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Nutrient issues, Reduction and removal. AMMONIA. Nitrogen Removal Needs. Environmental protection Meet limits Mostly done thru normal treatment that is running perfectly Your treatment will use up all the nitrogen (ammonia) that comes into your plant naturally through biological means

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nitrogen removal needs
Nitrogen Removal Needs
  • Environmental protection
  • Meet limits
  • Mostly done thru normal treatment that is running perfectly
  • Your treatment will use up all the nitrogen (ammonia) that comes into your plant naturally through biological means
  • Additional treatment is necessary if loadings are high in nitrogenous compounds
optimize for nitrogen treatment
Optimize for Nitrogen treatment
  • Nitrification is conversion of ammonia, NH3-N (from influent) to nitrate
  • Denitrificaton converts NO3-N to nitrogen gas, N2
  • Nitrification is ammonia removal
  • Denitrification is nitrate removal
  • Since nitrogen gas is stripped off, denitrification is total nitrogen removal
  • Bugs necessary for the removal are typically present in MLSS
optimize for nitrogen treatment1
Optimize for nitrogen treatment
    • 1.1 pounds of oxygen per pound BOD (conventional)
    • 4.6 pounds of oxygen per pound of ammonia
  • The bacteria responsible for nitrification reproduce at a much slower rate than those responsible for BOD removal
  • Thus, the danger always exists for the "wash out" of the nitrifying organisms
  • Unless the nitrifying bacteria reproduce at the same or greater rate than they are removed from the system (by waste sludge) then the population of bacteria will be insufficient to carry out nitrification
  • For this reason, nitrification systems are operated at higher return sludge rates than conventional secondary treatment
  • The amount of sludge to be wasted is significantly less than from a conventional activated sludge system.
optimize for nitrogen treatment2
Optimize for Nitrogen treatment
  • Nitrification systems are sensitive to pH variation
  • Optimum pH has been found to be approximately 7.8 to 9.0
  • Alkalinity is also destroyed during nitrification
  • Theoretically, 7.2 pounds of alkalinity are destroyed in converting 1 pound of ammonia to nitrate
  • In low alkalinity wastewaters, Quick lime (CaO) or Ca(OH)2 is often used to provide alkalinity and pH control
optimize for nitrogen treatment3
Optimize for Nitrogen treatment
  • Incomplete nitrification, or partial nitrification, can result in higher levels of ammonia carrying over to the clarifier
  • Ammonia bubbles form and float to the surface, carrying along sludge
  • Ashing
  • This leads to sludge going over the weir and is seen as a BOD increase
optimize for nitrogen treatment4
Optimize for Nitrogen treatment
  • In order for denitrification to occur, a carbon source must be available
  • Most commonly, methanol is used
  • The methanol must be added in sufficient quantity to provide for cell growth and to consume any dissolved oxygen which may be carried into the denitrification reactor. 
  • Usually 3 to 4 pounds of methanol per pound of nitrate are required
  • Careful control of methanol feed is necessary to prevent waste of chemicals
optimize for nitrogen treatment5
Optimize for Nitrogen treatment
  • Denitrifying bacteria grow very slowly and are extremely sensitive to temperature. 
  • Denitrification rates have been shown to increase five-fold when the temperature is increased from 10°C to 20°C
  • Operating parameters such as sludge age and retention time must be varied with temperature. 
nitrogen removal and do
Nitrogen Removal and DO
  • Denitrification can only occur after nitrification (nitrification produces nitrates)
  • Denitrification only occurs in environments devoid of oxygen but where nitrates are present
  • A source of carbon must also be present
  • Carbon can be in the form of BOD
  • Denitrification saves energy costs
  • During denitrification, part of BOD removal will occur without DO
  • Denitrification also restores alkalinity which is necessary for other processes in treatment
how to do it
How to Do It
  • Creating an anoxic place in a carousel basin is fairly easy
  • Aerate basin at a level that takes care of your BOD and ammonia oxidation…but not in excess
  • Trial and error to find this point, but monitor basin to find an area that has a very low DO (<0.5 mg/L)
what it looks like
What It Looks Like

Area of

Higher DO

DO Depletes as flow

Travels down channels

Anoxic zone


Area of

Lower DO


  • Monitoring DO around the basin can target the anoxic area
  • Changing aeration can move anoxic areas towards effluent discharges or weirs
  • Misconception is that DO has to be 1.0 to 2.0 mg/L
  • DO goes down as water moves down the channel, therefore a lower DO is seen in areas just before aeration zones
  • NaOH used for pH adjustment and alkalinity
  • Alum dosed into post anoxic zone for phosphorus precipitation
  • Methanol could be dosed into post anoxic zone for more nitrogen removal
  • All influents go thru anoxic zone for nitrogen removal
  • This system has reached 3.1 mg/L nitrogen consistently
  • Alum and NaOH dosed in influent for alkalinity and pH control
  • Uses turbine aerators for aeration, modified (by slowing down) to use as mixers
  • Resulting separation of anoxic/

aerobic zones provides 0.6 mg/L ammonia consistently

ammonia procedure
Ammonia Procedure
  • Make sure meter is warmed up!
  • 1. Pour out 50 or 100 mL of sample.
  • 2. Place the electrode in the beaker.
  • 3. Turn on the magnetic stirrer.
  • 4. Set the meter to begin reading
  • 5. Add 1 ml or 2 ml of buffer solution (typically 10 M NaOH) whichever is called for.
    • (Orion buffer stays blue if the sample pH is > 11)
  • 6. Read millivolts and concentration (if using onboard software).
ammonia procedure1
Ammonia Procedure

Keep the electrode at an angle to minimize air bubbles

Stir at the same speed for standards and samples.

Prevent heating the solution; insulate between beaker & stirrer

Do not add NaOH before immersing electrode

--ammonia is in gaseous form at this pH and will be lost!

ammonia procedure2
Ammonia procedure
  • ..\Lab transfer\Ammonia benchsheet New NR149 98.xls
ammonia procedure3
Ammonia procedure

Probe, Probe, Probe!

  • Probes do NOT last forever!
    • Average life expectancy is 2 years or less.
    • If your probe is > 2 yrs old, consider getting a new one
  • DO NOT store probes in lab reagent water!
    • Your probe will be deader than the proverbial doornail.
    • DO store the probe in 1000 ppm NH4Cl solution
  • AVOID calibrating below about 0.2 mg/L!
    • It takes longer to stabilize than meter pre-set timer.
    • Result will often be a poor slope or bias at the low end

Probes now cost around $550

new ammonia procedure2
New Ammonia procedure
  • Method calibrates like phosphorus
  • Calibrate once per yeaer
  • Analyze CCV/LCS, Blank and samples
  • Fully accepted by DNR
  • Costs around $45 for 25 vials
  • $1.80 per test
  • If you test 3 times per week=$9.00
  • $468 per year
  • Savings is in time, ease and accuracy
  • What do we know for sure
  • DNR Bureau of Watershed Management has proposed new phosphorus criteria for rivers and streams into NR 102.6
  • Criteria is now 100 ug/L (0.1 mg/L) for listed rivers
  • 75 ug/L (0.075 mg/L) for all other streams, unless exempted
  • Limits for Lake Superior is 5 ug/L (0.005 mg/L)
  • 46 Listed streams:
    • Bad River from confluence w/Marengo River w/I Bad River Res. Downstream to L. Superior
    • Chippewa River from L. Chippewa in Sawyer county downstream to Mississippi River, excluding Holcombe, Cornell Old Abe L. Wissota and Dells Pond
    • Flambeau River from Turtle-Flambeau in Iron county to Chippewa River, excluding Pixley, Crowley, Dairyland flowages
  • 46 Listed streams:
    • Jump River confluence w/ North Fork & South Fork of Jump River in Price County to Holcombe Flowage
    • Namekagon River from outlet of Trego Lake to St. Croix River
    • Red Cedar River from Confluence w/Brill River, excluding Rice, Tainter, Menomin
    • St. Croix River from confluence w/Namekagen River downstream to Miss. River, excluding Lake St. Croix near Hudson
  • 46 Listed streams:
    • St. Louis River from state line to the opening between Minnesota Point and Wisconsin Point at Lake Superior
    • S. fork of Flambeau River from HWY 13 near Fifield to Flambeau River
    • Tomahawk River from outlet of Willow Reservoir to L. Nokomis
    • White River from outlet of White River Flowage in Ashland county to Bad River
  • Support from:
    • Lakes and river associations
    • Environmental groups
    • Individuals who want strong rules limiting phos inputs into lakes & streams
    • Lakeshore property owners, small businesses municipalities that depend on tourism
  • Opposition:
    • Municipalities
    • Paper industries
    • Dairy farmers
comments and responses
Comments and Responses
  • Basically, the DNR is stuck because 7 groups of “environmentalists” are threatening to sue EPA if they do not set these limits.
    • Clean Water Action Council of North East Wisconsin
    • Gulf Restoration
    • Milwaukee River Keepers
    • River Alliance of Wisconsin
    • Wisconsin Wildlife Federation
    • Midwest Environmental Advocates
no really
No, Really
  • It looks like DNR is handing out limits right along NR guidelines
  • If you’re on a named river, 0.1 mg/L
  • If you’re on any other receiving stream, 0.075 mg/L
  • We’re starting to see some movement on getting down to compliance
  • Looks like economic hardship is a viable solution
phos updates
Phos Updates
  • NR217.19-if the resulting cost of implementing the phosphorus WQBEL is greater than 2% of the MHI of the municipality, it would be concluded that the economic impact is adverse enough to warrant granting of the variance
  • Still may involve rate increases
  • Variance for forever???
phos updates1
Phos Updates
  • Economic hardship won’t work by itself
  • WWTPs will have to do “Something” for phos treatment
  • Add chemical (or more chemical)
  • Try to remove sources
  • Interim phosphorus limits
  • Nothing official yet
  • Cumberland Model is most successful and has been established for a long time
  • Trading is going to depend on working with… and paying for…agents to work with farmers and farm organizations
trying to get answers
Trying to Get Answers
  • WRWA has been trying to get plain answers so we can start getting out the compliance processes
  • Ask our DNR friends for who would we talk to to confirm these interpretations of the rule
  • A final word so to speak
newest guidances aren t a huge help
Newest guidances aren’t a huge help
  • New guidances aren’t a huge help-Mostly engineering stuff
  • FAQs neither
  • Are all waters of the state covered under the phosphorus revisions?
  • It’s in NR 102.06(6)
  • Who needs to be evaluated for phosphorus limits?
  • It’s in NR 217.02, 217.04(1), 217.04(1)(a)(2) (blah)(blah)(blah)
  • Not really an answer
we re tryin
We’re Tryin’
  • WRWA has submitted plain questions to DNR-Stepp, Rasmussen and other to get plain answers
  • We were told nothing is going to happen because of the recall
  • They were right because nuthin’ happened
by the way
By the Way
  • Phos LODs will have to meet levels for the low limits
  • Means your LODs will have to be around 0.02-0.03 mg/L and be “real”
  • We’ll get to that later
phosphorus removal
Phosphorus Removal
  • Most phosphorus removal done thru addition of chemicals
  • Alum-Hydrated Aluminum sulfate (Al2(SO4)3.14H2O);

Al3+ + PO4 AlPO4

reacts on a one to one basis

  • Ferric chloride (FeCl3)-

FeCl3 + PO3- FePO4

phosphorus removal1
Phosphorus Removal
  • Pickle liquor (ferrous chloride or sulfate) is used rarely, expensive, hard to get and hard to calculate amount of iron in the solution
phosphorus removal2
Phosphorus Removal
  • Ferric creates a thicker, drier sludge cake, is slightly more expensive, but you use less
  • Alum creates a “slicker” sludge cake, is less expensive, but more is used
  • Ferric chloride is very corrosive and produces fumes
  • Must be stored in non reactive vessels
phosphorus removal3
Phosphorus Removal
  • Optimum pH range is 4.5-5.0
  • Significant removal at higher pHs
  • If wastewater has a high buffering capacity, little pH change noticed
  • Wastewater with low buffering cap. Might have problems with ammonia or nitrates in summer
phosphorus removal4
Phosphorus Removal
  • Alum is moderately corrosive but the piping and storage materials is greater
  • Optimum pH for phosphorus removal is 5.5-6.5
  • There is destruction of alkalinity
  • At pH above 6.5 more alum is needed to remove the same amount of phosphorus
biological phosphorus removal
Biological Phosphorus Removal
  • Theory: System is best for phosphate-accumulating organisms (PAOs)
  • PAOs, under anaerobic conditions (absence of oxygen and nitrate), PAOs can break phosphorus bond to create energy to uptake volatile fatty acids (VFAs). These acids are stored in their cells primarily as poly-β-hydroxybutyrate (PHB)
biological phosphorus removal1
Biological Phosphorus Removal
  • When these organisms pass into an aerobic environment, they metabolize the PHB and uptake additional phosphorus
  • By creating an anaerobic zone at the beginning of the treatment process, PAOs gain a competitive advantage. These organisms contain 2-5 times more phosphorus than regular activated sludge
biological phosphorus removal2
Biological Phosphorus Removal
  • BOD to phosphorus ratio of 20:1
  • As ratio is increased more phosphorus can be removed
  • Soluble BOD can be a limiting factor
  • A BOD of 200 mg/L will remove 2 mg/L phosphorus even without enhancing BPR
biological phosphorus removal3
Biological Phosphorus Removal
  • 2 important factors that lead to poor BPR
    • Substrate availability (soluble BOD) and nitrate control
  • Others
    • DO & nitrate recycle
    • Competition w/glygogen accumulating organisms
    • Return phos loadings
    • Temp & pH
    • Effluent TSS
biological phosphorus removal4
Biological Phosphorus Removal
    • Variability of wastewater and flow
    • Inconsistent loadings
    • Physical restraints (mixing, baffling, detention time)
    • Control parameters (RAS, WAS, solids retention time)
    • Secondary release of phos
  • Most plants control by RAS, WAS and DO concentration
biological phosphorus removal5
Biological Phosphorus Removal
  • RAS Control-RAS rate allows solids to remain in the system longer than the wastewater which allows acclimation to pollutants and develop good settling. If there is nitrates present, reducing RAS may help. If pre-anoxic zones are present lowering RAS rates help lengthen detention time
biological phosphorus removal6
Biological Phosphorus Removal
  • WAS Control-Phosphorus needs to be wasted from the system to be removed. WAS control allows solids to be removed as bacteria grows. SRT may need to be reduced to accommodate phos removal. Particularly true of aeration systems (like oxidation ditches) that operate at high sludge ages
biological phosphorus removal7
Biological Phosphorus Removal
  • DO Control-Optimized aerations includes DO meters or ORP probes. Oxygen and nitrate inhibits the process so control is important if the zone is supposed to be anaerobic. If there is too much DO in the aerobic area there is a better chance to have oxygen to return to anaerobic areas. Aeration rates also affect nitrates. Must avoid low DO bulking
biological phosphorus removal10
Biological Phosphorus Removal
  • Monitor
    • Influent BOD, TKN, NH3, O-PO4
    • Anaerobic zone NO3, O-PO4
    • Aeration basin NO3, O-PO4, TSS
    • RAS NO3, O-PO4, TSS
    • Effluent NO3, O-PO4, NH3, TSS
  • Nitrates are the enemy!!!
  • Take on soluble BOD as much as you can!!
phosphorus treatments
Phosphorus Treatments
  • Forms and Sources
  • Prevention First
  • Water Treatment
  • Wastewater Treatment-Easy
    • Cheaper?
  • Wastewater Treatment-A little More Work
  • Wastewater Treatment-Hard (Expensive)
  • Municipal waste contains phosphorus anywhere from 2-20 mg/L as total phosphorus
  • Only about 1-5 mg/L is organic phosphorus, the rest is inorganic (an organic molecule must have carbon in its makeup)
  • Phosphorus sources include domestic, commercial, industrial and natural runoff
  • Organically bound phosphorus originates from body and food waste and, upon biological decomposition of these solids, is converted to orthophosphates
  • Detergents, used for domestic and industrial cleaning (about half)
  • Most states have banned the sale of phosphate-containing clothes washing detergent, so phosphorus levels in household wastewater have been reduced significantly from previous levels
  • Now automatic dishwasher detergent is the largest source

Business users that are likely to contribute phosphorus to your POTW can include:

  • Agricultural co-ops
  • Car/truck washing facilities
  • Dairies
  • Food processing plants
  • Meat packing plants and


Additionally, industrial cleaning and sanitizing operations in any facility may result in high discharge levels of phosphorus

Metal finishing facilities

Nursing homes


Schools and other


banned sources
Banned Sources
  • Wisconsin has banned the sale of fertilizer containing phosphorus
  • Also banned phosphorus from laundry detergent in the ‘70s
  • Recently made illegal to sell or use household dishwasher detergent with more than 0.5 percent phosphorus by weight
remove sources
Remove Sources?
  • Initially we should keep phosphorus out of the wastewater system
  • Meet with businesses in town and find phosphorus containing items
  • Bring in non phosphorus chemicals(cleaners do not have to contain phosphorus to be effective-enzymes more important)
  • Carwashes discharge large loads of phosphorus
    • Alternative detergent is cheaper and works better
  • Schools discharge quite a bit during school closings
    • Emulsifiers also
  • Dairies discharge milk and cleaning chemicals
    • Milk is extremely high in phosphorus
  • Metal finishing places often use phosphoric acid
  • Any place with a spraying booth will have large discharges of phosphorus
    • Metal prep, just like other metal finishers
  • Pre-treatment or complete haul away are best options if you cannot keep these discharges out
groundwater disposal systems
Groundwater Disposal Systems
  • Soil Based Treatment Systems
    • Slow Rate
    • Rapid Infiltration
    • Overland Flow
  • Aquatic Based Systems
    • Natural and Constructed Wetlands
    • Aquatic Plant Treatment Systems
slow rate system
Slow Rate System
  • Treatment Systems dating back to 1880
  • 1972 Clean Water Act
  • Most Recent Developments Constructed Wetlands
  • Groundwater Impacts and Monitoring
slow rate system1
Slow Rate System
  • Wastewater Treatment is Objective
    • Soil Permeability is Limiting
    • Uses Vegetation
    • Evaporation and Percolation
    • Treatment through the Soil
    • Low Application Rates 2 to 6 Feet of Water per Year
slow rate system2
Slow Rate System
  • Crop Production is Objective
    • Crop Produced
    • Landscape Irrigation (Golf Course)
    • Groundwater Reclamation

Center Pivot

Fixed Head


Canopy Evaporation

Droplet Evaporation

Plant Transpiration



Plant Interception


Deep Percolation

Crop Root Zone

biomass production
Biomass Production

Hybrid willows uptake thousands of gallons of water, sequester phosphorus and uptake ALL the nitrogen

Can be cropped off every 4-5 years and roots will re-sprout

Crop production and management is supplied by vendor

rapid infiltration seepage cell
Rapid Infiltration (Seepage Cell)
  • Seepage Cells
    • No Vegetation Provided
    • Evaporation is Low
    • Most of Water Percolates Through the Soil
    • High Application Rates 20 to 300 Feet of Water per Year
  • NR 207 requires 10 mg/l Total Nitrogen in Wastewater
what happens to the phosphorus
What Happens to the Phosphorus

Chemical Precipitation/Absorption

  • Clay Minerals
  • Organic Soil Fractions
  • P Held Very Tightly
  • Plants take up Little (Wetlands)
why seepage
Why Seepage
  • Water Cycle says that groundwater from a well not recharged back into the ground gets sent down river and is lost
  • With seepage, phosphorus is less of an issue than nitrogen (in most cases)
why not seepage
Why Not Seepage
  • Not all soils are suitable for seepage
    • Depth to groundwater
    • Groundwater phosphorus levels
    • Soil is impermeable or unusable for seepage
  • Soil has to have a percolation rate that allows the proper speed of absorption and will accept all of the water that is discharged
    • Usually several cells need to be constructed so as to allow for resting, weed control and provide enough area to accept all the discharge
    • To do this you need land and engineering
pond phosphorus treatment pilot
Pond Phosphorus Treatment Pilot
  • Small Sanitary District near Mauston, WI
    • Average Daily Flow – 30,000 gpd
    • Effluent BOD – 30 mg/L
    • Effluent TSS – 60 mg/L
    • Effluent Ammonia – 10 mg/L
    • Discharge to Castle Rock Lake (impaired waterway)
    • Currently no requirement for phosphorus removal
pond phosphorus treatment pilot1
Pond Phosphorus Treatment Pilot
  • Influent & Effluent Flow Metering
  • Complete-Mix Lagoon
  • Partial-Mix Lagoon
  • Settling Lagoon
  • UV Disinfection
  • Blower Building





pond phosphorus treatment pilot2
Pond Phosphorus Treatment Pilot
  • Fed Aluminum Sulfate (Alum) between Pond #1 and Pond #2
  • Three discrete pilot runs from July 2010 – September 2011
  • Effluent Phosphorus samples collected on a weekly basis
  • No pilot runs during winter







pond phosphorus treatment pilot3
Pond Phosphorus Treatment Pilot
  • Alum Storage
  • Chemical Feed Pump (flow paced)
  • Tubing
  • Injection Point Mixing
pond phosphorus treatment pilot4
Pond Phosphorus Treatment Pilot
  • Pilot Run # 1 – 3.6 mol Al:mol P
    • 36 day test; October 14 – November 20, 2010
    • Average Dosage: 3.6 mol Al per mol P
    • Influent Phosphorus = 3.60 mg/L
    • Effluent Phosphorus = 0.43 mg/L
    • $10.88 per pound of P removed
pond phosphorus treatment pilot6
Pond Phosphorus Treatment Pilot
  • Pilot Run # 2 – 1.7 mol Al:mol P
    • 27 day test; July 27 – August 23, 2011
    • Average dosage: 1.7 mol Al per mol P
    • Influent Phosphorus = 6.00 mg/L
    • Effluent Phosphorus = 2.05 mg/L
    • $5.14 per pound of P removed
pond phosphorus treatment pilot8
Pond Phosphorus Treatment Pilot
  • Pilot Run # 3 – 2.2 mol Al:mol P
    • 37 day test; August 24 – September 30, 2011
    • Average dosage: 2.2 mol Al per mol P
    • Influent Phosphorus = 4.92 mg/L
    • Effluent Phosphorus = 0.91 mg/L
    • $6.65 per pound of P removed
chemical phosphorus removal
Chemical Phosphorus Removal
  • Most phosphorus removal done thru addition of chemicals
  • Alum-Hydrated Aluminum sulfate (Al2(SO4)3.14H2O);

Al3+ + PO4 AlPO4

reacts on a one to one basis

  • Ferric chloride (FeCl3)-

FeCl3 + PO3- FePO4

tertiary filtration
Tertiary Filtration
  • For consistent ultra-low phosphorus treatment we need to take another step in the process
  • Most of the phosphorus in your effluent is in the solids
    • If the solids are filtered out and caught in the treatment one would be able to remove much more phosphorus
  • This step is a tertiary treatment and involves reverse osmosis (RO), nanofiltration (NF) or filtration through sand or a similar media
    • Reverse osmosis and nanofiltration are generally used for water reclamation and is becoming very popular in areas with problems finding enough water for domestic use
  • Since we in Wisconsin do not have several tens of millions of customers to support, RO and NF are not viable
  • Sand filters are the least expensive and simplest to use in small wastewater treatment plants
  • Sand filters are able to contain or catch very small particles and are removed occasionally through a backwash
ballasted sedimentation
Ballasted Sedimentation
  • Process combines conventional coagulation/flocculation chemistry with inorganic silica microsand to provide a high rate clarification process
  • Differs from conventional clarification in that it provides microsand as a ballasting agent in the flocculation process step. The microsand serves several important roles in the process:
ballasted sedimentation1
Ballasted Sedimentation
  • The high specific surface area to volume ratio of the microsand particles serves as a "seed" for floc formation;
  • The microsand and polymer "seed" promote the enmeshment of suspended materials and result in the formation of large stable floc;
  • The relatively high specific gravity of the microsand (~2.65) serves as a ballast for the formation of high-density floc;
  • The high microsand concentration within the process dampens the effects of changes in the raw water quality;
  • The chemically inert microsand does not react with the process chemistry, allowing it to be removed from chemical sludge and reused in the process.

Ballasted Settling– Process Schematic

  • High Rate Clarifier, 30-50 gpm/ft2
continuous backwash filter
Continuous BackWash Filter
  • Regenerative Adsorptive Column
  • Coagulant Ferric Sulfate or Ferric Chloride
continuous backwash filter1
Continuous BackWash Filter






Back Wash Filter



Optional 2nd Pass




Reject Recycle

continuous backwash filter2
Continuous BackWash Filter

Clean Water

Secondary Effluent

Rapid Conditioning


Reject Stream







continuous backwash filter3
Continuous BackWash Filter



  • Hydrous Ferric Oxide-Coated Sand
    • Images from scanning electron microscopy
  • X-ray Flourescence
disc filtration
Disc Filtration
  • The Discfilter is a mechanical and self-cleaning water filter that offers a large filter area in a small footprint. This design is superior to any filtration in fine solids removal and product recovery within microscreens.
disc filtration1
Disc Filtration

The water to be treated flows by gravity into the filter segments from the centre drum. Solids catch on the inside of the filter panels mounted on the two sides of the disc segments.

disc filtration2
Disc Filtration

As the solids catch on the inside of the filter media impeding the flow of water through the disc, the water level inside the discs begin to rise, triggering a level sensor to start the disc to rotate and a backwash cycle begins.

disc filtration3
Disc Filtration

High pressure rinse water backs the solids off the filter media and into the solids collection trough. Typically the backwash requires 0,05-3% of the total flow and filtered water is used.




Emergency bypass channel

Access platform elevation

Inlet trough

Outlet weir

Bypass weir

Filter effluent channel


Influent channel

membrane reactors
Membrane Reactors

The MBR device introduces air and mixed liquor into the bottom of the membrane modules through an "airlift effect".  The air bubbles blend with the mixed liquor and rise up into membrane fibers, providing effective scouring to the membrane surface and refresh the membrane surface to prevent solids concentration polarization.  The two-phase cross-flow reduces scour air energy dramatically

membrane reactors2
Membrane Reactors
  • MBR Basics
    • Biological Treatment + Membrane Filtration
      • Still Activated Sludge!
      • Membranes submerged in treatment tanks
      • Membranes replace clarifiers
        • No need for sludge settling
        • Reduced Man-Hours
        • Flexible solids inventory
      • High Rate System
        • MLSS 10,000 – 18,000 mg/L, SRT 50 days
          • Process Stability
          • High level of treatment (<2 mg/L BOD/TSS/NH3-N)
          • Smaller Footprint
          • Reduced Sludge Production
membrane reactors3
Membrane Reactors
  • MBR Basics, Cont.
    • Membrane Filtration
      • Physical Treatment
      • Porosities ranging from 0.035 – 0.4 mm (hair = 40 mm)
      • Ultimate barrier to solids and insoluble pollutants
      • Turbidity <0.1 NTU
      • Virus Reduction
      • Non-detect Fecal Coliforms
        • Most State regulatory agencies require disinfection (except Ohio)
membrane reactors6
Membrane Reactors
  • Flat Plates
    • Polyethylene composite
    • 0.4 micron pore size (human hair >40 microns)
    • Biofilm
      • Provides most of the filtration
      • Protects membranes from fouling
      • Allows for lower TMP operation
      • Provides pathogen removal
    • Coarse Bubble aeration limits biofilm thickness
    • 1/8” Screening sufficient
    • Simple/flexible operation
membrane reactor
Membrane Reactor
  • Cost
    • Overall Project Construction
      • $2,400,000
      • Includes 2 lift stations, forcemain, drainfield
    • MBR System Package
      • $830,000
    • How does that compare?
      • $35/gallon including forcemain/drainfield
      • $31/gallon excluding
  • Operational Costs
    • Low Alpha = More Air = More $$$ ($25,000 per year at design)
    • Supplemental Carbon
  • Seeding Plant
    • High MLSS seed sludge for biofilm maturation
    • Recommend only ½ MMF allowed until 8,000 mg/L
    • Adequate Start-Up Loadings (must maintain F:M)
levels of treatment
Levels of Treatment
  • Disc Filtration > 0.15 mg/L TP
  • Ballasted Settling > 0.06 mg/L TP
  • Continuous Back Wash

Filter < 0.06 mg/L TP

  • Membranes < 0.06 mg/L TP

Disc Filtration – Take Aways

  • Tertiary Polishing Phosphorus Treatment
  • Phosphorus Reduction – Need Coagulation or Flocculation
    • In-pipe dosing not sufficient
    • Mixing, energy critical
  • Floc needs structural integrity
  • Use existing tankage(if possible)

Ballasted Settling - Takeaways

  • Enhanced Floc Formation
  • Shorter HRT Higher Loading Rate
  • Mixing energy critical
  • Use existing tankage(if possible)

Continuous Backwash Filters - Takeaways

  • Regenerative Adsorption Process
  • Hydrous Ferric Oxide- Coated Sand
  • Multiple Passes for Additional Treatment
  • Lower Coagulant Dose
  • Reject Stream
    • Possible Re-use




MEMBRANE - Takeaways

  • High level of treatment
    • P
    • Water reuse
    • Micropollutants
  • Energy intensive
  • High Capital Cost
  • Compact footprint
  • Membrane fouling critical
    • Aeration
    • Intermittent relaxation
    • Backwashing
    • Citric Acid
thank you s
Thank You’s
  • DNR
  • MSA Professional Services
  • Ruekert / Mielke
phosphorus testing
Phosphorus testing

Number of standards

  • Use an appropriate number of standards
  • MUST be constructed using at least 3 standards and a blank.



DO analyze a blank

DO include in calibration.

phosphorus calibration
Phosphorus calibration
  • Range should be appropriate for the samples being analyzed
  • Be aware of the linear range of the method used!
  • Standards should also be evenly spaced.
  • Where possible…bracket samples with calibration standards.
  • Low standard not more than 2 - 5X the LOD (best is = LOQ).
  • Suggested range: Phosphorus: 0, 0.1, 0.2, 0.4, 0.6, 0.8, 1 mg/L
sample and reagent handling
Sample and reagent handling
  • Sample handling considerations
    • Refrigerate at 4C; preserve w/ H2SO4 to pH < 2
    • Holding time = 28 days (not an issue for WWTPs)

*** Collect sufficient sample to allow re-testing if necessary ***

  • Critical reagent requirements
    • Dry potassium dihydrogen phosphate (KH2PO4) at 105C for  1 hour before weighing ( better yet...purchase standards!).
    • Prepare ascorbic acid (last addition to the combined color reagent) fresh weekly, store 4C.
    • The combined solution should be mixed well after each solution addition.
    • Combined color reagent stable for only 4 hours. Warm all solutions; mix after each.
    • Wait > 8 mins. After addition; read samples within 30 mins.
phosphorus digestion
Phosphorus digestion
  • 50 mL sample.
  • +1 drop phenolphthalein; if pink, acidify with 30% H2SO4
  • Add 1 ml of 11 N H2SO4
  • Add 0.4 g ammonium (or 0.5 g potassium)persulfate
  • Hotplate Digestion
  • Boil samples 30-40 mins. or until a final volume of 10 mL(whichever comes first)
  • in no case should samples be boiled dry

Autoclave Digestion

  • Autoclave for 30 minutes in an autoclave or pressure cooker
  • Set the conditions for 15-20 psi. (98-137 kPa)
  • Samples are not boiled dry
  • Cool samples, standards, and blanks.
  • +1 drop phenolphthalein. Neutralize w/ 1N NaOH ‘til faint pink.
  • Dilute to 100 ml, but don’t filter.

Conventional NCL

Procedure Modification

Initial sample volume (or diluted to)

50 mLs

50 mLs

Reduce volume during digestion

~10 mLs

10-20 mLs

Bring volume back up after digestion

100 mLs

Add 8 mL color reagent AND dilute to volume

50 mLs

50 mLs

50 mLs

Use only 50 mL portion for coloring; Add 8 mL color reagent

Final volume after color reagent addition

58 mLs

50 mLs

Source: North Central Labs at

test n tube instructions
Test n tube instructions
  • Turn on COD Reactor; set at 150o C
  • Add 5.0 mL sample to a Test n’ TubeTest Vial
  • Add one Potassium Persulfate Powder Pillow
  • Cap; shake; set in COD Reactor for 30 minutes
  • Cool
  • Add 2.0 mLs of 1.54 N sodium hydroxide; cap & mix
  • Add one PhosVer 3 Powder Pillow (does NOT fully dissolve)
  • Cap; shake 10-15 secs.
  • Time for 2 minutes
  • Put vial into instrument and read at 610+ nm*
  • * Read samples between 2 and 8 mins. after PhosVer 3 addition


                  • To increase detection and accuracy
  • Use cuvettes instead of test tube
  • Hach develops cuvettes with long light path


  • After calibration, LOD is performed
  • After LOD, check with an ultra-low series of checks
  • 0.003-0.004 mg/L