Wastewater test 2

Differences between type 1 and type 2 settling

Type 1: discrete non flocculating particles. shape, size do not change
Type 2: particles flocculate and aggregate on contact changing size, shape and specific gravity

What does stokes law describe

Describes the drag force on a particle moving at low velocities

What are the requirements for stokes law

Laminar flow, terminal settling velocity in water, spherical particle

3 mechanisms/efficiencies of media filtration

1) Interception: Catches particles on top of media good for large particles
2) Sedimentation: Catches particles throughout media, good for large/dense particles. Stokes law applies
3) Diffusion: Catches particles through brownian/van der wal forces, good for submicron particles

List the different types of membrane filtrations from largest pore size to smallest

Microfiltration, Ultrafiltration, Nanofiltration, Reverse Osmosis

List the major design and operating parameters for membranes

Quality of influent, Level of treament required, type of target contaminants, Budget

Major design parameter for clarifiers/settling tanks

Surface overflow rate Flow/surface area

Major design parameter for filter

Filtration rate (flow/surface area)

Conditions for when backwash is needed

Breakthrough turbidity (NTU’s)
Headloss (ft)

What is precoat and why is it used

Pre-coat is coagulant added to media. Chemically induces particles to be larger during flocculation

List the three different chemical disinfectants for most to least efficient

Ozone, Chlorine Dioxide, Free Chlorine

Most efficient disinfectant

UV radiation

Describe each type of disinfectant and their benefits and drawbacks

Ozone: strong oxidant, no residual
Chlorine dioxide: strong oxidant, unstable residual
Free chlorine: HOCL at low ph or OCL at high ph, stable residual
Chloramines: NH₂Cl, weak oxidant, stable residual

What is the CT concept of disinfection

Disinfection activity expressed as a product of disinfection concentration (C) and time (T) ie C=10mg/L then T=10min for CT=100mg/L-t

What is Monod Kinetics

Monod kinetics is a mathematical model that shows relationship of growth rate and limiting substrate

Where would you find u_max and K_s on a curve

u_max is the value that the curve levels off at
K_s is the point on the x axis where the y=u_max/2

what does Yield (Y) represent

Y represents the relationship between Biomass produced over the substrate consumed

What are the differences of Aerobic, Anoxic and Anerobic processes

Aerobic: uses molecular oxygen
Anoxic: uses Nitrogen (NO₃)
Anerobic: does not use oxygen or nitrogen

What are we disinfecting in wastewater and drinking water

Wastewater: indicator organisms
Drinking water: Coliforms

What are the different types of carbon sources

Heterotrophic: organic carbon (COD, BOD)
Autotrophic: inorganic carbon (CO₂)

Describe each variable in this image

a= alpha (chemistry)

n_t= efficiency
L = bed depth

d_m = diameter of media

epsilon = porosity