combined mbbr and microscreen for tertiary upgrade...combined mbbr and microscreen for tertiary...
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Combined MBBR and Microscreen for tertiary upgrade
Andrew Cannon, Kieran Healey - VWS
Steve Green - YW
7th EWWM - 15 October 2013
1. MBBR Technology
2. Discfilter Technology
3. Why combine?
4. Cudworth STW’s Upgrade
5. Performance
6. Questions
Contents
The process is based on the biofilm principle and the core of the process is the biofilm carrier elements made from polyethylene /polypropylene with a density slightly below that of water.
These are designed to provide a large protected surface for the bacteria culture.
The reactors are filled up to 67% of their volume with these carrier elements.
The biofilm carrier elements are kept suspended in the water by air from diffusers in the aerobic reactors and by means of a mixer in the anoxic reactors.
MBBRTM process features ...
MBBR = Moving Bed Biofilm Reactor
Continuous media movement provides self controlling biofilm thickness
Continual erosion of biofilm maximises use of installed surface area
High aerobic specific biofilm surface area
Compact process
Low head loss
Range of media types
Fill ratio provides for future capacity flexibility
MBBR™ process advantages ...
AnoxKaldnes™ biomedia ...
Kaldnes™ K1 Kaldnes™ K3 Biochip TM M
Media Protected SA Material
KaldnesTM K1 500 m2/m3 HDPE
KaldnesTM K1 Heavy 500 m2/m3 HDPE + Lime
KaldnesTM K3 500 m2/m3 HDPE
Biochip M 1200 m2/m3 HDPE/HDPP
AnoxKaldnes™ biomedia, cont...
BiofilmChipTM P F3
Media Protected SA Material
Biochip P 900 m2/m3 HDPE/HDPP
F3 200 m2/m3 HDPE/HDPP
K5 800 m2/m3 HDPE
K5
MBBR aeration...
Medium bubble diffusers
Fine bubble diffusers
Conventional DO control
Advanced process control – ion selective electrode for insitu NH4-N measurement
Hydrotech Discfilter ...
13
Small footprint
10 to 25% of sand filter space
1.7m, 2.2m and 2.6m diameter
Max filter area: 228 m²
Up to 30 discs
Low head loss, 250mm max
Pore size: 10 to 1000 microns
Filtration during backwash
Low backwash reject <3%
Automatic backwash …
Level sensor activated
All discs cleaned with each rotation during backwash, with a moving spray bar
Basin not drained during backwash
Filter not off line for backwash
No clean water tank required
Uses filtered water
< 3% Required for backwash
Compact technologies
Low head loss
Low maintenance
With tertiary application no chemicals for coagulation/flocculation
MBBR Moving BedTM Biofilm Reactor
DISCFILTER
Advantages of combining MBBR+ Discfilter ...
Cudworth STW’s upgrade ...
19
Client - Yorkshire Water
Delivery Partner – Morgan Sindall Grontmij Joint Venture
Project – Cudworth STW’s upgrade
Contract award – February 2012
Commissioning Trials - October to December 2012
Upgrade objectives…
Design horizon for 2025 population equivalent of 10,693
Parameter Units Value
Minimum flow m3/d 2418
Average flow m3/d 2946
FFT m3/d 5440
BOD5 load kg/d 74
mg/l 25
NH4-N load kg/d 44
mg/l 15
TSS load kg/d 118
mg/l 40
Need for increased secondary capacity
Upgrade objectives …
Tighter discharge standard
Parameter Unit Value
Total BOD5 as 95%ile mg/l 10
NH4-N as 95%ile mg/l 3
TSS as 95%ile mg/l 55
Need for both improved nitrification capacity and solids removal
Options considered ...
Gravity flow activated sludge + disc filter
Pumped flow activated sludge + disc filter
Additional trickling filter/ humus tank + MBBR + discfilter
0.9
0.95
1
1.05
1.1
1.15
1.2
Gravity ASP + DF
Pumped ASP + DF
Additional filter + MBBR +DF
Re
lati
ve W
LC
MBBR Design Criteria ...
Parameter Units Value
Media type K5
Specific surface area m2/m3 800
Media volume m3 176
Plant configuration Two streams of two reactors
Fill fraction % 0.3
Total tank volume m3 588
Water depth m 5.0
Overall dimensions m 12 x 12 x 6
Average air requirement Nm3/min 15.1
K5 media specification …
•Produced by extrusion
•800 m2/m3 protected surface area
•High-density polyethylene
•Ø = 25 mm; thickness = 3.5 – 4 mm height
•Density = 0.95, but adjustable
•331 000 pieces/m3
•118 kg/m3 at a density of 0.95 kg/dm3
Discfilter Design Criteria ...
Parameter Units Value
Model HSF 2208/7 – 1F
Filter area m2 36.2
Disc diameter m 2.2
Filter opening micron 10
TSS influent mg/l 40
TSS outlet mg/l 15
Backwash rate % 3.0
Commissioning performance – NH4-N removal …
Unit In Out
Average mg/l 2.9 0.2
95%ile mg/l 6.4 0.5
14 days after start up
MBBR Start up
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0 N
H4
-N -
mg/
l
Filter NH4-N MBBR NH4-N Target NH4
0
10
20
30
40
50
60
70 Tu
rbid
ity
- N
TU
Filter Effluent MBBR Effluent Turbidity Target
MBBR start up Discfilter start up
Unit In Out
Average mg/l 32 7
95%ile mg/l 49 11
14 days after start up
Commissioning performance – Turbidity removal …
0
10
20
30
40
50
60
70
Turb
idit
y -
NTU
Filter Turbidiity First MBBR Cell Second MBBR Cell Ex Discfilter
Discfilter start up MBBR Start up
Commissioning performance – Turbidity profile …
Post commissioning performance - NH4-N removal …
0
1
2
3
4
5
6
7
8
9
1.6.12 1.7.12 1.8.12 1.9.12 1.10.12 1.11.12 1.12.12 1.1.13 1.2.13 1.3.13 1.4.13 1.5.13 1.6.13 1.7.13 1.8.13
NH
4-N
- m
g/l
NH4-N 95%ile
MBBR Start up
Average NH4-N = 0.37 mg/l 95%ile NH4-N = 1.1 mg/l
Post commissioning performance - Turbidity removal …
0
5
10
15
20
25
30
Effluent turbidity 95%ile
Average NTU = 6.5 95%ile NTU= 12
Filter Effluent MBBR/Discfilter
Conclusions ...
38
The MBBR has demonstrated reliable NH4-N removal well within the design consent requirement, with the flexibility to adapt to future load conditions
The discfilter has also demonstrated its ability to remove MBBR biomass solids to enable the BOD5 discharge standard to be achieved.
The MBBR and discfilter combination has proved a cost effective compact upgrade solution for the Cudworth STW’s
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