Nitrogen, Septic

Systems, Great

Bay and Why it

Matters

Hugh Gregg Center

October 31, 2017

Christopher Albert

Hydrologic Cycle

• Why we care

• What are they

– Impacts

– Alternatives

Presentation Overview

• Water Usages

• Homeowner Maintenance

• Septic System History

• The Septic Tank

• Nitrification

• Advanced Systems

“Typical” household

DeOreo, et al. Residential End Uses of Water. 2016.

• 1999

– 177 gphd

• 2016

– 138 gphd

“Typical” per capita

• 1999

– 69 gpcd

• 2016

– 59 gpcd

Where do we use it?1. Bathroom = 57%

– Toilet = 24%

– Bathing = 23%

– Faucets = 10%

DeOreo, et al. Residential End Uses of Water. 2016.

2. Laundry = 17%

3. Leaks = 12%

4. Kitchen = 11%

SEPTIC SYSTEMS

Over 1 trillion gallons of septic tank effluent

disposed from individual septic systems per year.

Septic systems performance depends upon

• Location on the landscape

• Design

• Constructed

• Used or Abused - Homeowner

• Maintained / Serviced

• Technology

SIGNS THE SYSTEM IS

FAILED or FAILING

• warning signs of a failing system:

– Slowly draining sinks and toilets

– Gurgling sounds in the plumbing

– Plumbing backups

– Sewage odors in the house or yard

– Ground’s wet or mushy underfoot

– Grass growing faster and greener in one

particular area of the yard

• The Do’s

• Have it pumped when needed not when there

is a problem.– Inspect condition of tank

– Inlet and outlet baffles

– Scum layer

– Sludge layer

– Inspect D-box for signs of flooding

• Install a drywell for water treatment systems

• You don’t need septic tank additives

• Maintain Records of your Septic System

• Know the Location of you field and tank

• Flush Responsibly– Don’t Flush

• Coffee grounds

• Diapers

• Handi wipes

• Cat litter

• Cigarette buts

• Feminine hygiene products

• Kleenex

• Grease / Oil / Fats

All these items are non-organic and non-

biodegradable

• Garbage disposal – Increase Septic Tank Size 50%

• THE Don’ts• Flush Household chemicals down drain

• Paints

• Paint thinners

• Use of heavy bleach cleaners

• Use toilets bowl fresheners

• Pesticides

• Unused Medications

– These products will stress a septic tank

and destroy anaerobic biological

treatment in a septic tank and could

contaminate surface or groundwater

Septic Systems

• Outhouse

Commercial

Outhouse

• Two Seater

CESS POOLS pre 1970

MATERIALS USED

• CINDER

BLOCKS

• FIELD STONES

• RAILROAD

TIES

• BARRELS

DRYWELLSWILL HAVE A PRIMARY SEPTIC TANK BEFORE

DRYWELL

• Precast Concrete Structure – 1970’s

• PRECAST CONCRETE

• CINDER BLOCKS

• FIELD STONES

• RAILROAD TIES

Pipe and STONELeach Beds or Trenches 1970’s – 1980’s

ChambersConcrete Chamber or Plastic Chambers 1980’s – 1990s

Fabric Base SystemsEarly 1990’s – present

Alternative TechnologyLate 1990’s – present

CONVENTIONAL LEACH FIELD SEPTIC SYSTEMTreatment occurs within the leach field components

Septic Tank

Solids settle out in an

Anaerobic environment –

partial treatment

Leach Field

Aerobic treatment occurs along the interface

between the leaching component and the sand

at the “Biomat” (bacterial film)

High Vent

Low Vent

Treatment with the leach field

Further treatment occurs with the the soil below the Biomat

Treated effluent recharges the groundwater

Septic Tank Functions

• Solids removal by settling &

floatation

– 60-80% solids removal

• Anaerobic digestion

• Storage of solids

Function of a Septic Tank

full when total solids 25-30% tank

Image from University of Minnesota

TURBULENCE FROM HEAVY

USAGE

Checking the Sludge Levels

• Should be three distinct layers if functioning properly

• Heavy accumulation means excess inputs

• One uniform layer ~ excess chemical inputs?

Literature Review of

Raw and Septic Tank Effluent

Parameter Source Median

Value (mg/L)

Range

(mg/L)

Removal

%

CBOD5 Raw

STE

337

158

30 - 598

39 - 861

~60

COD Raw

STE

905

325

495-2,404

157-1,931

~60

TSS Raw

STE

280

61

18-2,233

20 - 276

~75

TN Raw

STE

63

54

44 - 189

26 – 124

~10

TP Raw

STE

19

10

13 - 26

3 – 40

~50

Nitrogen in Wastewater

• Urine contributes about 75% of the

nitrogen found in domestic wastewater

• Feces contributes about 20% of

nitrogen

• Soaps, cleaners and fertilizers, when

unregulated, can contribute to the

nitrogen concentrations

Nitrogen in Wastewater

• Organic nitrogen….. Organic-N

• Ammonium nitrogen…. NH4-

• Nitrite nitrogen…. NO2

• Nitrate nitrogen… NO3

Nitrogen Treatment Process

• Organic-N Urea 02

• Ammonification Nitrification

Denitrification

N2

NH3

NO3

Ammonification

• Ammonification is the transformation of

organic nitrogen to ammonium (NH4)

and ammonia (NH3) inorganic forms

pH dependant

• The septic tank provides 70% +/-

ammonification and about ¾ of the

remaining organic nitrogen is converted

through the secondary aerobic process

Nitrification

• Nitrification is the microbial conversion of

ammonium to nitrate

• Is a two-phase process that occurs in the

highly aerobic environment.

• Nitrite-oxidizing bacteria convert nitrite to

nitrate

Denitrification• Denitrification occurs under an anoxic

condition, DO <0.3 mg/L

• Nitrate (NO3) is reduced to nitrogen gas

(N2), which is passed back into the

atmosphere

• Microbial denitrification consumes 4 mg

carbon for each mg nitrate

• BOD/NO3 ratio is 4:1 and 8:1

• Recovers 3.57 mg alkalinity (CaCO3)

Nitrification Limiting Factors

• High organic concentrations (BOD, COD)

• Lack of sufficient dissolved oxygen >2

• Insufficient alkalinity, CaCO3 > 100 mg/L

– Sufficient to buffer the process

• Low pH, optimum range 7-9

• Low temperture > 45 degree

• Toxic Inhibitors

• Carbon Source for denitrification

Innovative Technology

For

Nitrogen Reduction In NH

Solutions for Decentralized Wastewater

Treatment

HIGH GROUNDWATER

IMPAIRED WATERS AND SENSITIVE AREAS

GROUNDWATER SOURCE PROTECTION

SMALL LOTS OF RECORD

Organic Overload- High Strength

Waste (HSW)

• National glossary definition of HSW

Effluent from a septic tank or other pretreatment component that has:

BOD5 > 170 mg/L,

and/or TSS > 60 mg/L,

and/or (FOG) > 25 mg/L and is applied to an infiltrative surface

Hydraulic and Organic

Loading• Two main design parameters

– Hydraulic Loading• Rate that water will pass through the device

• Must provide sufficient retention time

• Wash-outs can occur on laundry day

– Organic Loading• Organic matter is food for microbes

• More food than microbes – poor quality effluent

• More microbes than food – high quality effluent

Recirculating sand/ gravel

filters (RSFs or RGFs)

Limitations

• Land Area

– Large area required

• Media Quality

– Lack of good quality media

• Installation Quality

– Installing contractors

• Serviceability

– Replacement of system

PRETREATMENT UNITS

Two General Types of Treatment:

Suspended and Attached Growth

Aerobic Treatment Units (ATUs)

Saturated units – bubble air through water

Media Filters

Unsaturated units – diffuse air through pore space

ATUs: Miniature WWTP• Aerobic

Treatment Units

• Biological

processes are

well understood

• Mix microbes,

wastewater, and

dissolved oxygen

To FinalTreatment

Influent

WatertightTank

AirDiffusers

SettlingSolids

AerobicBacteria and other Microorganisms

Air Supply

Clear Water Zone

Aeration ChamberDirty Water ZoneUpflow

Clarifier

Grade Elevation

(from primary treatment)

Treatment Train

May all be in one or

two units

Septic

TankATU

Pump

tank

Final

treatment &

dispersal

Comparisons of Domestic

WW Effluent

Constituent Septic tank ATU

BOD (mg/L) 140-220 5-50

TSS (mg/L) 50-100 5-100

Total (N mgN/L) 40-100 25-60

Total P (mgP/L) 5-15 4-10

Fecal col/100ml 1 million to

100 million

1,000 – 10,000

Siegrist, 2001

Single-Pass Media Filters (SPMF)

• Usually pressure dosed, but

some are gravity fed

• Applied wastewater

infiltrates the filter surface

• Percolates through the filter

only once,

then flows to the next

treatment step

• BOD = 5 mg/L

• TSS = 5 mg/L

• NO3 = 30 mg/L

SeptiTech Unit

• Recirculating biological trickling filter System

– Polystyrene hydrophobic bead filter media

– Circulated through filter media 70 times in a 24 hour time period - Mixed-liquor

– Programmable Logic Controller (PLC)

– Periodically pump back to ST for anaerobic digestion (denitrification)

Primary Septic Tank

SeptiTech Processor4” Inlet

1-1/2” Return

4” Inlet 2” Discharge

2/3 1/3

Effluent

Filter

2”

Air

1”

Elec

SeptiTech

SeptiTech Processor

Polystyrene Bead

Treatment Media

Self Cleaning Processor

Primary Septic Tank2 CompartmentEffluent Filter

External PipingInlet / Discharge Line

Return Line

Air Intake

Electrical Conduit

Textile-based Packed Bed Filter• Watertight structure with

media of particular specifications

• After being collected in a processing tank, effluent is distributed (by pressure or gravity) over the surface of the media

• Media provides surface area for bacteria and other microorganisms to treat the effluent

• Aerobic treatment zone

Orenco AdvanTex®

Control panel

Primary tank

Textile- Based

Packed Bed

Filters (PBF’s)

Recirc-return (5:1

ratio)

Leach Field vs Dispersal Field4 – Bedroom Single Family Home with 12 min/in perc. rate

Chamber Leach Field 768 SQ.FT. Req’d ( 16’ x 48’)

Fabric Wrapped Pipe Leach Field 220 L.F. Req’d ( 7.5’ x 62’)

Aerobic systems can receive between 75 to 90% reduction

Pipe & Stone Leach Field 1,200 SQ.FT. Req’d ( 20’ x 60’)

Cost and Maintenance

• Typical Cost Three Bedroom House

– Purchase Price between $7,000- $10,000

• Annual Inspection Cost

– $200 to $350 per year

• Energy Cost

– $5 to $15 per month

Testing Results

Orenco

• NSF testing

– 27 sites, mean 13 mg/L

Septitech

• Rye – Less then 14 mg/L Total Nitrogen

• Pinelands, NJ:

– 19 sites, mean 9.58 mg/L

SEPTIC SYSTEMS PROTECT OUR

LAKES, RIVERS, GREAT BAY AND

GROUNDWATER

FOR

FUTURE GENERATIONS

Thank You

Questions

Acknowledgements

Sara Heger, Univer. of Minnesota

Tracey Rioux- Sepitech

Cory Lyons - Orenco