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Technology Review

Filtration or water and wastewater treatment

WABAG fltration


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TaiPo, HongkongAerated Drainage Filtration or nitrication and

multilayer Drainage Filtration or mangenese removal

Commissioning 2002, capacity 450000 m3/d

WABAG fltration

Filtration is an essential process in water treatment. It is

requently the case that it either represents the main proces-

sing phase, or is integrated into multi-barrier systems. Many

membrane ltration plants also include conventional lters or

pre- or post-treatment.

Thus, the continuous development o ltration technology has

always been one o WABAGs most important objectives and

or more than ty years, the t echniques originally developed by

Sulzer have been subjected to on-going optimisation.

Today, WABAGs lter design constitutes an optimum solution

or both, single- and multi-layer lters based on various uniqueeatures.

Wastewater ltration is necessary when discharge limits are

particularly stringent, e.g. in sensitive areas. In addition, waste-

water ltration in combination with disinection also oers a

reliable and economic solution or water reuse.

WABAGs wastewater ltration technology derives rom its

experience with water ltration, which has been acquired since

the late 1970s. It incorporates all the necessary know-how

about the particular actors related to wastewater ltration such

as the biological activity in the lter bed and control o lter

operation with fow variations.

Like water lters, wastewater lters are realised as single- andmultilayer lters and oer the s ame eatures.

Fllanden WWTP, SwitzerlandNozzle Floor Filtration or tertiary treatmentCommissioning 2003, capacity 1800 m3/h

Berne WWTP, SwitzerlandNozzle Floor Filtration or tertiary treatmentCommissioning 1984, capacity 14400 m3/h

Kunming, ChinaDrainage Filtration or treatment o surace waterCommissioning 2003, capacity 400000 m3/d

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Wastewater fltrationor tertiary treatment and water reuse

Water fltrationor drinking and process water

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The available lter foor systems oer optimised solutions or

lter rehabilitation. The upgrading o pure water rinsing into

air-water backwashing is entirely easible. Extensive experience

in lter rehabilitation also allows the optimisation o conventio-

nal backwash principles based on continuous fow and sludge

water withdrawal channels.

n Outlet regulated (constant water level) deep bed

ltration results in high ltration perormance

n Ecient backwashing without lter media loss

n Low backwash water consumption

n Various lter foor systems enable tailor-made solutions

and a wide range o l ter media combinations

n Compact design

n Flexible realisation due to a wide range o lter surace

areas (10-150 m2)

Romanshorn WWTP, Switzerland

Drainage-Nozzle Floor Filtration or tertiary treatmentCommissioning 2007, capacity 1080 m 3/h

Daugava Riga, Latvia

GAC Nozzle Floor Filtration or surace water treatmentCommissioning 2001, capacity 240000 m3/d

WABAG fltrationadvantages in brie

WABAG fltrationrehabilitation


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Sludge water extraction is based on the gradual opening o the fap valve, which prevents lter media

loss, even where this is highly possible as in the case o specically light media. This allows an additional

degree o fexibility with regard to lter media combinations.

The repetition o the two phases leads to an ecient backwash with low backwash water use.

Filtration process

General

The ltration process is based on a downfow operation mode and ltrate outlet regulation. This maintains a constant water level in

the lter, which oers the best process conditions or high elimination rates.

Deep bed ltration with long lter running times is achieved by the selection o the optimum lter media in a single- or multilayer

conguration.The lters can take the orm o rectangular concrete cells (open or closed) or steel vessels.

Filter foor

The lter foor is a key system component. The design has to ensure the uniorm distribution o the corresponding media during

operation and backwashing, while the construction should be simple, cost-ecient and fexible enough to accommodate various

lter dimensions.

WABAG has developed diering types o lter foors, which allow a design in accordance with specic requirements, which is parti-

cularly important when existing lters are reurbished. The types o lter foors available are either based on the WABAG nozzle foor

or the WABAG drainage system.

Backwashing

Eective backwashing is vital or the optimised long-term operation o lters. The uniorm distribution o the backwash media and eci-

ent backwash sequences are thereore essential elements in backwashing.

As ar as operational costs are concerned, backwash water consumption should be as low as possible and lter media loss has to be

avoided.

These objectives are achieved by WABAG lter foor systems and a sophisticated backwash principle (excess head backwash, see

below) using an internal fap valve or sludge water withdrawal. The fap valve is either situated on the ront or the rear side o the lter

cell, just above the top level o the lter medium.

The excess head backwash principle divides the backwash sequence into a rst phase o backwash medium introduction and a

second phase o sludge water withdrawal. Backwash medium introduction can t hereore be precisely matched to individual operational

conditions.

WABAG drainage system

The drainage system consists o cast-in distribution batteries and parallel drainage pipes, which are arranged across the lter bottom.

The drainage pipes are surrounded by a s upportive gravel layer. The appropriate orices in the individual drainage pipes allow ltrate to

pass out o the lter material and scouring air and water to move in the opposite direction. The drainage pipes are individually con-

nected with the ltrate channel by means o distribution pipes. The gravel layer, drainage pipes and distribution batteries ensure the

even distribution o the fushing media.

An alternative drainage design consists o drainage pipes equipped with nozzles instead o orices. In this case, the drainage pipes are

also cast-in and there is no supporting layer o gravel needed.

WABAG nozzle foor system

This system is based on a concrete nozzle foor with a plenum chamber. The latter is ed rom the ront via a special backwash con-

nection. The nozzle foor can easily be built using shuttering elements.

Backwash

water outlet

Scouring air

BackwashSchematic diagram o the fap valve

Filter eaturesor most efcient backwashing

Raw water

Filtrate

Excess head

Washout fap valve

Filter media

Nozzle foor

Filter underdrain

Air distribuntion pipe

Scouring air

Water distribution pipe

Backwash water

Filter material

Orice or scouring air

Supporting layer

Drainage pipe

Filter bottom

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sustainable solutions. or a better lie.

VA TECH WABAG GmbH

Dresdnerstrae 87-91

1200 Vienna,

Austria

Tel.: +43 1 251 05 0

[email protected]

www.wabag.com

WABAG is an international supplier o systems or:

n Drinking water treatment

n Industrial and process water treatment

n Water reclamation

n Sea and brackish water desalination

n Municipal wastewater treatment

n Industrial wastewater treatment

n Sludge treatment

WABAG is one o the worlds most innovative water

treatment companies with know-how in specic techno-

logies and in-house developed processes such as:

n Fluidised bed biology FLUOPUR

n Bioltration BIOPUR

n Activated sludge Hybrid, SBRprocesses

n Anaerobic biological EKJTM, UASB, an-OPURTM,processes EGSB

n Membrane bioreactor MARAPUR, MegamodulTM

n Membrane ltration RO, MF, UF, NF

n Denitrication BIODEN, ENR

n Oxidation processes ADOX, BIOZONE

n Thermal desalination MED, TVC, MVC, MSF

n Sludge digestion and BIOZONE-ADdisintegration

The WABAG Group represents a leading multinational

player with companies and oces in 18 countries and

a ocus on emerging markets in Europe, North Arica,

Middle East, South East Asia, China and India.

VA TECH WABAG Ltd.

11, Murrays Gate Road

Alwarpet , Chennai 600 018,

India

Tel. +91 44 422 323 23

[email protected]

WABAG Water Technology Ltd.

Brglistrasse 31,

CH-8401 Winterthur,

Switzerland

Tel. +41 52 262 43 43

[email protected]

Consulting

Planning

Design &

Engineering

Construction

Commissioning

Operations

(DBO, BOT, BOOT)

Maintenance &

After Sales Services

Equipment

Supply

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