Imagination at work.

Preserving the Environment by minimizing nutrient discharge and reusing high quality WWTP effluent

Presenting author: Gabriel Kicsi, M.Eng. APAC UF/MBR RO-ED Domain Leader, GE Water & Process Technologies,

AustraliaCoauthors: Mark Vis & Anna Whelan, Townsville City Council, Australia

Chris Harpham, GE Water & Process Technologies, Australia

8th Pacific Water & Wastewater Conference

Holiday Inn, Port Moresby, Papua New Guinea

14th -17th September 2015

2 /Connelly /

Background: Preserving the Environment

Cleveland Bay Purification PlantTownsville, QLD, Australia • Stringent discharge requirement to limit impact on Great Barrier Reef Marine Park• High Quality treated effluent available for reuse• 5 yrs severe drought • MBR upgrade-membrane tanks in center of retrofit clarifiers• 29MLD ADWF (7.6 MGD ) • 75MLD PWWF (19.8 MGD )

Challenge: Minimize nutrient discharge to sensitive water body (Great Barrier Reef) Solution: Complete wastewater treatment and reuse system

3 /Connelly /

Background: Max. Reuse of Existing Infrastructure

1. Hydraulic & Structural Refurbishments: Existing Primary Screening & Aerated Grit Removal

2. Conversion of existing flat floor Secondary Clarifier No1 into a sloping floor Primary ST

3. Conversion of existing Secondary Clarifier No2&3 into hydraulically linked but separate MBR (BNR OxDitch + MT)

4. Prefabricated SS Membrane Tanks and Pipework reduced fabrication & erection time

5. Reuse of existing sludge thickening and digester’s

Challenge: Minimize construction time & ensure quality effluent during constr. Solution: Stage-wise implementation of retrofitting 2 existing secondary clarifier

4 /Connelly /

Key Reasons for MBR Selection

• MBR effluent quality is consistently better than conventional treatment: Filtration requirements for reuse applications and/or feed to downstream process

• Compact footprint: Hollow Fibre vs Flat Sheet• Heated civil construction market• Most cost effective solution to produce feed water to

the proposed irrigation and potential industrial Water reuse scheme

• Membrane Technology advances and membrane cost reductions

5 /Connelly /

Design Basis of the UpgradeCapacity:Community served: 126,000 EP Average dry weather flow (ADWF): 29,000 m3/d

Peak Wet Weather flow MBR: 75,000 m3/d

Peak Wet Weather flow (PWWF): 145,000 m3/d

Average Loads (t/d)COD 14.5 SS 5.7TKN 1.45

Phosphorus (Ptot) 0.23

6 /Connelly /

Conventional activated sludge (1988) with:• Primary screens• Aerated Grit tanks

• Extended aeration – oxidation ditch

• Secondary clarifiers

Waste sludge Treatment Stage 1 (1994) with• DAF Thickener• Anaerobic sludge digestion: 2 Primary + 1 Secondary

Digesters• Sludge Drying Lagoons

Existing Plant – Unit Operations

7 /Connelly /

Existing Plant Unit Operations & Upgrade Design

8 /Connelly /

Upgraded CBPP – Aerial Photograph

9 /Connelly /

• Primary screens (3mm): 2 immersed Trommel Screens• 2 Aerated Grit tanks with a single hydrocyclone for grit dewatering• 1 Primary Sedimentation Tank converted from a previous Secondary

clarifier• Secondary Fine Screening (1mm): 4 rotary Huber screens• 2 parallel, mirror imaged MBRs each comprising:

Anaerobic reactor (subdivided into 3 cells in series) Denitrification/Nitrification (Oxidation Ditch –OxD-) with scum

harvester 4 Membrane Trains (MT) with 6 ZW500d48/48 cassettes

• 2 Rotary screw thickeners for primary sludge thickening• Single Dissolved Air Flotation (DAF) Thickener for WAS (extracted

from MT)• Anaerobic sludge digestion: 2 heated and mixed Primary + 1 pump

mixed Secondary Digesters• 2 Centrifuges for digested sludge dewatering (lime dosing)• Sludge storage: concrete apron, partly roofed before trucking to

pastoral land application

Upgraded Plant – Unit Operations

10 /Connelly /

• Chemical Dosing Systems comprising : Ethanol Dosing: to OxD for supplementary N removal Alum Dosing: to MBRs for supplementary P removal Polymer dosing: to sludge thickeners (rotary screw & DAF)

and centrifuge NaOCL & Citric acid for membrane MC & RC Caustic (when req.) when odour control is off line & during

maintenance

• Odour Control with 3 single pass BTFs of: Inlet screens (both primary & secondary), Raw sewerage channel Primary sedimentation tank (PST launders), Primary effluent & outfall pump station Primary Sludge Thickeners/ RST & WAS

• Treated Effluent discharged either to upgraded ocean outfall or storage Tank for reuse

Upgraded Plant – Unit Operations (Cont’d)

11 /Connelly /

CBPP Process Flow Schematic

Raw Wastewater

Treated water

to WRF or Ocean outfall

Sludge for disposal

Primary screen

Grit removal Fine

screens

Anoxic

Aerobic

Membranes

Anaerobic Sludge

Digestion

Centrifuge

Anaerobic

Primary ST

SQ-4

RQ-1

AQ

DAF

WAS

To Inlet structure

Rotary Screw

Thickener

12 /Connelly /

CBPP – Site Plan

Head Works

Digesters

Fine Screens

Perm. Pump Pit

MBR 2

MBR 1

Distribution Chamber

PST

Blowers + MCC

13 /Connelly /

CBPP – Unit Operations (Cont’d)

14 /Connelly /

CBPP – Unit Operations (Cont’d)

15 /Connelly /

CBPP – Process Equipment

Permeate Pumps during Installation

16 /Connelly /

CBPP – Process Equipment

2 R-Recycle Pumps

4 S-Recycle Pumps

2 WAS Pumps

2 A-Recycle mixers

17 /Connelly /

CBPP – converted clarifier into BNR MBR

18 /Connelly /

CB WWTF – Membrane Installation

Chemical dosing and Sludge Storage

19 /Connelly /

CBPP MBR Design Notes• MT MLSS concentration: 9-12 g/l (maximum of

15 mg/l)• Membrane Cleaning Strategies:

– Air Scouring: 10/10 for PWWF and 10/30 for ADWF

– Relaxation/Backpulse selectable options– Maintenance cleans: weekly NaOCl and

Citric acid cleans - 1x/month in dry season and 1x/every 2 wks in wet season

– Recovery Cleans: 2x/year (before and after wet season)

• MBR Control: Permeate pumps trimmed based on OxD level

20 /Connelly /

CBPP - Operating Performance

21 /Connelly /

CBPP - Operating Performance

22 /Connelly /

CBPP - Operating Performance

23 /Connelly /

CBPP - Operating Performance

0

50

100

150

200

250

300

350

400

14/11/2007 18/12/2008 22/01/2010 26/02/2011 1/04/2012 6/05/2013 10/06/2014 15/07/2015

Permeability before BP (Lmh/bar) - Ave of 8 Trains

24 /Connelly /

CBPP - Operating Performance

25 /Connelly /

CBPP - Operating Performance

26 /Connelly /

CBPP - Operating Performance

27 /Connelly /

CBPP - Operating Performance

28 /Connelly /

CBPP - Operating Performance

29 /Connelly /

CBPP - Operating Performance

30 /Connelly /

CBPP - Operating Performance

31 /Connelly /

CBPP - Operating Performance

Annual Inflow Annual Outfall

m3/a m3/a AveMedian (50%) 90%ile Ave

Median (50%) 90%ile Ave

Median (50%) 90%ile Ave

Median (50%) 90%ile Ave

Median (50%) 90%ile Ave

Median (50%) 90%ile

2009 11,299,056 11,010,287 238 246 364 32 36 45 7.5 7.2 8.8 27 23 53 4.4 4.6 8 0.5 0.4 1.52010 12,668,969 12,555,423 273 255 523 33 32 51 6.6 6.4 9.3 29 20 76 5.0 4.6 10 0.7 0.3 1.7

2011 12,496,711 11,935,910 233 262 355 34 38 48 6.6 7.1 9.1 29 19 80 4.9 3.8 10 0.6 0.4 2.0

2012 11,322,298 10,832,493 258 237 374 34 37 42 11.0 6.8 18.6 20 18 41 4.7 4.9 8 0.3 0.2 1.2

2013 9,012,140 8,739,220

2014 9,937,220 10,043,570 22 23 38 3.6 3.6 6 0.6 0.5 1.5

2015* 5,037,400 5,079,890 24 23 40 3.3 3.0 5 0.8 0.7 1.9

25 21 78 4.5 4.2 10.0 0.5 0.4 1.9

*J an-J ul'15 - not a full year not included in the overall quality calculations

Overall 2009 - 2014 quality results

TP (g/m3)

Fine Screened Raw Sewage Final Effluent (Composite)

COD (g/m3) TN (g/m3) TP (g/m3)COD (g/m3)

Total FlowYear

TN (g/m3)

32 /Connelly /

CBPP - Operating Performance

COD (mg/L) 200 21.3 78 2,086

SS (mg/L) 30 35 45 4 1,315

NH3 - N (mg/L) 3 0.2 2,012

Total N (mg/L) 25 25 3.8 10 2,101

Total P (mg/L) 8 0.5 1.9 2071

No. Results

510

96

38

Final Effluent (Composite)

Compliance

-< 2Enterococcus (CFU/100mL) (CFU/100mL)

- -

- -

Final Effluent Parameter

Units 28 wks 50%ile

52 wks 80%ile

5 wks 80%ile

Licence Requirement for Ocean discharge

Faecal Coliforms

Maximum

(CFU/100mL)

E. Coli (CFU/100mL)

(CFU/100mL)

1,000 4,000

Achieved Median

52 wks 90%ile

< 2

< 2

17.7

-

33 /Connelly /

Summary - Conclusions• MBR technology offered a smaller footprint, by integrating

membranes and BNR processes within existing WWTP infrastructure• Retrofitting existing structures reduced on-site construction which

in turn reduced erection time and overall project cost (Total cost: $ 65M AUD)

• The long term, 7+ years, average of 8 trains membrane permeability ranged between 350 and 150 Lmh/bar, respectively.

• The main plant specific power consumption varied between 0.46 and 1.03 kWh/ m3, which is well in line with the reported values

• MBR + BNR minimised nutrient load to Great Barrier Reef Marine Park (61 ton nutrients – 56 ton TNand 5 ton TP - per annum on 90%ile basis

• Nutrient Recycled to land and high quality effluent available for reuse the achieved median and 52 weeks 90%-ile faecal coliform values of the treated composite effluent were < 2 CFU/100mL and 17.7 CFU/100mL, respectively