2003 Environmental Technology Business Forum
Modified Upflow Anaerobic Anaerobic Sludge Bed
UASB
Technology
Pollution Abatement Technology Department Center for Environmental, Safety and Health Technology Development Industrial Technology Research Institute Hsinchu, Taiwan
Introduction The modified Upflow Anaerobic Sludge Bed (UASB) technique developed by Industrial Technology Research Institute (ITRI) has been applied to industrial wastewater treatment in Taiwan for more than 17 years. Twenty five full scale treatment plants and more than fifty modified UASB reactors have been installed for industrial wastewater purification including food processing, brewery, distillery, pulp and paper, textile, chemical and petrochemical industries.
Sludge Blanket Zone
Biogas Gas/ Liquid/ Solid Separator
Overflow Weir
Effluent
Sludge Bed Zone Distributor
Influent
Figure 1. Schematic diagram of the modified UASB reactor UASB process is the most widely used process in anaerobic wastewater treatment. High concentration wastewater is introduced into the button of modified UASB reactor through the inflow distributor. The wastewater passes upwards upwards through anaerobic sludge bed where the microorganisms microorganisms contact with wastewater substrates. The sludge bed is composed composed of microorganisms that naturally form granules (pellets) of 0.5 t o 2 mm in diameter that have a high sedimentation velocity and thus resist wash-out from the system even at high hydraulic loads. Upward flow speed speed is controlled under under 10 m/d with recirculated recirculated effluent effluent and inflow wastewater. wastewater. The upward motion motion of released gas bubbles causes hydraulic hydraulic turbulence that provides provides reactor mixing without any any mechanical agitation. agitation. At the top of the reactor, the water phase is separated from sludge solids and gas in a three-phase separator.
2003 Environmental Technology Business Forum
Purified water is discharged in the effluent while biogas is collected at the top of the reactor and sludge solids settle back down to the reactor. reactor. A schematic diagram of the modified modified UASB reactor is shown above.
Process Description The key parts in designing the modified UASB reactor are a three-phase separator on the top of reactor and inflow distributors on the bottom bottom of reactor. reactor. ITRI has acquired two patents for the three-phase separator and inflow distributor. distributor. To separate gas/liquid/solids successfully, several factors, including air-lift, fluid turbulent, inertia force, and specific gravity difference must work properly. properly. The patented three-phase separator separator installed several parallel plates and inclined tubes tubes to enhance gas/liquid/solids gas/liquid/solids separation efficiency efficiency.. The structure of the separator is simple and can be installed as a module. module. Thus, the cost is lower than other separators. separators. The modified inflow distributor improves uneven uneven inflow distribution and reduces clogging clogging problems. In addition to the modified UASB reactor, reactor, there are are also improvements in the treatability assessment, sludge granules seeding, system startup, and operation strategy for for this technology. technology. The whole package package of the technology technology offers a complete solution to wastewater treatment by the UASB process. The key parts in designing the modified UASB reactor are summarized in Table Table 1. Table 1. Key parts in designing the modified UASB reactor Item Reactor design
1. 2. 3. 1. 2. 3. 4. 5.
Operation and control
Descriptions Reactor volume, height, and configuration Three-phase separator Inflow distributor Reactor seeding and start-up Anaerobic sludge acclimation and growth pH (alkalinity) control Loading control Control of inhibitor in wastewater
Table 2 lists the COD loading rate and removal percentage for various anaerobic processes. Compared to the other anaerobic anaerobic treatment processes, UASB UASB has a higher COD loading rate and COD removal percentage. Table 2. Comparison of various types of anaerobic treatment technologies t echnologies Reactor Types Anaerobic contact digester Upflow anaerobic filter Downflow anaerobic filter Anaerobic fluidized bed UASB
COD loading 3 (kg/m -d) 1-6 1-10 5-15 1-20 5-30
COD removal percentage (%) 80-95 80-95 80-87 75-88 85-95
The main UASB technology licensors in the world are Gist Brocades, Paques, Biotim, and ITRI. The history of developing developing UASB in ITRI is shorter than Gist Gist Brocades, but longer 2
2003 Environmental Technology Business Forum
than Paques and Biotim. Currently, Currently, ITRI has the capability to design the UASBs with single 3 reactor volume of 3,500 m . The basic theory of UASBs are the same, same, However, However, ITRI offers more economic choice than other competitors based on higher efficient design. Full-scale engineering practices showed that ITRI’s modified UASB reactor is highly efficient and reliable in long long time operation. It is also cost competitive competitive in construction and operation. The features of the modified UASB reactor can be be summarized as follows: 3 1. High volumetric loading, VLR>5 kg COD/m -day 2. Small footprints, low land cost. 3. Low sludge yield, sludge production rate < 0.1 kg SS/kg COD 4. No oxygen supply equipment required, r equired, more energy efficient 5. Can afford higher rage of organic loading. 6. Stable in changes of hydraulic loading.
Industrial Applications UASB technology was commonly applied to industrial wastewater of t he breweries and beverage industry, distilleries and fermentation industry, food industry, and pulp and paper industry. industry. Together, ogether, these four industrial sectors account for 87% of the UASB applications in the world for the last two decades. ITRI successfully applied the the modified UASB technology to textile and petrochemical industry wastewater treatment, especially with polyester, nylon, and polyvinyl alcohol alcohol as major wastewater components. components. ITRI has installed 11 11 modified UASB systems for petrochemical and textile wastewater treatment in Taiwan since 1988. 3 3 The largest unit installed so far was a 3500 m UASB reactor treating 4,000 m /day of textile wastewater. wastewater. A photograph of of the modified UASB reactor design by ITRI is shown shown in Figure Figure 2. Table 3 lists the full-scale modified UASB applications installed installed by ITRI since 1988.
Figure 2. Photograph of the modified UASB reactor of ITRI
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2003 Environmental Technology Business Forum
Table 3. Modified UASB applications installed by ITRI Factory name
Date of installation
Reactor 3 Size (m )
Asia Asia Chem Chemic ical al Co. Co. Kwan Kwang g Cheng heng Co.
1988 1988 1991 1991
1,00 1,000 0 80
6 Wine plants
1992
2,200
1992
450× 2
1993
Type of Wastewater
COD-in (mg/l)
CODr (%)
400 400 80
9,00 9,000 0 8,00 8,000 0
98 95
60-1,000
4,000-30,000
90
Textile industry
800
5,000
90
500× 2
Textile industry
1,000
5,000
90
1993
1,350× 2
Petr Petroc oche hemi mica call indu indust strry
3,50 3,500 0
4,20 4,200 0
≧70
1994
600+240
Fermentation and distillation process
200
30,000
90
1994
600× 2
Textile industry
1,200
5,000
90
1994
3,300
Textile industry
4,000
2,500
≧65
1995 1995 1995
135 1,30 1,300 0
Food processing Dist Distil illa lati tion on proc proces esss
250 1,30 1,300 0
2,000 10,0 10,000 00
≧70 90
1995
600× 2
Textile industry
1,200
5,000
90
1996
600× 2
Textile industry
1,200
5,000
90
1996
500
Chemical cal process essing
200
8,000
≧70
1997
1,680
Food processing
4,000
2,500
90
1999
800
Chemical cal process essing
124
12,00 ,000
80
1999
900
Chemical cal process essing
400
8,000
80
2002
900 x 2
Food process essing
4,0 4,000
2,500
90
2002
900 x2
Pulp and paper
3,600
7,000
80
2003
1,350× 2
Petr Petroc oche hemi mica call indu indust strry
2,00 2,000 0
3,00 3,000 0
≧70
Kinm Kinmon on dist distil ille lery ry
2003 2003
1,00 1,000 0
Disti Distill llat atio ion n proc proces esss
650 650
6,00 6,000 0
90
Toppoly
2004
1760
TFT-LCD TFT-LCD
1400
8000
70
ChiMei
2005
400
TFT-LCD TFT-LCD
650
1600
70
F&NCC (Malaysia)
2006
405
Food processing
550
5000
80
SafViet (Vietnam)
2006
2850
Yeast production
960
14000
70
Hualon Co./Toufen Co./Toufen head plant Hualon Co. / Toufen Ⅱ plant Chang Chun Petrochemical Co./Miaoli plant Unit I Yilan Wine plant, ( total 7 plants) Hualon Co. / Toufen Ⅲ plant Far Eastern Textile Co. TransAsia airways Hual Hualie ien n dist distil ille lery ry
Hualon Malaysia Co. Unit I Hualon Malaysia Co. Unit II Dahin Co./Chuan Hsing plant President Enterprises Co. / Hsinshih plant Unit I Taiwan petrochemical Co Dahin Co./Hsiensie plant President Enterprises Co. / Hsinshih plant Unit II Der-Yien Paper Industry Chang Chun Petrochemical Co./Miaoli plant Unit II
Chem Chemic ical al proc proces essi sing ng Chem Chemic ical al proc proces esssing ing Fermentation and distillation process
Qw.w. (CMD)
The following plant retrofit projects were examples of modified UASB technology applied to distillation, petrochemical and textile wastewater treatment.
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2003 Environmental Technology Business Forum
Table 4. Examples of ITRI’s modified UASB technology applied to distillery, petrochemical and textile industry. industry. Technical aspect Hualien distillery
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Economical benefits
Compare to existing aerobic treatment process: 2 Small footprints, over 1,500m land requirement are saved. Save 50% of capital cost in reactor construction. A total 100 million NT of construction cost was saved. Save operation cost in power requirement and waste sludge processing by 10 million NT per year. Compare to conventional activated Achieve 75% of COD sludge process: removal rate under 4.5 kg 3 2 COD/m -day of organic Save land requirement by 600 m loading and 24 hours of Reduce 35 million NT of reactor hydraulic retention time. construction cost. Design and construct two Save over 10 million NT of UASB reactors with 12 meter operation cost annually in (in diameter) by 12 meter electricity and sludge processing (height) (height) and a total volume volume of 1350 cubic meter. Achieve over 90% of COD Compare to conventional activated sludge process: removal efficiency under organic loading of 5 kg Reduce 30% of construction cost. 3 COD/m .day. Save 30 million NT in capital cost. Treat textile wastewater with Save over 10 million NT of ethylene glycol and aldehydes operation cost annually in average loading 6000 kg per electricity and sludge processing. day. Reduce land requirement by 50%.
Combined modified UASB with fixed film aerobic treatment and Fenton chemical oxidation in treatment process. Wastewater with COD over 10,000 mg/l was treated to under 100 mg/l.
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•
•
Chang Chun Petrochemical Co./Miaoli plant Unit I
•
• •
•
Hualon Texitle Co. / Toufen Ⅲ plant
•
•
•
•
•
•
ITRI is one of the four UASB licensors in the world （they are Gist Brocades, Paques, Biotim, and ITRI）that can license and transfer UASB UASB technology to other companies. companies. ITRI has well developed know–how in UASB process and equipment design for different kinds of industrial wastewater. wastewater. With 17 years years of technology development development experience and over over 25 successful plant retrofit projects, ITRI illustrates its superior in technical consulting and engineering design in industrial industrial wastewater wastewater treatment. Consulting service including wastewater treatability evaluation, sludge granules seeding, UASB system start-up, microorganism inhibition prevention and mitigation are provided under customer requisition.
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2003 Environmental Technology Business Forum
References Horng R.-Y., Wu H.-S., Tzou W.-Y. and Perng M.-J. (2001), A Reduction of Biosolids: A Case Study of Integrated Anaerobic Process, 9th World Congress on Anaerobic Digestion, Antwerpen, Belgium, 169-171. Horng R.-Y., Shao H., You H.-S., Liu Y.-C., Tzou W.-Y., Chen C.-H., Wu H.-S. and Cheng S.-S. (1998), An Integrated Process to Abate Sludge yield and Promote Sludge Granular in An Anaerobic Process, 8th International Conference on Anaerobic Digestion, 216-223. Horng R.-Y. Shao H., You H.-S., Liu Y.-C., Tzou W.-Y., Chen C.-H., Wu H.-S. and Perng M.-J.(1996), A Case Study of A brewery Factory Wastewater Treatment by Anaerobic /Aerobic and Fenton Process, WEFTEC ’96, 69th Annual Conference & Exposition , Dallas, Texas, USA, 531-538.
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