441 Midterm 1

A successful engineer needs to realize the importance of life-long learning and continuously update knowledge and job skills

True

To express contaminant concentrations in water, 1 ppm is equivalent to 1,000 mg/l

false

Removing carbon dioxide (CO2) in water will increase the pH of the water

true

Adding salts to a water sample will raise its boiling point

true

Coliform is commonly used as an indicator microorganism with regards to water quality

true

Our drinking water needs to be both potable and palatable

false

Saturated dissolved oxygen (DOsat) concentration in water open to air is ~30 mg/L @ 20 degrees celsius

false

The sulfate buffer system controls the pHs of our ambient rivers and lakes

false

The concentration inside a plug flow rector (PFR) is the same as the reactor effluent

false

Batch reactors are operated under unsteady state

true

Na2CO3 is the chemical formula for soda ash

true

Chloride ion (Cl-) is considered as part of the hardness in water

false

Coagulants are added to the coagulation process to destabilize the colloidal particles

true

Colloidal particles in our ambient water typically carry positive charges

false

For a coagulation/flocculation process, the velocity gradient of coagulation is larger than that of flocculation

true

For three reactors in parallel, the entire flow goes through all the three reactors

false

In a lime-soda softening process, carbonate hardness is harder to remove than non-carbonate hardness

false

In a lime-soda softening process, magnesium ions are harder to remove than calcium ions

true

In zone/hindered settling, particles will accelerate downward until reached a terminal velocity

false

The hydraulic loading rate can be used to determine the top surface area of a sedimentation tank

true

According to Schultz-Hardy rule, Al+3 is a more effective coagulant than Na+

true

For coagulation/flocculation, the velocity gradient of flocculation > that of coagulation

false

For coagulation/flocculation, typical hydraulic detention time for coagulation is about 20 minutes

false

In discrete particle settling, a particle will accelerate downward until reached its terminal velocity

true

Saturated dissolved oxygen (DOsat) concentration in water open to air is ~150 mg/L @ 20 degrees celsius

false

To express contaminant concentrations in water, 1ppm is equivalent to 1.0 g/L

false

Na2CO3 is the chemical formula for hydrated lime

false

Compared to CFSTRs, PFRs are a better type of reactors for chlorine contact tanks

true

The hydraulic loading rate is often used to determine the water depth of the process tank

false

____ tests are often used in bench-scale studies to determine optimal coagulant and dosage

jar

According to Stokes Law, the terminal velocity of a 30μ particle would be ___ times faster than that of a 10μ particle

nine

Alkalinity of water is its capacity to neutralize

acids

BOD5 values represents the amount of biodegradable ___ in water samples

organics

For water balance, precipitation = infiltration + evapotranspiration + storage + ____

runoff

For water quality, conductivity is an on-line indicator of ___ solid concentrations

dissolved

Give a commonly-used unit for power: ____

watts

Hydraulic detention of a process tank = ____ / Influent flow rate

volume

MCL = Maximum ____ Level

Contaminant

pH + pOH = ___ at 20 degrees celsius

14

SDWA = ____ Drinking Water Act (Note: it is a federal regulation for drinking water)

Safe

The oxidation state of sulfur in sulfate (SO4-) equals to

+6

TSS = FSS + ____

VSS

Two sources of water for drinking water supply: surface water and ____

groundwater

Weight density of water = 9.81 kN/m^3 = ____ lb/ft^3 at 4 degrees celcius

62.4

A water treatment plant contains filtration, flocculation, coagulation, and sedimentation (put thesefour unit processes/operation in a right order)

coagulation, flocculation, sedimentation, filtration

Groundwater and surface water are two main sources for potable water supply.

True

More constant water composition - groundwater or surface water?

Ground water

Higher dissolved oxygen concentration - groundwater or surface water?

Surface water

Higher pathogen concentration - groundwater or surface water?

surface water

TDS = VDS +

FDS

For water quality, turbidity is an on-line indicator of ___ solid concentrations

suspended

The oxidation state of carbon in carbonate ions (CO3= ) equals to ___

+4

After lime and soda softening, the magnesium concentration in water should be kept below ___ mg/L to prevent formation of hard scale.

40

According to Stokes Law, the terminal velocity of a 10-μ particle would be ___ times faster than that of a 2-μ particle of the same type

25

VSS+FSS=

TSS

TDS+TSS=

TS