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CTC 450 Review

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Title: CTC 450 Review


1
CTC 450 Review
  • WW Systems Operations

2
Last Homework
  • Will replace your lowest homework grade
  • http//www.epa.gov/climatechange/ghgemissions/usin
    ventoryreport.html
  • http//www.ipcc.ch/
  • How significant are wastewater treatment plants
    in contributing to greenhouse gasses?
  • Due next Monday

3
Objectives
  • Understand the basics with respect to advanced WW
    treatment

4
Two systems
  • Advanced (tertiary and ww reclamation)
  • Remove phosphorous
  • Convert ammonia to nitrate (nitrification)
  • Convert nitrate to nitrogen (denitrification)
  • Inactivate pathogens
  • Remove heavy metals
  • Remove organic chemicals
  • Remove inorganic salts
  • Eliminate all pathogens

5
Limitations-Biological Treatment
  • Doesnt remove phosphorous or ammonia
  • Incomplete disinfection
  • Doesnt remove all toxins
  • Doesnt remove non-biodegradable soluble
    chemicals

6
Excess Phosphorous
  • Fertilizes receiving waters
  • Causes algal blooms
  • Depletes DO
  • Reduces water transparency
  • Releases foul odors
  • Can lose finer fish species

7
Excess Nitrogen
  • Ammonia can be toxic to fish/aquatic animals
  • Can increase eutrophication (but usually
    phosphorous is limiting)

8
Pathogens
  • Conventional biological treatment
  • Up to 99.9 removal
  • With disinfection up to 99.99
  • Protozoal cysts and helminth eggs are resistant

9
SS Removal-Advanced
  • Granular-Media filters (similar to water
    treatment)
  • Cloth Media filters
  • Membrane filters

10
Pathogen Removal-Advanced
  • Remove solids first via filtration (pathogens can
    be protected in the solids)
  • Chlorination (similar to water treatment)

11
Toxic Substance Removal
  • Toxic-Hazardous to aquatic life or human health
  • Priority toxic water pollutants-over 100
  • Evaluating toxicity
  • Test influent/effluent for specific substances
  • Biomonitor-fathead minnows, water fleas

12
Phosphorous Removal
  • Soluble or organic (organically bound)
  • Conventional treatment removes 20-40 of
    phosphorus
  • Example 13-1
  • Advanced treatments
  • Chemical-biological
  • Reverse osmosis

13
Example 13-1 (Where is the PO43-)
  • Given the following, trace the inorganic, organic
    and total phosphorus through a conventional
    activated-sludge treatment plan.
  • Assume
  • Primary clarifier removal of 35 BOD
  • Primary clarifier removal of 50 solids w/ 0.9
    phosphorous
  • Activated sludge
  • F/M ratio of 0.40 2 phosphorus in the sludge
  • Filtrate recycles 5 of the influent phosphorus

14
Example 13-1
Parameter Raw After Primary After Secondary
SS 240 120 30
BOD 200 130 30
Inorganic N 22 22 24
Organic N 13 8 2
Total N 35 30 26
Inorganic P 4 4 3
Organic P 3 2 2
Total P 7 6 5
15
Example 13-1 (Refer to Figure 13-11)Plant
Influent / Primary Influent
  • Total P is 7 mg/l into the plant (100)
  • Primary influent is not the same as plant
    influent because of recycle of dewatered sludge
    filtrate
  • Recycled P5 so influent P105
  • Total P is 7.35 mg/l into the primary

16
Example 13-1 (Refer to Figure 13-11)Primary
Effluent (2 routes)
  • Sludge (15)
  • 0.9120 mg/l 1.1 mg/l
  • 1.1/7 15
  • Effluent (90) 7.35-1.16.25 mg/l total
  • Pi4.35 (see table no change in inorganic P)
  • Po1.90 (6.25-4.35)
  • 6.25/7 90

17
Example 13-1 (Refer to Figure 13-11)Secondary
Effluent (2 routes)
  • Sludge (20)
  • From Fig 11-45 (pg 415) k0.5
  • Biological sludge solids0.5130 mg/l65mg/l
  • 2 of 65 mg/l 1.3 mg/l
  • 1.3/7 20
  • Effluent (70) 7.35-1.16.25 mg/l total
  • Pi3.05 (see table inorganic P is removed)
  • (6.25-1.3-1.9)
  • Po1.90 (see table organic P is not removed)
  • 4.95/7 70

18
Example 13-1 (Refer to Figure 13-11)
  • 70 of P remains in the treated WW
  • 30 of P removed in sludge solids

19
Chemical-Biological
  • Chemicals used
  • Alum
  • Iron Salts
  • Chemical-Biological
  • Chemicals added in primary clarifiers
  • Chemicals added before secondary
  • Chemicals added before final clarifier

20
Example 13-2 (Refer to Figure 13-12)Add alum to
remove P
  • Alum applied to primary tank
  • 18 of P remains in the treated WW
  • 82 of P removed in sludge solids

21
Nitrogen-Atmospheric
  • Atmospheric Nitrogen to Organic Molecules
  • Nitrogen-fixing bacteria (rhizobia)
  • Live in root nodules of plants (symbiotic
    relationship)
  • Legumes (beans, clover, peas, peanuts,)
  • Plants get nitrogen in a usable form
  • Animals get nitrogen from eating plants
  • Animals excrete nitrogen as a waste product,
    usually in the form of ammonia

22
Nitrogen
  • Organic
  • Excreted or Decomposed to ammonia
  • Ammonia
  • Nitrosomonas oxidize ammonia to nitrite
  • Nitrite
  • Nitrobacter oxidize nitrite to nitrate
  • Nitrate
  • Under anaerobic conditions via facultative
    heterotrophs, nitrates are converted to nitrogen
    gas (which escapes into the atmosphere)
  • Nitrogen gas

23
New Type of Microbe
  • Ammonia to nitrogen directly
  • NH4 NO2- ? N2 2H2O
  • Anammox (anaerobic ammonium oxidation)
  • Advantage No oxygen needed
  • Strangeness anammox bugs also produce hydrazine
    (rocket fuel)
  • Bugs store the hydrazine in a dense membrane
    structure of fused carbon rings
  • Ref The Invisible Kingdom, Idan Ben-Barak

24
Nitrogen in WW
  • 40 ammonia 60 is bound in organic matter
  • Usually not enough oxygen is available to convert
    to nitrites or nitrates

25
Nitrogen Removal-Conventional
  • Primary sedimentation (15 removal)
  • Biological treatment (another 10)
  • Remainder is mainly in the form of ammonia unless
    oxidation occurs (activated sludge at low BOD
    loading)

26
Nitrogen Removal-Advanced
  • After biological treatment
  • Aeration
  • Final settling
  • Alkalinity is reduced when nitrification takes
    place lime or soda ash is added to maintain
    alkalinity

27
Nitrate removal
  • Nitrate can pollute groundwater
  • Denitrification converts nitrates to nitrogen gas
  • Process is anaerobic or anoxic
  • Process requires an organic carbon source
    (methanol or raw ww)
  • Via recycle, denitrification can be placed ahead
    of nitrification

28
EBPR-Enhanced Biological Phosphorous Removal
  • Anoxic zone (0.5 to 3 hours detention time)
    followed by aerobic zone (6-24 hrs)
  • Helps remove both N and P
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