation by the U.S. EPA would be desirable
and funds were, made available for that purpose. While all of the AEES facilities have been
indued in the evaluation, an independent data collection was undertaken at the Frederick, MD
system since it was expected to be operating at "steady state" conditions when the study period
commenced. The results of the detailed evaluation of the AEES "Living Machine" facility at
Frederick, MD are presented in a separate report (Interim Report-Evaluation of the Advanced
Ecologically Engineered System (AEES) "Living Machine" Wastewater Treatment Technology-
Frederick, MD) (1).
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The AEES "Living Machine" technology benefits from the experience gained at previous
OAI pilot systems in Massachusetts, Vermont and Rhode Island, and represents a "second
generation" design. This "Living Machine" technology has been claimed by its developers to
clean wastewater to advanced treatment standards using "natural solar powered greenhouse
based technology without the use of chemicals" (8). A predecessor concept now called Solar
Aquatics'"* was developed by OAI and also utilizes a greenhouse and contained similar
treatment elements. The Solar Aquatics technology is now marketed by a private firm, and is
sometimes confused with the AEES "Living Machine" process.
Parsons Engineering Science, Inc. was selected by the U.S. EPA, under Contracts
68-C2-0102 and 68-C6-0001, to perform both the special evaluation of the Frederick, MD facility and
to assist in the preparation of this report. Under the same contracts, Mr. Sherwood Reed of
Environmental Engineering Consultants, Norwich, VT, was retained as the Technical Director for
both efforts.
1.2 Scope and Purpose
i .
In their Report 104-318 dated July 11, 1996, the Senate Committee on Appropriations notes
that the "solar aquatic waste water treatment demonstration projects have received funding for
several years." The Committee report was referring to the four AEES demonstration projects funded
by EPA through a grant to MFEMPS. In their report, the Committee further directed EPA to report
on (1) what has been achieved, (2) the viability of applying this technology widely, (3) an assessment
of the costs and benefits, and (4) the amount of future Federal funding required.
The intent of this report is to describe the various AEES demonstration project configurations,
their purpose and documented performance relative to wastewater treatment. Where possible, the
functional aspects of the AEES technologies and their performance are compared to available
conventional technologies. The cost of the AEES technology is also compared to conventional
wastewater treatment technologies providing the same level of treatment. The overall purpose of
these evaluations and comparisons is to provide information to the U.S. Congress on the status of
this technology, and provide recommendations regarding future funding of the demonstration
projects.
1.3 Organization of the Report
Chapter 2 presents a description of the process components of the AEES "Living
Machine" demonstration projects. Chapter 3 provides a comparative evaluation of process
function and performance, and costs, where such data are available. Chapter 4 presents the
conclusions and recommendations drawn from these demonstration projects to date, and
Chapter 5 lists the references utilized in developing this report.
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CHAPTER 2
DESCRIPTION OF THE AEES "LIVING MACHINE" PROCESS
DEMONSTRATIONS
2.1 Introduction
Ocean Arks International (OAI), a non-profit educational and research institution, in Falmouth,
MA has developed technologies for treating wastewaters and achieving other water quality
improvements based on their prior ecological research. In May 1992, the House Subcommittee on
Fisheries and Wildlife Conservation, of the U.S. Congress, conducted hearings to discuss the
potential benefits of using "advanced ecological engineering of living systems to clean wastewater."
These hearings have led to the allocation of $7.2 million in federal funding to date (with funds
provided in FY's 1992-97) by the U.S. Congress for the development and demonstration of
Advanced Ecologically Engineered Systems (AEES) "Living Machine" wastewater treatment projects
in Frederick Co., MD, South Burlington, VT, San Francisco, CA, and Harwich, MA. This Chapter
describes the physical components at each location and their functional aspects. The performance
of these projects is discussed in Chapter 3.
2.2 Frederick Co., MD
The City of Frederick is located in central Maryland at about latitude 39:25 and elevation
300 feet. The mean annual air temperature in the Frederick area is about 11 °C (52 °F). The
minimum winter temperatures can be less than -1 °C (30 °F) so a greenhouse structure was
required to protect the AEES "Living Machine" treatment components. The AEES "Living '
Machine" was located next to the Ballenger Creek municipal wastewater treatment plant (WWTP)
in Frederick, MD. The components in this AEES facility are described in detail since the other
AEES demonstration projects contain many of the same basic elements.
The system in, Frederick was constructed in 1993 and was in ^continuous operation until it
was decommissioned in June 1996. The design flow at this AEES system was 40,000 gpd and
the influent was taken from the WWTP after its screening and grit removal unit. The final effluent
from the AEES system and any sludge residuals were returned to the WWTP for further
. treatment and disposal. The treatment goals established by OAI for this facility are shown in
Table 2.1.
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Table 2.1
Treatment Goals for the Frederick Co. AEES "Living Machine"
Parameter Goal
All units in mg/L
Biochemical Oxygen Demand (BOD5) <10
Total Suspended Solids (TSS) <10
Ammonium/Ammonia Nitrogen (NH^NHJ <1
Nitrate Nitrogen (NOJ <5
Total Nitrogen (TN) <10
Total Phosphorus (TP) <3
An independent U.S. EPA performance evaluation took place during the spring and *
summer of 1995 (1). It was intended that the system would be in "steady state" operation during
the study but that proved not to be the case, as discussed in Chapter 3.
A schematic of the AEES process at Frederick, MD, is shown in Figure 2-1. All of the
components except the anaerobic bio-reactor (ABR) were housed in a greenhouse with plastic
glazing (Nexus design steel frame, Serac glazing). The anaerobic bio-reactor was outside the
greenhouse and was partially buried with an exposed floating cover. The greenhouse structure
enclosed three sets of the components shown in Figure 2-1. Two of these process "trains" were
used to demonstrate the capability to treat the design flow rate under steady state conditions.
The third train was used for testing and experimentation but typically received one third of the
40,000 gpd design flow. The pumice stone filters are termed "ecological fluidized beds" (EFB) by
the system developers.
The conceptual design and structural details of the anaerobic bio-reactor were developed
by Sunwater Systems, Inc. located in Solano Beach, CA. The "Living Machine" concept, and the
conceptual design of the AEES facilities were developed by Ocean Arks International (OAI), a
non-profit institute located in Falmouth, MA. The engineering and structural details for the
greenhouse and enclosed components were provided by Living Technologies, Inc. (LTI), located
in Buriington, VT. The computer controls for the greenhouse units were provided by Q Com
Environmental Control in Irvine, CA.
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Raw
Influent
to Trains A and C
Anaerobic Bio-reactor
Aerated Tanks
Clarffier
Treated
Effluent
High-rate Marsh
Final
Qarifier
Pumice Stone Fillers
Figure 2-1 Schematic Diagram of the AEES "Living Machine" at Frederick, MD
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2.2.1 Anaerobic Bio-reactor
The first treatment unit at the Frederick facility was the partially buried anaerobic
bio-reactor. It had a concrete floor and concrete block side walls and was lined with 30 mm high
density polyethylene. The floating plastic membrane liner contained a layer of insulation for
thermal protection. The reactor was 15 feet wide and 28 feet long and maintained a 9 feet water
depth. As shown in Figure 2-1, an internal dam about 6 feet tall retained a permanent sludge
blanket in the first compartment. The untreated wastewater entered this zone via diffuser pipes
on the bottom of the tank, flowed upward through the sludge blanket and then entered the
second compartment. A unique aspect of the second compartment were the strips of
polypropylene mesh netting suspended from the reactor cover which spanned the full width of
the tank. This mesh assisted in trapping and settling solids, and provided significant surface
area for colonization by attached growth microorganisms. The settled sludge in this
compartment underwent some anaerobic digestion. Sludge was removed from this compartment
on a weekly schedule via perforated pipes on the bottom of the reactor. At a flow rate of 37,000
gpd the theoretical fluid detention time was 18.5 hours in this reactor. Untreated wastewater was
pumped, at a constant rate, from the Ballenger WWTP screening and grit removal unit to the
ABR. A depth of about two feet of settled sludge from the Ballenger facility was added to the first
compartment at start-up to serve as the initial sludge blanket.
The ABR was similar in concept and configuration to another commercially available unit
called a "Bulk Volume Fermenter" (BVF) offered by ADI, Ltd (2,3). Both units have an initial
upflow sludge blanket zone followed by a second zone for clarification. The Sunwater Systems
ABR utilizes strips of polypropylene mesh in the second compartment to assist in treatment and
solids removal. The BVF unit offered by ADI uses mixers in the first and second compartments
to enhance contact and treatment. A typical hydraulic residence time (HRT) in the ADI-BVF is
six to eight days whereas the HRT in the Sunwater ABR at Frederick was less than one day.
Except for these differences, the physical configuration of the two systems are very similar, so
the concept does not represent a unique advance in the state-of-the-art for wastewater
treatment.
In order to control odors in the greenhouse and in the area, the effluent from the ABR
was piped to small, covered aerated tanks with a detention time of about 20 minutes at design
flow. The effluent leaving this unit was aerobic and odor-free and ready for treatment in the
greenhouse. The exhaust gasses from this aeration unit were routed to an underground earth
filter for odor control. . _ "
The basic purpose of the ABR was to reduce significantly the concentrations of BOD5 and
solids (TSS) in the wastewater prior to treatment in the greenhouse. Supplemental heat was not
added to this reactor so a relatively warm climate, and a longer HRT would be required for
significant sludge solids digestion. The short detention time (<1 day) in this reactor was not
sufficient to support significant biological reactions so the unit served primarily to settle and
separate the solids entering with the untreated wastewater. The designers have replaced the
anaerobic bio-reactor with an aerated aerobic unit in the 80,000 gpd "Living Machine" now in
operation at South Burlington, VT. The wastewater at South Burlington has lower concentrations
of organics and solids so the use of a preliminary ABR,is less critical, and the very low winter
temperatures would limit the potential for microbial activity in an unprotected, unheated unit.
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2.2.2 Aerated Tanks :
As shown in Figure 2-1, the aerated effluent from the anaerobic bio-reactor flowed to the
first of two aerated tanks in series. At Frederick, MD each tank was 10 feet in diameterand9
feet deep, the top 4 feet of the tank being above the concrete greenhouse floor while the
remainder was below ground. The cylindrical tank walls were corrugated steel, of the type
commonly used for culvert pipe. The interior of the tank was lined with a 20 mm plastic
membrane container to insure complete fluid retention. Both aerated tanks were operated in the
complete-mix aeration mode to keep all solids in suspension and to insure rapid circulation and
contact with the submerged roots of the plants floating on the water surface of these tanks.
Wifley Weber circular diffusers were used as the aeration source in these tanks and the other
process units. Air was supplied for the entire system with three Roots blowers (1-1 hp, 1-1.5 hp,
1-2 hp) which operated continuously. The tank design at South Burlington, VT has been
modified and waterproof, glass lined steel tanks are now used, eliminating the need for the
plastic membrane liner. The aeration intensity in these tanks is comparable to that used in
"complete mix" conventional activated sludge processes.
The plants used on these tanks were floating macrophytes; the first tank usually was
covered with water hyacinth (Eichhomia crassipes), the second with pennywort (Hydrocotyle
umbellate). About 1 hour per week of operator time was required for the care of these plants.
Plant material removed from these tanks was composted. The theoretical HRT in each tank was
8.5 hours at design flow (13,300 gpd/train).
A variety of biological, bacterial, and mineral additives were applied to the wastewater
prior to the aerated tanks to enhance treatment responses and maintain the health of the plants
Bacterial additions included Bactapure N for nitrification, and XL to assist in breakdown of grease
and sludges; mineral additions consisted ofMariah powder which was intended to improve
mineral content and the health of the plants; the biological additive was Kelp meal to supplement
the potassium content in the wastewater. Additions of this type are not routinely used in
conventional wastewater treatment, except for during upsets and emergencies.
The basic purpose of these aerated tanks was to reduce the dissolved wastewater BOD5
to low levels and to commence nitrification of ammonia. The roots of the floating plants were
intended to serve as a substrate for the support of attached growth nitrifying organisms.
In the original design and layout of units in the Frederick greenhouse, the flow from the
second aerated tank passed directly to the next treatment component which was the first
"ecological fluidized bed." Sludge accumulation in these beds required very frequent cleaning so
a small clarifier was added to the process train after the second aerated tank, as shown
in Figure 2-1. Most of the sludge removed from this clarifier was wasted to the anaerobic
bio-reactor; a small percentage was recycled to the first aerated tank. The mixed liquor
suspended solids in these tanks was typically less than 150 mg/L In a complete mix activated
sludge process the mixed liquor solids might range from 1500 to 4000 mg/L depending on the
purpose of the aerated reactor. '
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2.2.3 Ecological Fluidized Beds
As shown in Figure 2-1, there were three "ecological fluidized beds" (EFBs) in each
process train. The outer container of these tanks was the same size and constructed of the
same materials used for the aerated tanks. These units also included an inner tank which
contained the pumice gravel which was the media used in these beds. Flow entered in the
annular space between the inner and outer tanks and was lifted by air lift pipes to the top of the
inner ring containing the pumice media. The bottom of the inner tank was not sealed so the
down flowing liquid returned to the outer annular space and was again circulated onto the top of
the pumice gravel. The air lifts not only moved the liquid but the air bubbles provided the oxygen
source to maintain aerobic conditions in the circulating liquid.
The depth of pumice in the inner tank was about 8 feet and the pumice gravel had a
median size of about 0.5 inch. This size media was selected to provide a high surface to volume
ratio for the attachment of the microbial organisms for effective nitrification in the bed. Pumice
was selected as the material because of its low density which renders it nearly buoyant. This
feature was critically important to successful operation of the unit. As sludge was separated
from the fluid stream in the bed the hydraulic capacity in the forward flow direction was impeded
and, if accumulation were allowed to continue, the bed would eventually become completely
clogged. To correct this potential problem the unit was designed with additional aeration
diffusers beneath the pumice bed. When these aerators were on, the whole inner tank acted as
an upflow airlift so the flow direction was reversed; this aeration "fluidized" the pumice bed and
suspended the buoyant pumice gravel in the liquid. This also released the trapped sludge which
was washed over into, and settled at the bottom of, the outer annular space. Most of this sludge
was removed manually from this space and was returned to the anaerobic bio-reactor.
The choice of "ecological fluidized bed" as the name for this unit is somewhat misleading.
It is normal practice to define the function of a treatment unit while operating in the forward flow
direction. In this case, when the bed is in the treatment mode, the pumice.is not fluidized and
the bed acts as a downflow, coarse media, contact filter unit. It was only during the backwash
cleaning operations that the pumice was fluidized. Both contact filters and truly fluidized media
beds have been available for some time as components in conventional treatment processes.
The three EFB tanks were originally designed and operated as three aerobic units in
series. Operational experience soon indicated that nitrification was essentially complete after the
second unit. The third tank was therefore converted to an anoxic unit to provide additional
capacity for denitrification. This was accomplished without major physical changes in the unit.
The airlift delivery pipes were turned off and a 1.5 hp recirculating pump was located at the top of
the central tank. This induced an upflow direction in the pumice bed and delivered the fluid to
the bottom of the annular space. The lack of aeration and the resulting low oxygen levels
created anoxic conditions in the pumice creating an environment suitable for denitrification. This
modified unit was still backflushed in the.same manner described previously.
Denitrification requires a carbon source for the reaction to function'. The available carbon
(BODs) in the wastewater was, by design, very low at this point in the system and, consequently,
was insufficient to support denitrification. As a result it was necessary to add a carbon source to
the water prior to the denitrification process. A variety of carbon sources were tried, including
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sugar and acetate, but ultimately methanol became the standard addition in the AEES process,
as it is in conventional wastewater treatment processes.
The theoretical HRT in each of these EFB units was about seven hours at design flow. It
was the basic purpose of the first two units to essentially complete the removal ofBOD5 and to
nitrify the ammonia contained in the wastewater. The third unit was then used for denitrification
of that nitrified ammonia. The water surface of the annular space in these tanks was used to
support the hydroponic growth of tree seedlings and other plants suspended in pots around the
perimeter of the tank: The plants probably removed some nutrients and micronutrients from the
water but their contribution to the treatment function of the system was believed to be minimal.
However, these plants can provide a beneficial return since they can be sold. It was estimated
that an annual revenue of about $1,200 could be achieved from sale of these plants during the
spring/summer gardening season in Maryland.
'- ' .1 . -
2.2.4 Final Clarifier '
The three EFB tanks were followed by a hopper bottomed clarifier for final separation of
most of the remaining sludge prior to the final marsh component in the system. The tank for this
clarifier and the materials used were the same as previously described for the aerated tanks.
The settled sludge was periodically removed from this tank and discharged to the Ballenger
Creek WWTP. The water surface on this tank is covered with duckweed (Lemna sp.) and other.
small floating plants. It is not believed that these plants contribute significantly to treatment in
these tanks, owing to their very small root structure and the relatively short detention time in this
unit. The theoretical HRT in the final clarifier was calculated as 8:5 hours at design flow.
2.2.5 High-rate Marsh
The high-rate marsh was the final component in the process train. It was similar in
concept to the subsurface flow (SF) constructed wetland concept widely used for treatment of
municipal and domestic wastewaters. This high-rate marsh consisted of a lined excavation in the
floor of the greenhouse. The excavation was filled with clean selected gravel and planted at the
top with a variety of plant species. The rectangular bed is about 13 feet wide and 30 feet long
and contained a 3.5 feet depth of gravel. The top foot of gravel was small 3/8" stone, the
remaining depth was composed of 11A" stone. The theoretical HRT in this unit was about 9 hours
at design flow. ,
The high-rate marsh was operated and maintained differently than the conventional
subsurface flow treatment wetlands. In the latter case, the depth of the SF wetland bed typically
does not exceed 2 feet to allow trie roots of the vegetation to interact with all of the wastewater
flowing through the bed. Deeply rooted emergent vegetation such as bulrush (Scirpus) or
common reeds (Phragmites) are typically used (4, 9). This is necessary in the SF system since
the plant-roots supply the oxygen which is necessary for nitrification of the wastewater ammonia.
The plant litter is allowed to accumulate on top of the bed and the decomposition of this material
provides some of the carbon source needed for denitrification. The SF wetland bed is sized to
accomplish the limiting treatment response, typically either nitrification or denitrification. One of
these SF wetland units, depending on only the plant litter as a carbon source for denitrification,
would have to be much larger than the "Living Machine" high-rate marsh.
2-7
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The "Living Machine" high-rate marsh did not have to provide significant nitrification since the
ecological fluidized beds were intended for that purpose. Since methanol was used, the plant litter
was not necessary as a carbon source and was not allowed to accumulate on top of the bed. In
addition, as deeply rooted plants were not really needed a variety of plants could be grown for,
aesthetic and commercial horticultural purposes. These plant roots were in contact with the flowing
wastewaterand certainly provide some uptake of nutrients and micro nutrients but they were not one
of the major components responsible for treatment as in the SF concept. In essence, this final
high-rate marsh acted as a final polishing filter with the upper surface maintained as a commercial
horticultural operation. Seedlings were planted and raised to marketable size and then replaced with
new plant material. It was estimated that a revenue of about $3,600 per year could be achieved
from sale of these plants during the summer gardening season in Maryland.
2.3 South Burlington, VT, AEES
The AEES "Living Machine" system at this location is located on the grounds of the South
Burlington wastewater treatment plant (WWTP) in Chittenden Co., VT, at a latitude of 44:28 and
elevation of 330 feet. The mean annual temperature at this site is 7 °C (45 °F) with minimum
January temperatures of -22 °C (-8 °F). The extended periods of sub-freezing temperatures
require a greenhouse structure at this location to protect the "Living Machine" treatment
components. The extended low temperature periods were also thought by the system designers
to limit the anaerobic reactions in the preliminary bio-reactor so it was replaced with additional
aeration units inside the greenhouse.
The design flow at this system is 80,000 gpd of raw, untreated wastewater. Influent for
the AEES system is taken after screening and grit removal by the South Burlington WWTP. The
treated AEES effluent and sludge residuals are all returned to the WWTP for further
treatment/disposal. The treatment goals established for this AEES facility are the same as the
40,000 gpd system in Frederick, MD. The raw wastewater at Burlington is not as strong as that
received at the Frederick AEES, but the water temperatures are much lower. Influent
temperatures in the range of 4° to 7 °C (39 ° to 45 °F) are expected during the winter months.
Start-up of this system occurred in October 1995 and it has been in continuous operation since
that time.
The enclosing greenhouse at the South Buriington facility covers 8,000 fee/2, and the
80,000 gpd design flow is split equally for treatment in two 40,000 gpd process trains. A third
train of much smaller tanks is also included for research purposes. The expected hydraulic ;
residence time at 80,000 gpd is expected to be about three days. The total detention time under
design flow conditions at the Frederick AEES was measured at 3.6 days; 2.4 days of that time
were in the aeration tanks and ecological fluidized beds which are the only biological components
to be used at South Buriington. .
2-8
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2.3.1 Aerated Tanks ,
There are five aerated tanks in series at the Burlington AEES as compared to two at
Frederick, MD. A clarifier follows the last aerated tank and effluent from this clarifier flows to
three EFB units in series. Sludge separated by the clarifier flows to a holding tank and is then
returned to the South Burlington WWTP. Sludge return from this clarifier to the AEES process is
apparently not intended. There is a recycle line for return of liquid from the fifth aerated tank to
the first. The use of five aerated tanks at this location was considered necessary by the designer
because of the lower temperature sewage during the winter months and because there is no
preliminary anaerobic treatment provided.
These aerated tanks are larger and constructed differently than those at Frederick, MD.
Each tank is 14 feet in diameter (10 feet at Frederick) and 13 feet deep (9 feet at Frederick).
They are glass lined, bolted steel tanks manufactured by Aquacare Inc. of Seattle, WA. This
new tank composition is expected to eliminate the potential maintenance problems with the
plastic membrane lined tanks that were used at Frederick, MD. The aeration equipment used is
similar to what was at the Frederick installation. The process design anticipates at least partial
nitrification of the wastewater ammonia by the fifth aerated tank. The total HRTin the aerated
tanks is about two days at design flow. Floating racks on the water surface of these tanks
support a wide variety of plant species, ranging from grasses to tree seedlings.
2.3.2 Ecological FluidizedBeds
These ecological fluidized beds are functionally the same as described in Section 2.2.4
for the Frederick facility. A higher density, harder volcanic stone is used at South Burlington
instead of the softer pumice used at Frederick, MD. The pumice suffered significant abrasion
losses during the "fluidizing" portion of the operational cycle and the fine particles can also create
maintenance problems. The EFB units at South Burlington contain about 0.1 feet3 of media per 1
gpd of process flow which is a slightly higher ratio than used at Frederick, MD.
The process design anticipates complete nitrification in the first EFB unit. Methanol will
be added as a carbon source of the influent of the second EFB unit which is operated as an
upflowanoxic reactor in the treatment mode. The third EFB tank is intended for final effluent
polishing. Backflushing these filter beds uses the same general procedure described in Section
2.2.4 for the Frederick AEES. The backflushed sludge accumulates in the outer annular space
in these tanks and is then pumped to the clarifier located after the fifth aerated tank.
The third EFB tank is the final unit at the South Buriington AEES system: The final
clarifier and high rate marsh used at the Frederick facility were eliminated in this system based
on their marginal contribution to treatment observed at Frederick and because of space
limitations in the South Burlington greenhouse.
2-9
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Steady state operations were achieved in May 1996 and have continued to date with actual
flows at or near the 80,000 gpd design flow. Since natural carbon sources are not,present in
sufficient quantities to support denitrification, methanol is again used routinely for this purpose.
Comparative experiments are underway, using the two process trains, to determine if the bacterial
bioaugmentations routinely used at Frederick, MD actually provide significant treatment benefits.
2.4 San Francisco, CA AEES
The AEES system at this location was sited at the Oceanside Water Pollution Control
Plant (WPCP) operated by the Department of Public Works for the City and County of San
Francisco. The Oceanside WPCP provides adyanced secondary treatment for a design flow of
21 mgd. The site is at latitude 37:46 at an elevation of about 10 feet. The mean annual air
temperature is 13 °C (55 °F) with minimum winter temperatures of4°C (40 °F) and, consequently,
the AEES facility did not need a protective greenhouse at this location.
The AEES system at this location was trailer mounted and designed for high-rate, tertiary
polishing of the Oceanside WPCP advanced secondary effluent; it did not therefore include all of
the units previously described for either Frederick, MD or South Burlington, VT. The San
Francisco AEES was composed entirely of EFB units with two fish tanks as a side stream. The
intended total design flow of the two parallel treatment trains was 60,000 gpd.
The goal of this AEES system was to produce a final effluent which would satisfy the
"Title 22" water quality requirements of the State of California for unrestricted irrigation reuse.
Unrestricted reuse in this case means irrigation of food crops to be eaten raw and full body
contact recreational activities. "Title 22" does not have specific limits for wastewater pollutants
but is written in terms of treatment functions. A "Title 22" effluent must have undergone
coagulation, sedimentation, filtration and disinfection, in the final polishing processes, or the
equivalent thereof. The intent of these requirements is to produce a water with very low turbidity
and zero virus. Since monitoring for virus is complex and expensive, California accepts non-
detectable levels of total conforms (<2.2/100 ml) as an acceptable indicator of a virus free water.
If alternatives to the "Title 22" treatment sequence are proposed it is incumbent on the
proponents to prove that the alternative treatment produces an equivalent quality, virus free
water.
It was the purpose of this AEES system to demonstrate that the process is capable of
producing an effluent comparable to the "Title 22" requirements through the production of an
effluent with very low turbidity and total conforms. The State of California would also have to
agree that the process is comparable prior to any widespread use of the AEES process for this
purpose. OAI established specific water quality goals for this system. These are compared to
the typical effluent quality produced by the Oceanside WPCP in Table 2.2.
2-10
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Table 2.2
Oceanside WPCP Effluent and San Francisco AEES Process Goals
Parameter Oceanside WPCP Effluent AEES Goal
All units in mg/L
BOD5
TSS
Turbidity.
Ammonia
N03 ,
TN
Fecal Conforms (#/100 ml)
17
22
4
22
" 1
29
57
<10
<10
2 '
1
5
<10
<2.2
Although nitrogen removal is not a "Title 22" requirement it was included as an AEES goal
in case the treated water is to be used for recharge of sensitive groundwater aquifers. However,
reducing nitrogen to below the federal drinking water nitrate limit of 10 mg/L will not necessarily
allow either direct reuse of this water for drinking water purposes or recharge of potable
groundwater aquifers.
The two process trains at this AEES facility each contained seven compartments in
series. Each compartment was an ecological fluidized bed which had a surface area of 16 feet2
(4 feet x 4 feet) and contained a 6.25 feet depth of the same gravel media used at the South
Burlington "Living Machine." The units originally contained the same pumice gravel used at
Frederick, MD but this was replaced owing tp excessive abrasion and clogging of the drains.
When the system was in the treatment mode the first five units in series served as downflow
nitrifying filter beds with water circulation and oxygen provided by a central air lift in each cell.
The final two cells served in an upflow anoxic mode for denitrification (with methanol addition as
a carbon source) with a submersible pump in the center well providing water circulation. Each
cell was backflushed as required when aeration lines at the base of the cell convert the entire cell
to an airlift mode and thereby flush wastewater solids out of the media. Released solids were
removed manually from the top of the cell (see section 2.2.4 fora more detailed description of
the EFB concept).
Ten percent of the process effluent was recycled to aerated fish tanks, and ten percent of
the fish tank effluent was recycled to the AEES treatment process. The fish tanks contained
fathead minnows and striped bass and could represent a potential revenue source. Small potted
tree seedlings were also rafted on the water surface in the EFB cells and also may provide a
horticultural revenue source. The same bacterial supplements that were used at the Frederick
facility (see Section 2.2) were also routinely used at San Francisco. Additionally, calcium
carbonate was routinely added to increase the alkalinity levels in the water to support nitrification.
Asian clams were also added to the EFB cells and the fish tanks as they were expected to
reduce TSS and fecal conforms in the system. Snails were present in both the fish tanks and on
the EFB beds.
2-J1
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Each of the 14 EFB cells at San Francisco contained a 6.25 feet depth of gravel media.
Ignoring the center well and other piping, that is approximately 128 feet3 of media per cell or
1,792 feet3 of media in the whole system.. This quantity represents about 0.03 feet3 of media per
gpd of design flow. This ratio was 0.1 feef/gpd at South Burlington and about 0.07 feef/gpd at
Frederick, MD, however, the BOD5 and TSS entering the EFB units at Frederick and at South
Burlington are significantly higher than the influent to this system in Table 2.2. However, if the
ratio of media volume to flow used at South Burlington proves to be a critical requirement then
the actual capacity of the San Francisco AEES system may have been less than the intended
60,000 gpd. ,
Start-up for this system occurred in February 1995 and it operated intermittently until
December 1996 when it was deactivated. Numerous changes and operational modifications were
incorporated during this period. The average daily flow rate in the two process trains was about
9,000 gpd during September 1996, which is only 15 percent of the intended 60,000 gpd design flow
rate.
2.5 Harwich, MA AEES
The AEES unit located in Harwich, MA was not intended for sewage or wastewater ,
treatment. It was developed to improve the water quality in natural water bodies and is called the
"Lake Restorer." The prototype unit was installed on the surface of Flax Pond, in Harwich, MA in
October 1992. Harwich is on Cape Cod at a latitude of about 41:40 and an elevation, at the pond
site, of about 50 feet. The mean annual temperature is 10°C (50 °F) and minimum winter
temperatures of about -12 °C (11 °F) are experienced. The low winter temperatures and
occasional ice on the pond do not impact on the routine operation of the "Lake Restorer" but the
presence of ice can affect the monitoring program since access by a boat is needed for
sampling.
The central section of the "Lake Restorer" raft included three ecological fluidized bed
containers with the same pumice gravel media used at Frederick, MD and originally at San
Francisco, CA. The media was supported by a structural bottom so the units were isolated from
the in-situ waters in Flax Pond. The six containers on the outside perimeter of the unit did not
contain any pumice media and were also open to the waters of the pond. All of these containers
were covered with a variety of plants. A wind powered electrical generator served to recharge
the batteries which provided the power source for the airlift pump which circulated water to the
pumice cells in series and then to the outer containers. The three EFB units on this raft were
about 4 feet x 4 feet x 3 feet deep and contained a total of 144 feet3 of pumice. The progress
reports issued by OAI claim a flow rate of 100,000 gpd for the "Lake Restorer" but a .
communication from OAI staff in July 1995 indicated an average flow rate of 20,000 gpd (5). An
average flow rate of 20,000 gpd provides a media volume to flow ratio or 0.007 feet3 of
media/gpd of average flow. That is an order of magnitude less than provided at the San
Francisco AEES and about two orders of magnitude less than provided at the South Burlington
AEES. However, the water in Flax Pond had an ammonia level which was about an order of
magnitude less than the wastewater being treated in the other AEES facilities.
2-12
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Wind power proved to be an insufficient energy source at this location so an inclined rack
of solar cells was added as a supplemental energy source. The airlift pump drew the water from
the pond-at a depth of about 5 feet. The amount of water circulated was dependent on the
availability of wind and solar energy and averaged about 20,000 gpd. Hydrologists have
estimated that the baseflow into the pond from the adjacent groundwater system is
approximately 78,000 gpd (5).
Flax Pond is shaped like an "exclamation point." The smaller circular lobe at the eastern
end'has a surface area of about two acres, the larger and longer end has an area of about 13
acres and a maximum depth of about 20 feet. The two segments are separated by a sand bar
which is submerged in wet weather and exposed during the dry season and as a result, the two
pond segments are not always directly connected. The "Lake Restorer" was anchored in the
smaller of the two segments; the maximum water depth in this smaller segment of the pond is
about 9 feet. The volume at this end of the pond is about 2,000.000 gallons, so the "Lake
Restorer" would have taken approximately 100 days to circulate an equivalent volume through
the unit at a 20,000 gpd flow rate. Assuming that about one third of the groundwater recharge
entered this southern lobe, all of the contents of this end of the pond could be displaced with
contaminated groundwater in less than 80 days. Water exchange between the two pond
segments could not be defined with the currently available data.
Flax Pond intersects the local groundwater table and the former poor water quality in the
pond was thought to be a result of the impact of the Harwich landfill andseptage pits which are
immediately adjacent to the pond and upgradient on the groundwater flow path. The septage
pits were closed in 1991 but the landfill remains in operation to date. The "Lake Restorer"
remained in place at the same location, on the eastern lobe of Flax Pond from October 1992 until
the project was inactivated in October 1996. Specific water quality goals for this unit were not
. established, the general goal being to restore the "health" and biodiversity in Flax Pond. Water
quality samples were not taken from any portion of the operating "Lake Restorer" device.. The
impact of the device was measured indirectly via water quality and sediment samples obtained at
seven sampling stations in and around the perimeter of Flax Pond. Only three of these were in
the eastern lobe of the pond.
2-13
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CHAPTER 3
PROCESS EVALUATION OF THE AEES "LIVING MACHINE'
3.1 Introduction
This chapter contains an evaluation of the AEES process at the demonstration projects in
Frederick, MD, South Burlington, VT, San Francisco, CA, and Harwich, MA. The major focus of this
evaluation is on the Frederick, MD, facility since that was the site of the independent EPA data
collection effort. The final section of this chapter also compares costs of the AEES process (as used
at Frederick and South Burlington) to the costs for conventional technology providing the same
water quality benefits. These cost comparisons and the evaluation of the Frederick facility were
drawn from Reference 1. The evaluation of the other AEES demonstrations are based on site visits
and data provided by Ocean Arks International.
3.2 AEES, Frederick, MD
The independent evaluation by the U.S. EPA of this facility was conducted during the
spring and early summer of 1995. The effort included flow measurement, tracer studies to
determine the HRTineach process unit, weekly composite water quality sampling to determine
performance of the major process units, and a special study to evaluate the contribution of the
plants in the system. Reference 1 describes all of these efforts in detail. A summary of average
water quality-data over the 11 week EPA study period is given in Table 3.1.
Based on the EPA test data shown in Table 3.1 it would appear that the AEES "Living
Machine" at Frederick, MD, did not meet any of its treatment goals during the study period, with
the exception ofTSS. However, if became obvious during the study period that the system was
not yet in true "steady state" operation. The utilization of methanol as the denitrification carbon
source began, for example, during the eariy stages of the testing program. Inexperience on the
part of the AEES staff with the methanol dosages resulted in unusually high values for BODS,
COD, and NO3. Consequently, it can be concluded that the data collected during the 11 week
test period was not truly representative of the "steady state" capabilities of the process.
3-1
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Table 3.1
EPA Water Quality Data Summary for Frederick, MD, AEES
(March-June 1995)
Parameter
Raw
Sewerage
Influent
Anaerobic
Bio-reactor
Aerated
Tanks
First
EFB
Third
EFB
High-rate
Marsh
Treatment
Goals
Mean Water Quality, mg/L
Total COD
Sol. COD
Total BOD
Sol. BOD
TSS
VSS
TKN
Ammonia
N03
TP
TN
Fecal Co//
1307
158
469
70
470
364
56
26
0.2,
14
56.2
8x 1tf
cfu/100 ml
445
216
160
108
78
64
43
34
0.2
8
43.2
399
64
106
10
148
122
46
28
0.4
8
46.4
150
51,
49
6
43
34
30
23
2
8
32
73
43
18
11
10
6
10
8
10
7
20
53
38
12
10
4
2
8
6
5
7
13
170 cfu/100 ml
-
<10
<10
<1
<5
<3
<10
__
Another purpose of the independent EPA data collection program was to compare test
results with similar data collected by the AEES staff. As described in Reference 1, this
comparison indicated a reasonable correlation between the two data sets. Such a correlation
should be expected since many of the AEES samples were actually tested in the certified
laboratory at the Ballenger Creek WWTP. This correlation allows an extension of the evaluation
to include data collected after the EPA test period. The performance data shown in Figures 3-1
to 3-6 covers the period from March 1995 through March 1996. This provides data on a full
annual cycle of system operation and may suggest seasonal influences because of low winter
temperatures.
Figures 3-1 to 3-6 present these data in graphical form. All six figures are constructed in
a similar manner and show the treatment goal, the concentration in the raw wastewater influent,
in the final effluent (both EPA and AEES test results), and in the case ofBOD5, COD, TSS, and
TP the concentration of the influent entering the greenhouse (GH Input) after anaerobic
pretreatment. The graphs for SOD& COD, and TSS are plotted to a logarithmic scale because of
the broad range of concentrations observed. Sampling and testing occurred on a weekly basis
(for both EPA and AEES results) but are shown on "the graphs as monthly averages for clarity.
The EPA study also included additional sampling and testing between the major system
components in the greenhouse to define the role of these units. These data and the related
discussion can be found in References 1 and 7.
3-2
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400
100 r
o>
E
a
O
m
MAR 95 APR MAY JUN JUL AUG SEP OCT NOV DEC JAN 96 FEB MAR
MONTH
Raw In
Effluent -. Goal
GH Input A EPA
Figure 3-1 Frederick AEES BOD5 Input Versus Output, March 1995 - March 1996
The annual average concentration pfBOD5 in the raw sewage was 230 mg/L which is
within the range normally expected for municipal wastewaters. The input to the greenhouse
(effluent from the preliminary anaerobic treatment) was measured during the EPA study period
and averaged 156 mg/L so, during the study period, the anaerobic reactor removed about 68
percent of the incoming BOD5. During April and May the final effluent BOD5 exceeded the 10
mg/L project goal, but this was probably a result of the introduction of methanol as a carbon
source for denitrification. Once experience was gained in the management of this methanol the
effluent BOD dropped to about 4 mg/L The annual average SOD5; including the higher values,
was 7 mg/L which is still significantly below the project goal. It can be concluded that the
"Living Machine" at Frederick, MD has displayed a reliable capability to remove BOD5 to below
the 10 mg/L target goal. Most of that removal occurred in the anaerobic bio-reactor and the
aerated tanks, both of which are comparable to conventional wastewater treatment processes.
3-3
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en
S"
O
O,
Q
111
Q
Z
tu
O
X
O
O
UJ
X
O
MAR 95 APR MAY JUN JUL AUG SEP OCT NOV DEC JAN 96 FEB MAR
MONTH
Raw Infl
Effluent ~ Goal
GH Input
EPA
Figure 3-2 Frederick, MD, COD Input Versus Output, March 1995 - March 1996
. The chemical oxygen demand (COD) performance shown on Figure 3-2 is similar to that
shown previously for BOD5. The majority (60%) was removed in the anaerobic bio-reactor, and
the elevated values during April and May 1995 are again probably a result of the introduction of
methanol as a new carbon source. The annual average effluent COD was 30 mg/L which is
well below the target performance goal, indicating that the "Living Machine" at Frederick, MD
can provide reliable and consistent COD removal.
3-4
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co
CO
co
Q
' _I
o
CO
Q
111
Q
Z
UJ
Q.
CO
3
CO
700
100
MEAN - 70 mg/L
1
MAR 95 APR MAY JUN JUL AUG SEP OCT NOV DEC JAN 96 FEB MAR
MONTH
Raw in
Effluent Goal
GH Input
EPA
Figure 3-3 Frederick, MD, TSS Input Versus Output, March 1995 - March 1996
The removal of total suspended solids (TSS) is shown on Figure 3-3 and, in this case,
82 percent of the TSS were removed in the preliminary anaerobic bio-reactor. Slightly elevated
effluent values were experienced during the spring and early summer but, with improved solids
management procedures, the effluent values were consistently at or near 1 mg/L The annual
average effluent value was 2 mg/L which is significantly below the 10 mg/L target goal,
indicating again that the "Living Machine" at Frederick can provide reliable and consistent
removal of TSS. The EFB units which serve as filter beds are very effective in reducing TSS
concentrations to very low levels.
3-5
-------
O)
E
HI
CD
O
o:
<
z
o
MAR 95 APR MAY JUN JUL AUG SEP. OCT NOV DEC JAN 96 FEB MAR
MONTH
GH input
Effluent
1 mg/L Goal
EPA
Figure 3-4 Frederick, MD, Ammonia Nitrogen Input Versus Output,
March 1995-March 1996
The removal of ammonia nitrogen (NH^NH^ is shown on Figure 3-4. In this case,
ammonia concentrations were only measured in the greenhouse influent and averaged 22 mg/L
which is within the typical range for municipal wastewaters. The effluent showed some
elevated values during the spring and early summer and this may also be a result of
inexperience with the methanol additions. The mean annual effluent value was 3 mg/L which is
relatively low but was still above the target performance goal of 1 mg/L that was established for
this process. If the higher values that occurred during the spring of 1995 are not included, the
average for the remainder of the year would still exceed the 1 mg/L project goal. The "Living
Machine" in Frederick, MD did not, therefore, meet its intended goal for ammonia removal.
However, it is believed that the ammonia target could be achieved with improved operation and
management procedures, and this has been established with the preliminary results from the
80,000 gpd system in South Burlington, VT (see discussion in a later section of this report).
3-6
-------
LU
O
O
O
MAR 95 APR MAY JUN JUL AUG SEP OCT NOV DEC JAN 96 FEB MAR
. MONTH
GH Input
Effluent Goal
EPA
Figure 3-5 Frederick, MD, Total Nitrogen, Input Versus Output, March 1995 - March 1996
Figure 3-5 presents input versus output data for total nitrogen, at the Frederick "Living
Machine." Data for this parameter are only shown for the influent to the greenhouse and the final
effluent It is again likely that the higher effluent values during the spring of 1995 were owing to
inefficient denitrification because of inexperienced management of the newly introduced
mefhanol as a carbon source. The divergence during the winter of 1995-96 is believed to be a
result of other causes, possibly the low winter temperatures inside the greenhouse. The mean
annual effluent TN concentration was 11 mg/L which exceeds the 10 mg/L target goal. If the
divergence in the spring of 1995 were ignored, the average effluent value would still exceed the
target goal.
3-7
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MAR 95 APR MAY JUN JUL AUG SEP OCT NOV DEC JAN 96 FEB MAR
MONTH
Raw Inp
Effluent Goal
GH Input-
EPA
Figure 3-6 Frederick, Mb, Phosphorus Input Versus Output, March 1995 - March 1996
Figure 3-6 compares input versus output data for total phosphorus at the Frederick
"Living Machine." In this case, the concentration in the raw sewage, the greenhouse influent and
the final effluent were all measured. The mean annual phosphorus concentration in the effluent
was 6 mg/L which is double the target goal of 3 mg/L. Most of the phosphorus was removed at
the Frederick facility (30 percent) in the preliminary anaerobic bio-reactor, probably in conjunction
with the settling of suspended solids in this unit. The biological components in the greenhouse
accounted for another 15 percent removal. None of the biological pathways available in the
current AEES process can be expected to remove large quantities of phosphorus. Biological
phosphorus removal is possible in specially designed and operated treatment plants. Several
commercially available processes induce biological uptake of phosphorus by the activated sludge
microorganisms and result in the production of significant quantities of sludge. The other
commonly used phosphorus removal method in wastewater treatment is the use of chemical
additions to precipitate the phosphorus; these also produce large quantities of sludge.
It is also possible to remove phosphorus via plant uptake and harvest. However, the
plant density and the harvesting program at the AEES facilities are not sufficient to account for
significant amounts of phosphorus. Based on the data presented in Reference 1 it can be
calculated that about 751 kg/yr of phosphorus enters the AEES with incoming wastewater, at a
flow rate of 40,000 gpd. Approximately 0.44 kg/yr of phosphorus would leave the facility with the
3-8
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routinely harvested and composted plant material. Additional phosphorus is removed during the
horticultural operations but it is unlikely that the total annual phosphorus for all plants leaving the
greenhouse exceeds 1 kg/yr. The plants in the Frederick AEES system can, therefore account
for about 0.1 percent of the phosphorus entering the system. Either significant phosphorus
removal should be dropped as an AEES performance goal or additional processes for
phosphorus removal should be incorporated in the system.
A summary of the performance data from the Frederick, MD facility is compared to
preliminary data from the South Burlington, VT facility in Table 3.2.
Table 3.2
Mean Effluent Quality, Burlington, VT, and Frederick, MD
Parameter AEES Process
All units in mg/L
BOD5
TSS
NHg/NHj
A/03
TN
TP
Goals
10
10
1
5
<10
3
South Burlington, VT
Performance
May '96 - Nov '96
4.9
2.8
0.2
6.2
7.4
2.6
Frederick, MD
- Performance
Mar '95 -Mar '96
7.0
2.0
3.0
7.0
11.0
6.0
3.3 AEES, South Burlington, VT
Start-up for this 80,000 facility occurred in October 1995 and steady-state operations at
the design flow were achieved in May 1996. The target performance goals are the same as
previously specified for Frederick, MD and are summarized in Table 3.2. A separate independent
evaluation of this facility by the US EPA has been proposed but had not been undertaken at the
time this report was prepared. Based on the experience established in the previous study at the
Fredenck, MD system, it can be assumed that the test data collected by the AEES staff will
provide a reliable basis for the evaluation. Data summaries and discussions in this report are
based on AEES test results produced from May through November 1996 (6). These results are
compared to the annual average data from Frederick, MD and to the original project aoals in
Table 3.2 below. .
It would appear from this comparison that the "Living Machines" at both locations produce
comparable results for BOD5 and TSS removal. The ammonia removal seems to have improved
at the Burlington facility, probably because of the increased aeration capacity. The effluent
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nitrate is in the same range at both facilities and still does not meet the 5 mg/L target goal. The
average total nitrogen at South Burlington is below the target goal for the seven month period
summarized in Table 3.2. The nitrate exceedence would suggest that the South Burlington
facility needs to further improve the denitrification capability. It is believed that this system
should be capable of meeting these nitrogen goals with optimum operation and management. It
would appear that the South Burlington facility may be meeting the phosphorus target with an
effluent concentration of 2.6 mg/L,but this interpretation may be misleading since the influent
phosphorus was only 4.7 mg/L at this location as compared to 14 mg/L influent phosphorus at
Frederick, MD. The removal of phosphorus by the greenhouse components at South Burlington
is actually in the same range as'described previously for Frederick, MD. If the wastewater
phosphorus at South Burlington was in the "normal" range (i.e., 8-12 mg/l), it is not likely that the
system could meet the 3 mg/L effluent goal. .
In summary, it seems the "Living Machine" in its present configuration cannot consistently
meet the 3 mg/L phosphorus goal and, although the potential exists, the system is not meeting
the goal for nitrate either. These tentative conclusions are based on only seven months of
steady-state data from the South Burlington facility and are subject to change. Data from the
1996-97 winter period is essential for final conclusions since this is the most difficult time for
effective nitrogen removal owing to the low air and water temperatures. The facility at Frederick,
MD appeared to have difficulty achieving nitrogen removal goals during the winter months
(Figure 3-5) and the winter conditions are much more severe at South Burlington, VT.
The full potential capabilities of a complete "Living Machine" system still needs to be further
demonstrated. Unfortunately, neither of the process demonstrations at Frederick, MD and South
Burlington, VT are well suited for this ultimate purpose. In both cases, wastewater is pumped into
the AEES facility at a uniform rate so the system is not exposed to the normal diurnal flow variations
or the peak flows which occur in response to storm events. In addition, sludges are returned to the
adjacent municipal treatment plant without processing. Dewatering on reed beds has been proposed
for future applications of the "Living Machine." In this case, the leachate from these reed beds would
have to return to the AEES facility for treatment, or be otherwise handled. The need to include
treatment of this very strong leachate with the normal wastewater stream would likely reduce the
claimed capacity of the system by at least 5 percent (i.e., a 40,000 gpd unit could only treat 38,000
gpd of wastewater and 600 gpd of very strong sludge leachate). In effect, the AEES facilities in
Frederick, MD and South Burlington, VT are only suited to demonstrate the capabilities of the
process under relatively "ideal" operating conditions. In addition, an analysis of the treatment
functions of the various components inside the greenhouse indicates that most of the treatment is
occurring in response to conventional aeration/mixing, filtration, and the use of methanol as a
chemical addition and not because of the ecological components and solar energy.
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3.4 Process Residuals
The residuals leaving the Frederick AEES "Living Machine"process include sludges from
the anaerobic bio-reactor and sludges from the clarifiers and the plants removed from the water
surfaces on the various tanks. The plants removed during the horticultural operations are not
included in the "residuals" estimate since they are intended for replanting and not disposal The
sludge removed from the EFB filter beds at Frederick, MD was returned to the anaerobic
bio-reactor and was accounted for.in the sludge wasted from that unit
Samples of sludge and plant material were collected on several occasions during the
EPA study at Frederick, MD and tested for nitrogen, phosphorus, fecal conforms, and the metals
of concern for land application of sludge (under 40 CFR, Part 503 regulations). These results
can be found in Reference 1. The plant material shows no unusual concentrations of any
material and the final compost could be used for any agricultural or horticultural purposes The
sludges from the system met all of the 503 limits for High Quality sludge, except those for fecal
conforms and the metal molybdenum. The fecal conform limits could be satisfied with additional
stabilization and treatment of the sludges. The mean molybdenum concentration of 30 mg/kg in
the sludge wasted from the anaerobic bio-reactor exceeded the 18 mg/kg high quality pollutant
limit in the 503 regulations published in February 1993 but this limit has since been dropped from
the rule. This molybdenum concentration is well below the 75 mg/kg limit required for land
applied sludge.
The total amount of residual materials removed from the AEES facility in Frederick can be
estimated from the data in Reference 1. Based on these data an average of 4434 gallons of sludge.
per week were wasted from the anaerobic bio-reactor; at 2.8 percent solids; that is about 472 kg/wk
of dry solids, the final clarifier would contribute about 2 kg/wk, and the plant residuals about 1 kg/wk
of dry material. On an annual basis, the residuals production would be about 12 dry tons (metric)
per year. A comparable 40,000 gpd extended aeration package plant, with a final denitrification filter,
would waste about 1000 gallons of sludge per day with about 2 percent solids, this would equal 76
kg/dofdry solids or 14 dry tons (metric) of sludge per year. The AEES system appears to produce
slightly less sludge than a conventional extended aeration treatment process, which also includes
final filtration, when effluent characteristics are comparable for the two systems. This should not be
surprising since the process functions in each system are also similar. The difference in residuals
production between the two systems is probably a result of the estimated 20 percent sd/ids reduction
achieved in the AEES anaerobic bio-reactor.
3.5 Role of Plants in the AEES "Living Machine" Process
Plants supported by solar energy are included in almost every unit in the AEES system
and their contribution has been claimed to be essential to the performance of the process (10).
Ha ving committed to plants and solar energy the design logic then requires the use of a
greenhouse when colder seasonal climates prevail, for protection and continued year-round
growth of the plants. A commitment to a greenhouse then creates a design dilemma since the
high cost of the space enclosed by a greenhouse then requires deep high-rate treatment units for
cost effective use of that space. Such high-rate units then minimize the surface areas available
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for utilization of plants so the role of the plants is diminished along with the original highly
desirable intent to utilize plants and solar energy as major components in the system. A
treatment system based on the use of plants and solar energy as major components must
provide sufficient surface area so that the plants are in fact a major physical presence in the
system. Unfortunately, this does not appear to be the case at either Frederick, MD or Burlington,
VT.
Plants were utilized on all of the treatment units at the AEES in Frederick, MD and at
South Burlington, VT. The plants are claimed to be essential for treatment on some units and
used for horticultural purposes on others, depending on the plant species used. Regardless of
their purpose, the presence of these plants in the AEES greenhouse creates an aesthetically
pleasing and often beautiful environment unlike any conventional wastewater treatment system.
At the plant density and harvesting schedule used at the Frederick AEES facility the plant
uptake of pollutants and then removal via harvesting accounts fora negligible fraction of pollutant
removal in the system. The major removal mechanisms are believed to be microbial activity and
physical separation of particles via settling and filtration. It is believed that the floating plants can
contribute to this microbial activity through colonization of their root systems by the organisms
responsible for treatment and this was the intent of the floating macrophytes used on the two
aerated tanks at Frederick, MD.
The plants were present and completely covered the water surfaces in the aerated tanks
during the first eleven weeks of the EPA study period, so their contribution to treatment is
included but could not be separately defined in the performance data collected during that period.
At the suggestion of the EPA study team, and with the concurrence of the grantee, MFEMPS, all
of the floating macrophyte plants were removed from the aerated tanks in one treatment train for
the second phase of the study, which included three additional weeks of data collection.
A comparison of the data collected during these two periods of the study indicate no,
significant difference, with or without the floating macrophyte plants, for removal of COD, SOD&
TSS, VSS and phosphorus, for either the final system effluent or for the effluent from the aerated
tanks (1). There are very small but significant differences for the nitrogen forms. The TKN'and
ammonia are lower and the nitrate levels are higher when the aerated tanks contain plants. Since
the nitrate concentrations leaving the aerated tanks is somewhat higher with plants on the tanks, this
suggests that the microbial activity on the plant roots does contribute to nitrification. However, this
slightly diminished nitrification capacity without the plants can apparently be compensated by
nitrification in the EFBs so there is no major difference in performance of the overall system with or
without plants in the aerated tanks. This observation was confirmed by continued operation without
the plants after the EPA study period ended and, consequently, it can be concluded that the floating
macrophytes used in the aerated tanks do not contribute significantly to treatment. The potential
is there for the plants to contribute more but the water surface area available on these deep AEES
tanks is limited which suggests that there are not enough plants available to make a significant
difference in treatment performance. In other "natural" systems, the plant roots and the associated
microbes have been shown to provide the major source of treatment. However, these other natural
systems have a very large water surface area and a relatively shallow water depth so the use of
protective greenhouses may not be economical under most circumstances.
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3.6 Chemical Additions to the AEES "Living Machine" Process
The developers of the "Living Machine" process have claimed that treatment to advanced
levels is possible without the use of chemicals (8). In actual practice, however, both chemicals and
bacterial supplements are routinely added to the system. Sodium acetate, for example, was being
used as a denitrification carbon source when the EPA study commenced. This was changed to
methanol part way through the study and the use ofmethanol is now routine at the South Burlington
facility. At the Frederick, MD design flow of 40,000 gpd these additives would be: 1900 Ib/yr of
methanol, 150 gallons/yr (1250 Ib/yr) of bacterial supplements and 1500 Ib/yr of other organic and
inorganic supplements. The routine addition.of over two tons ofmethanol and other supplements
each year would seem to contradict the claim that chemicals are not necessary in this process.
Chemicals are not now used for phosphorus removal and phosphorus removal is marginal.
However, if chemicals are added for this purpose, the annual chemical usage and residuals
production could easily ihcrease by an order of magnitude or more.
3.7 AEES "Living Machine" System Costs
Detailed cost estimates for the AEES process as used at Frederick, MD and South
Burlington, VT are presented in Reference 1 for design flow rates of 40,000, 80,000 and
1,000,000 gpd. The costs of conventional processes capable of producing the same effluent
quality at the same flow rates were also presented in Reference 1 for comparative purposes.
Phosphorus removal was not included in these comparisons since the AEES process has limited
phosphorus removal capability. These conventional technologies were:
i. 40,000 gpd: A prefabricated packaged extended aeration plant with a final anoxic filter
for denitrification and filtration, followed by ultraviolet (UV) disinfection. The only
chemical addition is methanol as a carbon source for denitrification.
, //. 80,000 gpd: A sequencing batch reactor (SBR) followed by a filter with backwash and
UV disinfection. Methanol is not needed in this case since the wastewater BOD5
provides sufficient carbon in an anoxic period which is developed during the SBR
operational sequence. Two options were developed: a prefabricated package plant, and
on-site constructed concrete tanks. . ' . .
///'. 1,000,000 gpd: Two options were developed for this flow rate: A prefabricated extended
aeration package .plant with a cylindrical steel tank erected on a concrete pad, the
system includes an anoxic filter for denitrification, and UV disinfection; methanol is used
as a carbon source. The second alternative is a Carrousel oxidation ditch process with
typical concrete aeration/anoxic zone tanks, final clarifiers and sludge return pumping,
a polishing filter and UV disinfection. Methanol is not needed in this case because the
wastewater BOD5 provides sufficient carbon for denitrification in the anoxic zone of the
oxidation ditch.
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The AEES system concept costs, in Table 3.3, is essentially the South Burlington system
but located in a more temperate climate. Costs for the 40,000 gpd AEES "Living Machine" are
based on the actual costs of the facility at Frederick, MD, minus any costs for special features
which were included for research or educational purposes. The costs for the 80,000 gpd "Living
Machine" are based on actual costs for the Burlington, VT, facility again minus the costs of any
special features for research or education. The costs for the 1,000,000 gpd "Living Machine" are
based on extrapolation from the Burlington, VT, system costs, since a 1,000,000 gpd "Living
Machine" has not actually been built. All of the "Living Machine" costs were derived by LTI
personnel. The costs for the conventional treatment alternatives were derived by Parsons
Engineering Science using quoted costs from various system suppliers.
A summary of the cost comparisons from Reference 1 is shown in Table 3.3 and shown
graphically on Figure 3-7.
Table 3.3
Present Worth Comparison, AEES and Alternative Systems (1)
System Type 40,000 gpd 80,000 gpd 1,000,000 gpd
AEES System
With Greenhouse $960,000 $1,835,600 $11,486,700
Without Greenhouse $866,700 $1,705,700 $10,207,800
Alternate System
Package Plant $1,093,200 $7,902,800
SBR
Steel tanks $1,695,000 .
Concrete tanks . $1,567,500
Carrousel . $7,606,200
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0.00
12
Capacity, mgd
(Millions)
0.11 0.21 0.32 0.42 0.53 0.63 0.74 0.85 0.95 1.06
T
O
o
o
o"
o
o
V)
o
O
o
*-
c
0)
o
(L
CONVENTIONAL PROCESS
500
1000
1500
2000
2500
3000
3500
4000
Capacity, m /d
Figure 3-7 Cost Comparison, "Living Machine" Versus Conventional Technology
The cost differences at the 40,000 gpd and 80,000 gpd are within 15 percent and
therefore not significant at the level of precision expected for the estimating procedure. The cost
difference at 1,000,000 gpd is very significant and favors either of the two conventional treatment,
alternatives. Therefore, it can be concluded that the AEES process is not more economical than
conventional technology at flow rates less than 100,000 gpd and is considerably more expensive
at flow rates of 100,000 gpd or higher. This is probably a result of economy of scale issues. An
oxidation ditch at 100,000 or 1,000,000 gpd can usually be a single process unit whereas the
AEES system must have several replications of greenhouses and process tanks. OAI and LTI
have suggested that there are ways to reduce the system costs to make the "Living Machine"
more cost competitive with conventional processes at flow rates up to 1,000,000 gpd. However,
these claims remain to be fully documented and require further evaluation.
The cost comparisons presented above only consider the economics of providing wastewater
treatment. Other benefits which are more difficult to quantify include public acceptance and
aesthetics. The use of attractive plants in a greenhouse setting can significantly enhance the public
acceptance of the AEES concept as compared to conventional wastewater treatment processes.
Significant marketing opportunities may exist, particularly at design flow rates less than 100,000 gpd
where the costs seem to be comparable. However, the costs associated with any centralized
treatment alternative, including the AEES "Living Machine" may still be considered excessive for
many poor, small communities and further attention needs to be given to comparisons with
decentralized wastewater treatment alternatives, the subject of another recent EPA report to
Congress (11).
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3.8 AEES, San Francisco, CA
The AEES facility in San Francisco started operation in February 1995 with a target goal
of 60,000 gpd. It had reached a "steady state" flow rate of less than 10,000 gpd at the time it
was deactivated in December 1996.
The original pumice media in these EFB units experienced more significant abrasion than
the units at Frederick. The fine particles and the dust from the pumice created clogging
problems in the piping, requiring extra maintenance activity, as a result this media was replaced
with the higher density volcanic stone also used at South Burlington, VT. Typical performance
results (September 1996), at an average flow rate of 8,962 gpd per train are summarized in
Table 3.4
Table 3.4
San Francisco AEES "Living Machine" Performance Results for September 1996
Parameter AEES Influent Effluent Train A Effluent Train B
AH units in mg/L
COD
BOD
TSS
Total coli. (#/100 ml)
Fecal coll (#/1 00 ml)
NO./NO3
A/Wy7VW<
TKN
TP
Alkalinity
36
9
6
66,000
32,500
1
34
36
2
190
29
<5
1
76
47
14
1
2
2
100
22
<5
1
41
50
18
0
1
2
70
This system did not demonstrate the capability to meet the 2.2 coliform limit which is required
for 'Title 22" waters, even at the low flow rates (less than 10,000 gpd); UV disinfection would
probably be needed to insure satisfactory performance. The system was capable of producing a
very low turbidity at flow rates under 10,000 gpd. However, it is not clear that the process will be
cost effective at a flow rate which is only 30 percent of the intended goal.
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3.9 AEES, Harwich, MA
The AEES "Lake Restorer" has been in place, and in year-round operation since October
1992. Water quality sampling is not done on or directly around the "Lake Restorer." The impact
of the, "Lake Restorer" has been inferred from apparent improvements in water and sediment
quality from samples taken at seven sampling points around Flax Pond. Three of the sampling
points are in the eastern lobe of the pond which is generally isolated from the larger western
lobe. The "Lake Restorer" is located in the smaller eastern lobe of the pond.
It is probable that the waters and>sediments in Flax Pond have, in the past, been polluted
by the adjacent community landfill and septage disposal pits. The sandy glacial till in the area
allows a direct connection for contaminated groundwater to flow directly from the landfill to the
pond. It is believed that the greatest impact occurs in the smaller eastern lobe of the pond.
However, operation of the septage disposal pits ceased in 1991, about one year before the "Lake
Restorer" was put in place.
Unfortunately, the quality of the groundwater directly entering Flax Pond has not been
measured prior to or during the five year Study period so it is not possible to determine if changes
in pond or sediment quality are a result of the action of the "Lake Restorer" or to a cessation of
septage pit operations. Considering the porous nature of the soils and the close proximity of the
pond and land fill, it is likely that much of the liquid fraction of the septage percolated rapidly into
the soil and traveled with the upper levels of the groundwater to Flax Pond. Cessation of
septage disposal pit operations should have had a noticeable impact on water and sediment
quality in the pond, and could account for most of the improvements noted in the western lobe of
the pond. As noted in a previous section the "treatment" rate for the Lake Restorer is 20,000
gpd, but the groundwater recharge rate to the pond has been estimated to be 78,000 gpd. It is
difficult to understand how the "Lake Restorer" could have a significant impact on water quality
when the treatment rate is less than the groundwater exchange rate, unless the groundwater
quality has improved since the septage disposal pit operations ceased.
The available project funding limited the sampling frequency to a few grab samples on a
quarterly basis at the seven sampling stations. These data provide an inconclusive basis for
evaluation of the "Lake Restorer" capabilities. Also, this study did not focus directly on the
performance of the "Lake Restorer" device itself but instead looked at the water quality within the
pond. Characterization of the improvements in pond and sediment quality should include all
inputs and sinks before defensible inferences can be drawn regarding the contribution from the
"Lake Restorer." -
The present database is somewhat confusing and conflicting. The OAI reports claim a
significant reduction in sediment depth owing to "digestion" but the method used to estimate
sediment depth during most of the five year period is questionable. The progress reports claim a
very significant reduction in TKN and other pollutants has occurred in the sediments and infer
that the "Lake Restorer" is responsible. However, most of the reduction in sediment pollutant
concentration is reported in the samples collected from the western lobe of the pond while the
"Lake Restorer" is in the eastern lobe. The sediments at Station 6 (in the western lobe), for
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example, show a TKN concentration of 11,385 mg/kg in 1990 but only 2942 mg/kg by 1993,
which may be linked to the cessation of the septage pit operations. In April 1994 the
concentration is 5110 mg/kg and in April 1995, 3400 mg/kg, indicating that there has been no
apparent further improvement since septage pit operations ceased.
The same type of inconsistencies are apparent in the water quality data. In April and May
of 1994 the ammonia concentration in the eastern lobe averaged 1.1 mg/L and during the same
period in 1995 the ammonia concentration averaged 1.54 mg/L indicating no improvement during
the year. In the western lobe, where the "Lake Restorer" would have much less direct influence,
the average ammonia was 1.03 mg/L in 1994 and 0.5 mg/L in 1995 during the same April and
May period. The improvement in numbers and diversity of benthic life forms also should not be
claimed as a benefit of the "Lake Restorer" until the other potentially responsible factors have
been defined and eliminated.
It would appear that Flax Pond in Harwich, MA is an inappropriate location for an evaluation
of the "Lake Restorer" because of the uncontrolled and undocumented external influences on water
quality in the pond. The device depends on the use of the EFB modules for any treatment which
occurs. In the other applications of the AEES concept at Frederick, MD, South Burlington, VT, and
San Francisco, CA, the EFB units have shown a consistent ability to remove BOD and TSS and to
remove ammonia nitrogen via oxidation to nitrate. The "Lake Restorer" may find future application
in situations where these parameters are a concern. If any further evaluation of the concept is
intended it is suggested that it not be conducted at the Flax Pond site but at a location where an
adequate "control" can be established and where external influences do not impact on performance
of the system.
3.10 Summary '''
The four AEES demonstrations discussed in this report were supported by federal funding
provided by the U.S. Congress. The intent of the demonstration projects has been to show that
this technology can produce improved water quality under a variety of different circumstances
and to help encourage the implementation and use of this new technology if it is proven
successful, reliable, and cost effective: An independent EPA evaluation of the technology has
been undertaken to determine the effectiveness of the various demonstration projects, if they
have met their stated treatment goals, and to evaluate the cost of the AEES "Living Machine"
technology as a wastewater treatment process. However, application of the technology has
already commenced prior to completion of these demonstrations and evaluation. The AEES
technology is commercially available through Living Technologies Inc.; Burlington, VT, and at
least three facilities treating commercial or industrial wastewatersare either in operation, under
construction or planned in the U.S., Great Britain, and Australia.
The EPA evaluation of the AEES "Living Machine" technology indicates that it is capable
of reliable performance with respect to removal ofBOD^ TSS, and ammonia to target levels.
The process should also be capable of meeting target requirements for nitrate and total nitrogen
but that has not been conclusively demonstrated to date. However, it appears that the system
will not likely be capable of meeting the target goal for phosphorus (<3 mg/L) as presently
configured.
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As operated the EFB units at the San Francisco location were not capable of meeting the
target bacterial goals. Since they were operating at about 30 percent of the intended flow rate it
is questionable if the process would be cost effective. It does not appear possible to evaluate
the capabilities of the "Lake Restorer" at Harwich, MA, with the level of effort focused on that
system, since other local factors may be responsible for at least part of the apparent
improvements in water quality and benthic conditions in Flax Pond.
Based on the study at Frederick, MD (1) it can be concluded that the plants used in the
AEES system contribute minimally to treatment, and that the same process goals could likely be
achieved without any plants at all. The plants dp have the potential to contribute to treatment,
but there needs to be a larger number of plants to contribute significantly. The water surfaces
available in the current AEES process design are not sufficient to support enough plants to
contribute significantly to treatment. ' ,'
Cost comparisons with conventional wastewater treatment technology show that the
vAEES process is comparable in cost to construct and operate at flow rates less than 100,000
gpd. At flow rates higher than 100,000 gpd the conventional systems would be expected to be
more cost effective wastewater treatment systems. Still, the costs associated with centralized
treatment for small systems are often excessive for poor communities and greater attention
needs to be given to decentralized treatment alternatives which is the subject of another EPA
report recently submitted to Congress (11). ,
The AEES technology started out to be a true ecological system with a balanced
population of bacteria, algae, protozoa, plants, fish and other higher animals contributing to
wastewater treatment and dependent primarily on "solar powered greenhouse technology without
the use of chemicals." The early configurations called "Solar Aquatics " were developed and
demonstrated in Massachusetts, Vermont, Indiana, and Rhode Island. Translucent tanks were
used in these earlier systems to take advantage of solar energy on all of the tank surfaces.
However, the current AEES process was designed to use higher rate operation with smaller
numbers of larger and deeper tanks. As a result, the process has become less and less
"ecological" and more and more "conventional." The AEES system, as configured at Frederick,
MD and Burlington, VT, could be characterized as a conventional extended aeration process
followed by aerobic/anoxic filtration, with aesthetically pleasing plants growing on the water
surfaces. .
The proponents of the "Living Machine" technology claim that the technology is an
ecologically based process supported by solar energy and minimally dependent on mechanical
equipment and chemicals. However, the "Living Machine" actually utilizes the same mechanical
energy sources (at the same levels) and the same chemicals as many conventional wastewater
treatment systems. Solar energy appears to be incidental to the successful performance of the
AEES process. Solar energy, or the equivalent, is needed for support of the plants grown on the
system but it has been shown that the plants are not needed for the system to achieve its treatment
goals. The plants provide mostly an aesthetic and horticultural benefit.
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CHAPTER 4
CONCLUSIONS
1. The "Living Machine" in the present configuration can reliably meet process goals for removal
ofBODs, COD, TSS, A/HyA/H* and can produce an effluent with a fecal coliform of less than
200/100 mL
2. The "Living Machine" in the present configuration does not appear capable of meeting the
<3 mg/L phosphorus goal, and has not reliably met the nitrate goal of <5 mg/L The
determination of reliable capability for achieving the total nitrogen goal of <10 mg/L will
. depend on the performance of the South Burlington, VT, AEES "Living Machine"
demonstration project during further operations under steady state conditions at design
flows, especially during severe winter conditions.
3. The vegetation used in the "Living Machine" process, as presently configured, provides only
a marginal contribution to treatment. This is because there are not enough plants on the
limited water surfaces available to play a significant role in treatment. The plants do,
however, provide a very pleasing aesthetic environment which significantly enhances public
acceptance of the AEES "Living Machine" wastewater treatment technology.
4. The residuals (sludge and plant litter) produced by the "Living Machine" are comparable
volumeirically to that produced by an equivalent capacity extended aeration activated sludge
process.
5. The life cycle costs (construction.plus operation & maintenance) of the "Living Machine" are
comparable to conventional technologies capable of achieving the same treatment
performance at flow rates less than 100,000 gpd. At flow rates higher than 100,000 gpd the
"Living Machine" becomes more expensive. OAI and LTI have suggested that there are
ways to reduce the system cost, but this still remains to be demonstrated. .
6. Solar energy plays an incidental role in the "Living Machine" process. , The "Living Machine"
depends on the same mechanical energy sources (at the same levels) and the same
chemicals as many conventional wastewater treatment systems. The claims made by, the
concept developers that "the system can treat wastewater to advanced standards using solar
powered greenhouse based technology, without the use of chemicals" have not been
demonstrated.
4-1
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wastewater treatment systems.
water quality in the ^^£$$^ Frederick, MD and Burlington, VT. The
not yet been established under controlled conditions.
11 in context with the overall Agency budget constraints the continuation of federal funding
' support for these demonstration projects is not warranted.
4-2
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CHAPTER 5
REFERENCES
1. U.S. EPA. Interim Report^Evaluation of the Advanced Ecologically Engineered System
(AEES) "Living Machine" Wastewater Treatment Technology-Frederick, MD.-EPA 832-B-96-
002. Office of Water. Washington, D.C. September 1996.
2. Malina, J.F. and F.G. Pohland. Design of Anaerobic Processes for the Treatment of
Industrial and Municipal Wastes. Technomics, Inc. Lancaster, PA. 1992.
3. Landine, R.C., S.G. Bliss, G.J. Brown and A.A. Cocci. Anaerobic and Aerobic Treatment
of Potato Processing Wastewater-Case Study. In: Proceedings 46th Purdue Industrial
Waste Conference, 1991. Lewis Publishers. Boca Raton, FL 1992.
4. Reed, S. C., R. W. Crites and E.J. Middlebrooks. Natural Systems for Waste Management
and Treatment. McGraw Hill. New York, NY. 1995.
5. Josephson, Beth. Personal Communication - fax message. July 25, 1995.
6. Living Technologies, Inc. Interim Performance Report for the South Burlington, Vermont
"Living Machine." January - August 1996. Living Technologies, Inc. Burlington, VT.
September 1996; plus supplemental data supplied byMFEMPS for August - November 1996
with a memorandum dated January 22, 1997.
7. Reed, S. C., J. Salisbury, L Fillmore and R. Bastian. "An Evaluation of the "Living Machine"
Wastewater Treatment Concept." In: Proceedings, WEFTEC '96, Dallas,TX, Water
Environment Federation. Alexandria, VA. October 1996.
8. Ocean Arks International. Descriptive Information and Various Promotional Brochures.
1994.
9. U.S. EPA. Subsurface Flow Constructed Wetlands for Wastewater Treatment: A Technology
Assessment. EPA832-R-93-008. Office of Water. Washington, D.C. July 1993.
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11. U.S. EPA. Response to Congress on Decentralized Wastewater Treatment (Including
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EPA832-R-97-001b. Office of Water. Washington, D.C. March 1997.
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