sonication of sludge by high-power ultrasound technology
TRANSCRIPT
Sonication of sludge by
high-power ultrasound technology -
Practical Experiences
Dr.-Ing. K. Nickel, Prof. Dr.-Ing. S. Yang, G. Klingspor &
Prof. Dr.-Ing. U. Neis
ULTRAWAVES GmbH
Water & Environmental Technologies
Email: [email protected]
Internet: www.ultrawaves.de
Technical University of Hamburg-Harburg
Institute of Wastewater Management
Email: [email protected]
Internet: www.tuhh.de/aww/neis
Contents
1. Ultrasonic Disintegration of Biomass
2. Enhancing Aerobic Biomass Digestion
3. Enhancing Anaerobic Biomass Digestion
4. Combating Filamentous/Foaming Sludge
5. Development of US-reactor
1
1. Ultrasonic Disintegration of Biomass
on WWTP
2
Options for Biosolids Disintegration
• Intensification of anaerobic
biosolids digestion
• Intensification of aerobic
biosolids digestion
• Combating bulking and
foaming sludge
3
4
Disintegration of Biosolids
bacteria inert particles extracellular polymers
sludge floc sludge water
energy energy
5
Light-microscopical Analysis
untreated WAS 30s sonicated 90s sonicated
energy energy
6
Effect of sonication on particle size
distribution
0%
25%
50%
75%
100%
1 10 100 1000
Particle size [µm]
Vo
lum
e c
um
ula
tive [
%]
Reference
30 W/L, 20s (= 0.17 Wh/L)
80 W/L, 20s (= 0.44 Wh/L)
220 W/L, 20s (= 1.28 Wh/L)
310 W/L, 20s (= 1.72 Wh/L)
2. Enhancing Aerobic Biomass Digestion
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Bünde WWTP, Germany
Case Study
8
Initial Conditions:
– Design capacity: 40,000 PE
– Actual Load: 54,000 PE
– Alternating nitrification and denitrification
@ 22 d sludge age
– Floating sludge due to excessive growth of
filamentous micro-organisms
Desired Goal: Reduction of process fluctuations
– Minimization of waste activated sludge production
– Sustainable reduction of N-conc. in the effluent
– Combating filamentous organisms
Bünde WWTP, Germany
9
Bünde WWTP, Germany
Ultrasound Installation in 2006:
Sonication of 30% of the TWAS (~ 30 m³/d) @ 4.0 kWh/m³
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US-Reactor
30 %
70 %
Activated Sludge Process
WAS Thickener
Final Clarif ier
RAS
Primary Clarif ier
To Anaerobic Digestion To Anaerobic Digestion
Bünde WWTP, Germany
Results of US Installation:
– No foaming or bulking sludge in the activated sludge tank
– 25% reduction of waste activated sludge mass
11
– Reduction of the nitrogen concentration in effluent (N < 5 mg/l)
3. Enhancing Anaerobic Biomass Digestion
12
Bamberg WWTP, Germany
Case Study
13
Bamberg WWTP, Germany
Initial Conditions:
– Design capacity: 220,000 PE
– Actual Load: 330,000 PE
– 150 m³/d primary sludge, 250 m³/d TWAS
– (3) Egg-shaped digesters with 18 d HRT
– 35% average VS degradation
Desired Goal:
– Achieve a minimum of 40% VS degradation
• Solution 1: Build another 3,000 m3 egg-shaped digester
• Solution 2: Use of ultrasound to increase VS destruction
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17
Smagua, Saragossa, March 2008
Ultrasound installation in 2004:
Sonication of 30% (in 2004) - 80% (in 2008) of the WAS (~ 70 – 100 m³/d) @ 2 - 3 kWh/m³
THICKENED
WAS
PRIMARY
SLUDGE
SONICATION
DIGESTER 1
DIGESTER 2
DIGESTER 3
Bamberg WWTP, Germany
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Bamberg WWTP, Germany
16
Results of US Installation:
– Significantly increased biogas production (+ 45%)
– Avoided construction of a new digester = savings of 1.5 million EUR
– Volatile solids destruction improved from 34 to 50%
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65%
75%
85%
95%
105%
115%
125%
200.000
250.000
300.000
350.000
400.000
450.000
01.0
1.2
004
01.0
1.2
005
01.0
1.2
006
01.0
1.2
007
01.0
1.2
008
01.0
1.2
009
01.0
1.2
010
01.0
1.2
011
01.0
1.2
012
Stromerzeugung Kläranlage kWh/Monat
Stromverbrauch Kläranlage kWh/Monat
Eigendeckung Prozent
Mittelwert Eigendeckung in einem Jahr ProzentkWh/Monat
Neue Gasmotoren ab Okt. 2010
Desi ab Sep. 2004
Energy-self-sufficient operation on Bamberg WWTP
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US-Trial on Shek Wu Hui STW,
Hong Kong
19
Shek Wu Hui STW, Hong Kong
Initial Conditions:
– Design capacity: 300,000 PE
– 191 m³/d primary sludge, 179 m³/d TSAS
– 4 Anaerobic digesters with 21 d HRT
– Ca. 42% average VS degradation
US-Trial:
– Sonication of 15% (ca. 1 m3/h) of
TSAS @ 5 kWh/m3
0
1000
2000
3000
4000
5000
6000
7000
01/04/14 01/05/14 01/06/14 01/07/14 01/08/14 01/09/14 01/10/14
bio
ga
s p
rod
uc
tio
n [
m3/d
]
20
Shek Wu Hui STW, Hong Kong Biogas production
Biological adaptation period
US suspended since 18/8/14
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4. Combating Filamentous/Foaming Sludge
Original Short Sonication Long Sonication
energy energy
22
Combating Filamentous Sludge
Seevetal WWTP, Germany (165,000 PE)
Sonication of Return Activated Sludge (1% RAS @ 2 kWh/m³)
23
5. Development of US-reactor
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US-reactor for Biosolids Treatment
Requirements
• Treatment of large volumetric sludge streams
• High degree of biosolids cell disintegration
• Continuous operation in spite of varying sludge properties
• Resistant against reactor blockage (sludge impurities)
• Automatic system
• Low maintenance
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• Reactor volume: 30 L
• Power consumption: 5 kW
• Continuous operation
• No. of oscillators: 5
• Frequency: 20 kHz
• Intensity: 25 to 50 W/cm²
• Sonication time: 1 to 3 min
• Sonication dose: 3 to 9 kWh/m³
inflow
outflow
converter
ultrasound
generatorsonotrode
Full-scale Ultrasound Reactor 2006 Technology Transfer
Innovation 2002
Innovation Award
German Industry 2006 Innovation Award Baden
Württemberg 2007
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ULTRAWAVES – Partners
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Conclusions
• Biomass treatment with ultrasound is a
mature technology
• Detailed and specific lab, pilot and full-scale
studies have demonstrated the potential of and
the practical uses of ultrasound biomass
disintegration for biodegradation
enhancement.
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Thank you for your attention!