1/34
Flashcards related to groundwater remediation.
Name | Mastery | Learn | Test | Matching | Spaced |
---|
No study sessions yet.
What is the formula for the saturation index (SI)?
SI = log(products/Keq)
What does it mean if SI > 0?
Supersaturated conditions
What does it mean if SI = 0?
Equilibrium
What does it mean if SI < 0?
Undersaturated conditions
How does surface area affect the rate of precipitation-dissolution reactions?
Greater surface area leads to a greater reaction rate.
How does the saturation index affect reaction rates?
Rates slow close to saturation.
What does redox potential (Eh) indicate?
A system's tendency to gain or lose electrons.
Low Eh indicates what type of conditions?
Reducing conditions
What is a redox couple?
Pairs of oxidized and reduced species that participate in electron exchange
How do environmental factors influence redox processes?
Oxygen availability and pH influence which redox processes dominate in natural systems.
Name the electron acceptor in denitrification.
NO3- (nitrate), reduced to N2
Name the electron acceptor in aerobic respiration.
O2
Name the electron acceptor in sulfate reduction.
SO42- (sulfate), reduced to H2S (hydrogen sulfide)
What does the Monod equation model?
How microbial reaction rates depend on substrate concentration.
What is Dual Monod kinetics?
Kinetics that account for both electron donor and acceptor availability.
What does a small Damköhler number (Da < 1) imply?
The reaction is slow compared to transport.
What does a large Damköhler number (Da > 100) imply?
The reaction is fast relative to transport, and local equilibrium assumption is valid.
How does Da help in designing remediation systems?
It helps identify the reactive zone length and residence time needed for remediation.
For what type of contaminants do pump and treat systems often work well?
Non-aqueous phase liquids (NAPLs)
What is a Light NAPL (LNAPL)?
A NAPL less dense than water that floats on the water table surface.
What is a Dense NAPL (DNAPL)?
A NAPL more dense than water that is typically more difficult to remediate.
What is the tailing phase in pump and treat systems?
The long period of slow release of contaminants to groundwater.
What is pulsed pumping?
Turning wells off and allowing concentrations to rebound before pumping again.
Define the zone of influence.
The zone around the well.
Define the zone of capture.
The zone within which all water flows to the pumping well.
Define the zone of travel.
An area defined by some chosen travel time (e.g., 10 years).
In anisotropic media, how does hydraulic conductivity vary?
Hydraulic conductivity varies by direction.
How many components does the hydraulic conductivity tensor have in 3D?
9
What is intrinsic bioremediation?
Naturally occurring bioremediation without augmentation.
What is engineered bioremediation?
Bioremediation involving biostimulation from the addition of electron acceptors or substrate.
How do redox conditions affect contaminant degradation?
Redox conditions control which contaminants can be degraded and how fast.
What are key design considerations for PRB systems?
PRB permeability, hydraulic capture, thickness, and lifespan.
What is zero-valent iron (ZVI) used for in PRBs?
To reduce contaminants by supplying an electron donor (Fe0 → Fe2+).
What are the advantages of PRBs?
No active pumping required (low maintenance costs), treats plume in place, minimal above-ground infrastructure.
What are the limitations of PRBs?
Plume depth, ability to only remediate certain contaminants, reliance on natural groundwater flow, and clogging.