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EVT: ENVS 359 Section 9 - 12 > EVT: ENVS 359 Section 9 - 12 > Flashcards

EVT: ENVS 359 Section 9 - 12 Flashcards

1
Q

Five problems associated with TSS

A
  1. aesthetics
  2. filterability - remove TSS prior to filtering to reduce costs associated with cleaning filters
  3. disinfection - pathogens can be protected from disinfection if incased in TSS
  4. pumps - suspended solids damage pumps
  5. corrosion - slow water flow in pipes if suspended solids build up in elbows of pipes
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2
Q

Five analytical techniques for detecting and characterizing TSS

A
  1. XRF - xray fluorescence
    largely quantitative, can be done using portable device
  2. XRD - xray diffraction
    very expensive, require crystalline solid
  3. PSA - particle size analyze
    assume particles spherical, scattering/light absorbed ultrasound
  4. SDI - silt density index
    very old, can be done in field using applied pressure across a membrane
  5. Turbidity
    good for drinking water, vague for problem solving
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3
Q

Ways to improve separation of suspended solids from water (6)

A

Increase terminal velocity

  1. Increase difference in density to be as great as possible
  2. Make particle size as large as possible
  3. Change gravitational force with centrifugation
  4. Change continuous viscosity by adjusting temperature
  5. Reduce separation time without changing velocity - use thinnest film of continuous medium possible
  6. Increase time spent separating by using large tanks and low flow rates
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4
Q

Why do surface contribute so much to the properties of colloids?

A

High surface to volume ratio

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5
Q

What is the surface property which stabilizes colloids

A

Surface charge

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6
Q

When is coagulation and flocculation used?

A

Sedimentation

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7
Q

What factors in Stokes’ are used to decrease time needed to remove TSS in:

  1. Coalescence
  2. Inclined Plane Settlers
  3. Tube Settlers that use waste heat from another process
  4. Centrifugation
A
  1. Coalescence - diameter of particles
  2. Inclined Plane Settlers - distance that particles have to fall
  3. Tube Settlers - viscosity of water (viscosity of water decreases as temperature increases)
  4. Centrifugation - gravitational constant
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8
Q

Why is it an advantage to have a shallow stream running up an inclined plane settler?

A

Because with a fixed terminal velocity, the shorter the distance the particles have to fall -> the less time required to separate them from water

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9
Q

Filter size must match TSS diameter to be separated -> how to arrange for a filter when two distinct sizes present?

A

If two different densities and size ranges are used for the two media then after fluidization settling rates will result in separation

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10
Q

Sludge blanket clarifier

A 
Inside top - rapid mix - coagulation
Inside middle - slow mix - flocculation
----- rapid and slow mix control kinetics of clarification process
Bottom outside - settling zone
----- take advantage of stokes' law
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11
Q

What will be done to a waste stream from a depth filter if no option for deep well injection

A

Remove water mechanically to reduce cost of landfill

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12
Q

Extraction

A

Use of two phases to extract a third substance from one of two phases

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13
Q

Kh

A

Equilibrium constant/partitioning coefficient for gas partitioning with aqueous

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14
Q

Kow

A

Equilibrium constant/partitioning coefficient for partitioning between octane and water

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15
Q

Partitioning

A

Equilibrium for a compound as it moves across the surface for two phases

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16
Q

Vapour Pressure

A

Equilibrium constant/partitioning coefficient for partitioning between liquid and gas

17
Q

What factors will affect the rate of oxygen dissolving in water?

A

Concentration of reactants, surface area, temperature, catalyst (if available)

18
Q

What will affect rate at which oxygen is consumed in water?

A

Kinetics of metabolism and oxidation - concentration of oxygen and organics, temperature, surface area, and catalyst (bacteria)

19
Q

Distinguish between dissolved oxygen concentration equilibrium vs steady state

A

If DO not at equilibrium, but concentration not changing then it is steady state

20
Q

Compare concentration of dissolved oxygen in a quiet, shallow lake and a crazy wildin’ fountain

A

If temperature and pressure the same in both place, then DO equilibrium will be the same

21
Q

Describe how GC uses partitioning to separate organic compounds from water

A

There is a narrow tube with two phases: solid phase (beads), and mobile phase (washed past beads.

Dissolve mixture to be separated into mobile phase and inject into top of column.

As mixture passes through column different compounds partition between mobile and stationary phase.

The larger the partition coefficient = greater the solubility of compound in stationary phase = slower it moves through the column.

—-Adjust phases, temperature, rate of mobile phase flow to separate many compounds from complex mixtures.

22
Q

Which compound when dissolved would produce solution with highest PE?

A

Compound whose reduction half reduction has highest E value.

23
Q

Nitrogen compounds associated with new and old sewage

A

New: organic nitrogen (proteins) and ammonia
Old: ammonia, nitrate, nitrite

24
Q

What tests run to determine TOC for a sample of waste water?

A

Burn everything at a very high temperature, burnt material analyzed for CO2, TSO (total suspended organics) subtracted for TOC

25
Q

Three complications that arise in waste water treatment from presence of o+g

A

Most complications arise from the poor solubility of o+g in water -> two phases present

  1. Transportation through pipelines (deposits on pipes, clogging pumps)
  2. Destruction by biological treatment units (oxidation only on surface of oil phase)
  3. Disposal into receiving waters (surface spill limits O2 intake, sinking spill can coat sediments)
26
Q

Five ways of analyzing for suspended organics in water

A
  1. Centrifugation: Spun at a high G value and measure separated components
  2. Partition gravimetric: hexane separated from water, evaporate off, weigh residue
  3. Partition infrared: analyzed using IR spectrophotometry
  4. Soxhlet extraction: acidify, hexane ran through, evaporate hexane, weigh residue
  5. Hydrocarbon analysis: preparation for other techniques where silica is added to hexane

EVT: ENVS 359 Section 9 - 12 (1 decks)

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