microwave technique in wastewater and sludge processing university of szeged, faculty of engineering...
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MICROWAVE TECHNIQUE
IN WASTEWATER
AND SLUDGE PROCESSING
University of Szeged, Faculty of Engineering Department of Process Engineering
Moszkvai krt. 5-7, H-6725 Szeged, HungaryE-mail:[email protected]
Sándor Beszédes
INTRODUCTION
• water• microorganisms (viruses, pathogens)
• organic particles• organic compounds• heavy metals• micro pollutants (pharmaceuticals, endocrin disruptors)
Sludge: semi-solid residual from wastewater
Heavy degradable compounds are concentrated into the sludge
Sludge handling technology determines the capacity and economical parameters of WWTP Common alternatives of sewage sludge treatments:
• using in agriculture (cropland application)• incineration • composting
MainMain aim of sludge handling aim of sludge handling:: volume reductionvolume reduction (thickening, dewatering)(thickening, dewatering) elimination of pathogenselimination of pathogens modify sludge structuremodify sludge structure (stabilization)(stabilization) recycling and recovery recycling and recovery (fertiliser, composting, biogas)(fertiliser, composting, biogas)
MICROWAVE APPLICATIONS IN WASTEWATER
AND SLUDGE TECHNOLOGIES
MW-induced pyrolysis• Soil, sludge and sediments are poor absorbers - slow heating up• Solution: mixing with carbon,metal-oxides microwave-hybrid heating (MHH)
Sludge conditioning• MW destroy EPS and cell walls – bound water releasing• Improve sludge dewatering, but increase organic matter content of sludge liquor (MW treatment – polyelectrolyte dosing – filtration)
Improving digestibility•EPS with divalent ions form compact sludge flocks•MW cause the breakage of EPS network and the hydrogen bounds
Sludge sanitation• MW irradiation is more effective for inactivation of fecal coliforms than conventional heating
MW enhanced stabilization of heavy metals• Reduce the leachable Cu2+ and Pb2+ from hydroxyde sediment of printed circuit board manufactoring sludge
• Enhance the binding of metal ions with dipolar polymeric molecules
MW-assisted regenaration of activated carbon• Enlargement of narrow microspores under MW irradiation result in slower deposit forming
• Adsorption capacity is stable during 8-10 regeneration cycle
. .
MWPUVD: Microwave powered UV disinfection• use of MW energy to power electrodeless quartz UV lamps
• Compare to conventional UV systemsLess frequent lamp change/longer lamp lifeQuicker start-upIncreased efficiency Minimized foulingLower operational cost/less energy lostMore economical in partially-filled water channels
Kent County Regional Wastewater Treatment Plant (WWTP), Delaware, U.S.
MW enhanced advanced oxidation techniques
Microwave technique in demulsification processes Energy absorption is influenced by dielectric properties Dielectric loss of oil is small Effect of MW irradiation on water in oil (W/O) emulsions
• viscosity decreasing faster than density difference (temperature effect)
• when viscosity decreases size of oil droples increases
• efficiency of coagulation process increases if viscosity is higher
• coalescence of water molecules is easier, because boundary layer around water molecules is ruptured in oscillating EM field
rapid and selective heating high dissipated energy level affect the structure of macromolecules enhances chemical reactivity (via thermal and athermal effects)
• improves pathogen destruction • transforms suspended solids
into soluble compounds • leads to disruption of EPS and sludge flocs broken•cell-liquor and extracellular organic
matter release into the soluble phase • proteins release more quickly than carbohydrates, but the total change of sCarb i higher than sProt
Effects of MW irradiation on sludge
RESULTS OF MW SLUDGE PRE-TREATMENT
OF FOOD INDUSTRY SLUDGE
22
212121 x036.0x237.0xx0706,0x014.0x301.08085.0SLI
20
30
40
50
60
70
80
0 10 20 30 40
Microwave irradiation [min]
sCO
D/t
CO
D [
%]
0,5 W/g 1 W/g2.75 W/g 5 W/g
ORGANIC MATTER SOLUBILITY
max)/(
)/()/(
TCODSCOD
TCODSCODTCODSCODSLI it
R2 = 0.997R2(adj) = 0,996Q2 = 0,994
22
212121 x043.0x298.0xx0109,0x02.0x071.08921.0BDI
BIODEGRADABILITY
)/(
)/()/(
maxmax5
55
SCODCBOD
SCODCBODSCODCBODBDI it
1.0
1.2
1.4
1.6
1.8
0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8
Ob
serv
ed
Predicted
Biodegradability with Experiment Number labels
N=22 R2=0.998 R2 Adj.=0.997DF=16 Q2=0.995 RSD=0.01892
1
2
3
4
5
6
78
91011
12
13
14
15
16
17
1819
202122y=1*x-1.954e-007
R2=0.9976
MODDE 8 - 5/5/2010 5:47:32 PMR2 = 0.998R2(adj) = 0,996Q2 = 0,995
Dairy sludge
0
5
10
15
20
25
30
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30Digestion time [day]
Dai
ly b
iog
as p
rod
uct
[mL
day
-1]
Raw CH pretreated MW pretreated
Meat processing sludge
0
5
10
15
20
25
30
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Digestion time [day]
Dai
ly b
iog
as p
rod
uct
[mL
day
-1]
Raw CH pretreated MW pretreated
Pig manure
0
5
10
15
20
25
30
35
40
45
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Digestion time [day]
Da
ily b
iog
as
pro
du
ct
[mL
da
y-1
]
Raw CH pretreated MW pretreatedAcid whey
0
5
10
15
20
25
30
35
40
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Digestion time [day]
Da
ily b
iog
as
pro
du
ct
[mL
da
y-1
]
Raw CH pretreated MW pretreated
CH and MW treatment prior to AD process
Dairy sludge
0
5
10
15
20
25
30
35
40
0 3 6 9 12 15 18 21 24 27 30
Fermentation time [day]
Dai
ly b
iog
as p
rod
uct
[m
Lg
-1d
ay-1
]
Cont. Konv.
0,5W/g 30m. 1 W/g 30 m.
1,5W/g 30m. 2W/g 30m.
5W/g 30m.
Meat processing sludge
0
5
10
15
20
25
30
35
40
0 3 6 9 12 15 18 21 24 27 30
Fermentation time [day]
Dai
ly b
iog
as p
rod
uct
[m
Lg
-1d
ay-1
]
Cont. CH1W/g 30m. 1,5W/g 30m.2W/g 30m. 5W/g 30m.0,5W/g 30m.
Daily biogas product
)P()Vq(E nirradiatiomagnetronmethanecomb
0
50
100
150
200
250
300
350
400
450B
iog
as p
rod
uct
[m
Lg
-1]
Biogas Methane
0
100
200
300
400
500
600
Bio
gas p
rod
uct
[mL
g-1]
Biogas Methane
MPWSDWS
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