Josef Lahnsteiner, VA TECH WABAG

1sustainable solutions. for a better life.

sustainable solutions. for a better life.

Freshwater Membrane Filtration including Retentate Disposal/Recycling

Josef Lahnsteiner, VA TECH WABAG

HydroSilesia

Konferencja Hydrointegracje 2011

Sosnowiec, October 13th, 2011


O u t l i n e

Introduction

Case study 1 - Lake water treatment, Männedorf and Meilen, Switzerland

Case study 2 - Treated sewage transformed into potable water, Windhoek, Namibia

Case studies 3 - Ground water treatment, Delhi, India

Conclusions


Major Potable Water Membrane References

Plant Raw Water Capacity Start-up[m3/day]

Membrane Supplier

Chennai/Nemmeli, India Sea water 100,000 2012 X-Flow

Cudrefin, Switzerland Lake water, Backw. w. 3,000 2012 Inge & Zenon

Horgen, Switzerland Lake water 25,000 2012 Zenon

Duqm, Oman Sea water 16,000 2010 Pall

Delhi/CWGV, India Well water 4,545 2010 X-Flow

Grabs, Switzerland Spring water 2,500 2010 Zenon

Männedorf, Switzerland Lake water, Backw. w. 16,000 2005 Inge & Zenon

Meilen, Switzerland Backwash water 360 2005 Zenon

Windhoek, Namibia Secondary effluent 21,000 2002 X-Flow

Tavannes, Switzerland Spring water 2,400 2002 Zenon


Main advantages of Ultra Filtration

Complete removal of suspended solids

Partial removal of dissolved matter (TOC, DOC, COD, BOD)through binding to suspended matter

Removal of micro-organisms

> Log 6 removal of protozoa

> Log 6 removal of bacteria

> Log 4 removal of viruses

Superb quality as RO feed water (low SDI15)

Certified for use in potable water treatment


Männedorf WTP, Switzerland

Lake water treatment

Multi Barrier System

Operational since 2005


Männedorf WTP, SwitzerlandRaw water source

Lake water

Capacity

8,000 m³/d of drinking

water

Peak flow 1,000 m³/h

Pre-treatment

Ozonisation

BAC

Membrane filtration

Tubular membranes (Inge)

Start-up

2005


Männedorf WTP

Pressurised Membranes Dizzer 5000

No disinfection of clean water or

protection of the network needed

anymore

Chemical cleaning every 24 – 30 hours

Recovery cleaning once per year

Backwash water treatment


Männedorf WTP - Backwash water treatment

Submerged Membranes - Zenon

ZW500D

Start-up 2006

Capacity 100 m3/h

No pre-treatment

Chemical cleaning every 36 hours of

service


Permeate flows back to the lake


Männedorf – Submerged Membranes for Backwash Water Treatment

The permeability on both treatment lines remains stable;

the diagram shows the course of the permeability over a 8

month period, the values remain at high levels between

140 und 170 l/m2*h*bar.

The plant is in operation since January 2006.

Filtration for 15 min

Back wash for 30 sec

Maintenance 48 h of operation

Recovery once per year


Process Technology

Client: Municipality of Meilen Contract award: June 2004

Capacity: 24,000 m3/d Start-up: May 2005

Plant Key Data

Project

The existing plant from 1972 had to become rehabilitated. During the whole construction time the municipalities were supplied with

sufficient water in good quality. The upgrading of the treatment plant is not only the result of new equipment but also by an extension of

the process engineering from double to multi-layer filtration and from one ozonation stage to a pre- and intermediate ozonation.

Characteristics

Water from lake Zurich is treated and supplied to the municipalities of Meilen

(52%), Herrliberg (35%) and Egg (13%).

The lake water contains small amounts of various micro-pollutants which

means a challenge to the conventional treatment chain.

The produced drinking water meets at minimum the Swiss drinking water

standards.

• Dosing of flocculant

• In-line pre-ozonation by partial flow system

• Filtration through multi-layer filters (filter media: expanded lay, anthracite and quartz sand)

• In-line Intermediate-ozonation by partial flow system

• Filtration and adsorption through Activated Carbon Filters

• Supply net protection

• Drinking water distribution to the municipalities

• Fully automatic backwash sequences

• Used backwash water ultrafiltration by submerged membranes

• Automatic control system

• On-line quality supervision


Process Scheme

1 Lake Zurich, raw water source

2 Raw water pump station

3 Dosing of flocculant

4 pre-ozonation

5 Multi-layer filtration

6 Intermediate pump station

7 Intermediate ozonation

8 Activated carbon filters

9 Supply net protection

10 Clean water tank

11 Multi-stage pump station for water supply to the municipalities

12 Backwash water pumps

13 Used backwash water tank

14 Ultrafiltration with submerged membranes (used backwash water treatment)

15 Recycle of permeate to the multi-layer filter inlet

Production capacity 1000 m3/h

Numbers of treatment lines 2

Output of main water treatment > 97 %

Wastewater amount to sewage system < 0.4 %

Technical data

WABAG Wassertechnik AG, Winterthur/Switzerland, [email protected], www.wabag.com


Meilen WTP, Switzerland

Backwash Water Recycling

Submerged Membranes ZW500C

Start-up 2006

Capacity 18 m3/h

No pre-treatment

Chemical cleaning every

week of service


Permeate flows back to the raw

water and into the process


Backwash Water Treatment by Submerged Membranes

Maennedorf WTP Meilen WTP

Parameter Unit

Retentate

concentrated

Backwash Water

Permeate

Membrane Filtrate

Retentate

concentrated

Backwash Water

Permeate

Membrane Filtrate

Turbidity NTU n.d. (not detected) <0.02 n.d. (not detected) <0.02

Suspended Solids mg/l 244 n.d. 560 n.d.

DOC mg/l 11.6 1.2 5.9 1.3

UV254nm 1/m 5.32 1.26 4.24 1.35

Volatile Suspended Solids mg/l 80 n.d. 183 n.d.

Volatile Suspended Solids % 32.8 n.d. 32.6 n.d.

Heterotrophic Plate Count (30°C) CFU/ml n.d. <10 n.d. <10


Maennedorf WTP - Water Balance in May 2009

Parameter UnitPotable Water

ProductionBackwash Water

DemandRecycled Backwash

WaterSludge Water

disposed

Absolute Quantity [m3/month ] 147.232 20.598 17.747 2.851

Relative Quantity [%] 100 14.0 12.1* 1.9**

*86,2 % of backwash water is recycled;

**13.8 % of backwash water is discharged into the sewer


Meilen WTP - Water Balance in 2006

Parameter UnitPotable Water

ProductionBackwash Water

DemandRecycled Backwash

WaterSludge Water

disposed

Absolute Quantity [m3/a] 1.591.582 24.996 20.609 4.393

Relative Quantity [%] 100 1.57 1.29* 0.28**

*82,5% of backwash water is recycled;

**17,5% of backwash water is discharged into the sewer


Potable Water from Secondary Domestic EffluentWindhoek, Namibia


Goreangab dam

Gammams WWTP

New Goreangab WRP

City of Windhoek

24,000 m³/d

Simplified Water Reuse Scheme

Von Bach Dam WTP

average approx.40,000 m3/d

approx. 30,000 m3/d

Industrial WW


Concerns to Potable Reuse

Transmission of pathogens including viruses

Trace organics and its potential toxic effects

Aesthetic concerns

Reliability of employed treatment process

Multiple barrier principle


New Goreangab Water Reclamation Plant


NGWRP - Major Quality Parameters

Major Parameters Units Raw water (design values)

Treated water (guarantee values)

Results at performance test

Physical & Chemical

Turbidity NTU 53 0.1 0.08

DOC mg/l 15 5 1.0

THM µg/l 169 20 11

Microbiological

Giardia per 100 ml 214 0 or log 6 removal 0

Cryptosporidium per 100 ml 334 0 or log 6 removal 0

E. Coli per 100 ml 20,347 0 0


Ultrafiltration process step – Goreangab Water Reclamation Plant


NGWRP - Membrane Plant Average Figures

Normal Backwashes with Permeate - Recycling

Racks in Operation 4

Hours of Operation 18

Duration before Back flush (min.) 40

Duration of Back flush (sec) 40

Flow Rate during Back flush (m3/h) 490

Daily Avg. Total Water Consumption for Back flushes (m3) 588

Chemical Enhanced Backwash (CEB) – Discharge into the Sewer

CEB2 after 8-9 water back flushes with NaOCl + NaOH

CEB1 follows after 4 x CEB2 with HCl

Typical Chemical Enhanced Back washes

Total Daily Avg. Consumption of HCl [35%] (L) 20

Total Daily Avg. Consumption of NaOCl [12-14%] (L) 40

Total Daily Avg. Consumption of NaOH [47%] (L) 130


Commonwealth Games Village WTP, Delhi, India

Ground water treatment

Capacity: 4,600 m3/d

Start-up: 2010

Akshardham Temple


Inlet Parameters Outlet Parameters

Flow 4,773 m³/d 4,546 m³/d

(Hydraulic design margin 20%)

pH 7.2 – 8.6 7.5 – 8.5

Turbidity 50 NTU <0.5 NTU

CO2 2 mg/l

Alkalinity 550 mg/l

Total hardness as CaCO3 500 mg/l <200 mg/l

Ca as CaCO3 375 mg/l 100 mg/l

Mg as CaCO3 125 mg/l 80 mg/l

Sulfate as SO4 115 mg/l 250 mg/l

Chloride as Cl 190 mg/l

Nitrate as NO3 20 mg/l 10 mg/l as N

Total Iron as Fe 0.85 mg/l 0.3 mg/l

Nitrite as NO2 0.50 mg/l 1.0 mg/l as N

Fluoride as F 0.90 mg/l 1.5 mg/l

Colour 0.05 Hz Units

Residual Chlorine 0.2 – 0.5 mg/l

Coliforms (E.coli/Total) Nil #/100 ml


Borewell 1Ranney Well 4

Borewell 2

Borewell 3

Borewell 1

Cascade Aerator

Reaction Tank

Reactor Clarifier (HRSCC)

Recarbonization Reactor

Tube Settler

Filter Feed Buffer Tank

Membrane Filtration

(UF)

UV Disinfection

Treated Water

Reservoir

Sludge Collection Sump

CentrifugeChlorine Dosing

Thickener

DWPE Dosing

CO2 Dosing & HCl Dosing

Provision

PAC & Polyelectrolyte

Dosing

Centrate / Supernatant Sump

Centrate

Supernatant

Chlorine Dosing

Waste Backwash Water

Sludge

Sludge for Disposal

Polyelectrolyte Dosing

For Distribution

PAC Dosing

Lime Dosing

Coarse Bubble

AerationBasket Strainer

140 MGD WTP at Sonia Vihar (Act as standby source if ground water quality /

quantity is insufficient)

Borewell 1Ranney Well 4

Borewell 2

Borewell 3

Borewell 1

Cascade Aerator

Reaction Tank

Reactor Clarifier (HRSCC)

Recarbonization Reactor

Tube Settler

Filter Feed Buffer Tank

Membrane Filtration

(UF)

UV Disinfection

Treated Water

Reservoir

Sludge Collection Sump

CentrifugeChlorine Dosing

Thickener

DWPE Dosing

CO2 Dosing & HCl Dosing Provision

PAC & Polyelectrolyte

Dosing

Centrate / Supernatant Sump

Centrate

Supernatant

Chlorine Dosing

Waste Backwash Water

Sludge

Sludge for Disposal

Polyelectrolyte Dosing

For Distribution

PAC Dosing

Lime Dosing

Coarse Bubble

AerationBasket Strainer

140 MGD WTP at Sonia Vihar (Act as standby source if ground water quality /

quantity is insufficient)


AquaFlex™ Ultrafiltration

8” Aquaflex modules:

DIN 0.8 mm / L 1.5 m � 40 m2

PES fibrespore size 25 nm

Corrugated plates:optimal

hydrodynamics


Conclusions

Water processes using membrane filtration are state of the art

However, optimization is carried out - mainly for pre-treatment, membrane properties, membrane cleaning and recovery

High water recovery rates are demanded, especially in water stressed regions; retentate recycling is technically feasible

However for safety reasons, only water which comprises a better quality than the raw water should be recycled; chemical back wash water should be discharged

Whatever the case, membrane filtration - if properly designed -improves the water quality and subsequently increases the safety ofthe consumers


Thank you for your attention!

Josef Lahnsteiner, VA TECH WABAG

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