Contents Introduction Membrane fundamentals Membrane Bioreactor - - PDF document

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Presenter: Javad Saadati Supervisor: Dr. Gheshlaghi

Ferdowsi University of Mashhad Chemical Engineering Department

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Contents

• Introduction
• Membrane fundamentals
• Membrane Bioreactor Systems
• Applications
• Conclusion
• References

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Introduction

• A membrane is defined as a material that

forms a thin wall capable of selectively resisting the transfer of different constituents of a fluid and thus effecting a separation,

• f

the constituents [1].

• For many processes the membrane acts in a

way to reject the pollutants, which may be suspended or dissolved and allow the “purified” water through it.

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Membrane fundamentals

Membranes can be classified by [1]:

1) the driving force used for the separation of

impurities, such as pressure, temperature, concentration gradient, partial pressure, electrical potential etc;

2) the structure and chemical composition, 3) the mechanism of separation and 4) the

construction geometry

• f

the membrane.

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Membrane fundamentals

There are six commercially used membrane separation processes [2]:

 Microfiltration (MF)  Ultrafiltration (UF)  Nanofiltration (NF)  Reverse Osmosis (RO)  Dialysis  Electrodialysis (ED)

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Membrane fundamentals

• Microfiltration (MF) and ultrafiltration (UF) are low

pressure driven processes.

• Reverse osmosis (RO) is a high pressure driven process

designed to remove salts and low molecular organic and inorganic pollutants.

• Nanofiltration (NF) operates at a pressure range in

between RO & UF targeting removal of divalent ion impurities [1].

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Membrane fundamentals

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Membrane fundamentals

Membrane Materials:

 Organic polymer  Ceramic

*All of commercial MBR manufacturers use polymeric

MF membranes.

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Membrane fundamentals

Polymer Membranes:

 Low cost production  Natural variations in pore size  Prone to fouling and degradation

Ceramic Membranes:

 Excellent quality and durability  Economically unfeasible for large operations

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Membrane fundamentals

 The most common types of MBR are hollow fiber

and plate and frame.

 Hollow fiber membranes are extruded into long

fibers and joined into bundles, called modules.

 The modules are submerged in the wastewater

and permeate is drawn into center of the fiber by an applied vacuum.

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Membrane fundamentals

 Plate and frame modules are made from large

membrane sheets loaded into cassettes.

 Permeate is drawn through the membrane

due to an applied pressure differential.

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Membrane Bioreactor Systems

 Membrane

Bioreactor (MBR) systems essentially consists

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combination

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membrane and biological reactor systems.

 These systems are the emerging technologies,

currently developed for a variety of advanced wastewater treatment processes.

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Membrane Bioreactor Systems

 In general, MBR applications for wastewater

treatment can be classified into four groups, namely:

I.

Extractive Membrane Reactors

II.

Bubble-less Aeration Membrane Bioreactors

• III. Recycle Membrane Reactors
• IV. Membrane Separation Reactors

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Membrane Bioreactor Systems

Extractive Membrane Reactors

 Extractive membrane bioreactors (EMBR) enhance

the performance capabilities of biological treatment of wastewater by exploiting the membrane’s ability to achieve a high degree of separation.

 This

separation aids in maintaining

• ptimal

conditions within the bioreactor for the biological degradation of wastewater pollutants.

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Membrane Bioreactor Systems

Extractive Membrane Reactors

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Membrane Bioreactor Systems

Extractive Membrane Reactors

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Membrane Bioreactor Systems

Bubble-less Aeration Membrane Bioreactors

 In a conventional aerobic wastewater treatment unit

such as an activated sludge process, the process efficiency is controlled by the availability of air.

 Due to inefficient mode of air supply, 80-90% of the

• xygen diffused as air in an activated sludge process is

vented to the atmosphere.

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Membrane Bioreactor Systems

Bubble-less Aeration Membrane Bioreactors

 The membrane aeration bioreactor (MABR) process use

gas permeable membranes to directly supply high purity

• xygen without bubble formation to a biofilm.

 As the gas is practically diffuse through the membrane,

very high air transfer rate is attained.

 The membrane also acts as a support medium for the

biofilm formation, which reduces the potential for bubble formation and air transfer rate.

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Membrane Bioreactor Systems

Recycle Membrane Bioreactors



The membrane recycle bioreactor consists of a reaction vessel operated as a stirred tank reactor and an externally attached membrane module.

 The substrate (feed wastewater) and biocatalyst are

added to the reaction vessel in pre-determined

• concentrations. Thereafter the mixture is continuously

pumped through the external membrane circuit.

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Membrane Bioreactor Systems

Recycle Membrane Bioreactors

 The smaller molecular compounds, the end products

• f the biodegradation reaction, are permeated through

the membrane.

 While

the large molecular size biocatalyst are rejected and recycled back into the reaction tank.

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Membrane Bioreactor Systems

Membrane Separation Bioreactors

 Application of membrane separation (micro or ultra filtration)

techniques for biosolid separation in a conventional activated sludge process can

• vercome

the disadvantages

• f

the sedimentation and biological treatment steps.

 The membrane offers a complete barrier to suspended solids

and yields higher quality effluent.

 In

this system, the solid-liquid membrane separation bioreactor employs filtration modules as effective barriers.

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Applications

MBR treatment is applicable to many sectors, including:

 Municipal  Industrial  Water reclamation

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Conclusion

 The application of MBR technology is rapidly expanding,

with new installation occurring every year.

 MBR technology is highly suited for the reclamation of

waste water due to the ability to produce drinking water quality effluent.

 The small foot print and ease of operation of the MBR

system makes it ideal for application in remote areas where waste water can be reused for irr

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References

[1] C. Visvanathan, R. Ben Aim. Membrane Bioreactor Applications in Wastewater Treatment [2] Stacy Scott, Application of membrane bioreactor technology to waste water treatment and reuse. [3] Neha Gupta, N Jana, submerged membrane bioreactor system for municipal waste water treatment process: an

• verview, Indian journal of chemical technology, Vol. 15, pp. 604-

612.