Advanced Onsite Wastewater Treatment Technologies and Nitrogen Removal

Advanced Onsite Wastewater Treatment

Technologies for

Nitrogen RemovalPete Sabo

Hydro-Action

Overview• Nitrogen in the Environment• Wastewater Characteristics • Nitrogen Loading• Impacts of Nitrogen Pollution• Onsite Wastewater Treatment Technologies That

Reduce Nitrogen Loading• Types of Technologies in Suffolk County

Sources• Oakley, S. 2005. Onsite Nitrogen Removal Text. in (M.A. Gross and

N.E. Deal, eds.) University Curriculum Development for Decentralized Wastewater Management. National Decentralized Water Resources Capacity Development Project. University of Arkansas, Fayetteville, AR.

• Suffolk County Officials• Peconic Green Growth Organization• US EPA• NOWRA

Nitrogen• 78% of Earth’s atmosphere is Nitrogen gas• Natural occurring in the environment• Nitrogen is transformed in the environment

through multiple methods: fixation, ammonification, synthesis, nitrification, and denitrification (US EPA, 1993).

Nitrogen & Wastewater Pollution

• Range of Concentrations Cited in Literature, mg/L

Constituent Without Effluent Filter

With Effluent Filter

BOD5 (mg/l) 7 to 480 100 to 140TKN (mg/l) 9 to125 50 to 90Alkalinity

(as CaCO3) (mg/l) --- 70 to 594

Wastewater Pollution

• Basic calculations: • Family of 4; conventional septic; ¼ acre lot

• Total of 50 lbs/year (Hantszche and Finnemore, 1992)

• Comparing it to natural biological uptake: ¼ acre of Bermuda grass can absorb 50 lbs/year Nitrogen (WEF, 2001).

Wastewater Pollution

• Build up of nitrates in groundwater is the most significant long term consequence of onsite wastewater disposal

• (Hantzsche and Finnemore, 1992)

Wastewater Factors• 69% of Total Nitrogen

loading from septic tanks & cesspools • (source: Kinney, E. L. and Valiela, 2011)

Effluent Disposal Factors

• Location of plants roots, soil bacteria, all soil biota• Effluent being distributed below the zone where plants

and soil biota can absorb nitrogen• Closer to the water table and aquafer• Not evenly distributed either; dependent on water

consumption of the home• Great variation between per capita GPD, BOD, and

nitrogen effluent

Wastewater Factors•Urban density is largest factor•Higher density, less ability for plants to absorb Nitrogen

• (Gold and Sims, 2000; County of Butte, 1998; Hantzsche and Finnemore, 1992).

QUESTION #1

•What is the biggest long term concern of onsite wastewater treatment?

QUESTION #2

•What is the most significant factor for wastewater disposal?

Nitrogen Loading• Average per capita Nitrogen mass

loading of wastewater • 4 to 18 lbs per capita• 1.1 million people in Suffolk County with

onsite wastewater systems

• 360,000 homes with onsite treatment• 209,000 priority (proximity to water)• 252,000 without septic tank (pre-1972)

Existing Infrastructure

• 26% (388,180) Sewered• 194 WWTP• Need 550 more

• 74% (1.1 mil) Unsewered• Cesspools• Septic Tanks

QUESTION #3

•How many homes in Long Island utilize onsite wastewater treatment?

Human Health Impacts

Human Health Impacts

1.Methemoglobinemia

2.Cancer3.Birth Defects

MethemoglobinemiaStrong Evidence / Positive Correlation

Definition: • Lack of sufficient oxygen in blood• Nitrate ingested in infants less than 6 months• Hemoglobin to Methemoglobin • Reduced oxygen carrying capacity of circulatory

system• “Blue Baby Syndrome”

CarcinogenesisMedium Evidence/ Some Positive Correlation

Definition: • Cancer-causing• High nitrate levels in drinking water• Formation of nitrosamines (converted

nitrates/nitrite), which several are carcinogenic• Tested on animals and proven correlation

Birth DefectsWeak Evidence/ Lack of True Positive Correlation

Definition• Statistically significant increase in congenital

malformations associated with nitrate-rich well water

• Limited evidence/studies

QUESTION #4

•What are the human health concerns of nitrogen pollution?

Environmental Health Impacts

Ecological Impacts1.Eutrophication2.Oxygen Demand though Nitrification

3.Ammonia Toxicity to Aquatic Organisms

Eutrophication• Excess nitrogen can cause the stimulation of

growth, resulting in algal blooms or overgrowth of aquatic plants

• Dissolved oxygen depletion in the water: fish kills, aquatic species like shell fish, oysters, turtles, etc. die, decomposition and odors, biomass accumulation,

Oxygen Demand from Nitrification

• Nitrogenous biochemical oxygen demand (NBOD): Nitrification requires high levels of oxygen and will utilize as much as possible

• Greater demand on oxygen than carbonaceous biochemical oxygen demand

Ammonia Toxicity to Aquatic Organisms

• Nitrogen in the form, NH3-N can be toxic to aquatic organisms and kill them

QUESTION #4

•What are the three environmental impacts of nitrogen pollution?

Onsite Wastewater Treatment

• Primary Treatment• Collection• Sedimentation• Effluent Disposal

Advanced Onsite Wastewater Treatment• Primary Treatment• Collection• Sedimentation

• Secondary Treatment• Aerobic Treatment• Filtration• Effluent Disposal

Onsite Wastewater Treatment

How a Septic Tank Works

• Collection: • Collects the wastewater into a proportionally sized

vessel where sedimentation and anaerobic digestion occur

• Anaerobic digestion:• In an oxygen deprived environment, anaerobic

bacteria will treat a small percentage of the total wastewater mass, nutrients, etc. including Nitrogen

How a Septic Tank Works

• Sedimentation and Flotation: • Flotation occurs as well: mass density less than

water floats, such as fats, oils, greases, etc. which will coagulate and form a scum layer that sits above the septic tank outlet

• Septic tanks can remove 10-30% of Nitrogen mostly through settling the BOD solids and organic material

Advanced OWTS• Post-tank treatment can include aerobic (with oxygen)

or anaerobic (with no or low oxygen) biological treatment in:• suspended reactors• fixed-film reactors, • physical/chemical treatment, • soil infiltration, • fixed-media filtration• disinfection – chlorination -> UV

• Suspended Growth• Attached Growth• (Source: US EPA, 2002)

Nitrogen Removal• Sequential Nitrification -> Denitrification • Aerobic bacteria process first used to

remove BOD (solids) and nitrify organic Nitrogen and NH4; need to send aerobically treated wastewater to an anoxic environment

Nitrogen Removal• Sequential Nitrification -> Denitrification • Then in an oxygen deprived environment

(anoxic zone), denitrifiying bacteria will further metabolize the organic-N and NH4 into NO3 to N2 gas

• Using wastewater as the carbon source or including a technological feature that supplements the anoxic zone with external carbon source

Nitrogen Removal• “Biological nitrification/denitrification is

the only process that has been demonstrated to be feasible, both economically and technically, for onsite nitrogen removal (the same can be said for large-scale wastewater treatment plants)”

• (Whitmeyer, et al., 1991)

Nitrogen Removal• Nitrification requires high dissolved oxygen due

to the high nitrogenous biochemical oxygen demand of nitrification (NBOD).

• If there’s not enough oxygen, nitrification will be limited, and thus overall denitrification and total Nitrogen removal will be limited as well.

QUESTION #7

•What is the only process that’s economically & technically feasible to remove nitrogen?

Nitrogen Removal• Influent wastewater can be used as the carbon source

by recycling nitrified effluent to an anoxic reactor that precedes the aerobic nitrification reactor

• Operating alternating aerobic/anoxic zones on one reactor (sequencing batch reactor), or conveying the flow sequentially through alternating aerobic/anoxic zones

• (US EPA, 1993).

• Denitrification reactors can be designed as • suspended-growth • attached-growth processes

Nitrogen Removal• Nitrifying bacteria reproduce significantly slower than

heterotrophic bacteria, thus nitrification is controlled by heterotrophic oxidation of CBOD;

• High organic loading of CBOD will lead to heterotrophic bacteria dominating the environment of the biofilm.

• This affects the rates of nitrification and overall reduction in Total N.

• Sufficient capacity and detention time must be engineered in order to allow the nitrifying bacteria time to develop.

Nitrogen Removal• Temperature: Cold temperatures affect overall nitrogen

removal: colder temperatures require longer cell residence times in suspended-growth systems and lower hydraulic loading rates in attached-growth systems due to slower growth rates of nitrifying bacteria.

• Denitrification rates can be significantly affected by temperature drops below 20 °C, with the denitrification rate at 10 °C ranging from 20% to 40% of the rate at 20°C (US EPA, 1993).

Suspended Growth• Biological treatment processes in which the

microorganisms responsible for treatment are maintained in suspension within the liquid, usually through mechanical or diffused-air aeration (Metcalf & Eddy, 1991).

• Concentration of dissolved oxygen (DO) has significant effect on nitrification rates

• 2.0 mg/L is the target• Aerobic Treatment Units• Sequencing Batch Reactors

Suspended Growth• Aerobic Units (with pulse aeration)• Extended aeration activated sludge systems in

which aeration is periodically stopped or pulsed to promote denitrification.

• Continuous aeration• 38-61% Nitrogen Removal; 37 to 60 mg/L

Suspended Growth• Sequencing Batch Reactors• fill-and-draw, and alternating aerobic and anoxic

cycles, are created within a single reactor• 60% removal; 15.5 mg/L average influent TKN

concentration of 38.4 mg/L (Ayres Associates, 1998).

Attached Growth• “Biological treatment processes in which the

microorganisms responsible for treatment are attached to an inert medium such as sand, gravel, or plastic media, and can include either submerged or nonsubmerged processes (Crites and Tchobanoglous, 1998; Metcalf & Eddy, 1991).

• Surface area is crucial to the media in order to maximize oxygen transfer rates and maintain sufficient nitrification levels beyond the heterotrophic bacteria rates of growth.

Attached Growth• Single Pass Sand Filters (SPSF)• Most studied of all proposed nitrogen removal

technologies• Combination of CBOD removal and nitrification

within the sand medium at low organic loadings• Denitrification within anoxic microenvironments in

the sand• 8% to 50% removal• SPSF systems will always be denitrification-limited

due to the lack of availability of both a carbon source and anoxic conditions.

Attached Growth• Recirculating Sand/Gravel Filters (RSF)• Well studied• 15% to 84% removal • High nitrification rates and consistently higher

denitrification rates than SPSFs because the nitrified effluent can be recycled back to a recirculation tank where it mixes with wastewater from the septic tank, thus using the incoming wastewater as a carbon source.

• Sludge accumulation in the rock tank, however, can potentially cause serious operation and maintenance problems.

Technology Type Total-N Removal %

Effluent Total-N mg/L

Suspended GrowthAerobic units w/ pulse aeration 25-61 37-60

Sequencing batch reactor 60 15.5     

Attached GrowthSingle-Pass Sand Filters (SPSF) 8-50 30-65

Recirculating Sand/Gravel Filters (RSF) 15-84 10-47Multi-Pass Textile Filters 14-31 14-17

RSF with Anoxic Filter 40-90 7-23RSF with Anoxic Filter and External

Carbon Source 74-80 10-13

Onsite Technologies >85% NitrificationProcess Effectiveness Onsite Status In Suffolk County

Suspended GrowthAerobic Units Potential Insufficient design

and performance data. Operation and

Maintenance unknown.

Yes

       Attached Growth

Single Pass Sand Filters (SPSF)

Proven Widespread use. Need more design and performance

data.

Recirculating Sand Filters

Proven Widespread use. Need more design and performance

data.

Single-Pass Textile Filters

Potential Limited data to date. Probably similar to SPSF. Need design data for organic

loadings nitrification.

Multi-pass Textile Filters

Potential Limited data to date. Need design and

performance data.

Yes

SUMMARY OF INNOVATIVE/ALTERNATIVE ONSITE WASTEWATER TREATMENT FOR SINGLE FAMILY HOMES AND SMALL COMMERCIAL USES

Company Name of System Suffolk Cty. Status

NSF 245 or EPA 3rd Party

Test

NSF 350 reuse NSF

41 Dry Test

Seasonal Uneven Use No Possible

GoodTN mg/L (lower

is better) TN % ReduceOrganic/

Food loads Yes No

Option

H-20 Vehicular

loading Yes No Option

Function in Power Outage Yes/ No

Option2Capital Cost

Energy Cost/ month $0.18/

kWh

Replace septic tank Yes/No

OptionReplace

leaching PitFootprint

SF Depth Ft1More (link to

Fact Page)

TRICKLING FILTER / FIXED FILM (aerobic)/PACKED BEDAquaPoint BioClere Model 16/12 Y P 11-16 57-70% N N Y $$$ $19 N N 20 4-7' Link FP1

SeptiTech SeptiTech / STAAR Pilot 2 Y P 11 75% N O N $$$$ $29 N N 51 4.25 Link FP2

Eliminite C-Series Y G <15 >70% - 90% Y O N $$$* $5-11 O N 96 6-7' Link FP4

Orenco Systems AdvanTex AX20 Pilot 1 Y G 14-16 63- 82% N N N $$$* $2.60-$5.00 N N 20 0-2.6' Link FP5

Orenco Systems AdvanTex AX-20RT Pilot 1 Y G 14-16 63-82% N N N $$$* $5 N N 44 8.33' Link FP6

Premier Tech Aqua (div, Premier Tech Technologies Ltd.)

Ecoflo CoCo Filter ECDn Model Series Pilot 2 Y G <19 54% N N O $$$* $3.40 O N 50-93 SF 6.4' Link FP7

Waterloo Biofilter Waterloo Biofilter Pilot 2 Y G 14 59-65% N N N $$$* $7 N N 25-75 0-7 Link FP8

EXTENDED AERATION/ACTIVATED SLUDGEHydro-Action

Industries AN Series Pilot 1 Y P 11-15 58+% N O Y $$ $23 Y N 55 7.5' Link RP10

Norweco, Inc. Singulair TNT Pilot 1 Y P 12-14 68% N N Y $$ $17 Y N 55.5 8/10 Link FP11

EXTENDED AERATION/FIXED FILM (Submerged)/SUSPENDED GROWTH/ACTIVATED SLUDGEInfo Pending Adelante Consulting,

Inc. Pugo Systems Pilot 2 Y P 17 61% N N Y $$$* $14 Y N 40 8'

Bio-Microbics MicroFAST Pilot 2 Y P ~12 70% O O Y $$$ $15-$25 Y/O N Var. 4.6' Link FP12

Delta Environmental Products/ Pentair ECOPOD N Series (500-1500) Y Y/O 20 50% O N Y $$ $21 N/O N ~50 6-7' Link FP13

F. R. Mahony & Associates inc. Amphidrome Pilot 2 Y P 11 69% N N $$$$ $13 N N 120 10' Link FP17

Fuji Clean USA, LLC Fuji Systems CEN5, CEN7, CEN10 Pilot 2 Y P 10 74% N N Y $$ $7 Y N 33 sf 6.5' Link FP18

Jet, Inc. Model J-500CF Y N 13.2 72.6+% N Y $$ $25+ Y N 50 7' Link FP19

Norweco, Inc. Hydro-Kinetic Pilot 1 Y P 8 80% N N Y $$$ $14 Y/O N ~120 8' Link FP20

MEMBRANE BIOREACTORS with ACTIVATED SLUDGEBio-Microbics BioBarrier MBR Series Pilot 2 Y Y P <10 80-90% O O N $$$$ $18-27 O N ~ 150 7-8' Link FP21

BUSSE Green Technologies BUSSE MF - B - 400 Pilot 1 Y Y 16 60-90% Y N O $$$$ $16-27 Y N 40 0 Link FP22

QUESTION #6

•What are the two main types of advanced OWTS technologies?