4/04/13

MembraneBiological Reactor

(MBR)

Membrane Biological Reactor (MBR)

Biological Process where the clarifier is replaced by a membrane.

What is an MBR

Aerobic Bacteria+Oxygen

Solids

FromDNF

SecondaryClarifier Effluent

RecycleSolids

Waste

Aeration Basin

SludgeThickener

Anoxic

N-removal

Activated Sludge Process

Membrane Biological Reactor (MBR)

§ What does that do?– No Settling time required– Higher MLSS in Reactor– Smaller foot print (potentially 50% to 75% less)– Treat difficult to biodegrade waste streams– Stable environment, not subject to upsets.– Less sludge production– High quality effluent: Turbidity <0.2 NTU, BOD <5, TSS < 1 mg/l– Operator Friendly (less operator attention.

What is an MBR

Membrane Biological Reactor (MBR)

§ Application characteristics– Difficult to biodegrade waste – Water reuse applications– Expansion of existing facilities.– Small available foot print.– Desire to simplify process

Where to use an MBR

Low-Pressure Polymeric Membrane

Mixed Liquor Permeate

MLSS 5,000 –16,000 mg/l

Flow

BOD < 5 mg/lTSS < 1 mg/lTurbidity < 0.2 NTU

MBR PROCESS

Basic MBR Concept

Backwashpump

Permeate

Permeate suction pump

Feed pump3.3 – 6.6 ft/s

16 ft

Waste water

BIO-Reactor

MBR Concept

Aerobic Bacteria+Oxygen

Solids

FromDNF

SecondaryClarifier Effluent

RecycleSolids

Waste

Aeration Basin

SludgeThickener

Anoxic

N-removal

Activated Sludge Process

Types of Membranes Utilized

§ External:– Tubular– Spiral wound– Hollow Fiber

§ Immersed:– Hollow Fiber– Plate and Frame

Tubular Membrane Feed & Bleed MBR’s

PermeateCommercialized Mid 1970’s

Bleed

Recirculation

Feed

Pump

Pump

Bioprocess

External Membranes

ADVANTAGES

� Sealed system� No exposure to mixed liquor� Cleaning without exposure to

fluid� No need to expose personnel

above open tanks� No handling of membranes

– membranes are fixed on racks

� No confined space entry� Safe and healthy environment

Permeate

Recirculation

low vacuum pressure(up to 7.5 psi)

Bioreactor

Commercialized 1990’s

Immersed Membrane MBR

High surface area – reduced energy consumption

Immersed

§ Flat Sheet– Kubota– Microdyn

§ Hollow Fiber– Zenon GE– Siemens– Koch– Various Asian– Berghof

Advantage and Disadvantage of Submerged Hollow Fiber Modules

Advantage: - Flexibility- back flushable- high package density

Disadvantage: - high tendency for sludge deposition

- high tendency for braiding- difficult to clean - extensive pre-treatment

Hollow Fibres

Braiding

Silting-up

Risk of Hollow Fibre Modules

Advantage and Disadvantage of Submerged Modules based on Flat Sheet/Plate Construction

Advantage: - less tendency for braiding- good hydraulic flow behavior

Disadvantage: - most commercial modules are not back flushable

- low package density- poor cleanability- limitation of plate size - sludge deposition at the

boundary of the plate

Plate Modules

• No Frame – No edge clogging

• No Plate – Self opening gaps

Gap-blocking

Edge-blocking

Risks of Flatsheet/Plate Construction

P h o t o g r a p h 1 : S l u d g e c a k i n g b e t w e e n m e m b r a n e s h e e t s c a u s i n g d i s p l a c e m e n t o f n e i g h b o u r i n g s h e e t s ( T e A r o h a 2 4 / 0 5 / 2 0 1 0 )

P h o t o g r a p h 2 : E x a m p l e s o f s e v e r e s l u d g e c a k i n g [ f r o m l e f t ; T e A r o h a W W T P ( 2 6 0 5 2 0 1 0 ) , T e A r o h a W W T P ( 2 7 0 5 2 0 1 0 )

P h o t o g r a p h 3 : E x a m p l e s o f s p e c t r u m o f s l u d g e c a k i n g o b s e r v e d

What’s in a MBR Package?

Equalization Aerobic Sludge

2 mm Fine Screen Re-screen 1X FF

Denit. recycle

Anoxic Aerobic

Permeate

Dual Membrane System

Gravity Return of ML

Pump ML to MOS

Rotating Equip. Skid& Control

Features• Piping in tanks• Conduit below skid• Stainless MOS• Duel Membrane Systems• Aluminum Safety Rails• Closed tanks with man ways• Membranes oversized 16/24• Prescreen 2 MM Perforated

MBR Benefits Summary

§ The UF replaces the solids separation function of secondary clarifiers and sand filters in a conventional activated sludge system.

§ MBR process combines the unit operations of aeration, secondary clarification and filtration into a single process, producing a high quality effluent, simplifying operation and greatly reducing space requirements.

§ Provides a physical barrier.

§ Overcomes the problems associated with poor settling of sludge in conventional activated sludge processes.

MBR Benefits Summary

§ Operation with considerably higher mixed liquor solids concentrations than conventional activated sludge systems that are limited by sludge settling. MBR process is typically operated at a mixed liquor suspended solids (MLSS) concentration in the range of 8,000 to 10,000 mg/L.

§ Elevated biomass concentrations allow for highly effective removal of both soluble and particulate biodegradable material in the waste stream.

Application Review

§ Existing facility with limited space to expand.

§ Greenfield facility with water reuse option.

§ Existing facility looking at water reuse.

§ Greenfield facility with 30/30 BOD TSS limits for discharge.

§ Greenfield facility with 30/30 BOD TSS limits for discharge and <.5 ppm phosphate.

§ Existing facility with continuous issues with permit excursions because of loss of biomass.

QUESTIONS

QUESTIONS?