U.S. Environmental Protection Agency
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Residential Nutrient Reduction
Tlie U.S. EPA Environmental Technology Verification
(ETV) Program's Water Quality Protection (WQP) Cen-
ter, operated by NSF International under a coopera-
tive agreement with EPA, has verified the performance
of six technologies for reducing the nutrient nitrogen in
domestic wastewater discharged from single-family
homes.1 These technologies are designed for homes that
rely on onsite wastewater disposal, and remove total
nitrogen from the wastewater by biological nitrification
and denitrification. Unlike traditional onsite systems
consisting of septic tanks and soil adsorption systems,
the ETV-verified technologies are designed to actively
promote nitrogen removal via nitrification/
denitrification processes.
Test Description and Results
ETV testing of the six residential nutrient reduction
technologies verified the nitrogen reduction perform-
ance of systems designed to treat residential wastewater.
Verification testing of five of the systems was conducted
over a 12 to 13 month period at the Massachusetts Alter-
native Septic System Test Center (Otis Air National
Guard Base, Bourne, MA). Sanitary sewage from base
residential housing was used for the testing. The sixth
system, the RetroFAST®, was tested over a 12 month
period at the Mamquam Wastewater Technology Test
Facility located at the Mamquam Wastewater Treatment
Plant (British Columbia, Canada). Verification testing
of all six systems included, at a minimum, monthly sam-
pling of influent and effluent wastewater and five test
sequences designed to test the unit response to differing
load conditions and power failure (washday, working
parent, low load, power/equipment failure, and vacation
conditions). Monitoring for nitrogen reduction was ac-
complished by measuring nitrogen species (TKN, NH3,
NO2, NO3) in influent and effluent wastewater. Total
and carbonaceous five-day biochemical oxygen demand
(BOD5/CBOD5) and other basic parameters
(continued on page 2)
Residential Nutrient Reduction at a Glance
EPA and states recognize septic systems as major
sources of ground water contamination. States
have identified septic systems as the second most
frequently reported contaminant source. Typical
pollutants from septic systems include nitrogen.
Nitrogen compounds also present concerns to the
nation's surface waters. EPA and states have iden-
tified nutrients, which include both nitrogen and
phosphorus, as the leading pollutant in lakes, reser-
voirs, and ponds. For surface waters, no data are
available concerning the nationwide distribution of
nutrient or nitrogen loading by source, but septic
systems are thought to contribute a significant
source of nutrients.
While nitrogen is an essential nutrient for plants,
excessive levels in surface waters can have detri-
mental ecological effects, such as large algae
blooms and proliferation of nuisance rooted
aquatic plants. EPA has also established drinking
water quality standards for nitrogen species such as
nitrate and nitrite because of human health con-
cerns.
Conventional septic system technology relies on
primary treatment (settling) for solids and organic
reduction prior to dispersion to the ground. The
ETV-verified technologies combine the primary
treatment with biological treatment to achieve a
higher level of treatment. Table 1 shows the resi-
dential nutrient reduction technologies verified by
ETV and the types of biological processes used by
the technologies to achieve nutrient reduction. The
biological processes utilized by the verified tech-
nologies promote the removal of nitrogen from
wastewater through the multi-step bacterial con-
version of ammonia and organic nitrogen to ni-
trates (nitrification) and the reduction of nitrates to
gaseous nitrogen (denitrification).
Table 1. Verified Residential Nutrient Reduction Technologies
Technology Name
Aquapoint, Inc., Bioclere™ Model 16/12
BioConcepte, Inc., ReCip® RTS -500 System
Bio-Microbics, Inc., RetroFAST® 0.375 System
F. R. Mahony & Associates, lnc.,Amphidrome™ Model
Single Family System
SeptiTech, Inc., SeptiTech® Model 400 System
Waterloo Biofilter Systems, Inc., Waterloo Biofilter®
Model 4-Bedroom
Design Capacity
(gallons per day)
400
500
375
400
440
440
Technology Description: Biological Process
Fixed film trickling filter biological treatment system
Media filter biological treatment system
Submerged attached-growth biological treatment system
Submerged growth biological treatment system
Fixed film trickling filter biological treatment system
Fixed film trickling filter biological treatment system
The ETV Program operates largely as a public-private partnership through competitive cooperative agreements with non-profit research institutes. The
program provides objective quality-assured data on the performance of commercial-ready technologies. Verification does not imply product approval or
effectiveness. ETV does not endorse the purchase or sale of any products and services mentioned in this document.
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Test Description and Results
(continued from page 1) (pH, alkalinity, TSS, tem-
perature) were monitored to provide information
on overall system performance. Operational char-
acteristics such as electric use, residuals genera-
tion, maintenance and labor, noise and odor pro-
duction were also monitored. ETV verified that
the six technologies reduced influent total nitrogen
by a range of approximately 51% to 64%, result-
ing in effluent total nitrogen concentrations of 14
to 19 milligrams per liter as nitrogen. Table 2
summarizes selected performance data for the
verified residential nutrient technologies. More
detailed performance data are available in the
verification reports for each technology which can
be found at http://www.epa.gov/etv/verifications/
vcenter9-3.html.
Selected Outcomes of Verified Residential
Nutrient Reduction Technologies
The most recent U.S. Census data estimate that
25,976,000 homes used septic tanks as of 2005,
representing approximately 22% of homes in the
United States (U.S. Dept. of Commerce, 2006).
ETV conservatively estimates that the potential
market for the ETV-verified residential nutrient
reduction technologies is about 10% (2.6 million
homes) of the 2005 Census estimate. Based on
two market penetration scenarios, 10% and 25%
of the total potential market, ETV estimates that:
• The ETV-verified residential nutrient reduc-
tion technologies could be applied at approxi-
mately 260,000 to 640,000 homes nationwide
where nitrogen could be a threat to ground
water or surface water (out of an estimated
potential market of 2.6 million homes).
• The technologies could reduce nitrogen load-
ing to ground water by 1,300 to 4,000 tons per
year (assuming they are applied by 260,000 to
640,000 homes), with associated benefits of
improved compliance with drinking water
standards and reduction of environmental
problems associated with nutrient loading.
The technologies also can address public policy
concerns associated with nitrogen and nutrient
releases to ground and surface waters from non-
point sources such as septic systems. Other bene-
fits include the establishment of a well-accepted
protocol that has advanced efforts to standardize
protocols across programs. At least four states
(North Carolina, Massachusetts, Pennsylvania,
and Florida) are currently using or are considering
use of ETV protocols in the evaluation of alterna-
tive technologies for the management of septic
systems or discharge of nitrogen.
2 Note that these estimates are based on a rough assumption about the
percent of homes with septic systems that represent a threat to ground
water or surface water. The 10% estimate is intended to provide an
approximation for the potential market for the ETV-verified systems
given a lack of quantitative estimates. For more information on how
this approximate potential market was developed, see Section 3.2 of
ETV Case Studies: Demonstrating Program Outcomes (U.S. EPA,
2006).
Table 2. Selected Performance of Residential Nutrient
Reduction Technologies
Vendor and
Model*
A
B
C
D
E
F
Average Total Nitrogen, mg/L as NB
Influent
36
37
39
37
39
37
Effluent
15
14
14
15
19
16
% Reduction0
58%
62%
64%
59%
51%
57%
A Because the ETV Program does not compare technologies, the performance results
shown in this table do not identify the vendor associated with each result and are not in
the same order as the list of technologies in Table 1 .
B mg/L as N = milligrams per liter as nitrogen
c Table in Metcalfand Eddy shows the following values of nitrogen reduction using older
technologies: Total Nitrogen Raw 35-80 mg/L and effluent of septic systems, 25-60 mg/
L, corresponding to 25 - 30 % removal. These numbers show that the new ETV technol-
ogy is an improvement - doubling previous removal rates.
References
U.S. Dept. of Commerce, 2006. American Housing Survey
for the United States: 2005. U.S. Census Bureau. July.
U.S. EPA, 2006. ETV Case Studies: Demonstrating Pro-
gram Outcomes, Volume 1. EPA/600/R-06/001. January.
(Primary source, with updates based on data from U.S.
Dept. of Commerce, 2006).
U.S. EPA ETV, http://www.epa.gov/etv.
Tcobanoglous, G. and F. Burton. Wastewater Engineer-
ing:Treatment, Dispossal and Resue. Metcalf & Eddy, Inc-
3rd Edition McGraw-Hill, me 1991.
Mamquam Test Facility
ETV Water Quality Protection Center
Ray Frederick, EPA Project Officer
frederick.rav@epa.gov
Tel: (732) 321-6627
Tom Stevens, NSF International
stevenst@nsf.org
Tel: (734) 769-5347
EPA/600/S-07/004
January 2007
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