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ETV Joint Verification Statement

THE ENVIRONMENTAL TECHNOLOGY VERIFICATION

PROGRAM

TECHNOLOGY TYPE: BIOLOGICAL WASTEWATER TREATMENT –

NITRIFICATION AND DENITRIFICATION FOR NITROGEN 

REDUCTION

APPLICATION: REDUCTION OF NITROGEN IN DOMESTIC WASTEWATER 

FROM INDIVIDUAL RESIDENTIAL HOMES

TECHNOLOGY NAME: SEPTITECH® MODEL 400 SYSTEM

COMPANY: SEPTITECH, INC.

ADDRESS: 220 LEWISTON ROAD PHONE: (207) 675-5252

GRAY, MAINE 04039 FAX: (207) 657-5246

WEB SITE: http://www.septitech.com

EMAIL: info@septitech.com

NSF International (NSF) operates the Water Quality Protection Center (WQPC) under the U.S.

Environmental Protection Agency’s Environmental Technology Verification (ETV) Program. The WQPC 

evaluated the performance of a fixed film trickling filter biological treatment system for nitrogen removal 

for residential applications. This verification statement provides a summary of the test results for the 

SeptiTech® Model 400 System. The Barnstable County (Massachusetts) Department of Health and the 

Environment (BCDHE) performed the verification testing.

The U.S. Environmental Protection Agency (EPA) created the ETV Program to facilitate deployment of 

innovative or improved environmental technologies through performance verification and dissemination 

of information. The goal of the ETV program is to further environmental protection by substantially 

accelerating the acceptance and use of improved and more cost-effective technologies. ETV seeks to 

achieve this goal by providing high quality, peer reviewed data on technology performance to those 

involved in the design, distribution, permitting, purchase, and use of environmental technologies. 

ETV works in partnership with recognized standards and testing organizations, stakeholder groups 

consisting of buyers, vendor organizations, and permitters, and the full participation of individual

technology developers. The program evaluates the performance of innovative technologies by developing 

test plans that are responsive to the needs of stakeholders, conducting field or laboratory tests (as

appropriate), collecting and analyzing data, and preparing peer reviewed reports. All evaluations are 

conducted in accordance with rigorous quality assurance protocols to ensure that data of known and 

verifiable quality are generated and that the results are defensible.

NSF International U.S. Environmental 

Protection Agency
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ABSTRACT

Verification testing of the SeptiTech® Model 400 System was conducted over a twelve month period at 

the Massachusetts Alternative Septic System Test Center (MASSTC) located at Otis Air National Guard 

Base in Bourne, Massachusetts. Sanitary sewerage from the base residential housing was used for the 

testing. An eight-week startup period preceded the verification test to provide time for the development of 

an acclimated biological growth in the SeptiTech® System. The verification test included monthly 

sampling of the influent and effluent wastewater, and five test sequences designed to test the unit 

response to differing load conditions and power failure. The SeptiTech® System proved capable of 

removing nitrogen from the wastewater. The influent total nitrogen (TN), as measured by TKN, averaged 

39 mg/L, with a median of 39 mg/L. The effluent TN (TKN plus nitrite/nitrate) concentration averaged 

14 mg/L over the verification period, with a median concentration of 14 mg/L, which included an average 

TKN concentration of 6.8 mg/L and a median concentration of 5.7 mg/L. The system operating conditions 

(pumps and float settings) were controlled by a programmable logic controller (PLC), which was adjusted 

at the end of the startup period and then remained constant during the test. All mechanical equipment, 

pumps, level switches, alarms, etc. operated properly throughout the test. There were two servic e calls 

during the test. During the first call, eight months into the test, the system was cleaned and the PLC reset. 

The second call for a high water alarm determined that the effluent pipe had collapsed due to an 

installation problem not related to the system itself. After a lightning strike at the test site, the modem for 

the PLC was replaced.

TECHNOLOGY DESCRIPTION

The following description of the SeptiTech System was provided by the vendor and does not represent 

verified information.

The SeptiTech®System is a two stage treatment technology, based on a fixed film trickling filter, using a 

patented highly permeable hydrophobic media. The first stage of treatment occurs in the primary tank (for 

this test a 1,500 gallon two compartment septic tank, standard unit uses a 1,000 gallon tank) in which the 

solids are settled and partially digested. The second stage of the SeptiTech® System, is a processor that 

provides secondary wastewater treatment. Microorganisms present in the wastewater grow within the 

media, using the nutrients and organic materials provided by the constant supply of fresh wastewater to 

form new cell mass. Air is drawn into the system via an air intake pipe at the top of the SeptiTech System. 

Venturis located in the sprinkler head distribution piping aerate the wastewater sprayed onto the media. 

The system does not have a fan or compressor.

The SeptiTech® System is designed to remove total nitrogen from the wastewater by nitrification and 

denitrification. Nitrification occurs in the second stage of the SeptiTech System, where ammonia nitrogen 

is converted to nitrite and nitrate (predominately nitrate), while denitrification occurs in the

anaerobic/anoxic primary tank. According to SeptiTech, denitrification also occurs in the BioPack SF 30

Random Stack Media used in the system tested, which floats in the reservoir below the aerobic media.

The verification testing was performed using a full scale, commercially available unit, which was

received as a self-contained system ready for installation. Wastewater from the septic (primary) tank 

flows by gravity to the Processor reservoir section, located below the filter media. There are four pumps 

located in the reservoir. One pump recirculates wastewater from the reservoir to the top of the Processor, 

where the wastewater is sprayed over the filter media. The second and third pumps are used to return 

wastewater and solids from the reservoir back to the septic tank. The fourth pump is for the discharge of 

treated wastewater to the disposal location. The SeptiTech® Model 400 System is supplied with a PLC, 

which controls the frequency and duration of pump operation, as well as all alarm functions, data 

collection, and communication packages.
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VERIFICATION TESTING DESCRIPTION 

Test Site

The MASSTC site is located at the Otis Air National Guard Base in Bourne, Massachusetts. The site uses 

domestic wastewater from the base residential housing and sanitary wastewater from other military 

buildings in testing. A chamber located in the main interceptor sewer to the base wastewater treatment 

facility provides a location to obtain untreated wastewater. The raw wastewater, after passing through a 

one-inch bar screen, is pumped to a dosing channel at the test site. This channel is equipped with four 

recirculation pumps that are spaced along the channel length to ensure mixing, such that the wastewater is 

of similar quality at all locations along the channel. Wastewater is dosed to the test unit using a pump 

submerged in the dosing channel. A programmable logic controller (PLC) is used to control the pumps 

and the dosing sequence or cycle. 

Methods and Procedures

The SeptiTech® System was installed by a contractor, with assistance from the BCDHE support team, in 

June 2001. The unit was installed according to installation instructions supplied by SeptiTech, Inc. On 

June 14, 2001, the primary tank was filled with wastewater and the dosing sequence began. An eightweek startup period allowed the biological community to become established and the operating conditions 

to be monitored. The standard dosing sequence was used for the entire startup period.

The system was monitored during the startup period, including visual observation of the system, routine 

calibration of the dosing system, and collection of influent and effluent samples. Three sets of samples 

were collected for analysis. Influent samples were analyzed for pH, alkalinity, temperature, BOD5, TKN, 

NH3, and TSS. Effluent samples were analyzed for pH, alkalinity, temperature, CBOD5, TKN, NH3, TSS, 

dissolved oxygen, NO2  , and NO3 . 

The verification test consisted of a twelve-month test period, incorporating five sequences with varying 

stress conditions simulating real household conditions. The five stress sequences were performed at twomonth intervals, and included washday, working parent, low load, power/equipment failure, and vacation 

test sequences. Monitoring for nitrogen reduction was accomplished by measurement of nitrogen species 

(TKN, NH3, NO2, NO3). Biochemical oxygen demand (BOD5) and carbonaceous biochemical oxygen 

demand (CBOD5) and other basic parameters (pH, alkalinity, TSS, temperature) were monitored to 

provide information on overall system performance. Operational characteristics, such as electric use,

residuals generation, labor to perform maintenance, maintenance tasks, durability of the hardware, noise 

and odor production, were also monitored.

The SeptiTech® Model 400 System has a design capacity of 440 gallons per day. The verification test was 

designed to load the system at design capacity (± 10 percent) for the entire twelve-month test, except 

during the low load and vacation stress tests. The SeptiTech® System was dosed 15 times per day with 

approximately 29-30 gallons of wastewater per dose. The unit received five doses in the morning, four 

doses mid-day, and six doses in the evening. Dosing volume was controlled by adjusting the pump run 

time for each cycle, based on twice weekly pump calibrations. Volume per dose and total daily volume 

varied only slightly during the test period. The daily volume, averaged on a monthly basis, ranged from 

432 to 449 gallons per day. This was within the range allowed in the protocol for the 440 gallons per day 

design capacity.

The sampling schedule included collection of twenty-four hour flow weighted composite samples of the 

influent and effluent wastewater once per month under normal operating conditions. Stress test periods 
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were sampled on a more intense basis with six to eight composite samples being collected during and 

following each stress test period. Five consecutive days of sampling occurred in the twelfth month of the 

verification test. All composite samples were collected using automatic samplers located at the dosing 

channel (influent sample) and at the discharge of the unit. Grab samples were collected on each sampling 

day to monitor the system pH, dissolved oxygen, and temperature.

All samples were cooled during sample collection, preserved, if appropriate, and transported to the 

laboratory. All analyses were performed according to “Standard Methods for the Examination of Water 

and Wastewater,” 19th Edition, 1998. Washington, D.C. or other EPA approved methods. An established 

quality assurance/quality control (QA/QC) program was used to monitor field sampling and laboratory 

analytical procedures. QA/QC requirements included field duplicates, laboratory duplicates and spiked 

samples, and appropriate equipment/instrumentation calibration procedures. Details on all analytical 

methods and QA/QC procedures are provided in the full Verification Report.

PERFORMANCE VERIFICATION

Overview

Evaluation of the SeptiTech® Model 400 System at MASSTC began on June 14, 2001, when the system 

pumps were activated, and the wastewater dosing started. Three samples of the influent and effluent were 

collected during the startup period, which continued until August 13, 2001. Verification testing began at 

that time and continued for twelve months, until August 12, 2002. During the verification test, 54 sets of 

samples of the influent and effluent were collected to determine the system performance. 

Startup

Overall, the unit started up with no difficulty. The installation instructions were easy to follow and

installation proceeded without difficulty. SeptiTech representatives setup the PLC, which controlled all 

recirculation, recycle, and discharge pump times. No changes were made to the unit during the startup 

period, and no special maintenance was required. 

The SeptiTech® System removed CBOD5 and TSS after the first three weeks of operation, and continued 

to improve over the next five weeks. At the end of the eight week startup, effluent CBOD5 was <2.0 mg/L 

and TSS was 2 mg/L. The effluent TN concentration dropped from 24 mg/L after three weeks of

operation to 8.5 mg/L at the end of the startup period. Influent TN concentration ranged from 30 to 42 

mg/L during this time. Both the nitrification and denitrification processes were established as shown by 

the effluent TKN and nitrate concentrations of 2.3 mg/L and 6.0 mg/L, respectively. During the startup 

period, ten percent of the treated wastewater was being recycled to the septic tank. Shortly after the end of 

the startup, SeptiTech changed this recycle ratio to twenty percent by adjusting the pump rates in the 

PLC. The discharge pump rate was also adjusted to account for daily dosing of the system at full design 

flow. No other changes were made to the system. 

Verification Test Results

The sampling program emphasizes sampling during and following the major stress periods. This results in 

a large number of samples being clustered during five periods, with the remaining samples spread over 

the remaining months (monthly sampling). Both average (mean) and median results are presented, as the 

median values compared to average values can help in analyzing the impacts of the stress periods. In the 

case of the SeptiTech® System results, the median concentrations for ammonia nitrogen are somewhat 

lower than the average concentrations due to reduced nitrification efficiency from February through May, 

which impacted the twelve month average concentration.

The TSS and BOD5/CBOD5 results for the verification test, including all stress test periods, are shown in 

Table 1. The influent wastewater had an average BOD5 of 250 mg/L and a median BOD5 of 240 mg/L. 
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The TSS in the influent averaged 150 mg/L and had a median concentration of 140 mg/L. The effluent 

showed an average CBOD5 of 5.4 mg/L with a median CBOD5 of 4.7 mg/L. The average TSS in the 

effluent was 3 mg/L and the median TSS was 2 mg/L. CBOD5 concentrations in the effluent typically 

ranged from 1 to 10 mg/L, and TSS ranged from 1 to 10 mg/L, except for two sampling days during the 

twelve month verification test.

Table 1. BOD5/CBOD5 and TSS Data Summary

BOD5 CBOD5 TSS

Influent

(mg/L)

Effluent

(mg/L)

Percent

Removal

Influent

(mg/L)

Effluent 

(mg/L)

Percent 

Removal

Average 250 5.4 98 150 3 98

Median 240 4.7 98 140 2 98

Maximum 380 22 >99 280 13 >99

Minimum 140 1.3 93 73 1 90

Std. Dev. 66 4.0 1.3 46 3 2.1

Note: Data in Table 1 are based on 54 samples.

The nitrogen results for the verification test, including all stress test periods, are shown in Table 2. The 

influent wastewater had an average TKN concentration of 39 mg/L, with a median value of 39 mg/L, and 

an average ammonia nitrogen concentration of 24 mg/L, with a median of 24 mg/L. The average TN 

concentration in the influent was 39 mg/L (median of 39 mg/L), based on the assumption that the nitrite 

and nitrate concentrations in the influent were negligible. The effluent had an average TKN concentration 

of 6.8 mg/L and a median concentration of 5.7 mg/L. The average NH3-N concentration in the effluent 

was 5.1 mg/L and the median value was 2.4 mg/L. The nitrite concentration in the effluent averaged 0.32 

mg/L. Effluent nitrate concentrations averaged 6.7 mg/L with a median of 7.0 mg/L. Total nitrogen was 

determined by adding the daily concentrations of the TKN (organic plus ammonia nitrogen), nitrite, and 

nitrate. Average TN in the effluent was 14 mg/L (median 14 mg/L) for the twelve month verification 

period. The SeptiTech® System averaged a 64 percent reduction of TN for the entire test, with a median 

removal of 64 percent.

Table 2. Nitrogen Data Summary

TKN

(mg/L)

Ammonia

(mg/L)

Total Nitrogen

(mg/L)

Nitrate

(mg/L)

Nitrite

(mg/L)

Temperature

(°C)

Influent Effluent Influent Effluent Influent Effluent Effluent Effluent Effluent

Average 39 6.8 24 5.1 39 14 6.7 0.32 16

Median 39 5.7 24 2.4 39 14 7.0 0.31 15

Maximum 69 27 29 20 69 27 15 0.70 28

Minimum 18 0.7 19 0.6 18 7.5 0.3 0.04 5.8

Std. Dev. 6.6 6.3 2.3 5.2 6.6 4.6 4.5 0.10 6.4

Note: The data in Table 2 are based on 54 samples, except for Temperature, which is based on 48 

samples.

Verification Test Discussion

By the end of the eight-week startup period and start of the verification test, the system was operating 

with an acclimated biomass for both nitrification and denitrification. From August to December, the TN 

reduction was typically in the 61 to 78 percent range with TN effluent concentrations of 8 to 11 mg/L. 

The washday stress test performed in October 2001 did not appear to have an impact on nitrogen 

reduction. Likewise, in December 2001, the working parent stress test was performed and the
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performance of the unit remained steady during and following the stress period. In January and early 

February, the normal monthly samples showed a decrease in nitrification efficiency as measured by

increases in TKN and ammonia in the effluent, to 18 mg/L and 14 mg/L respectively. TN in the effluent 

increased to 20 mg/L in early February, during a period that corresponded to lower wastewater

temperatures and outside air temperatures. 

The low load stress test was started on February 18 and was completed on March 10, 2002. During the 

months of February and March, which included the stress test, the TN concentration varied from 7.5 to 17 

mg/L. Nitrification was still occurring, but at lower efficiency than during the previous five months. This 

also corresponded with the time frame with low effluent temperatures. At the end of the stress test, the 

system was still reducing TN concentrations. It does not appear that the low load stress test had a direct 

impact on the system, as the reduced nitrification efficiency started in the four weeks prior to the stress 

test. The post stress test period from mid-March through May showed consistent results with TN 

concentrations in the 15 to 18 mg/L range, except for one day at 27 mg/L. The power/equipment stress 

test was performed from May 6 to 8, 2002, with no apparent change in the effluent quality in the post 

stress test monitoring period.

A major change in performance occurred in late May or early June. The June 5 sampling showed TN 

concentrations reduced to 10 mg/L, and both TKN and ammonia concentration in the effluent decreased 

as well (6.0 mg/L and 3.7 mg/L, respectively). The nitrification process had improved and was reducing 

the ammonia concentrations to levels similar to the first five months of the test. As the TKN and ammonia 

levels decreased, the nitrate levels began to increase in the effluent, indicating that while the

denitrification process was removing some nitrate, it was not removing the increased concentration 

produced by the improvement in nitrification.

The vacation stress test started on July 8 and continued through July 16, 2002. During this stress test, 

there was no wastewater dosed to the system. The TKN and ammonia levels remained low in the post 

stress monitoring period but the nitrate levels increased from 9 to 15 mg/L. During this period nitrate was 

the main contributor to the effluent TN concentration, which ranged from 16 to 24 mg/L. It is not clear if 

the vacation stress test had a direct impact on the denitrification process, as the increasing nitrate levels 

began to occur when the nitrification process improved prior to the start of the vacation test. It is possible 

that the nitrate levels would have been higher, even if the stress test was not performed. However, the 

lack of flow during the vacation stress test reduced the amount of recycle flow from the SeptiTech 

reservoir to the septic tank. Therefore, there was less nitrified wastewater being recycled, which may have 

impacted the response time for the denitrifying organisms. 

The system performance remained consistent for the duration of the verification test. The TKN and

ammonia nitrogen effluent concentrations were consistently low and similar to the first five months of the 

verification test. The nitrate levels remained in the 13 to 15 mg/L range and the TN concentration in the 

effluent ranged from 14 to 20 mg/L. Alkalinity concentration in the effluent remained lower at 50 mg/L. 

It is not clear why the denitrification efficiency was lower throughout the July and August period as 

compared to the previous August through December period. 

Over the twelve-month test, the system did exhibit some instability in the individual nitrogen removal 

mechanisms, i.e. the nitrification and denitrification processes, particularly during December 2001 to July 

2002. These changes could be due to stressors not apparent from the data. Despite these changes, the 

process continued to remove TN, providing an overall stable effluent quality for TN. The verification test 

provided a sufficiently long test period to collect data that included both a long run of steady performance 

by the SeptiTech® System and a period of reduced nitrification and denitrification efficiencies. During the 

five months following startup, the TN removal was in the 60 to 80 percent range, with effluent 

concentrations typically in the 8 to 11 mg/L range. The SeptiTech System continued to remove TN in the 
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later periods, even though the nitrification or denitrification processes were not operating as efficiently. 

During the last six months of the verification test, the TN removal was in the 32 to 82 percent range, with 

most results in the 50 to 60 percent range. Effluent TN concentrations ranged from 10 to 27 mg/L, with 

most concentrations in the 15 to 20 mg/L range. The net effect of the lower performance in these later 

periods increases the average effluent TN concentration for the verification test to 14 mg/L. 

Operation and Maintenance Results

Noise levels associated with mechanical equipment were measured once during the verification period 

using a decibel meter. Measurements were made one meter from the unit, and one and a half meters above 

the ground, at 90° intervals in four (4) directions. The average decibel level was 60.0, with a minimum of 

58.9 and maximum of 61.5. The background level was 37.7 decibels.

Odor observations were made monthly for the last eight months of the verification test. The observations 

were qualitative based on odor strength (intensity) and type (attribute). Observations were made during 

periods of low wind velocity (<10 knots), at a distance of three feet from the treatment unit, and recorded 

at 90° intervals in four directions. There were no discernible odors during any of the observation periods.

Electrical use was monitored by a dedicated electric meter serving the SeptiTech® System. The average 

electrical use was 8.4 kW/day. The electrical use included a heater for the PLC, which was located

outside at the test site. In normal applications, the PLC is placed in the home and an auxiliary heater is not 

needed. The SeptiTech® System does not require or use any chemical addition as part of the normal 

operation of the unit.

During the test, no mechanical problems were encountered with the operation of the system. The system 

was cleaned after eight months by spraying water over the nozzles and media. This cleaning was 

performed when a service call was placed to SeptiTech in April 2002, based on site operators observing a 

lack of sound coming from the unit. During the service call, no problems were found with the unit. The 

PLC was reset and the system continued in operation. In June 2002, a high water alarm sounded and a call 

was placed for service. SeptiTech responded the next day and found the discharge pipe had collapsed. In 

addition, lightning had struck the test site, damaging the modem and causing the PLC to enter a “safe” 

mode. The discharge pipe was repaired, a new modem installed, and the PLC reset. The discharge pipe 

failure was apparently due to improper soil preparation and was not related to the system itself. No 

changes or adjustments were needed to the float switches or pumps after the initial changes following the 

startup period. 

The treatment unit appeared to be of durable design and also proved to be durable during the test. The 

polyethylene piping used in the system meets the needs of the application. Pump and level switch life is 

always difficult to estimate, but the equipment used is made for wastewater applications. The only trouble 

with the PLC was when lightning hit the site, at which time the modem was replaced to reestablish remote 

communications. 

Quality Assurance/Quality Control

NSF International completed QA audits of the MASSTC and BCDHE laboratory during testing. NSF 

personnel completed a technical systems audit to assure the testing was in compliance with the test plan, a 

performance evaluation audit to assure that the measurement systems employed by MASSTC and the 

BCDHE laboratory were adequate to produce reliable data, and a data quality audit of at least 10 percent 

of the test data to assure that the reported data represented the data generated during the testing. In 

addition to quality assurance audits performed by NSF International, EPA QA personnel conducted a 

quality systems audit of NSF International's QA Management Program, and accompanied NSF during 

audits of the MASSTC and BCDHE facilities.
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Hugh W. McKinnon Date

Director

National Risk Management Research Laboratory

Office of Research and Development

United States Environmental Protection Agency

Gordon E. Bellen Date

Vice President

Research

NSF International

NOTICE: Verifications are based on an evaluation of technology performance under specific, 

predetermined criteria and the appropriate quality assurance procedures. EPA and NSF make no 

expressed or implied warranties as to the performance of the technology and do not certify that a 

technology will always operate as verified. The end user is solely responsible for complying with 

any and all applicable federal, state, and local requirements. Mention of corporate names, trade 

names, or commercial products does not constitute endorsement or recommendation for use of 

specific products. This report in no way constitutes an NSF Certification of the specific product 

mentioned herein.

Availability of Supporting Documents

Copies of the ETV Protocol for Verification of Residential Wastewater Treatment

Technologies for Nutrient Reduction, dated November 2000, the Verification Statement, 

and the Verification Report are available from the following sources:

1. ETV Water Quality Protection Center Manager (order hard copy)

NSF International

P.O. Box 130140

Ann Arbor, Michigan 48113-0140

2. NSF web site: http://www.nsf.org/etv (electronic copy)

3. EPA web site: http://www.epa.gov/etv (electronic copy)

(NOTE: Appendices are not included in the Verification Report. Appendices are

available from NSF upon request.)

EPA’s Office of Wastewater Management has published a number of documents to assist 

purchasers, community planners and regulators in the proper selection, operation and 

management of onsite wastewater treatment systems. Two relevant documents and their 

sources are:

1. Handbook for Management of Onsite and Clustered Decentralized Wastewater

Treatment Systems http://www.epa.gov/owm/onsite

2. Onsite Wastewater Treatment Systems Manual 

http://www.epa/gov/owm/mtb/decent/toolbox.htm