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Wastewater > Laboratory > Flashcards

Laboratory Flashcards

1
Q

The characteristics of typical domestic raw sewage:
BOD,
Suspended solids
Total solids

A
  • BOD5: 150-250mg/L
  • Suspended solids: 175 - 275 mg/L
  • Total solids: 1000 mg/L or 0.1 %
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2
Q

The pH scale.

A

0 - 14

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3
Q

pH values:
Acid
Alkaline or basic
Neutral

A
  • pH less than 7.0 (0.0 to 6.9)
  • pH higher than 7.0 (7.1 to 14.0)
  • pH 7.0
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4
Q

The strength of wastewater can be determined by measuring these.

A
  • BOD,
  • Suspended solids
  • COD
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5
Q

The relationship between the COD and BOD, of raw domestic sewage.

A

COD is approximately 2.2 times the BOD

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6
Q

The chemical oxidant use in the COD test procedure.

A

Potassium dichromate

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7
Q

These tests require grab samples only

A
  • Bacteriological samples
  • D.O.
  • PH
  • Temperature
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8
Q

Criteria of the BODs test procedure:
Incubation time
Incubation temperature
Standard bottle volume

A
  • Incubation time: 5 days +/- 3 hr
  • Incubation temperature: 20°C
  • Standard bottle volume: 300 ml
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9
Q

A test that measures the relative oxygen demand of wastewater and natural waters using
standardized laboratory procedures.

A

BODs

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10
Q

The test procedures indicated by the following acronyms:
BOD * COD * TOC * TKN

A
  • Biochemical oxygen demand
  • Chemical oxygen demand
  • Total organic carbon
  • Total kjeldahl nitrogen
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11
Q

Samples collected into a single container, at regular intervals, over a period of time

A

Composite sample

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12
Q

Settleable solids test:
Apparatus
Units oftest resul

A
  • Imhoff cone
  • ml/liter
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13
Q

Typical monitoring tests used for waste treatment ponds

A
  • pH
  • D.O.
  • Temperature
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14
Q

Characteristics of the fecal coliform test:
Method* Temperature * Incubation time * Media

A
  • Membrane filter - blue colored colonies are fecal coliform bacteria
  • 44.5 +/- 0.2° C
  • 24 hours
  • m-FC broth
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15
Q

De-chlorination chemical added to coliform sample bottles

A

SSodium thiosulfate, sometimes called “thio” (Na2S2O-)

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16
Q

Chemical used to dechlorinate BOD5 samples.

A

Sodium sulfite (Na,SO3)

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17
Q

Reagents used for BOD; dilution water

A
  • Calcium Chloride
  • Ferric chloride
  • Magnesium sulfate
  • Phosphate buffer
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18
Q

Reagents that can be used to titrate dissolved oxygen

A
  • 0.025 N Sodium thiosulfate (“thio”)
  • 0.025 N Phenylarsine oxide (“PAO”)
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19
Q

A pH probe should be stored in this solution

A

Probe filling solution or buffer solution - not distilled water.

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20
Q

The purpose of seed when added to a BOD, sample.

A

Provides necessary bacteria to utilize organic material in the sample

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21
Q

Samples that require the addition of seed when doing the BOD, test.

A
  • Chlorinated wastewater effluent
  • Industrial samples that lack bacterial population
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22
Q

Acid used in titration to determine total alkalinity.

A

Sulfuric acid (H2SO4)

23
Q

Approximate percent of the total BOD satisfied:
BODs . BOD2

A

BODs satisfies approx. 70% of the total BOD which is by definition the BOD20

24
Q

Compare
ppm (parts per million) * pounds per million pounds * mg/L

A

ppm = pounds per million pounds = mg/L

25
Q

Muffle furnace temperature for determining volatile solids (total, dissolved or suspended).

A

550 +/- 50° C

26
Q

Drying oven temperature:
Total solids, TS
Total dissolved solids, TDS
Total suspended solids, TSS

A

Total solids, TS 103 - 105° C
Total dissolved solids, TDS 180+/-2°C
Total suspended solids, TSS 103 - 105° C

27
Q

The acronym NPDES.

A

The National Pollutant Discharge Elimination System permit issued to all wastewater
treatment plants that discharge into receiving waters

28
Q

Textbook value for the daily per capita contribution:
BOD
Suspended solids

A
  • 0.17 lb BODs/capita/day
  • 0.22 lb suspended solids/capita/day
29
Q

Constant weight.

A

Weight loss of less than 4% of previous weight or 0.5 mg (whichever is less)

30
Q

Drying of solids must continue until this has been reached

A

Constant weight

31
Q

Three bacteriological indicators of adequate effluent disinfection.

A
  • Fecal coliform is still widely used
  • Enterococci and E. coli have been adopted by some states. The EPA considers these to be better indicators of health risk.
32
Q

Solution strength:
Normal solution
Molar solution

A
  • Gram equivalent wt. of solute per liter of solution
  • Gram molecular wt. of solute per liter of solution
33
Q

Standardized laboratory procedure that determines the oxygen required to stabilize the
biodegradable matter in wastewater by bacterial action.

A

BOD

34
Q

Sampling - preservation - storage:
BOD
COD
Solids
Bacteriological
Chlorine residual
Dissolved oxygen
pH

A

Test Sample Preservation Storage
* BOD OK to composite refrigerate up to 48 hr.
* COD OK to composite add H,SO, to pH 2 up to 28 days
* Solids OK to composite refrigerate up to 7 days
* Bacteriological grab sample cool to 4 °C up to 6 hr. transit to lab
* Chlorine residual grab sample none test immediately
* Dissolved oxygen grab sample none test immediately
* pH grab sample none test immediately

35
Q

Residual chlorine methods.

A
  • DPD colorimeter DPD turns pink/red in presence of chlorine residual
  • Amperometric titrator phenylarsine oxide (PAO) is the titrant
  • Starch iodide thiosulfate is the titrant
36
Q

Heat required to raise 1 gram water 1°C.
Heat required to raise 1lbof water 1° F

A
  • Calorie
  • BTU (British Thermal Unit)
37
Q

BOD test:
Allowable dilution water blank O, depletion
Valid 0, depletions
Seed control 02 depletion

CBOD test:
Used to dechlorinate samples
Aging BOD dilution water may allow this

A
  • Should not exceed 0.2 mg/L
  • 2-3 dilutions of each sample are prepared so that at least one of the dilutions meets this criteria: deplete at least 2 mg/L, but leave at least 1 mg/L residual D.O.
  • Same requirement as regular samples: deplete at least 2 mg/L, but leave at least 1
    mg/L residual
  • BOD with nitrification inhibitor added. Measures only the carbonacious BOD
  • Sodium sulfite
  • Growth of nitrifying bacteria in the dilution water which can cause artificially high
    BOD. Aging is not a problem when measuring CBOD because nitrification inhibitor is
    added to the BOD bottles.
  • Should not exceed 0.2 mg/L
  • 2-3 dilutions of each sample are prepared so that at least one of the dilutions meets this criteria: deplete at least 2 mg/L, but
    leave at least 1 mg/L residual D.O.
  • Same requirement as regular samples: deplete at least 2 mg/L, but leave at least 1 mg/L residual
  • BOD with nitrification inhibitor added. Measures only the carbonacious BOD
38
Q

Raw domestic sewage:
Typical water content * Temperature

A
  • 99.9% water. The total solids in sewage is about 0. 1 % or 1000 mg/L.
  • Slightly warmer than unheated tap water
39
Q

Used to determine average concenvaiions of influent and effluent flows over a 24 hour period.

A

24 hour composite

40
Q

Samples collected into a single container at an interval initiated by a specific flow volume passing the sample collection point.

A

Flow proportional composite

41
Q

Sample types:
Composite
Grab

A
  • Average or representative conditions over the time period that is sampled (usually 24 hr)
  • Representative of conditions (only) at the time of sampling
42
Q

Oxygen solubility in water decreases.

A
  • Atmospheric pressure is lower
  • Water salinity is lower is higher
  • Water temperature is higher
43
Q

Record of possession and handling of a sample from the time of collection, sample labeling, transport, storage and analysis.

A

Chain of custody

44
Q

Approved laboratory procedures for wastewater analysis.

A

Standard Methods for the Examination of Water and Wastewater

45
Q

Frequency of pH meter calibration

A

Calibrated prior to each use

46
Q

Used to titrate for D.O. in the starch-iodide method.

A

0.025 N thiosulfate

47
Q

TSS procedure:
Filter
Filter orientation on funnel support

A
  • Standard glass-fiber filter
  • “Wrinkled side up”
48
Q

These contribute to the total alkalinity of wastewater.

A
  • Bicarbonate (HCO)
  • Carbonate (CO,2)
  • Hydroxide (OH’)
49
Q

Effluent concentration is roughly the same as the influent concentration.

A

Total dissolved solids, TDS

50
Q

Media used for coliform bactcria:
m-TEC Agar
mfe Broth
ONPG-MUG (Colilert™)

A
  • Thermotolerant E. coli bacteria
  • Fecal coliform bacteria
  • Total coliform and E. coli bacteria
51
Q

Approximates organic content of solids.

A

Volatile Solids (dissolved, total or suspended)

52
Q

Comparing duplicate test results on the same sample.
Determining the percent recovery of a sample spike.

A
  • Test procedure precision
  • Test procedure interference
53
Q

pH meter calibration points.

A

Minimum two point. Calibrate to pH 7 buffer and then pH 4 or pH 10 buffer. Choose calibration buffers that “bracket” the pH range of the sample(s) to be tested.

Wastewater (10 decks)

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