Bioremediation Flashcards
ppm
mg/kg or L of sample
ppb
ug/kg or L of sample
TPH
Total petroleum hydrocarbons
4 common modes of biodegradation of organic compounds
- cellular metabolism
- detoxifying enzymatic reactions
- non-enzymatic reactions
- cometabolism
Catabolism
C used as NRG source, CO2 released
Anabolism
C converted to biomass
Detoxifying enzymatic reactions
Antibiotic degradation, metal transformations
Non-enzymatic reactions
By-products of microbial metabolism changing environmental conditions
Cometabolism
Compound modified but not used for generation of energy or biomass
Of the various remediation technologies, what is the most/least expensive
Incineration is most, bioremediation is the least
Conventional remediation technologies
Incineration, containment, chemical additions and soil washing… excavation is often the first step
How are sites remediated using chemical additions
Chelating agents or hydrogen peroxide addition
What are examples of containment
Landfill, land farming, solidification/stabilization
What is the downside to conventional remediation strategies?
Pollutants may be converted to another form or moved to another environment
Why is bioremediation better than conventional strategies
Pollutants are destroyed, cost is lower
What are the two divisions of in situ bioremediation
Intrinsic and enhanced
Intrinsic bioremediation
Rely on existing microbes
What are some downsides to intrinsic bioremediation
Slow, requires comprehensive monitoring program
What are two divisions of enhanced bioremediation
Bioaugmentation and biostimulation
Bioaugmentation
Addition of microbes
Biostimulation
Addition of O2 or another electron acceptor, or addition of fertilizers or inducers
What are 4 things that need to be considered when performing a bioremediation assessment study
- are the contaminants biodegradable
- are degrative microbes present
- are the environment parameters optimal for degradation
- what are some limiting parameters
Phase 1 of a bioremediation assessment
Use of controls and methods for detection of pollutants or bio-degradation end-products, detecting and quantifying pollutant-degrading microorganisms (lab tests)
What is a biopile?
A collection of contaminated soil in which fertilizers and air are pumped into to enhance biodegradation
What is bioventing in contaminated aquifers?
A vacuum is applied to bore holes to pump in oxygen, promote air flow, and pump out fumes which are collected for treatment
What is biosparging
Air is pumped into the groundwater zone to increase aerobic activity
What is needed for biosparging to work?
A porous environment
What is the difference between biosparging and bioventing
Bioventing pumps air into the unsaturated (vadose) zone, whereas biosparging pumps air into the groundwater zone
What is a permeable reactive barrier
A barrier used in shallow aquifers that contains metals/chemicals that degrade the contaminant when it comes in contact with it
What are 3 primary removal methods associated with permeable reactive barriers?
- sorption/precipitation
- chemical reaction
- biodegradation
What is phytoremediation?
Adding a plant to contaminated soil that has associated microbes that degrade the contaminant
What are some benefits to phytoremediation?
Looks good to the public, inexpensive, can occur in situ, production of biomass
What are some cons to phytoremediation
Slow, hard to predict, difficult to treat multi-contaminated sites
What is the major source of oil released into the oceans?
Drains
What is Alcanivorax borkumensis?
An obligate hydrocarbonoclastic bacterium – sole source of energy is hydrocarbons
What is a biosurfactant
A chemical produced by a bacterium to help with the emulsification of oil
What are some fates of an oil spill in a marine environment
Oil washed back into sea, oil slicks on shore, sedimentation, evaporation, mousse formation, suspended oil particles
What are some remediation treatment options for marine oil spills
In situ burning, dispersants, physical recovery, photooxidation, biodegradation
What was significant about the clean up of the EVOS?
It was the first time bioremediation was used for an oil spill on such a large scale
Major steps necessary when cleaning up a beach covered with crude oil
- clean up bulk by physical means
2. clean up remaining by in situ bioremediation
What are two examples of compounds added to stimulate biodegradation of crude oil on beaches?
Inipol EAP 22 and customblen
What is inipol EAP 22
An oleic acid fertilizer that sticks to the oil, slow release
What is customblen
Source of ammonium nitrate, good for anaerobic zones
What are 3 ways to know if a bioremediation approach was successful?
- quantify residual oil per area and type of hydrocarbon over time
- look for enhanced populations of hydrocarbon degraders using molecular genetics
- expect to see a difference between treated and untreated areas
How to test for biodegradation rate
Mix sedmient slurry from treated vs untreated areas with 14C labeled hexadecane or phenanthrene (microcosms) and compare the rate of 14CO2 produced over time
What is hexadecane
A C16 straight chain alkane used as a model in biodegradation studies
What is phenantherene
A 3-ring PAH used as a model PAH in biodegradation studies
What are examples of 2 hydrocarbon degrading genes
xylE and alkB
What does xylE encode for
catechol 2,3-dioxygenase (degrades aromatics)
What does alkB encode for
Alkane hydroxylase (degrades alkanes, usually from C10 to C16)
What is cytochrome P450 CYP153
A type of alkane degrading enzyme, commonly found in alkane degrading bacteria that lack AlkB
What were some clean up operations for the BP deepwater horizon oil spill
Skimming, burning, dispersants (Corexit 9500), and weathering
What is metagenomics
Sequencing of all the DNA from a polluted sample and looking for the biodegradative genes of interest
What is metatranscriptomics
Isolate all mRNA from an environmental sample, convert to cDNA, sequence, and compare metagenome
Indicates genes coming from active organisms
What is metaproteomics
Isolate all proteins from an environmental sample, sequence, and compare to metagenome
Indicates the genes that are being transcribed (most active)
How are plastics degraded
Biofilm formation secretes enzymes (biodeterioration) that fragment (biofragmentation) the plastic into soluble intermediates, then mineralization resulting in microbial biomass, CO2 and H20
What are halogenated compounds?
Organic molecules containing Cl, Fl, Br… very recalcitrant
What are some examples of halogenated compounds
PCP, 24D, PCBs
What are the 3 general steps of halogenated compound biodegradation
- Debranching ring-breakage
- dehalogenation hydroxylation
- ring-cleavage oxidation/reduction
What is the hardest step to do in halogenated compound biodegradation
The second step, dehalogenation hydroxylation
Dehalogenation of simple haloaromatic compounds can occur…
aerobically or anaerobically
What is an example of aerobic dehalogenation
Dehalo of dichloromethane by Hyphomicrobium dehalogenase
What is an example of anaerobic dehalogenation
Dehal of 2-chlorobenzoate via mono- or dioxygenases
PCP and PCB biodegradation can occur…
aerobically or anaerobically
What is PCP
Herbicide, insecticide, disinfectant, wood preservative…. highly toxic
How is PCP degraded anaerobically
By reductive dichlorination (chops off one Cl at a time)… H2 from other microbial activity acts as electron donor
PCB resistance to biodegradation increases with…
Number of chloro-substitutions
What is the product of aerobic degradation of chlorobiphenyl (PCB)
Chlorobenzoic acid (dead end product that accumulates in environment
What is 24D
Pesticide/herbicide used to control broadleaf weeds… highly toxic, readily biodegraded
What are the metabolites of DDT degradation and why do we care
DDD and DDE, they are more toxic and recalcitrant than the parent compound
How are nitroaromatics degraded
Anaerobically, nitro groups are reduced (used as TEAs) and aerobically, nitro groups are cleaved via mono- or dioxygenases
What are examples of nitroaromatic compounds and what degrades them
TNT and TAT, clostridium and desulfovibrio
What is a major problem with the reductive transformation of TNT
Metabolites become progressively less biodegradable and more recalcitrant
What are some key features of a super bug
Tough surface, biosurfactants, multi-functional respiration, high motility, has genes that encode different metabolic pathways
What is a problem with introducing GM microbes into the environment
Has to compete with existing microbes and it may not work like it does in the lab
What is JMS34
A GM strain of mircoorganism used to degrade the dead end products of PCB degradation, CBA (chlorobenzoates)
How did they create JMS34
They combined the chlorobiphenyl and chlorobenzoate/chlorocatechol degradation pathways of two other microorganisms and inserted the genes encoding for it
What was the Savannah River Site contaminated with
TCE and PCE… common industrial solvents that are highly toxic
What was involved in Plan A to remediate the Savannah River
Bioventing & air stripping
Two horizontal wells were place to inject oxygen (lower) and extract the gases (upper)
Vertical wells were drilled for sampling
What is air stripping
A process where a constant air stream is sent through the contaminated ground water to force chemicals from the water into the gas phase
What was the hypothesis of plan A in the Savannah River
Air will stimulate microorganisms to degrade TCE
Why did air stripping fail in the Savannah River?
TCE and PCE were not volatile enough under the conditions for it to work, and most microbes known for dehalogenation are anaerobes
How are TCE/PCE degraded anaerobically
SRB use them as TEA, reductive dehalogenation (dehalorespiration), yields ethene
How do methanogens degrade TCE/PCE
Anaerobically, reductive dehalogenation yields ethene
How do methanotrophs degrade TCE/PCE
Aerobically, oxidize methane as an energy source using methane monooxygenase, this can cometabolize TCE
Dehalorespiration
The use of halogenated compounds as TEAs in anaerobic respiration, yields ethene
What is the key reaction in the cometabolize of TCE with methanotrophs
The formation of TCE epoxide (unstable)
What was involved in plan B of the Savannah River/the hypothesis
To stimulate methanotrophs by adding O2 and methane
Hypothesis was that methanotrophic bacteria by methane and air will breakdown TCE via cometabolism
Why can PCE not be degraded by methanotrophs
PCE cannot be degraded by MMO (produced my methanotrophs) but it can be converted to TCE under anaerobic conditions by SRB and methanogens
What was plan C for the Savannah river
Add: air, methane, N2O and triethyl phosphate (sources of N and P)
What was the result of plan C for the Savannah river
Increased methanotrophs, decreased TCE and PCE levels, increase Cl and CO2 evolution
What happens when you add organic material to a water source
Environment becomes anaerobic as dissolved oxygen concentration decreases, die off of aerobic organisms
Autocthonous
Indigenous water column organisms
Allocthonous
Transient water column organisms that are harmless or pathogens
What are some fecal bacteria found in waste water
Salmonella, shigella, e coli, Vibrio chloera
What is the dissolved oxygen concentration in non polluted freshwater vs polluted
8-9… 4
What happens to the DO and BOD when waste water is added to a aquifer
DO decreases and BOD increases
What are the zones following the addition of waste water to an aquifer
Decomposition, septic, recovery and clean
What are some characteristics commonly measured in municipal wastewater
Dissolved and suspended solids, BOD, COD and free ammonia
BOD
Measures amount of O2 required for the aerobic degradation of organic material in a water sample, gives an index of pollution potential
BOD is an indirect measure of…
Biologically utilizable organic material via determination of dissolved O2 concentration
What is the equation for a BOD test
BOD = D1 - D2/ P
P - dilution of wastewater sample
BOD may include…
O2 required for inorganic oxidation, and O2 required by nitrifiers
COD
The amount of O2 consumed in the complete oxidation of organic matter
When will COD be higher than BOD
If biologically recalcitrant organic compounds are present
The reaction of COD is carried out under…
Acidic conditions, employs strong oxidizing agent to oxidize organic compounds to CO2
What are 3 objectives of waste water treatment
Removal of N/P, removal of pathogenic microbes, reduce organic C content (reduce BOD)
Primary and tertiary treatments are…
Physical/chemical processes
Secondary treatments are…
Biological processes
What are floculants
Aid in solid and colloid settling as well as some phosphate-removal
Primary treatment can remove great than….
90% of organic matter
What is a water clarifier
Skims of grease and foam, settled material removed from bottom, clear effluent from top flows into secondary treatment… grit and large debris are removed first
What are three divisions of the secondary treatment
Activated sludge, trickling filter, sludge digestor
What parts of 2nd treatment occur aerobically vs anaerobically
Aerobic: activated sludge and trickling filer
Anaerobic: sludge digestor
What are three microbial process that occur during aerobic secondary treatments
Nitrification, removal of pathogens, removal of nutrients
The activated sludge process can reduce BOD by…
90% in 4-8 hours
What happens in the activated sludge process
NPC are converted to biomass (flocs), flocs settle out of solution thus removing BOD, floc is recycled to the next treatment
What is a sequence batch reactor
Fill with water from primary treatment, react, settle and decant
What is bulking
A problem in the settling of floc because of an over abundance of filamentous organisms in the sewage population, they hold the flocs apart and prevent settling
What causes bulking
Nutrients, flooding, seasonal changes, toxic chemical influx, pH changes
How can you control bulking
Predation by ciliated protozoans on the filamentous bacteria, chemical amendments that may help control bulking species or promote settling
What is the concept of a trickling filter
Relies on formation of biofilm on the surface of the 2, deep loose gravel, apply highly aerated sewage spray, requires periodic backwash and disposal of sludge… as wastewater flows, nutrients are absorbed by biofilms
What is a sludge digestor
Similar to septic tank, big tanks that does anaerobic degradation
How can sludge digesting be sped up
Mix tanks, add heat, recycle ripe sludge, burn the methane produced
What are some microbial processes in anaerobic digestion
Denitrification, fermentation, acetogenesis, and methanogenesis
What happens to the residual sludge from digestors
Stabilized, good fertilizer except for heavy metals, usually dewatered and land-filled
What happens to the effluent after sludge digestion
High BOD, goes back to sewage treatment system (tertiary treatment)
Primary and secondary treatment only remove __ of P
30%
What are charcoal filters
Filter, remove organic compounds recalcitrant to biodegradation… burn charcoal after to destroy organics
Key points of primary treatment
Physical/chemical
Removes suspended solids
Removes 30-40% of BOD
Solid disposal
Key points of secondary treatment
Biological
Removes dissolved organic substrates, pathogens, NH4
Reduced BOD by 80-90%
Key points of tertiary treatment
Physical/chemical
Expensive
Reduces recalcitrant organics, PCBs, chlorophenols and PO4
What is a sewage pond
Natural waste water treatment, slow (7-50 days), requires a lot of land, low maintenance costs
Reduces BOD by 75-95%
Aerated lagoon
Transfer of air into basins, provides mixing to disperse the air
80-90% removal of BOD in 1-10 days
What is a septic tank
Anaerobic degradation, similar to sludge digestions
Artificial wetlands
Agricultural operations use them to replace treatment plants, not practical on the large scale
What are some protozoa found in contaminated water
Giardia, cryptosporidium
Coliform test
Detects fecal contamination in water
Coliforms
Enteric, gram neg, ferment lactose
Three stages of coliform test
Presumptive, confirmed and completed
What are some ways to determine numbers of bacteria in water
Filter plate method, direct count method
Why do we only test water for e coli
Current detection methods do not all for routine analysis of all microorganisms, but e coli is always present in human intestines so its presence would indicate fecal contamination
What are the guidelines for total coliforms when greater than 10 water samples are collected
No consecutive samples from the same site or no more than 10% of samples should show coliforms
MAC are only specified for…
E coli and coliforms
What are the 4 major steps involved in drinking water purification
Sedimentation, coagulation/flocculation, filtration, disinfection (chlorine gas of UV)
What are 2 drinking water filtration processes used
Rapid and slow sand
What is rapid filtration
Water most vertically through sand which often has a layer of activated carbon, traps organic C
What is slow sand filtration
Graded layers of sand, higher removal rates for all microorganisms
What are the objectives of disinfection
Kill pathogens, remove chemicals, contaminants, suspended solids
What are three methods of disinfection
Chlorine, ozone, UV irradiation
Chlorine disinfection
Residual activity, sodium hypochlorite, organic molecules in drinking water become chlorinated forming (THMs, carcinogenic)
What is an alternative to chlorine disinfection
Monocloroamines, less effective against viruses but much less THMs formed
Ozone disinfection
No THMs formed, but can form bromate (carcinogenic)
UV disinfection
Effective but not residual activity, optimization difficult
Sweage sludge
Residual, semi-solid material left from sewage treatment process
Biosolids
Sewage sludge that has been treated
What can biosolids contain
Trace metals, pathogens, organic contaminants, PPCPs, antibiotic resistant material
Eutrophication
Increase P and N inputs into water bodies from erosion and run-off from agriculture - result in algal blooms
Remediation strategies of eutrophic lakes
Chemical treatments, dredging lake sediments, ecological restoration (promoting macrophytes)
Dead zones
Zones of low oxygen areas in the worlds oceans and lakes caused by excessive nutrient pollution from human activities coupled with other factors that deplete oxygen
