Wastewater Laboratory Analysts Exam Study Guide2024\2025LATEST
VERSION | INCLUDES 2 RECENTLY TESTED EXAMS, A TEST BANK AND
A STUDY GUIDE | ACCURATE AND EXPERT VERIFIED FOR
GUARANTEED PASS | GRADED A
Chlor Acid vs. Base - ✔✔ANSW✔✔..Acid: hydrogen ion (H+) donor
Base: proton acceptor
*hydra= 1 H, -ic= multiple H, OH = Base
Ammonia Preservation - ✔✔ANSW✔✔..Plastic or glass. At least 500 mL, analyze ASAP
or preserve with H2SO4 to a pH <2, <6 C, 28-day hold time (with preservation)
anions - ✔✔ANSW✔✔..ions with a negative charge, they gain electrons
atomic mass - ✔✔ANSW✔✔..Number of protons and neutrons
Bacteria lack a _____ - ✔✔ANSW✔✔..nucleus
Basic Atomic Structure - ✔✔ANSW✔✔..Electron (-) on outer shell, neutron and proton
(+) in nucleus (center)
BOD Preservation - ✔✔ANSW✔✔..Plastic or glass. At least 1000 mL, <6 C, 48-hour
hold time
BOD:COD ratio in average WW is? - ✔✔ANSW✔✔..0.5:1
COD is usually double
BOD:N:P - ✔✔ANSW✔✔..100:5:1
Cations - ✔✔ANSW✔✔..ions with a positive charge, they lose electrons
Class A vs. Class B Glassware - ✔✔ANSW✔✔..Class B has double the tolerance of
Class A. Example, if Class A tolerance is +/- 0.30 than Class B tolerance is +/- 0.60.
Class A has a higher accuracy, so it's more $$$
,Clean Water Act - ✔✔ANSW✔✔..(CWA, 1972, named CWA in 1977) set maximum
permissible amounts of water pollutants that can be discharged into waterways; aims to
make surface waters swimmable and fishable. This creates the NPDES and DMR
COD Preservation - ✔✔ANSW✔✔..Plastic or glass. At least 100 mL, analyze ASAP or
preserve with H2SO4 to a pH <2, <6 C, 28-day hold time (with preservation)
Colilert 18 incubates for how long? - ✔✔ANSW✔✔..18 hours (up to 22)
Conductivity is inversely related to - ✔✔ANSW✔✔..Resistance
Conductivity = 1 / R unit = mhos ... its the inverse of ohm.
covalent bond - ✔✔ANSW✔✔..A chemical bond forms when two or more atoms share
electrons. Example- H2O (also H2O is a polar covalent bond)
Define coliform bacteria - ✔✔ANSW✔✔..Comprises all the aerobic and facultative
anaerobic gram negative, nonspore-forming, rod shaped bacteria that ferment lactose
(produces gas and acid) within 48 hours at 35 C.
Define total suspended solids (TSS) - ✔✔ANSW✔✔..the portion of total solids retained
by a glass fiber filter that remains after drying at 103-105 C
Describe TDS process. - ✔✔ANSW✔✔..First place evaporation dish into oven at 180
+/- 2 C for 1 hour. Desiccate, weight and record. Filtrate sample then pour filtrate into
evaporation dish and evaporate to dryness in a drying oven at 103-105. THEN dry
evaporated sample for at least 1 hour in oven at 180 +/- 2 C. Desiccate, weight and
record. Repeat until weight change is less than 4% of previous weight or 0.5mg.
Describe the iodometric direct method. - ✔✔ANSW✔✔..First acetic acid is added to
sample to reduce pH to 3/4. Then potassiom iodine (KI) is added to the sample where
the Cl libertaes the iodine. Then titrate with sodium thiosulfate, until the endpoint it
meant. Endpoint = sample turns blue.
Goes from yellow to blue
Describe the MPN/MTF process. - ✔✔ANSW✔✔..Begin the test with 15 test tubes,
using 3 dilutions (10mL, 1mL, and 0.1mL) then add lauryl tryptose broth to each.
Incubate for 24 +/- 2 hours at 35 +/- 0.5 C. Examine tubes for gas production and/or
acidic growth (turbidity). IF none then re-incubate for 48 +/- 3 hours. For positive tubes
transfer a loop full of material into tubes with Brilliant Green lactose broth with temp of
35 (for total coliform) and EC broth with temp of 44.5 (for fecal coliform).
Difference between BOD and CBOD? - ✔✔ANSW✔✔..CBOD has a nitrification
inhibitor, so it doesn't include nitrogenous materials.
,Drying oven temperature for TDS? - ✔✔ANSW✔✔..180 +/- 2 C
Each pH unit represents a factor of _____ change in concentration. - ✔✔ANSW✔✔..x10
EC mug is what? - ✔✔ANSW✔✔..For e. coli! Positives will be fluorescent.
EPA suggests that if a conductivity sample cant be read withing 24 hours, you should
do what? - ✔✔ANSW✔✔..Filter it through a .45 micron filter
Explain Beer's Law - ✔✔ANSW✔✔..The law states that the concentration of a chemical
is directly proportional to the absorbance of a solution. 0 absorbance = 100%
transmittance
Colorimeter is typically used for this.
The darker the color, the more absorbance. Thus, the darker the test the higher the
concentration. The only test that does not follow this rule is Fluoride.
Explain the safety diamond. - ✔✔ANSW✔✔..Top- red Flammability
Right- yellow Reactivity (like nuclear waste)
Bottom- white Special
Left- blue Health
Filter pore size for total solids? - ✔✔ANSW✔✔..2.0 um or smaller
For ammonia testing, sometimes distillation is required, this involves buffering the
sample pH to ____ using _____ - ✔✔ANSW✔✔..9.5 with borate buffer
For ammonia titration, what two indicators are uses and what is the titrant? -
✔✔ANSW✔✔..Indicators= methyl red and methylene blue dissolved in 95% ethyl
alcohol.
Titrant= 0.02 N sulfuric acid
For BOD, if sample is supersaturated, what are your 2 solutions to eliminate the
supersaturated DO? - ✔✔ANSW✔✔..Shake vigorously or aerate with clean filtered
compressed air
For BOD, if the pH has to be adjusted, what is it adjusted to? and what temp do the
samples need to be? - ✔✔ANSW✔✔..7-7.2 pH and a temp of 20 +/- 3 C
For COD what do you do if there is suspended solids in the sample? -
✔✔ANSW✔✔..Blend until homogeneous.
For COD- a sample is added to a solution of? What does each component do? -
✔✔ANSW✔✔..Potassium dichromate, sulfuric acid, silver nitrate, and mercury.
Potassium dichromate= oxidizes the organic material
, Sulfuric acid= reaction occurs in this\
Silver= is the catalyst (speeds it up)
Mercury= keep halides from interfering with the reaction
For colorimetric determination, the sample cell MUST be scratch and dust free. What
should be used to fill scratches? - ✔✔ANSW✔✔..Since colorimetric measure the
intensity of the color, the sample cell needs to be clean. Silicone oil is used to fill any
scratches.
For Fecal membrane filtration, what is the pore size of the filter? What is the typical size
of the bacteria? - ✔✔ANSW✔✔..The filter pore size is 0.45 um. The bacteria will have a
pore size of 0.5-0.8 um (unit = microns)
For fecal testing, what is media? what is the two types of media? - ✔✔ANSW✔✔..Media
is the material used to grow the bacteria of choice. There are two types of media, agar
(solid "jello"-like media) and broth (liquid media)
For membrane filtration, after filtering sample through the filter, where is the filter placed
(for fecal)? - ✔✔ANSW✔✔..The filter is placed on m-FC media and allowed to incubate
at 44.5 +/- 0.2 C for 24 hours +/- 2 hours in a water bath.
For MTF, what is the broth for phase 1 and phase 2? - ✔✔ANSW✔✔..Phase 1 = Lauryl
broth
Phase 2= Brilliant green broth
For titrations, what causes the color change? - ✔✔ANSW✔✔..A change in pH.
For TSS, what sample residue weight is required? - ✔✔ANSW✔✔..2.5-200 mg
Hardness Preservation - ✔✔ANSW✔✔..Plastic or glass. At least 100 mL, 28-day hold
time
How do you clean glassware for Bacteria testing? - ✔✔ANSW✔✔..Clean with hot soapy
water and rinse with distilled water. The pH and inhibitory residue checks should be
completed on glassware.
How do you clean glassware for Chlorine testing? - ✔✔ANSW✔✔..Glassware should be
soaked with water containing at least 10 mg/l chlorine for 3 hours or more. Before use
rinse with chlorine-demand-free water. (soaking in Cl water removes any Cl demanding
residue)
How do you clean glassware for Metal testing? - ✔✔ANSW✔✔..Acid washed and rinsed
with distilled water.
