Laboratory Flashcards
The characteristics of typical domestic raw sewage:
BOD,
Suspended solids
Total solids
- BOD5: 150-250mg/L
- Suspended solids: 175 - 275 mg/L
- Total solids: 1000 mg/L or 0.1 %
The pH scale.
0 - 14
pH values:
Acid
Alkaline or basic
Neutral
- pH less than 7.0 (0.0 to 6.9)
- pH higher than 7.0 (7.1 to 14.0)
- pH 7.0
The strength of wastewater can be determined by measuring these.
- BOD,
- Suspended solids
- COD
The relationship between the COD and BOD, of raw domestic sewage.
COD is approximately 2.2 times the BOD
The chemical oxidant use in the COD test procedure.
Potassium dichromate
These tests require grab samples only
- Bacteriological samples
- D.O.
- PH
- Temperature
Criteria of the BODs test procedure:
Incubation time
Incubation temperature
Standard bottle volume
- Incubation time: 5 days +/- 3 hr
- Incubation temperature: 20°C
- Standard bottle volume: 300 ml
A test that measures the relative oxygen demand of wastewater and natural waters using
standardized laboratory procedures.
BODs
The test procedures indicated by the following acronyms:
BOD * COD * TOC * TKN
- Biochemical oxygen demand
- Chemical oxygen demand
- Total organic carbon
- Total kjeldahl nitrogen
Samples collected into a single container, at regular intervals, over a period of time
Composite sample
Settleable solids test:
Apparatus
Units oftest resul
- Imhoff cone
- ml/liter
Typical monitoring tests used for waste treatment ponds
- pH
- D.O.
- Temperature
Characteristics of the fecal coliform test:
Method* Temperature * Incubation time * Media
- Membrane filter - blue colored colonies are fecal coliform bacteria
- 44.5 +/- 0.2° C
- 24 hours
- m-FC broth
De-chlorination chemical added to coliform sample bottles
SSodium thiosulfate, sometimes called “thio” (Na2S2O-)
Chemical used to dechlorinate BOD5 samples.
Sodium sulfite (Na,SO3)
Reagents used for BOD; dilution water
- Calcium Chloride
- Ferric chloride
- Magnesium sulfate
- Phosphate buffer
Reagents that can be used to titrate dissolved oxygen
- 0.025 N Sodium thiosulfate (“thio”)
- 0.025 N Phenylarsine oxide (“PAO”)
A pH probe should be stored in this solution
Probe filling solution or buffer solution - not distilled water.
The purpose of seed when added to a BOD, sample.
Provides necessary bacteria to utilize organic material in the sample
Samples that require the addition of seed when doing the BOD, test.
- Chlorinated wastewater effluent
- Industrial samples that lack bacterial population
Acid used in titration to determine total alkalinity.
Sulfuric acid (H2SO4)
Approximate percent of the total BOD satisfied:
BODs . BOD2
BODs satisfies approx. 70% of the total BOD which is by definition the BOD20
Compare
ppm (parts per million) * pounds per million pounds * mg/L
ppm = pounds per million pounds = mg/L
Muffle furnace temperature for determining volatile solids (total, dissolved or suspended).
550 +/- 50° C
Drying oven temperature:
Total solids, TS
Total dissolved solids, TDS
Total suspended solids, TSS
Total solids, TS 103 - 105° C
Total dissolved solids, TDS 180+/-2°C
Total suspended solids, TSS 103 - 105° C
The acronym NPDES.
The National Pollutant Discharge Elimination System permit issued to all wastewater
treatment plants that discharge into receiving waters
Textbook value for the daily per capita contribution:
BOD
Suspended solids
- 0.17 lb BODs/capita/day
- 0.22 lb suspended solids/capita/day
Constant weight.
Weight loss of less than 4% of previous weight or 0.5 mg (whichever is less)
Drying of solids must continue until this has been reached
Constant weight
Three bacteriological indicators of adequate effluent disinfection.
- 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.
Solution strength:
Normal solution
Molar solution
- Gram equivalent wt. of solute per liter of solution
- Gram molecular wt. of solute per liter of solution
Standardized laboratory procedure that determines the oxygen required to stabilize the
biodegradable matter in wastewater by bacterial action.
BOD
Sampling - preservation - storage:
BOD
COD
Solids
Bacteriological
Chlorine residual
Dissolved oxygen
pH
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
Residual chlorine methods.
- 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
Heat required to raise 1 gram water 1°C.
Heat required to raise 1lbof water 1° F
- Calorie
- BTU (British Thermal Unit)
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
- 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
Raw domestic sewage:
Typical water content * Temperature
- 99.9% water. The total solids in sewage is about 0. 1 % or 1000 mg/L.
- Slightly warmer than unheated tap water
Used to determine average concenvaiions of influent and effluent flows over a 24 hour period.
24 hour composite
Samples collected into a single container at an interval initiated by a specific flow volume passing the sample collection point.
Flow proportional composite
Sample types:
Composite
Grab
- Average or representative conditions over the time period that is sampled (usually 24 hr)
- Representative of conditions (only) at the time of sampling
Oxygen solubility in water decreases.
- Atmospheric pressure is lower
- Water salinity is lower is higher
- Water temperature is higher
Record of possession and handling of a sample from the time of collection, sample labeling, transport, storage and analysis.
Chain of custody
Approved laboratory procedures for wastewater analysis.
Standard Methods for the Examination of Water and Wastewater
Frequency of pH meter calibration
Calibrated prior to each use
Used to titrate for D.O. in the starch-iodide method.
0.025 N thiosulfate
TSS procedure:
Filter
Filter orientation on funnel support
- Standard glass-fiber filter
- “Wrinkled side up”
These contribute to the total alkalinity of wastewater.
- Bicarbonate (HCO)
- Carbonate (CO,2)
- Hydroxide (OH’)
Effluent concentration is roughly the same as the influent concentration.
Total dissolved solids, TDS
Media used for coliform bactcria:
m-TEC Agar
mfe Broth
ONPG-MUG (Colilert™)
- Thermotolerant E. coli bacteria
- Fecal coliform bacteria
- Total coliform and E. coli bacteria
Approximates organic content of solids.
Volatile Solids (dissolved, total or suspended)
Comparing duplicate test results on the same sample.
Determining the percent recovery of a sample spike.
- Test procedure precision
- Test procedure interference
pH meter calibration points.
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.
