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RemTech Final

Does not include midterm material

QuestionAnswer
Is soil vapor extraction in situ or ex situ? In situ
What is soil vapor extraction used for? Reduces volatiles in the vadose zone and useful on hydrocarbon contamination from USTs
Describe soil vapor extraction. Vacuum the vapors from extraction wells for combustion.
What are key parameters for soil vapor extraction? Soil permeability- the more the better Water table deeper than 1m volatility- volatilizes between 250 and 300 Moisture-the lower the better
Which contaminant can SVE not remove at all? a) gasoline constituents b)diesel constituents c)heating oil constituents d)lubricating oil constituents d) SVE cannot remove any part of a lubricating oil
Issues with SVE Upwelling- sucking the water table instead of volatiles Difficult to reduce by more than 90% Emission permits required
What is the radius of influence? The radius of the area affected by the SVE. Helps determine number of extraction locations needed.
Advantages of SVE Only $20-50 per tonne Can combine with other technologies Minimal disturbance
SVE enhancements Air sparging- adding oxygen Steam/hot air injection- increases volatilization Fracking - increases pore space
What is multi phase vacuum extraction? Simultaneously removes combinations of contaminated groundwater, free product, and vapor
Can you use MPVE in the long term? Not really, can be for a few hours once a month
What makes MPVE different from SVE? MPVE can be used on the water table and soil; SVE can only be used on soil. MPVE works better on clays and fine sands.
What technologies are MPVE usually combined with? Air sparging, bioventing, or bioremediation
Another term for multi phase extraction Bioslurping
Example of a case study that used MPVE. Knox church; pigeon lake
Limitations of MPE Requires both vapor and water treatment 85 000 to 500 000 per site
Can electrokinetic remediation be done on organics? Yes, if they are polar.
Explain how electrokinetic remediation works. A cathode and anode are inserted a bit apart from each other. Metal ions will accumulate at the cathode, anions will accumulate at the anode.
What pH issue can occur with electrokinetic remediation? Acid will form at the anode and base will form at the cathode. Mnemonic device: ABC (acid anode base cathode)
How could you fix the pH problem with electrokinetic remediation? Switch the electrodes
Primary mechanisms of electrokinetic remediation Electromigration- moving ions Electroosmosis- moving ion-containing liquids Electrophoresis- moving charged particles relative to a liquid
What is the lasagna process? a) Making a delicious pasta b)Layering positive and negative electrodes c)Layering other technologies between the electrodes Technically, both a and c are true, but in this case it is C
Two approaches to electrokinetic remediation. Enhance the removal or enhance the treatment
Would you use EK in high or low permeability soils? Low
Limitations to EK Moisture content ideal between 14% and 18% Redox rxns may occur and have undesirable products Ore deposits may interfere $120/m3
What is oxidation? Adding oxygen OR the loss of electrons
Common oxidants Persulfate, Fenton's hydrogen peroxide, permanganate
Why would you want a low organic carbon content when oxidizing? The oxidants react with organics, and do not differentiate. Organic soils could be destroyed.
Ozone oxiation - Fast - Hydroxyl radicals or on own - Effective in acid - May enhance biodegradation
Hydrogen peroxide oxidation - Fast - Hydroxyl radicals esp with iron - Acidic conditions best - Exothermic - Good for PCE and double bonds
Permanganate oxidation -Slow and persistent - May mobilize metals by pH decrease
You have to remediate some BTEX. Which oxidants could you use? hydrogen peroxide, or Fenton's
What is regenox? A combo of sodium percarbonate/bicarbonate and silica/ferrous sulfate compounds
What is an oxygen release compound? Phosphate intercalated magnesium peroxide that releases oxygen on contact with water
What is a waterloo emitter? Method of slow controlled release of ORC or other additives
Advantages to chemical oxidation - usually fast - in situ - cheap
Disadvantages to oxidation - acid - byproducts - health/safety concerns
What is phytoextraction? The plant accumulates the contaminant. This may be natural or induced. The plants are incinerated after.
Contaminants treated with phytoextraction. Mostly metals like silver, zinc, copper, or chromium
Plants for phytoextraction. Sunflowers (As and U) Poplar Samphires accumulate salt
Phytoextraction vs phytostabilization Phytostabilization reduces and immobilizes the metals but extraction removes them.
What is phytodegradation The plant transforms/breaks down the chemical. May be metabolic or enzymatic.
What contaminants are best for phytodegradation? LogKow between 0.5 and 3 BTEX, chlorinated organics, PAH, PCB
Plants for biodegradation Spearmint, poplar, grasses, canna lily
Plants that will undergo phytovolatilization. Poplar saplings and MTBE Arabidopsis and Hg
What is rhizofiltration Contaminants adsorb onto the root
What is rhizodegradation Enhanced microbial activity around root zone degrades organics. ex/ legumes and nitrates
Limits to phytoremediation Root depth, growth rate, contamination levels
What is a sievert the chance of 5.5% cancer
Types of remediation Alpha, beta, gamma
Alpha decay Can't go through paper, equivalent to helium nucleus ex/ radon 222
Beta decay Can't go through plastic, equivalent to electron or positron, transmutation. ex/ radium decay
Gamma decay Can't go through steel, lead, occurs with alpha and beta, no charge, x rays, ex/ bismuth decay
Why is radiation bad for tissues? Ionization and radical formation
Three naturally occurring decay series U238, U235, and Th232
Env concerning decay series U238 and Th232
Decay series important for human exposure U238
Radon 222 Formed from alpha radium decay, longer half life, most abundant
Sources of NORMs Uranium tailings, coal mining, fertilizer production, oil/gas production
NORM disposal Pembina, Ft St John, Unity
nZVI nano zero valent iron PCE/TCE degradadation More reactive due to more SA
Steps in remediation planning Identify your contaminants and levels Identify your impacted medium and amounts Decide what treatments are possible Decide on the best one Calculate the price and equipment needed
Created by: swilson67