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RemTech Final
Does not include midterm material
| Question | Answer |
|---|---|
| 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
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