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

1

MBBR Technology

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 ...

The basics ...

Aeration Manifolds

Media sieves

Process Tank

Air Blowers

Media

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

2

Discfilter Technology

11

Hydrotech Discfilter …

Hydrotech Discfilter ...

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

3

Why Combine?

Biomass separation following MBBRs ...

16

Clarifier

DAF

Actiflo Sandfilter Discfilter

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 ...

4

Cudworth STW’s Upgrade

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

Cudworth STW’s …

Cudworth STW’s …

Inlet Works

Primary tanks

Trickling filters

Humus Tanks

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

Distribution Chamber

Two stage, two stream MBBR

Blowers

Discfilters

MBBR + DF arrangement …

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

5

Performance

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

5 Thank You for your Attention

Any Questions Please