Case StudyPerthes - France

Experience regarding the difference in performance between 1 mm perforated holes and 1 mm slots in

membrane protection application.

1,0 mm

Perthes En Gatians

History

1999 The plant was built by OTV and 4 cities are connected. Now the plant is maintained by Veolia Water

At the beginning a NOGGERATH unit, channel screen 1 mm slot perforation, was installed for membrane protection.

2004 The original membranes where replaced due to wear and fatigue.

2005 The Roto-Sieve was installed and has been in operation since. The main reason to install the Roto-Sieve drum screen was to increase the protection of the membrane.

Hydraulic Flow: 900 m3/day (dry weather)

Hydraulic Flow: 1440 m3/day (wet weather)

OTV Process type biosep: • Activated sludge and physical separation by immerged membrane. • Type: ZENON ZEEWEED 500 TYPE C (hollow fiber and pore diameter between micro to ultra-filtration) • These has been installed since November 2004. (7 cassettes, each with 22 filter elements 20.4 m2/unit)

Process description

Original Channel Screen

Roto Sieve 3024-51 1,0 mm

Flow Chart (Simplified)

Roto Sieve

Wastewater Inlet

Piston Press

Treated water Outlet

Air from blowers

Sludge dewatering

Chalk silo

Sludge/chalk mixer

Back flush filter

Tank for aeration of sludge and membrane filtration

Screenings

Bio fertilizer

Plant view from entrance

Control room

Location of installed RS

Tank for aeration of sludge and membrane filtration

Silo for chalk

Location of installed membranes

Machine room(blowers, back flush filter, etc)

Roto-Sieve Installation

Membrane installation

Originally installed membranes

Zenon Zeeweed 500 – Installed 1999 Membrane Fiber

Operating principle

Veolia Water expects lifetime of the new membranes installed in 2004 to be 7 years instead of 4-5 years.

Originally installed membranesDamaged membranes after 5 years in operation with channel screen

Screenings from piston press

With channel screen: 1 plastic bag per week

With Roto-Sieve: 1 plastic bag per day

Membrane back flush filter

Previous cleaning/maintenance interval once every week. With Roto-Sieve 2-3 times a year.

Summary

More efficient pre-screening

Longer membrane lifetime

Less maintenance