Page 1 of 17 

### Performance of Passive Wastewater and Groundwater Nitrex TM 

### Nitrogen Removal System

Pio Lombardo

ABSTRACT Excessive nitrogen levels caused by inadequate wastewater treatment pose a threat to the ecological health of water resources in the United States. Very few appropriate options currently exist for nutrient removal from decentralized wa stewater flows. Conve ntional nutrient removal technologies, including carbon feed systems for n itrogen removal are generally operator intensive and complex. Decentralized wastewater management systems utilizing nutrient removal technologies provide a wastewater management option that is cost effective and protective of the environment, and avoids the need for centralized sewering. Based upon research at the internationally acclaimed University of Wa terloo, the new, patented, innovative NITREX TM 

### technology fulfills this need.

Also the passive NITREX TM 

### technology, which is a wood based reactive media, has been demonstrated to be capable of reducing wastewat er total nitrogen levels to less than 3 mg/l and nitrate levels below 0.10 mg/l N. The NITREX TM 

### technology can be incor porated into permeable reactive barriers (PRB) to remove nitrate-ni trogen from groundwater. The longevity of the NITREX TM 

### filter is estimated to be 20+ years with little operation and maintenance requirements.

The NITREX TM 

### Filter is the only known passive treatme nt technology to provide virtually complete single-pass nitrate removal to produce an effluent quality that meets the new stringent surface water discharge criteria for nitrogen.

The paper will present the results of indepe ndent EPA and State sponsored performance evaluations of Nitrex TM 

### wastewater nitrogen removal syst ems in Oregon, Montana, and Cape Cod, MA and field monitoring data from residential and commerci al installations. Moreover the results from a pilot project installed in su mmer 2005 will be presented demonstrating the effectiveness of the NITREX TM 

### permeable reactive barrier on Cape Cod for groundwater treatment. Testing and field applications show that the NITREX TM 

### technology can achieve high process reliability and strong performance in both wastewater and gr oundwater applications.

INTRODUCTION

This paper presents the results of a number of independent testing programs of nitrogen removal systems. In these testing programs, the passive NITREX TM 

### Filter system has demonstrated the ability to produce a wastewater effluent with a TN less than 3 – 4 ppm. The NITREX TM 

### Filter has been evaluated in the following testing programs:

__________ * Pio Lombardo, PE, President of Lombardo Asso ciates, Inc. of Newton, MA, Phone Number: (617) 964-2924, Email: pio@lombardoassociates.comPage 2 of 17 

###  LaPine, Oregon National Decentralized Wastewater Treatment and Disposal Demonstration Project funded by EPA evaluating 15 alternative, innovative denitrification systems. The Project is being performed by the Oregon Department of Environmental Quality, U.S.G.S. and the Deschutes County Environmental Heath Division. Project is ongoing. See http://www.deq.state.or.us/wq/la pinedata/SiteRptCriteria.asp The LaPine Oregon Project evaluated two NITREX TM 

### Filters at the reside nces of Flemming and Stone.

 Montana Department of Natural Resources ev aluation of three on-si te denitrification systems in Polson, MT. Project perfor med from Nov. 1999 to Aug. 2002. (Dupuis, MT DNR, 2001)

 Massachusetts Septic System Test Center, Otis Air Force Base Cape Cod, MA (2001 - 2005)

 University of Rhode Island

 6,000 gpd facility in Mashpee, MA

 Groundwater nitrate removal systems in Falmouth, MA

 Seven additional installations in Canada for individual and cluster wastewater systems, along with golf course and farmland r unoff treatment systems (since 1997)

A schematic of the NITREX TM 

### Filter system is presented on Figure 1.

Figure 1: NITREX TM 

### Filter system

Septic Tank N itrifying System NITREX TM Filter Drain fieldPage 3 of 17 

### The NitrexTM nitrogen removal mechanisms consist of ammonification and ni trification in a sand filter or other aerobic treatment system that provides complete nitrification as follows:

Organic Nitrogen → NH4 + NH4+ + 1.5 O2 → 2 H+ + H2O + NO3-

Denitrification in the NitrexTM filter occurs by hete rotrophic denitrificat ion using the NITREX TM


### media as a slow release carbon s ource by the following reaction:

4NO3 - + 5CH2O → 2N2 + 5CO2 + 3H2O + 4OH -
As stated in the EPA Nitrogen Cont rol Manual (1993), in nitrification:

 4.6 mg oxygen required/mg nitrogen oxidized

 7.1 mg CaCO3 alkalinity depl eted/mg nitrogen oxidized

 0.10 – 0.15 mg net volatile solids/mg nitrogen oxidized

in denitrification (anaer obic conditions required)

 2.9 mg oxygen liberated/mg nitrogen reduced

 3.6 mg CaCO3 alkalinity rec overed/mg nitrogen reduced

 net volatile solids removed/mg nitrogen redu ced is dependent upon carbon source and can be similar to other biological systems

For nitrification, alkalinity can become the limiting factor and is often adde d in high rate systems and in low alkalinity waters. With higher nitr ogen strength wastewater and in low alkalinity waters, alkalinity may limit complete nitrifica tion and thereby restrict nitrogen removal in heterotrophic denitrification systems. For wastew aters with 40 – 60 TN, alka linity levels need to be 284 – 426 mg/l for single pass filters and some other treatment processes. With recirculating media filters, the alkalinity requirements are reduced as the recirculating media systems regenerate some alkalinity and thereby net alkalinity requirements for complete nitrification are reduced. Typical alkalinity sources are (EPA, 1993):

 1.8 mg CaCO3 alkalinity added/ mg CaO (quicklime) added

 1.2 mg CaCO3 alkalinity adde d/mg NaOH (caustic) added

In biological denitrification, car bon feed/availability is usually the limiting factor and TN levels cannot generally be < 10 mg/l w ithout a carbon feed system.

As shown on Table 1, the passive NITREX TM 

### Filter system was determined to be the best performing nitrogen removal sy stem based upon testing 15 technol ogies at the LaPine, Oregon project ( http://www.deq.state.or.us/wq/onsite/LaPine.htm ), as it achieved an effluent TN quality of 3 ppm. All data for a ll the tested systems is publicly av ailable at the above web site and was subjected to extensive QA/QC procedur es performed by the Oregon Department of Environmental Quality.Page 4 of 17 Technology Mean Effluent TN Standard Deviation 1 NITREX 2.4 0.3 2 Biokreisel 14.0 0.9 3 A X-20 17.0 1.1 4 RX-30 18.8 1.1 5 A mphidrome 26.3 2.0 6 EnviroServe r 32.3 1.5 7 FAST, w/o RV 36.4 1.6 8 Nayadic 37.2 1.9 9 Dyno2 50.2 2.5 10 Puraflo 51.4 2.0 11 Lined Sand Filte r 51.4 2.6 12 Bottomless Sand Filter 56.5 2.5 13 NiteLess 61.0 2.3 14 Septic Tank 66.1 1.1 15 IDE A 96.8 30.5 Technology Total Nitrogen Effluent Quality (mg/L)



### Figures 2 through 7 present the La Pine Total Nitrogen Test Results for septic tank effluent, sand filter effluent and NITREX TM 

### Filter system effluent and NITREX TM 

### Filter effluent temperature for the LaPine Flemming residence, Stone Re sidence and Polson, MT site, respectively.

As can be seen from Figures 2 – 7, the NITREX TM 

### Filter system was able to consistently produce an effluent with a total nitrogen of less than 3 – 4 ppm. As it is known that denitrification slows with lower temperatures (EPA, 1993), the NITREX TM 

### Filter systems did exhibit less than complete denitrification during cold wastewater pe riods. The data shows that denitrification in the NITREX TM 

### Filter system occurs at reduced rates when wastewater temperatures are below 48°F. The lower reaction rate at lower temperatures can be addr essed with longer detention times in the Nitrex filter.Page 5 of 17 Figure 2 - La Pine, Oregon – Fleming Residence – Tot al Nitrogen Influent & Nitrex Effluent Quality

Figure 3 - La Pine, Oregon – Fleming Reside nce, Wastewater Effluent Temperature Total NItrogen

0 10 20 30 40 50 60 70 80 90

10/1/2000 1/9/2001

4 / 1 9 /20 0

1

7 /28

/20 0

1 11/5 / 200 1

2 /13

/20 0 2 5/24 / 200 2 9/1

/2

002 12/10/2002 3/2

0 /2003

6 / 2 8 /20 0 3

DateTN (mg/L) Septic Tank Effluent Sand Filter Effluent Nitrex Effluent

Temperature (C)

0 2 4 6 8 10 12 14 16 18 20

1 0/1/20 0 0

1 /9

/2001

4 /19/20 0 1 7/28/2001 11/5/2001 2/13/2002 5/2

4 / 20

02 9/1

/2

002 12/

10

/20

0 2 3/2

0/20 03 6/2

8/20 0 3

DateTemp (C)

Nitrex EffluentPage 6 of 17 Total NItrogen

0 10 20 30 40 50 60 70 80

1 0 / 1 / 2 0 0 0 1/9/2001 4/19/ 2 0 0 1 7/28/ 2 001

1 1 / 5 / 2 0 0 1 2/13/2002 5/2

4 / 2 0 0 2

9 /1/2002 12/10/ 2 002

3/20/2003

6 / 2 8 / 2 0 0 3

DateTN (mg/L) Septic Tank Effluent Sand Filter Effluent Nitrex Effluent Figure 4: La Pine, Oregon – Stone Residence – Wastewater Effluent Temperature

Figure 5: La Pine, Oregon – Stone Residence – To tal Nitrogen Influent & Nitrex Effluent Quality Temperature (C)

0 5 10 15 20 25

10

/1/2000
1/ 9/

2 00

1
4/

1 9/

2 001
7/

28/2001
11

/5/2001
2/

1 3/

2 002

5/

24/2002 9/

1/ 2 00

2 12/10/200 2

3/

20/2003

6/

28/2003

DateTemp (C) Nitrex EffluentPage 7 of 17 Figure 6: Polson, MT – Total Nitrogen Influent & Nitrex Effluent Quality

Figure 7: Polson, MT – Wastewater Effluent Temperature Total NItrogen

0 10 20 30 40 50 60 70

Ja

n

- 0 0

J

a n

- 0 0

J

a n

- 0 0

Ja

n

- 0 0

Feb-00 Feb-00 Feb-00 Ma r- 0 0

Ma r- 0 0

DateTN (mg/L)
Septic Tank Effluent Sand Filter Effluent Nitrex Effluent

Effluent Temperature (C)

0 5 10 15 20 25 30

Ja

n -0

0 Ja n -0

0 Jan - 00 Jan-00
F

e b-

0

0
F e b-

0

0 Feb-00 Mar-00

DateTemp (C)

Nitrex EffluentPage 8 of 17 Figure 8: Mashpee, MA 5,750 gpd NITREXTM Wastewater SystemsPage 9 of 17 

### Recent data for the 5,750 gpd design flow Nitrex sy stem in Mashpee, MA is presented below:

Date Total Nitrogen May 10, 2006 < 5.0 mg/l June 14, 2006 < 7.0 mg/l July 18, 2006 < 2.6 mg/l MDL Septic Tank Effluent Waterloo Effluent Nitrex Effluent

BOD 2 270 9 130 1. Nitrex TM Filter removed all nitrate TSS 1 174 6 16 2. Waterloo Biofilter did not completely nitrify - 1.3 mg/l NH3 -N TKN 0.5 57 4.5 4.4 Ammonia as N 0.02 47 1.3 1.3 Nitrite as N 0.01 < 0.2 0.68 < 0.2 Nitrate as N 0.02 < 0.4 15.9 < 0.4 Org-N Calculated 10 3.2 3.1 TN - Calcualted 57.6 21.08 5.0 Alkalinity 1 252 62 137 pH 0.01 7.2 6.6 6.33

MDL Septic Tank Effluent Waterloo Effluent Nitrex Effluent

BOD 2 320 < 7 160 1. Nitrex TM Filter removed all nitrate TSS 1 218 2 14 2. Waterloo Biofilter did not completely nitrify - 3.2 mg/l NH3 -N TKN 0.5 58 5.6 6.7 Ammonia as N 0.02 44 3.2 2.9 Nitrite as N 0.01 0.29 <0.1 Nitrate as N 0.02 32.4 < 0.2 Org-N Calculated 14 2.4 3.8 TN - Calcualted 58 38.29 <7.0 Alkalinity 1 262 10.5 147 pH 0.01 6.82 6.06 6.32

MDL Septic Tank Effluent Waterloo Effluent Nitrex Effluent

BOD 2 65 TSS 1 TKN 0.5 Ammonia as N 0.02 0.23 Nitrite as N 0.01 Nitrate as N 0.02 < 0.4 Org-N Calculated TN - Calcualted Alkalinity 1 pH 0.01

MDL Septic Tank Effluent Waterloo Effluent Nitrex Effluent

BOD 2 290 7 49 TSS 1 84 1 2 TKN 0.5 48 1.2 2 Ammonia as N 0.02 35 0.29 0.5 Nitrite as N 0.01 <0.2 <0.2 Nitrate as N 0.02 16 <0.4 Org-N Calculated 13 0.91 1.5 TN - Calcualted 48 17.4 2.6 Alkalinity 1 184 72 155 pH 0.01 6.45 6.9 4. Valves need repaired and by taking off line not needed NitrexTM Filter modules, effluent BOD expected to be reduced to be < 30 McShane Main Street Villages - Mashpee Design Flow 5,750 gpd

COMMENTS 10-May-06

COMMENTS 26-Jul-06 1. System adjustments appear to be working to reduce ammonia from Biofilter and BOD from Nitrex 3. Valves need repaired and by taking off line not needed NitrexTM

Filter modules, effluent BOD expected to be reduced to be < 30

COMMENTS 14-Jun-06

3. Insufficient recirculation in the Waterloo appears to be the cause of the not complete nitrification as alkalinity was virtually completely consumed and pH reduced to 6.06.

18-Jul-06 COMMENTS

1. System adjustments made on July 11 appear to be working to reduce ammonia from Biofilter and BOD from NitrexPage 10 of 17 

### Nitrex performance at the Massachusetts Alternat ive Septic System Test Center over five years has been a median of 5.1 m/l TN and a mean of 6.4 mg/l – of which 2.9 mg/l has been due to incomplete ammonia nitrification by the recirculating sand filter.Page 11 of 17Page 12 of 17 

### Summary of NitrexTM Use Results

 Numerous installations have shown Nitrex TM filter systems to ach ieve <3 - 5 mg N/l

 No maintenance required

 Wastewater Temperatures above 40 to 48 °F optimal - lower temp requires larger systems. In colder climates, system insulation is important

The Nitrex TM 

### Permeable Reactive Barrier (PRB) Groundw ater Treatment has been used for groundwater nitrate removal (Robert son, W.D. and J.A. Cherry. 1997) and was recently tested by the Woods Hole Marine Biologi cal Laboratory at two coastal installations in Falmouth, MA (Cape Cod) under a project funded by the Coope rative Institute for Coastal and Estuarine Environmental Technology (CICEET) funded by NOAA.

Figure 9 illustrates how a PRB ope rates in removing nitrogen by crea tion of a reactive zone in the groundwater in which heterotrophi c denitrification occurs.

Figure 9 Permeable Reactive Barri er for Groundwater Nitrate Removal

Freshwater Aquifer PRB

Coastal area PRBPage 13 of 17 

### Figure 10

The benefits of the PRB are:

 Treats all sources of N

 Immediate impact on water quality

 Significant cost savings potential

 Localized recharge to aquifers

PRB Demonstration systems were installed in July 2005, Figure 10, ad jacent to the Childs River and Waquoit Bay as illustrated in Figures 11 an d 12. Groundwater nitrat e levels from 1.5 – 3.0 mg/l have been reduced to non-detect levels.

Figure 11 – Childs River

The project interim results are presented at http://www.ciceet.unh.edu/ and indicate that groundwater nitrate has been eliminated by th e PRB installations.Page 14 of 17 Flow TN Effluent Requirement Total Cost/gpd 6,000 < 10 $167,000 $27.83 9,500 < 10 $267,000 $28.11 15,000 < 7 $450,000 $30.00 30,000 < 7 $850,000 $28.33

Turnkey Price Includes Engineering and Construction 

## Nitrex TM 

## Treatment Systems Capital Costs (Design, Install, & Start-Up) Figure 12 Waquoit Bay

NitrexTM Design – Build Delivery Mechanism
 

### Footprint and not to exceed Budget provided at no cost to assess project feasibility
 

### Phase I services – development of fixed cost, final design and permitting
 

### Phase II – installation, start-up and performance certification Individual residences only available on volume basis Costs

•Nitrex Unit only - single family home $4,000 installed •Large systems sized based upon: •Minimum Temperature •Total N to be removed – i.e. from 20 to 5 ppm of N •Total System costs for residential applications: New System $18,000 - $24,000

•Comparison with Membrane Bioreactors •Generally 25+ % savings on capital costs •40+ % savings on annual O&M costsPage 15 of 17 

### OPERATION AND MAINTENANCE AND DISCUSSION

The NITREX TM 

### Filter systems have not required any maintenance (Rich, 2003). These installations have demonstrated the ability of passive NITREX TM 

### Filter system to consistently achieve a high degree of nitrogen removal duri ng full-scale operation. Du ring start-up elevated BOD occur as illustrated in the following Figures. However, initial elevated BOD values have not been a problem in drainfields. As can be seen in the Figures, the BOD is virtually all soluble as the TSS levels are extremely low, typically < 5 mg/l. In cases where low BOD concentrations are required, a post-polis hing step is provided. During longer- term operation, BOD stabilizes to < 20 mg/l depending on factors such as actual flow. Current filter designs incorporate hydraulic controls and recycle lines to reduce the start-up period. Monitoring eviden ce indicates complete nitrate removal can be achieved (<0.1 mg /l) while maintaining BOD <20 mg/l.

Nitrex TM Effluent BOD

0 20 40 60 80 100 120 140 160 180 200 220 240 260

0 100 200 300 400 500 600 700 800 900 1000

Days After Start-UpBOD (mg/L) LaPine Stone Data LaPine Fleming MA Otis Data Mashpee, MA Start-up occurred in winter for LaPine sites, 2nd peak occurred during warmer weather.

Mashpee site is only one with hydraulic controls -adjusted at day 60.Page 16 of 17 

### REFERENCES:

Crites, R. and G. Tchobanoglous, 1998. Small and Decentralized Wastewater Management Systems, McGraw Hill, Boston, MA.

Robertson, W.D. and J.A. Cherry. 1997 “Long Te rm Performance of Wat erloo Denitrification Barrier”. Land Contamination & Reclamation , Vol. 5 No. 3, pp 183 – 188. Robertson, W.D., D.W. Blowes, C. J. Ptacek and J.A. Cherry. 2000. Long-term performance of in situ reactive barriers for nitr ate remediation. Ground Water 38: 689-695. U.S. EPA (Environmental Protection Agency). 1993. Nitrogen control manual. Technical report EPA/625/R-93/010, Washington, DC. Nitrex TM Effluent TSS

0 10 20 30 40 50 60 70 80 90 100

0 100 200 300 400 50 0 60 0 700 800 900 1 0 00

Days After Start-UpTSS (mg/L)

LaPine Stone Data LaPine Fleming MA Otis Data Mashpee, MA Start-up occurred in winter, 2nd peak occurred during warmer weatherPage 17 of 17 

### Valiela, I., M. Geist, J. McClel land and G. Tomasky. 2000. Nitroge n loading from watersheds to estuaries: Verification of the Waquoit Bay ni trogen loading model. Biogeochem. 49: 277-293.