bioremediation of land and water contaminated by toxic ... · chair professor of biology. city...
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Bioremediation of Land and Water Contaminated by
Toxic Chemicals
Nora F.Y. TAMChair Professor of Biology
City University of Hong Kong29 October 2008
Eco Asia Conference, Hong Kong
Water and land contamination, a pressing world wide problem, poses a major threat to
Hong Kong and Mainland, particularly the rapid urbanization and industrialization cities
Common pollutants
●
Excess nutrients●
Heavy metals
●
Petroleum products●
POPs (persistent organic pollutants)
Halogenated compounds
DDT, PAHs, PCBs, PBDEs……
PAH emission
Oil pollution in marine environment Oil drill platform in Norway
1989 Exxon Valdez Incident, 42 Million litres of crude oil spreading in Alaska
524,000 litres of crude oil has leaked in the South China Sea some 15 km from the mouth of the Pearl River (Dec 2004)
Need to develop technologies
(i) Remove pollutants from wastewater and prevent them
enter the ocean
(ii) Clean-up contaminated environments
Treatment Technology●
Physical, chemical and biological (using bacteria) treatments are available
Ion exchange
Chemical precipitation
Filtration (membrane filtration)
Reverse osmosis
Activated sludge, biofilm
●
Crucial problemsCost?Generate secondary pollution (sludge)?Effective?
Alternate Technology
Do not generate secondary pollution problem
No sludge disposal
Ultimate solution
Simple, flexible and robust
Easy to set-up
Easy to operate
Cost-effective
Natural and environmental friendly
Provide Alternate Solution to Sewage and Contamination Problems
Human activities, e.g. waste
Contamination in land & water
Bio- and phyto- remediation of POPs and oil
Constructed mangrove for wastewater
Bisorption(Free and immobilized
microalgae)
Constructed Wetland Treatment
Popular for municipal wastewater and shrimp pond effluent in Europe, UK and North America
Increasing rapidly in Central and South America, Africa, Australia and New Zealand, and in Asia
Recent years, some constructed wetlands started in Asia
Comparison of conventional treatment and constructed wetland
Conventionaltreatment system
•
Involve large capital investment and operating costs
•
Require technical support
•
Small villages would not be able to afford such expensive conventional treatment systems
Constructed wetland system
•
Can be constructed where the wastewater is produced
•
Can be maintained easily, technical know- how is easy to grasp
•
Relatively lower-energy requirements and low- cost
•
Environmental friendly
Constructed Wetland Plants
●
Most CW use annual or perennial plants with frequent harvesting
Phragmites (common reeds)
Typha (cattails)
Scripus (bulrush)
Eichhornia (water hyacinths)●
Need frequent harvesting
Fluctuating removal efficiency
Labor intensive
Disposal of plant materials
Mangrove as constructed wetland for treating
wastewater
Sewage discharge directly
to river channel flooded
mangroves
Cattail vs mangrove plantPlant species Cattail MangroveTypes of wetland plant Emergent plant Emergent plantMaximum water depths found in wetland
treatment systems 0.1 to 0.75 < 0.05 to 0.5Flooding duration found in wetland treatment
(%) 70 to 100 50 to 100root to shoot ratio 0.4 to 0.6 0.7Anoxia endurance (days) >28 N/AAdaptation to high salinity No YesVegetative structures Rhizomes SeedlingRates of vegetation reproduction High MiddleNeeds of harvesting annually N/ACommunity dynamics invasive non-invasivePhysiological adaptations shallow water intertidalGrowth rate (kg dry wet ha−1 d−1) 21.92 to 167.12 80Annual nutrient uptake (nitrogen) (kg ha-1) 600-2630 159.92Annual nutrient uptake (phosphorous) (kg ha-1) 75-403 27.59
Mangrove wetlands
•
Similar to constructed wetland using cattails
•
No need to harvest annually•
Sediment is an efficient trap
•
Plants are robust and good in transporting oxygen to anaerobic sediments
•
Diverse microbes•
Adapt to alternate wet and dry condition, like intermittent sewage discharge
Electrical pump
Schematic Diagram of SSF constructed wetland
Effluent
influent
Gravel Sandy Soil
Plastic Septa
PVC column
Plastic box
Mangrove vs Cattails
Kandelia candel Typha latifolia
Compared with other CW studies (% removal municipal sewage)
Klomjek and Nitisoravut (2005)
Kaseva (2004)
Wild et al.
(2001)
Hong Kong(our study)
Cattail Sedge Cattail Cattail Cattail K. candel
HRT (d) 5 5 2.5 ND 5 5
BOD/OM 74.3 77.8 60.7 - 34.4 74.3
NH4 75.4 67.4 23.0 74.3 80.8 77.9
TKN - - - 40.3 65.6 65.5
P 44.9 35.6 - 74.8 27.2 97.2
Different mangrove plant species
Aegiceras corniculatum Avicennia marina Bruguiera gymnorrhiza (Bg)
Sonneratia caseolarisSonneratia apetalaKandelia obovata (Ko)
Acanthus ilicifolius (Ai)
Kandelia Aegiceras Mixed
DOC 78.07 78.60 75.31
PO4 98.00 98.40 97.40
NH4 80.12 88.19 86.68
Inorg N 56.80 57.15 65.08
TKN 55.49 57.04 55.00
Removal % by different mangrove species with 5-days HRT
Mangrove plants
Kandelia obovata
Aegiceras corniculatum
Sonneratia caseolaris
Species COD BOD5 TN NH3 -N TP SP
Influent from Futian (mg/L)
119.03 53.02 16.17 13.53 1.61 1.26
S. caseolaris 43.3564.9%
13.3875.5%
8.5653.6%
6.8752.6%
0.6565.0%
0.4569.2%
K. candel 41.9862.8%
13.7573.8%
8.2550.0%
7.2745.2%
0.6462.2%
0.4764.8%
A. corniculatum 37.7567.8%
13.6174.1%
7.9855.1%
6.0058.4%
0.4574.5
0.3276.9%
Concentration of effluent (mg/L）and removal % in 2 years (HRT 2.5 days)
% removal (HRT = 2.5 days)
Sonneratia Kandelia Aegiceras
Total bacteria
91.3 89.1 93.0
Coliform group
95.8 94.0 99.2
E. coli 95.5 90.0 99.8
Different types of wastewater●
Primarily settled municipal sewage
High organic matter, N and P removal
Plant uptake, microbial transformation, retention in sediment
●
Aquaculture pond effluent: e.g. shrimp
Inorganic N (300 mg L-1) >80% removal
Inorganic P (70 mg L-1): >99.8% removal
DOC (600 mg L-1): >98.5% removal
●
Livestock wastewater: e.g. pig farm
Inorganic N > 85%; P > 95% removal
●
Electroplating industrial effluent
Heavy metals: Cu, Zn, Cr, Ni and Cd
Accumulation in root, retention in sediment
Provide Alternate Solution to Sewage and Contamination Problems
Human activities, e.g. waste
Contamination in land & water
Bio- and phyto- remediation of POPs and oil
Constructed mangrove for wastewater
Bisorption(Free and immobilized
microalgae)
Bio- and phyto-remediation:
Can mangroves be used for remediation of POPs
(Persistent organic pollutants)?
Plant detectstoxicant
Chemical toxicant
Enhancedmineralizationof toxicant
Exudates stimulatemicrobial community
Change inroot exudation
Bioremediation: Plant-microbe-toxicant interaction
Inorganic Heavy metalsWetland plants: Spartina alterniflora; Phragmites australis
Weis and Weis, 2004
Organic Atrazine Tall fescue (Pennisetum clandestinum)
Singh et al., 2004
PAHsTree (Hibiscus tiliaceus) and vetiver (Vetiver zizanoides)
Paquin et al., 2002; Muratova et al., 2003
Crude oil Sorghum bicolorBanks et al., 2003
BTX Legumes (Galega orientalis)Suominen et al., 2000
PCBLegumes: alfalfa Grass: reed canarygrass, switchgrass and tall fescue
Chekol et al., 2004
Examples of Phytoremediation
Mangroves were planted in contaminated sedimentPAHsSpent lubricating oilKai Tat Approach ChannelVictoria Habour
Remediation of sediment contaminated with spent lubricating oil
0
2
4
6
8
10
3MAi IYAi Bg OC
TPH
-F3
mg/
g
0d
120d
% loss = Day 0 – Day 120 TPH•
Day 0 vs Day 120 TPH
41% 44% 36% 22%
Pyrene-contaminated sediment was placed at the surface (TS)
Pyrene-contaminated sediment was placed at the bottom (TB)
Flooded8 hrs day-1
Contaminatedsediment
Removal of pyrene (%)
Plant employed
K. candel B. gymnorrhiza
TS 96.42.5a 90.185.2b
TB 92.81.5a 85.86.6b
CN(no vegetation)
/
88.30.5b
PyrenePyrene removal: removal: KcKc > CN = > CN = BgBg ((pp = 0.05)= 0.05)More removal when contamination is in surfaceMore removal when contamination is in surface
Removal of pyrene from contaminated mangrove sediment
Remaining in sediment
Unlikely, very little amounts of pyrene added remained in sediments, also relatively immobile
Abiotic loss
Insignificant
Plant uptake
Mainly in roots but at low amounts
Microbial degradation in bulk sediment or in the rhizosphere
Major route to remove pyrene
Fate of Pyrene in mangrove microcosm
Bacterial colony grown on Phe-coated MSM agar (Arrow showing the clear zone)
KLHS SKOO
YOWG
HCCW
MWFG SPNY MPFG
PAH-degrading bacterial strains isolated from the enriched consortia
Strains *Source Bacterial name (% similarity)KLHS KLH Sphingopyxis alaskensis (97)SKOO SK Rhodococcus ruber (99)SKNG SK Sphingobium yanoikuyae (99)HCSS HC Rhodococcus opacus (98)HCCW HC Novosphingobium pentaromativorans (97)MWFG MW Sphingomonas sp. (98)YOWG YO Mycobacterium chlorophenolicum (99)SPNT SPN Paracoccus versutus (99)SPNY SPN Novosphingobium aromaticivorans (99)MPFG MP Sphingobium herbicidovorans (98)MPSS MP Sphingobium yanoikuyae (96)* The abbreviation of the source was the same as Fig.1
Bioaugmentation potential of different isolates in sediment slurry
H H 1 H H 2 H H 3 H H 4 H H 5 H H 6
0
2 0
4 0
6 0
8 0
1 0 0
Bio
degr
adat
ion
of P
AH
s (%
)
F l u o r e n e P h e n a n t h r e n e A n t h r a c e n e F lu o r a n t h e n e P y r e n e
H L 1 H L 2 H L 3 H L 4 H L 5 M S M S W
0
2 0
4 0
6 0
8 0
1 0 0
Bio
degr
adat
ion
of P
AH
s (%
)
Provide Alternate Solution to Sewage and Contamination Problems
Human activities, e.g. waste
Contamination in land & water
Bio- and phyto- remediation of POPs and oil
Constructed mangrove for wastewater
Bisorption(Free and immobilized
microalgae)
Biosorption
Retention of pollutants through passive adsorption, complexation and active absorption by biomass (biosorbents)Low costEfficient especially at low pollutant levelLittle or no secondary pollutionEnvironmental friendlyshare similar set-up as ion exchange
Micro- and macro-algae, fungi, and even non-living materials, e.g. rice husks, straws
Biosorption vs conventional treatment for heavy metals
Biosorption Precipitation Ion Exchange
Conc. dependence no yes no
Effluent quality (mg l-1) <1 2 - 5 <1pH adjustment rarely needed must sometime
sSelectivity good poor
(except Sulfide)
good
Efficiency good poor good
Regeneration good Not required good
Cost low high (Sludge) moderate
Microalgae as biosorbent
Ubiquitous and abundant
Rich biodiversity
Small size (in µm), large surface area to
volume ratio and high binding affinity
Fast growth and simple life cycle
Easy to culture and robust
Primary producers: autotrophic
Grow on carbon source: heterotrophic
Green and environmental friendly
Different microalgal species
Removal of heavy metals•
Screen most effective species
Isolates from sewage and polluted water
•
WW1 (Chlorella miniata) (HK)•
LC6A (Synechocystis sp.) (HK)
•
2f2aii, 2f2c, 3f2c, 4foa, 2f5aia (Chlorella sp.) (HK)•
3f2aiia, 3f2aiib (Cyanobacteria sp.)
•
C. sorokiniana 275 (Wuhan)•
Scenedesmus quadricauda 43 (Wuhan)
Commercial species•
Chlorella vulgaris
•
Selenastrum capricornutum
Removal of single heavy metal
Cu removal was usually highMost achieved >80% Chlorella species had >95% removal
Ni removal was generally lowerSome isolate (e.g. LC6A, 3f2aiia, 3f2aiib, 2f5aia)
had removal <20%Except WW1 (Chlorella miniata) achieved 80-
90%●
Zn, Pb and Cr removal varied among species
Repeated uses of two algae for Ni removal (10 cycles of 30 ppm Ni)
Treatment Cycle0 1 2 3 4 5 6 7 8 9 10
5
10
15
25
30
35
20
Ni c
once
ntra
tion
(µg/
ml)
C. vulgarisWW1
Reloading of fresh Nickel solution
Link
Metal adsorption capacity
Micro- algae
Cell diameter
(µm)
Specific surface
area (m2/mg)
Langmuir Qmax (mg/g cell)
Ni Cu Cr(III)
CV 3.39 0.018 12.06 18.72 ND
WW1 2.35 0.026 20.37 23.26 41.12
Qmax : maximum metal adsorption capacityCr(III) removal was due to bioreduction and biosorption
Removal of mixed heavy metals by microalgae
Algal species
Heavy Metals
Cr Zn Pb Ni Cu
Removal (%)
3f2aiib 48.6 ±
0.9 35.9 ±
15.7 35.2 ±
1.2 2.7±1.5 84.4 ±
1.1
2f5aia 70.2 ±
5.9 22.4 ±
4.0 86.5 ±
0.8 7.0±1.5 92.0 ±1.1
SC 72.9 ±
2.1 59.9 ±
6.0 79.3 ±10.7 27.0 ±
1.6 86.7 ±
1.3
3f2aiia 74.4 ±
1.7 22.5 ±
0.9 86.5 ±
0.5 5.3 ±
2.9 91.1±
0.4
Time required (min)
3f2aiib 1440 60 180 720 360
2f5aia 1440 90 1440 30 15
SC 120 360 60 120 5
3f2aiia 1440 720 1440 360 30
Removal by SC: Cu > Pb > Cr > Zn > Ni;Other pollutants like PAHs had little effects on metal removal
Mass culture in municipal wastewater
DW(24-0) > DW(16-8)
> BM(16-8) > DW(8-16)
Only little growth at
8-1ight-dark cycle
Municipal sewage is
good culture medium for microalgae
Production of Chlorella miniata biomass in settled municipal sewage
Kinetics of Cr(III) removal by different algal biomass (Cr(III) 100 mg L-1, initial pH 4.5)
Cr(III) biosorption
Cr(III) biosorption capacity by different algal biomass at various Cr(III) conc. (initial pH 4.5)
Free cells as biosorbent
Possible to obtain cheap microalgal
biomass from primarily settled municipal sewage with same removal efficiency
Algal production cost0.5 kg dw biomass per ton wastewater per day under outdoor condition with natural sunlightElectricity cost: HK$7.2 per day (based on 0.18 kw.h per ton wastewater)Production cost :HK$ 0.29 / kg dw biomass (compensate by the cost for treating primarily settled wastewater)
Immobilized algal beads●
Free cells are troublesome in operation, difficult to separate from treated effluent
●
Immobilization agents
Alginate
Carrageenan
Agarose
Chitosan
Polyacrylamide, etc.
Cd
day
0 2 4 6 8 10 12 14 16 18 20mg
met
al g
-1dr
y w
eigh
t mon
itor
0123456
chitosanagarosealginatepolyacrylamide
Metal adsorption and release profiles of biomonitors immobilized in different matrices (water Cd, Cu, Ni & Zn, all 1 mg L-1, for 10 days then metal free water for 10 days(mean and standard deviation; n = 3)
Ni
day
0 2 4 6 8 10 12 14 16 18 20mg
met
al g
-1dr
y w
eigh
t mon
itor
0123456Cu
day
0 2 4 6 8 10 12 14 16 18 20mg
met
al g
-1dr
y w
eigh
t mon
itor
0123456
Zn
day
0 2 4 6 8 10 12 14 16 18 20mg
met
al g
-1dr
y w
eigh
t mon
itor
0123456
Viability of algal beads after exposure to water containing mixture of Cd, Cu, Ni & Zn
Cells bead-1 Day 10
Alginate 2.9 x 105
Agarose 0
Carrageenan Bead dissolved after 2 days
Chitosan 0
Polyacrylamide 0
Immobilized microalgal beads
Carrageenan beads: dissolved easily
Polyacrylamide beads did not adsorb metals
Alginate beads adsorbed the highest amounts of metals, followed by chitosan and agarose
•
Calcium alginate: the most suitable immobilized agent
Production of alginate algal beads
Alginate microalgal suspension
Suspension pumped intoa Ca2+ solution
Microalgal and blank bead
2.5 x 106 cells bead-1
400 beads1 x 107 cells ml-1
Alginate immobilize microalgal beads (Bead diameter: 3-4 mm, Cell density; 106 cells bead-
Immobilization matrix
Algal cells(cell diameter: 3-6m)
Immobilized microalgal bead (diameter: 3-4mm)
T i m e ( m i n )
0 2 0 4 0 6 0 8 0 1 0 0 1 2 0 1 4 0 1 6 0
Res
idua
l Cu
leve
l in
solu
tion
(mg
L-1)
0
5
1 0
1 5
2 0
2 5
3 0
3 5
Cyclic Cu removal by algal beads (batch condition, shaking : 180 rpm, algal beads: 5.6 cells x 105
cells/bead, algal bead : metal soln
= 1:3 v/v)
reservoirof metalsolution
Algal beadscolumn
Peristalticpump
Effluent
Continuous Upflow
operation of the algal column
H y d r a u l i c l o a d i n g ( m l )
0 1 0 0 0 2 0 0 0 3 0 0 0 4 0 0 0
Efflu
ent c
oppe
r lev
el (m
g l-1
)
0
1
2
3
4
5
2 5
3 0
3 5
Influent Cu level
Effluent Cu level
Copper removal by algal columnContinuous upflow, HRT: 30 min
Time (hr)0 1 2 3 4 5 6 7
Cu desorbed (m
g L-1)
0
500
1000
1500
2000
2500
3000
3500
4000
Desorption of Cu after saturation study by 2% HNO3
Operation cycles
RT RT
T : Treatment Stage
R: Regeneration Stage
1st Cycle2nd Cycle
T i m e ( h o u r s )
0 2 0 4 0 6 0 8 0 1 0 0 1 2 0
Cop
per c
once
ntra
tion
(mg
L-1)
0
1 0
2 0
3 0
4 0
2 0 0
2 5 0
3 0 0
3 5 0
4 0 0
T R T R T R
Cyclic performance of algal column; T: Treatment R: RegenerationIn: Influent E: Effluent
In
E
Repeated uses of algal beads for removal of
TBT from wastewater
10 ppb
0 4 8 12 16 20 24
TBT
conc
. in
med
ium
(g
Sn L
-1)
0
5
10
15
20
50 ppb
0 4 8 12 16 20 24TB
T co
nc. i
n m
ediu
m (
g Sn
L-1
)
0
20
40
60
80
100 ppb
Time (days)
0 4 8 12 16 20 24
TBT
conc
. in
med
ium
(g
Sn L
-1)
0
30
60
90
120
150
180
1st 2nd 3rd 4th 5th 6th
Removal of PAH (polycyclic aromatic hydrocarbon): no difference between
free cells and algal beadsPyrene
0
20
40
60
80
100
0 50 100 150
Time (Hour)
% R
emov
al
Immobilized Suspended
Phenanthrene (3-ring PAH) Pyrene (4-ring PAH)
Phenanthrene
0
20
40
60
80
100
0 50 100 150
Time (Hour)
% R
emov
al
Immobilized Suspended
PAHs removal by SCFluorene
60
70
80
90
100
Day 1 Day 4 Day 7
% R
emo
val
Phenanthrene
60
70
80
90
100
Day 1 Day 4 Day 7
% R
emo
val
Fluoranthene
60
70
80
90
100
Day 1 Day 4 Day 7
% R
emov
al
Pyrene
60
70
80
90
100
Day 1 Day 4 Day 7%
Rem
ov
alBenzo[a]pyrene
60
70
80
90
100
Day 1 Day 4 Day 7
% R
emo
val
% removal of different PAHs by SC and effect of heavy metals
PAHs only PAHs + Metals
Microalgal beads bioreactor
Efficient biosorbent for heavy metals, POPs such as TBT and PAHs
Cheap as it can be produced from municipal sewage Algal production: <HK$0.3 per Kg dry biomassOperation: < HK$ 5 per ton wastewater
No secondary pollution problem, green technology
Higher flexibility Continuous, semi-continuous or batch columnsSame algal beads could be repeatedly used
Provide Alternate Solution to Sewage and Contamination Problems
Human activities, e.g. waste
Contamination in land & water
Bio- and phyto- remediation of POPs and oil
Constructed mangrove for wastewater
Bisorption(Free and immobilized
microalgae)
Strain No. flo phe ant fla pyr Growth Isolated with 4-ring PAHsMycobacterium sp. HH1 2+++ 2+++ 7+ 2++ 2++ phe, pyrMycobacterium sp. HH2 3++ 1+++ - 1++ 1+ phe, pyrMycobacterium sp. HH3 3+ 1+++ - 3++ 8+ pheTerrabacter sp. HH4 3+ 2+ 7+ 1++ 14± flaTerrabacter sp. HH5 3+ 2+ 6++ 1++ 15± flaRhodococcus sp. HH6 2+ 2++ - 3+ - ngIsolated with 3-ring PAHsSphingomonas sp. HL1 1+ 1++ 4+ 1++ - pheSphingomonas sp. HL2 1++ 1++ 4++ 3± - pheSphingomonas sp. HL3 2+ 1++ 4+ - - pheSphingomonas sp. HL4 4++ 2++ 9++ 3+ - pheSphingomonas sp. HL5 2+ - - - - ng
Biodegradation of PAHs on R2A -PAH plates by the bacterial isolates obtained from HC sediment and their growth with PAHs as the sole carbon and energy source
Microalgal beads could degrade Pyrene but not blank alginate bead
Pyrene
0
20
40
60
80
100
0 50 100 150 200
Time (Hour)
% T
rans
form
ed /
Lost
Microalgal Bead Blank Bead
Pyrene
0
20
40
60
80
100
0 50 100 150
Time (Hour)
% R
emov
al
Microalgal Bead Blank Bead
Removal % Degradation %
Eutrophication and red tides due to excess nutrients
1998 Red tide in HK, killed >85% of culture fish; Loss > $300 M to mariculture industry;Unacceptable levels of toxins in shellfish
Persistent organic pollutants (POPs)CHCC lC lC l
C lC l
High level of pesticidesreported in human milk
ClCl
polychlorinated biphenyl
High level of PAHs and PCBs in marine mammals
Kinetics of Cr(VI) removal by different algal biomass (Cr(VI) 100 mg L-1, pH 2.0)
Cr(VI) removal by bioreduction and biosorption
Total Cr uptake by different algal biomass at various Cr(VI) conc. (initial pH 4.5)
Example of POPs: PAHs
PAHs (polycyclic aromatic hydrocarbons)
A group of aromatic compounds containing two or more fused benzene rings
Toxic, carcinogenic and mutagenic
16 PAHs: USEPA priority pollutants
Exist in various ecosystems, bind to soil and accumulate along food chains
Chlorella vulgaris
(commercial species)
WW1 C. miniata
(isolate from sewage)
Chlorella vulgaris
10 m
Chlorella miniata
10 m
Mangrove Wetland: complex and diverse biological system
Close to human activities, and has long been used as a convenient dumping site
Receive contaminants from tidal water, rivers, and land-based sources
Have an important role in pollution control through their absorptive capacity for organic pollutants and nutrients
Plants do not seem to suffer from waste discharge
T im e ( h r )0 1 2 3 4
Cu
deso
rbed
(mg
l-1)
0
5 0 0
1 0 0 0
1 5 0 0
2 0 0 0
2 5 0 0
3 0 0 0
0 2 4 60
2 0 0
4 0 0
6 0 0
8 0 0
Comparison of the desorption of Cu between the Algabiotor (20L) and the lab scale algal column (20 mL) (insert)
No scale up problem