United States
Environmental Protection
Agency
Site Technology Capsule
EcoMat Inc.'s Biological
Denitrification Process
Abstract
EcoMat, Inc. of Hayward, California (EcoMat) has developed
an ex situ anoxic biofilter biodenitrification (BDN) process.
The process uses specific biocarriers and bacteria to treat
nitrate-contaminated water and employs a patented reactor
that retains biocarrier within the system, thus minimizing solids
carryover. Methanol is added to the system as a carbon source
for cell growth and for inducing metabolic processes that
remove free oxygen and encourages the bacteria to consume
nitrate. Methanol is also important to assure that the nitrate
conversion results in the production of nitrogen gas rather
than the intermediate (and more toxic) nitrite.
EcoMat's BDN and post-treatment systems were evaluated
under the SITE Program at a former public water supply well
in Bendena, Kansas. Nitrate concentrations in the well ground-
water have historically been measured from approximately
20 to 130ppm, well above the regulatory limit of 10 mg/l. Low
concentrations of VOCs, particularly carbon tetrachloride
(CCI4), are a secondary problem. The overall goal of EcoMat
(the developer) was to demonstrate the ability of their pro-
cess to reduce the levels of nitrate in the groundwater and
restore the well as a drinking water source.
The SITE demonstration occurred between May and Decem-
ber of 1999 and was conducted in cooperation with the Kan-
sas Department of Health and Environment (KDHE). The study
consisted of fourseparate sampling events over714 months.
During these events EcoMat operated their system to flow
between three and eight gallons per minute. During that same
time period nitrate-Nitrogen (nitrate-N) concentrations in the
well water varied from greater than 70 mg/l to approximately
30 mg/l.
Since the post-treatment system implemented by EcoMat
varied for each of the four events, data from the four events
were analyzed separately. Formal statistical analyses were
used to address specific test objectives using a significance
level of 0.10. Events 1 and 2 were found to be successful in
meeting performance goals for significantly reducing levels of
nitrate-N and nitrite-N after BDN and after post treatment.
Events 3 and 4 were not shown to be successful in signifi-
cantly reducing levels of nitrate-N and nitrite-N after BDN and
after post treatment.
Dissolved oxygen (DO) measurements indicated that the
deoxygenating step of EcoMat's BDN process was not opti-
mized throughout the demonstration. The desired DO levels
of < 1 mg/l following the deoxygenating step in the process
were measured only during the first two events.
The effectiveness of the post-treatment systems was vari-
able fordifferent parameters. None of the post treatment sys-
tem combinations used during the demonstration was effec-
tive in removing residual methanol to the demonstration ob-
jective of < 1 mg/l. However, the increased level of filtration
incorporated following the first two events appear to have had
a substantial beneficial impact on solids carryover.
Introduction
In 1980, the U.S. Congress passed the Comprehensive Envi-
ronmental Response, Compensation, and Liability Act
(CERCLA), also known as Superfund. The Act is committed
to protecting human health and the environment from uncon-
trolled hazardous waste sites. In 1986, CERCLA was amended
by the Superfund Amendments and Reauthorization Act
(SARA). These amendments emphasize the achievement of
INNOVATIVE
TECHNOLOGY EVALUATION
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long-term effectiveness and permanence of remedies at
Superfund sites. SARA mandates the use of permanent solu-
tions, alternative treatment technologies, or resource recov-
ery technologies, to the maximum extent possible, to clean
up hazardous waste sites.
State and federal agencies, as well as private parties, have
for several years now been exploring the growing number of
innovative technologies for treating hazardous wastes. The
sites on the National Priorities List comprise a broad spec-
trum of physical, chemical, and environmental conditions re-
quiring varying types of remediation. The U.S. Environmental
Protection Agency (EPA) has focused on policy, technical,
and informational issues related to exploring and applying new
remediation technologies applicable to Superfund sites.
One such initiative is EPA's Superfund Innovative Technology
Evaluation (SITE) program, which was established to accel-
erate the development, demonstration, and use of innovative
technologies for site cleanups. EPA SITE Technology Cap-
sules summarize the latest information available on selected
innovative treatment, site remediation technologies, and re-
lated issues. These capsules are designed to help EPA reme-
dial project managers and on-scene coordinators, contrac-
tors, and other site cleanup managers understand the types
of data and site characteristics needed to evaluate effectively
a technology's applicability for cleaning up Superfund sites.
This Capsule provides information on a specific type of bio-
logical denitrification process owned and implemented by
EcoMat, Inc. (EcoMat) primarily to treat water contaminated
with high levels of nitrate (e.g., > 20 mg/l). This capsule pre-
sents the following information:
• Abstract
• Technology description
• Technology applicability
• Technology limitations
• Process residuals
• Site requirements
• Performance data
• Technology status
• Sources of further information
Technology Description
EcoMat's process is a type of fixed film bioremediation in
which specific biocarriers and bacteria are used to treat
nitrate-contaminated water. Unique to EcoMat's process is a
patented mixed reactor that retains the biocarrier within the
system, thus minimizing solids carryover. A 50% aqueous
methanol solution is added to the system as a source of car-
bon for cell growth and for inducing metabolic processes that
remove free oxygen. The resulting anaerobic environment
encourages the bacteria to consume nitrate. Methanol is also
important to assure that conversion of nitrate proceeds to the
production of nitrogen gas rather than terminating at the inter-
mediate nitrite, which is considered to be more toxic.
The mechanism for anoxic biodegradation of nitrate consists
of an initial reaction for removal of excess oxygen followed by
two sequential denitrification reactions (expressed in the equa-
tions below). The subsequent discussion refers to nitrate- and
nitrite-nitrogen values (nitrate-N and nitrite-N, respectively),
in which each mg/l of nitrate-N is equivalent to 4.4 mg/l of
nitrate and each mg/l of nitrite-N is equivalent to 3.2 mg/l of
nitrite.
Oxygen Removal:
CH3OH + 1.5O2
Denitrification Step 1:
CH3OH + 1.5O2 > CO2 + 2H2O
CH3OH + 3NO3 > 3NO2 + CO2 + 2H2O
Denitrification Step 2:
CH3OH + 2NO2
N2 + CO2 + 2OH + H2O
(1)
(2)
(3)
Overall Denitrification Reaction:
5CH3OH + 6NO3 > 3N2 + 5CO2 + 6OH + 7H2O (4)
In the first step, available oxygen must be consumed to a
dissolved oxygen (DO) concentration of < 1 mg/l. Then the
bacteria are forced to substitute nitrate as the electron accep-
tor and the nitrate is reduced to nitrite (equation 2). In the third
equation, nitrite is further reduced to nitrogen gas. Nitrite pro-
duction is an intermediate step and there is no a priori reason
to assume that the second reaction is at least as fast and/or
favored as the first reaction in the presence of a specific bac-
terial population. Consequently, any evaluation scheme must
establish that there is no buildup of nitrite, particularly since
the nitrite-N maximum contaminant level (MCL) for drinking
water sources is only 1 mg/l, one tenth that of nitrate-N. High
concentrations of nitrate and high nitrate/methanol ratios may
also affect the concentration of residual nitrite-N.
Figure 1 is a simplified process diagram of the EcoMat treat-
ment system used during the demonstration. As illustrated,
the system is comprised of two major components; a BDN
component and a post-treatment or polishing component. The
BDN component is intended to convert nitrates in the ground-
water to nitrogen, thus reducing nitrate-N concentrations to
acceptable levels. The post-treatment system is used for de-
stroying or removing any trace organics and intermediate com-
pounds potentially generated during the biological breakdown
of nitrate, and removing small amounts of bacteria and sus-
pended solids that are not attached to the biocarrier. The post-
treatment system can also incorporate traditional methods
for treating other contaminants, such as VOCs, that may be
present in the influent.
Biodenitrification (BDN) is conducted in two reactors, identi-
fied as R1 and R2 on Figure 1. The majority of the oxygen
removal step (Equation 1) occurs within R1, which EcoMat
also refers to as the "Deoxygenating Tank." Inside R1 are
bioballs (a standard type of biocarrier) which have been loaded
with denitrifying bacteria purchased from a commercial ven-
dor. These aerobic bacteria initially reduce DO levels of the
contaminated influent. A 50 percent aqueous methanol solu-
tion is metered to the tank to encourage the bacteria to begin
consuming nitrate in the resulting oxygen deficient water.
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INLET WATER
(FROM PWS # 1)
SI)
MeOH
(50%Aqueous
Solution)
Collection
Point
Perforated Plate
R1
Deoxygenating
Tank
I
(82)
M
ir
V /"
\ T
Biodenitrification
CARBON
FILTERS
, AIR STRIPPER
CARTRIDGE
FILTERS
S4)
Post-Treatment
Figure 1. Biodenitrification and Post-Treatment Systems Flow Diagram.
The deoxygenated water is pumped from the bottom of R1 to
the bottom of R2, referred to by the developer as "the EcoMat
Reactor". R2 is densely packed with a synthetic polyurethane
biocarrier called "EcoLink", which serve as the biocarrier for
a colony of specialized bacteria cultured fordegrading nitrate.
The EcoLink media is in essence small cubes of sponge-like
material, one centimeter on a side, that provide a large
surface area for growing and sustaining an active bacteria
colony. The cubes have contiguous holes so that bacteria
can propagate within them and nitrogen gas can exit. A
special additive to the polyurethane makes the surface more
hospitable to the bacteria.
A specially designed mixing apparatus within R2 directs
incoming water into a circular motion, which keeps the
suspended media circulating and enables the water to have
intimate contact with the media. Perforated plates within R2
retain the EcoLink biocarrier within the reactor, while
permitting passage of the water. The specific gravity of
EcoLink is slightly greater than that of water before nitrogen
production starts. Within R2, the majority of denitrification
(Equations 2 and 3) is conducted by the established
anaerobic bacteria that are continually fed methanol as a
carbon source. After a sufficient retention time the denitrified
water drains by gravity to an overflow tank, which allows for
a continuous and smooth transfer to the post-treatment
system.
EcoMat's post-treatment system can be subdivided into two
primary treatment parts: one part for oxidation and a second
part for filtration. The oxidation treatment is intended to
oxidize residual nitrite back to nitrate, oxidize any residual
methanol, and destroy bacterial matter exiting the EcoMat
Reactor (R2). The oxidation treatment may consist of
ozonation or ultraviolet (UV) treatment, or a combination of
both. Filtration usually consists of a clarifying tank and one
or more filters designed to remove suspended solids
generated from the BDN process. During the demonstration,
a variety of filter combinations were used, including a sand
filter and a series of variable-sized cartridge filters. The
cartridge filters used included "rough filters" (20um), "high
efficiency filters" (5|jm), and "polishing filters" (1 |jm). Carbon
cartridge filters were also used on occasion for removing
small amounts of CCI4.
During the demonstration,EcoMat experimented with
different levels and types of post-treatment. During Event 1
post-treatment consisted solely of chlorination without
filtration. During Event 2, post-treatment consisted of an
initial separation of suspended solids in a clarifying tank
("clarification"), followed by sand and cartridge filtration, and
finally by UV oxidation. Event 3 post-treatment consisted
initially of both ozone and UV oxidation, followed by
clarification, rough filtration, high efficiency filtration, carbon
adsorption, and polishing filtration. Event 4 post-treatment
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consisted of chlorination, clarification, high efficiency filtration,
air stripping for removing VOCs, and finally, polishing filtration.
Technology Applicability
The EcoMat BDN process was evaluated based on nine crite-
ria used for decision making in the Superfund feasibility study
(FS) process. Results of the evaluation are summarized in
Table 1.
The BDN process used during the demonstration was specifi-
cally targeted to the destruction/removal of nitrates in ground-
water. However, the developer views the EcoMat reactor as
an optimization vessel for growing different bacteria that can
degrade different contaminants. Thus, the developer's process
may have the potential to treat other contaminants, such as
perchlorate.
Table 1. FS Criteria Evaluation for the EcoMat, Inc. Biological Denitrification Treatment Process
Criteria
Overall Protection of Human
Health and the Environment
Compliance with Federal ARARs
Long-term Effectiveness and
Performance
Reduction of Toxicity, Mobility,
or Volume thru Treatment
Short-term Effectiveness
Implementation
Cost
Community Acceptance
State Acceptance
Technology Performance
Potentially provides protection of human health by reducing nitrate concentrations to below the regulatory
drinking water standards, improvement of the overall mechanical operation of the process and improvement
in the post- treatment portion of the process appear to be required for producing a more consistent treated
effluent with respect to nitrate-N, nitrite-N, methanol, and solids concentrations.
Requires compliance with RCRA and Safe Drinking Water Act treatment regulations. The post- treatment
system appears to need refinement for attainment of certain drinking water criteria (e.g., turbidity).
The technology is ex situ and is designed to treat nitrate- contaminated ground water within a very short time
period after the water is pumped from a well or holding tank. The areas of the country where this technology
is most applicable are in agricultural regions where substantial amounts of fertilizers are used seasonally. Thus,
the technology would not have a long term utility for the permanent restoration of an aquifer, but instead
would be capable of supplying potable water from perennially degraded aquifers.
Has the potential to reduce the toxicity of groundwater to an extent that would render the water a viable drinking
source. Does not pertain to reduction in mobility of groundwater. If applied to wastewater, the technology has a
significant potential for reducing the volume of wastewater that could potentially be released to the environment.
The short- term effectiveness ofthe technology is immediate. The biologicval processes used to treat nitrate-
contaminated waters have relatively short retention times. Presents minor short-term risks to workers from air
releases of ozone (if used) during post-treatment process activities.
Involves a testing or shakedown period. There is little to no environmental disturbance. Maintenance can delay or
prolong implementation.
An estimated $.50-2.50/1,000 gallons (excluding profits) with groundwater contaminated with 20-40 mg/1 nitrate,
using a flow rate of 100-1,000 gpm, with an online factor of 95%, over a one year period. Actual costs ofthe
remedial technology are site- specific and dependent on factors such as the local drinking water standards, the
influent nitrate concentrations, the presence of other contaminants in the groundwater, the well recharge capacity,
the level of post- treatment necessary, etc.
Presents minimal to not short term risk to community since all system components and treatment occur within a
secured building (the only exception being an air stripper, if used). If an ozone generator is incorporated into the
post-treatment system, monitoring for ozone emissions may be required. An air stripper, incorporated as a post-
treatment system for VOCs, would be the only exterior treatment and air emission source. The equipment is
relatively simple, easy to understand, and aesthetically acceptable to the public. There are minimal environmental
disturbances. No appreciable noise is generated.
State permits may be required if remediation is part of a RCRA corrective action. The permit may cover both the
biodenitrification and post-treatment processes as a whole, or may be required for specific proceses along the
treatment train (i.e., ozone, air stripping, etc.)
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Technology Limitations
The presence of additional contaminants in the water, other
than nitrate, can play a significant role in the effectiveness
and viability of the overall treatment system. The post-treat-
ment components that are required for treating these other
contaminants can complicate the system and increase the
potential for system irregularities.
Although the EcoMat BDN treatment system is designed to
operate unattended, several problems were encountered dur-
ing the demonstration which disrupted the system and led to
system shutdown. Examples of the types of problems en-
countered included malfunctioning pressure switches used
for controlling tank levels, clogging a perforated plate
withintheEcoMat reactor, and air leaks in piping that allowed
higher than desired DO levels in the bioreactor tanks. The
post-treatment system also required excessive maintenance
which necessitated shutting down the treatment system for
short periods of time (i.e., flushing and/or replacement of fil
ters to prevent microbial buildup, cleaning out of the clarifying
tank, etc.).
Process Residuals
There are essentially little to no process residuals associated
with the BDN component of EcoMat's process. The bioballs
used in the Deoxygenating Tank are durable and can be re-
used indefinitely. The EcoLink biocarrier, used in the mixed
reactor, is replaced only if they become overloaded to the
point where they sink out of suspension. (During the demon-
stration, the EcoLink biocarrier was changed out once.) Ac-
cording to the developer, other treatment units have operated
well over a year without the need for changing out the EcoLink
biocarrier.
Process residuals associated with post-treatment were evalu-
ated. For example, the clarifying tank generates sludge and
the cartridge filters periodically need replacing. If carbon fil-
tration is used for removing any VOCs from the water, the
carbon ultimately needs to be disposed of.
Site Requirements
Depending on the size and location of the treatment system,
a heated building may be required at a minimum to house the
system components. At the Bendena site the entire EcoMat
treatment system was contained inside a twelve foot wide,
twenty foot long, and twelve foot high shed. This provided
ample room for the Deoxygenating Tank and EcoMat Reactor
(both of which were two cubic yards in size with a total water
capacity of about 1,100 gallons), a small overflow tank, an
ozone generator, UV system, sand filter, cartridge filters, and
associated piping and pumps. The shed also provided work
space and enough storage space for equipment and reagents.
The main utility requirement is electricity, which is used to
operate the pumps and to provide heat during cold weather
conditions. The system used at Bendena required between 5
and 10 kW of electricity. Other utilities that may be required
include a telephone and facsimile hookup. If an on-line nitrate
analyzer is utilized, a phone modem can be installed to ac-
cess real-time data from a remote site.
Performance Data
The demonstration of the EcoMat BDN system was conducted
from May until December of 1999 at the location of a former
public water supply well in Bendena, Kansas. The study was
conducted in cooperation with the Kansas Department of
Health and Environment (KDHE), who provided for the con-
struction of a small building and the necessary utilities (elec-
tric, heat, and telephone services) to house and operate
EcoMat's systems. The KDHE also collected and analyzed
water samples independent of the SITE Program.
The demonstration focused on treating contaminated water
from the Bendena Rural Water District No. 2 Public Water Sup-
ply (PWS) Well # 1. This former railroad well, constructed in
the early 1900s, was at one time the sole source of water for
the town of Bendena. Nitrate is the primary contaminant. Ni-
trate-N levels in the well water have been historically mea-
sured at 20-130 ppm. Low levels of VOCs in the groundwater
are a secondary problem. CCI4 was the only VOC detected
during 1998 pre-demonstration sampling, at concentrations
ranging from 2-31 ug/l. During the demonstration, influent CCI4
concentrations were too low to evaluate.
The central goal of EcoMat was to demonstrate that its sys-
tem could produce water that would be in compliance with the
drinking water MCLs for both nitrate-N and nitrite-N, and at
the same time meet requirements for other parameters such
as turbidity, pH, residual methanol, suspended solids, and
biological material. With respect to both of their BDN and post-
treatment components EcoMat proposed the following perfor-
mance estimates:
I. With incoming groundwaterfrom Well #1 having nitrate-N
of 20 mg/l or greater, and operating at a flow rate of 3-15
gpm.theBDN unit would reduce the combined nitrate-N
and nitrite-N to a combined concentration (total-N) of 10
mg/l or less.
II. The post treatment or polishing unit will produce treated
groundwaterthatwill meet applicable drinking water stan-
dards with respect to nitrate-N (<10 mg/l), nitrite-N(<1mg/
I), and total-N (< 10 mg/l).
III. Coupled with the planned or alternative post-treatment,
the product water will consistently meet drinking water
requirements, except for residual chlorine. Specifically it
will not contain turbidity of greater than 1 NTU, detectable
levels of methanol (1 mg/l), or increased levels of biologi-
cal material or suspended solids, and will have a pH in
the acceptable 6.5-8.5 range.
The first two performance estimates formed the basis for the
statistically-based primary objective. The number of samples
needed for each event was calculated based on assumptions
about the variability of the final effluent. With the level of sig-
nificance set at 0.10 (i.e., statistical decisions were made
with 90% confidence), 29 samples were required for each
sampling event. In actuality 28 were collected for Event 1, 31
for Event 2, and 30 each for Events 3 and 4. So the 28-31
samples collected during the four events satisfied the desired
parameters for the hypothesis tests used for the demonstra-
tion.
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80
60
Combined
N03VNO?-
Concentration
(mg/l)
40
20
0.0
INLET
WATER
EVENT 1
(May)
EVENT 2
(August)
PARTIAL BDN
TREATMENT
EVENT 3
(October)
EVENT 4 34/ND
(December)
LEGEND
43/3 j = NO3-N/NO2-N Concentration in mg/l
(Rounded to two significant digits)
BDN = Biodenitrification
ND = Not detected at or above detection limits
POST BDN
TREATMENT
FINAL
EFFLUENT
Figure 2. Treatment Effectiveness for Nitrate-N and Nitrite-N for Each Event.
For each test conducted during the four sampling events,
water samples were collected from four specific sample
taps along EcoMat's process (shown on Figure 1). These
sample location points included the following:
1. An untreated ("Inlet Water") sample point located
between PWS Well # 1 and the Deoxygenating
Tank(S1);
2. A "Partial BDN Treatment"sample point located
between the Deoxygenating Tank and EcoMat
Reactor (S2);
3. A "Post BDN" sample point located between the
EcoMat Reactor and post-treatment system (S3);
4. A "Final Effluent" sample point located
downstream of the post-treatment system (S4).
To qualitatively illustrate the relative performance of the
four EcoMat sampling events, demonstration data were
plotted on Figure 2. Each of the sampling events is
graphed separately, with the four sample points
represented on the x-axis. Values within the boxes are the
average nitrate-N concentration and the average nitrite-N
concentrations, presented as a data pair. These data pairs
indicate how the process operated during the
demonstration with respect to the simultaneous destruction
of nitrate-N and production of nitrite-N. The plots also
indicate the effectiveness of post-treatment for destruction
of residual nitrite-N. Several interesting observations can
be made from the inter-event comparison shown in Figure
2 by tracing the levels of nitrate-N and nitrite-N across the
four sample points.
At the inlet water sample point, the levels of nitrate-N in
the untreated inlet water from PWS Well # 1 were well in
excess of the 10 mg/l MCL and the 20 mg/l threshold set
for the demonstration for all four sampling events. At this
point, the levels of nitrite-N are a For each test conducted
during the four sampling events. At this point, the levels of
nitrite-N are all reported as non-detects.
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At the partial BDN treatment sample point, nitrate-N levels
were reduced by a similar percentage (52-60%) for all four
sampling events. However, small amounts of nitrite-N were
being generated from the reduction of nitrate, causing nitrite-
N levels to rise slightly as expected. (See the Technology
Description section for technical discussion.) This pattern
held for all four sampling events.
At the post BDN treatment sampling point, the nitrate-N lev-
els were further reduced for all four sampling events. It is
interesting to note, however, that at this point the nitrate-N
levels for Events 1 and 2 fall below those for Events 3 and 4,
even though they were higher at the beginning of the demon-
stration. The nitrite-N levels for all sampling events are gener-
ally higher here, as expected. At the final effluent sample
point, the levels of nitrite-N remain essentially the same,
while levels of nitrite-N are generally reduced.
Table 2 presents the summary statistics for the critical data,
which is used to evaluate the effectiveness of EcoMat's
BDN and post-treatment systems with respect to nitrate-N,
nitrite-N, and total-N. To evaluate the post BDN and final efflu-
ent data against regulatory limits, the following analytical strat-
egy was used. For each event separately, an Exploratory Data
Analysis (EDA) was conducted for the post BDN total-N, the
final effluent nitrate-N, the final effluent nitrite-N, and the final
effluent total-N. The EDA consisted of graphing the data in
several formats and calculating summary statistics. These
graphs and summary statistics were used to make prelimi-
nary assumptions about the shape of the distributions of the
variables (i.e., in orderto identify possible appropriate statis-
tical hypothesis tests for the data).
After reviewing the graphs and summary statistics, Shapiro-
Wilk tests of Normality were performed. Based on the results
of these tests, either the Wilcoxon Signed Rank test or the
Student's t-test was chosen as the appropriate hypothesis
test. The mean or median of the variable (depending on which
hypothesis test was chosen) was evaluated against the ap-
propriate demonstration criterion, which was the regulatory
limitwhen rounded to a whole number. The post BDN total-N
data was tested against the demonstration criterion of 10.5
Table 2. Summary Statistics for the Demonstration (mg/1).
CRITICAL MEASUREMENT
Statistical Value
Post BDN
Total-N
Final Effluent
Nitrate-N
Final Effluent
Nitrite-N
Final Effluent
Total-N
Event I
Mean
Median
Std. Dev.
Statistical Hypothesis
Tests Results
1.917
1.270
1.474
1.654
1.600
1.509
0.410
0.113
0.424
2.064
1.676
1.445
Part I: Post BDN niediun total-N of 1.27 mg/1 was significantly below the criterion of 10.5 mg/1.
Part II: Final Effluent met combined criterion. The median total-N of 1.68 mg/1 is significantly below the criterion of 10.5
mg/1.
Event 2
Mean
Median
Std. Dev
Statistical Hypothesis
Test Results
6.145
4.600
3.781
4.132
2.220
4.237
1.459
1.200
1.155
5.590
3.610
4.898
Part I: Post BDN mediun total-N of 4.60 mg/1 was significantly below the criterion of 10.5 mg/1.
Part II: Final Effluent met combined criterion. The median total-N of 3 .6 1 mg/1 is significantly below the criterion of 10.5
mg/1.
Event 3
Mean
Median
Std. Dev.
Statistical Hypothesis
Test Results
10.613
10.950
3.706
8.347
8.350
2.854
1.550
1.400
0.851
9.897
9.825
2.978
Part I: Post BDN mediun total-Ndata, both the mean of 10.6 1 mg/1 and the median of 10.95 mg/1 were above the criterion
of 10.5 mg/1. Thus, no statistical test was needed to determine that the Post BDN data did not meet the criterion.
Part II: Final Effluent did not meet the combined criterion, since the nitrite-N mean was > 1.5 mg/1.
Event 4
Mean
Median
Std. Dev
Statistical Hypothesis
Test Results
11.197
10.550
5.079
10.63
11.750
5.023
0.870
0.076
1.523
11.993
12.076
5.324
Part I: For the Post BDN total-N data, both the mean and mediuan were above 10 mg/1, so no statistical test was needed
to determine that the Post BDN data did not meet the regulatory limit.
Part II: Final Effluent did not meet combined criteria since both the nitrate-N mean and median was > 10.5 mg/1.
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mg/l, using an error rate of 0.10. The results of this test are
referenced on the line entitled "Part I" in Table 2.
The final effluent had to meet a 3-part criterion:
• The mean or median nitrate-N was tested against the
demonstration criterion of 10.5 mg/l.
The mean or median nitrite-N was tested against the
demonstration criterion of 1.5 mg/l.
The mean or median total-N was tested against the
demonstration criterion of 10.5 mg/l.
All three of these criteria had to be met in order for the tech-
nology to be considered successful. Therefore, a family-wise
error rate was set at 0.10 for these three tests. The results of
this test are referenced on the line entitled "Part II" in Table 2.
As indicated in the "Statistical Hypothesis Test Results" rows
of the Table 2 summary statistics, Events 1 and 2 were found
to be successful in meeting performance goals for signifi-
cantly reducing levels of nitrate-N and nitrite-N after BDN and
after post treatment. However, Events 3 and 4 were not shown
to be successful in significantly reducing levels of nitrate-N
and nitrite-N after BDN and after post treatment.
Table 3 presents an overall summary of relevant criteria-ori-
ented data collected for key parameters during the demon-
stration as averages per event. As shown, neither the carbon
filtration employed during Event 3 nor the air stripping em-
ployed during Event 4 appears to have significantly impacted
methanol levels in the final effluent (methanol was not de-
tected above 1 mg/l in the untreated well water). Although
total suspended solids and turbidity parameters improved to
acceptable or near acceptable levels when filtration was em-
ployed, carryover of biological material from the EcoMat re-
actor to the final effluent remained considerable. The overall
EcoMat process appears to have little impact on pH.
Technology Status
The treatment system operated at Bendena, Kansas is
EcoMat's first application of their BDN process to nitrate-con-
Table 3. Summary of Averaged Results for the EcoMat SITE Demonstration1.
PARAMETER
CRITERION
SAMPLING EVENT
Event 1 (5/6-15)
Event 2 (8/3-12)
Event 3 (10/20-28)
Event 4 (12/7-14)
Process Parameters
Flow (gpm)
Total Gallons Treated
DO in Partial BDN Effluent (mg/l)
3-15
-
--
3.0
42,000
1.1
3.5
45,000
1.0
4.2
49,000
2.1
6.2
61,000
2.8
Biodenitrification Parameters
Nitrate-N (mg/l)
Nitrite-N (mg/l)
Total-N (mg/l)2
<10
<1
<10
J.7J
a 4
2.J
4.1
1.5
5.6
8.3
1.5
9.9
11
0.8
12
Post-Treatment Parameters
Post-Treatment System
Residual Methanol (mg/l)
Turbidity (NTU)
Total Suspended Solids3
pH Range (min-max)
Total Heterotrophs (% change)
Fac. Anaerobes (% change)
Fecal Coliform (% change)
<1 mg/l
<1 NTU
< iniet water
6.5-8.5
< iniet water
<_inlet water
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laminated groundwater. Prior to this, their systems have been
installed in-line with commercial size aquarium filtration sys-
tems for removing nitrate in saltwater.
EcoMat has indicated they also have the ability to cultivate
different microbes in their mixed reactor to treat other types
of inorganic pollutants. Recently, the company has designed
and delivered a biological reactor to treat perchlorate at a DoD
facility in California.
Sources of Further Information
An Innovative Technology Evaluation Report (ITER) for the
EcoMat technology has been prepared in unison with this
Capsule report. The ITER is anticipated to be available in the
summer of 2003. The ITER provides more detailed informa-
tion on the EcoMat technology, a categorical cost estimate,
and a more thorough discussion of the SITE demonstration
results.
EPA Contact:
U.S. EPA Project Manager
Randy Parker
U.S. Environmental Protection Agency
National Risk Management Research Laboratory
26 West Martin Luther King Jr. Dr.
Cincinnati, OH 45268
(513)569-7271
Parker.Randy@epa.gov
Developer Contacts:
Peter Hall / Jerry Shapiro
EcoMat, Inc.
26206 Industrial Blvd.
Hayward.CA 94545
(510)783-5885
e-mail: info@ecomatinc.com
www.ecomatinc.com
Sfafe of Kansas Contact:
Rick L. Bean, Chief, Remedial Section
Bureau of Environmental Remediation
Kansas Dept. of Health and the Environment
Forbes Field, Bldg. 740
Topeka.KS 66620-0001
(785)296-1675
References
SAIC. May 2001. EcoMat Inc.'s Biological Denitrification Pro-
cess. Draft Innovative Technology Evaluation Report.
SAIC. April 1999. Quality Assurance Project Plan for EcoMat
Inc.'s Biological Denitrification and Removal of Carbon Tetra-
chloride at the Bendena Site, Doniphan County, Kansas.
Shapiro, JL., P. Hall, and R. Bean, "Ground Water Denitrifica-
tion at a Kansas Well." Presented at the Technology Expo and
International Symposium on Small Drinking Water and Waste-
water Systems, Phoenix, Arizona, January, 2000.
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