Nitrogen, Septic Systems, Great Bay and Why it Matters

Transcription

1 Nitrogen, Septic Systems, Great Bay and Why it Matters Hugh Gregg Center October 31, 2017 Christopher Albert

2 Hydrologic Cycle Why we care What are they Impacts Alternatives

3 Presentation Overview Water Usages Homeowner Maintenance Septic System History The Septic Tank Nitrification Advanced Systems

4 Typical household gphd gphd DeOreo, et al. Residential End Uses of Water

5 Typical per capita gpcd gpcd

6 Where do we use it? 1. Bathroom = 57% Toilet = 24% Bathing = 23% Faucets = 10% 2. Laundry = 17% 3. Leaks = 12% 4. Kitchen = 11% DeOreo, et al. Residential End Uses of Water

7 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

8 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

9 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

10 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 nonbiodegradable Garbage disposal Increase Septic Tank Size 50%

11 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

12 Septic Systems Outhouse

13 Commercial Outhouse Two Seater

14 CESS POOLS pre 1970 MATERIALS USED CINDER BLOCKS FIELD STONES RAILROAD TIES BARRELS

15 DRYWELLS WILL HAVE A PRIMARY SEPTIC TANK BEFORE DRYWELL Precast Concrete Structure 1970 s PRECAST CONCRETE CINDER BLOCKS FIELD STONES RAILROAD TIES

16 Pipe and STONE Leach Beds or Trenches 1970 s 1980 s

17 Chambers Concrete Chamber or Plastic Chambers 1980 s 1990s

18 Fabric Base Systems Early 1990 s present

19 Alternative Technology Late 1990 s present

20 CONVENTIONAL LEACH FIELD SEPTIC SYSTEM Treatment occurs within the leach field components 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 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)

21 Septic Tank Functions Solids removal by settling & floatation 60-80% solids removal Anaerobic digestion Storage of solids

22 Function of a Septic Tank full when total solids 25-30% tank Image from University of Minnesota

23 TURBULENCE FROM HEAVY USAGE

24 Checking the Sludge Levels Should be three distinct layers if functioning properly Heavy accumulation means excess inputs One uniform layer ~ excess chemical inputs?

25 Literature Review of Raw and Septic Tank Effluent Parameter Source Median Value (mg/l) Range (mg/l) Removal % CBOD 5 Raw ~60 STE COD Raw ,404 ~60 STE ,931 TSS Raw ,233 ~75 STE TN Raw ~10 STE TP Raw ~50 STE

26 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

27 Nitrogen in Wastewater Organic nitrogen.. Organic-N Ammonium nitrogen. NH4- Nitrite nitrogen. NO2 Nitrate nitrogen NO3

28 Nitrogen Treatment Process Organic-N Urea 02 Ammonification NH3 Nitrification NO3 Denitrification N2

29 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

30 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

31 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)

32 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

33 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

34 Organic Overload- High Strength Waste (HSW) National glossary definition of HSW Effluent from a septic tank or other pretreatment component that has: BOD 5 > 170 mg/l, and/or TSS > 60 mg/l, and/or (FOG) > 25 mg/l and is applied to an infiltrative surface

35 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

36 Recirculating sand/ gravel filters (RSFs or RGFs)

37 Limitations Land Area Large area required Media Quality Lack of good quality media Installation Quality Installing contractors Serviceability Replacement of system

38 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

39 ATUs: Miniature WWTP Aerobic Treatment Units Biological processes are well understood Mix microbes, wastewater, and dissolved oxygen Air Supply Influent (from primary treatment) Watertight Tank Air Diffusers Clear Water Zone Upflow Clarifier Settling Solids Grade Elevation Aerobic Bacteria and other Microorganisms To Final Treatment Aeration Chamber Dirty Water Zone

40 Treatment Train Septic Tank ATU Pump tank Final treatment & dispersal May all be in one or two units

41 Comparisons of Domestic WW Effluent Constituent Septic tank ATU BOD (mg/l) TSS (mg/l) Total (N mgn/l) Total P (mgp/l) Fecal col/100ml Siegrist, million to 100 million 1,000 10,000

42 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

43 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)

44 2 Air 1 Elec SeptiTech Primary Septic Tank 2 Compartment Effluent Filter 1-1/2 Return SeptiTech Processor Polystyrene Bead Treatment Media Self Cleaning Processor External Piping Inlet / Discharge Line Return Line Air Intake Electrical Conduit 2/3 1/3 4 Inlet Effluent Filter 4 Inlet SeptiTech Processor 2 Discharge Primary Septic Tank

45 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

46 Orenco AdvanTex Control panel Primary tank Textile- Based Packed Bed Filters (PBF s) Recirc-return (5:1 ratio)

47 Leach Field vs Dispersal Field 4 Bedroom Single Family Home with 12 min/in perc. rate Pipe & Stone Leach Field 1,200 SQ.FT. Req d ( 20 x 60 ) 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

48 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

49 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

50 SEPTIC SYSTEMS PROTECT OUR LAKES, RIVERS, GREAT BAY AND GROUNDWATER FOR FUTURE GENERATIONS

51 Thank You Questions Acknowledgements Sara Heger, Univer. of Minnesota Tracey Rioux- Sepitech Cory Lyons - Orenco