10643380091184165

7/27/2019 10643380091184165

1/49

This article was downloaded by: [78.38.187.58]On: 12 May 2013, At: 10:44Publisher: Taylor & FrancisInforma Ltd Registered in England and Wales Registered Number: 1072954 Registered office: Mortimer House,37-41 Mortimer Street, London W1T 3JH, UK

Critical Reviews in Environmental Science andTechnologyPublication details, including instructions for authors and subscription information:http://www.tandfonline.com/loi/best20

Membrane Separation Bioreactors for WastewaterTreatmentC. Visvanathan a , R. Ben Aim b & K. Parameshwaran ca Environmental Engineering Program, Asian Institute of Technology, P.O. Box 4, Klong Luang,Pathumthani 12120, Thailand; Email: [email protected] Institute National des Sciences Appliques de Toulouse, Complexe Scientifique de,Rangueil 31077, Toulouse Cedex, Francec 3Center for Membrane Science and Technology, The University of New South Wales, Sydney

2052, AustraliaPublished online: 03 Jun 2010.

To cite this article: C. Visvanathan , R. Be n Aim & K. Parameshwaran (2000): Membrane Separation Biore actors forWastewater Treatment, Critical Reviews in Environmental Science and Technology, 30:1, 1-48

To link to this article: http://dx.doi.org/10.1080/10643380091184165

PLEASE SCROLL DOWN F OR ARTICLE

Full terms and conditions of use: http://www.tandfonline.com/page/terms-and-conditions

This article may be used for research, teaching, and private study purposes. Any substantial or systematicreproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form toanyone is expressly forbidden.

The publisher does not give any warranty express or implied or make any representation that the contentswill be complete or accurate or up to date. The accuracy of any instructions, formulae, and drug doses shouldbe independently verified with primary sources. The publisher shall not be liable for any loss, actions, claims,proceedings, demand, or costs or damages whatsoever or howsoever caused arising directly or indirectly inconnection with or arising out of the use of this material.
http://www.tandfonline.com/page/terms-and-conditionshttp://dx.doi.org/10.1080/10643380091184165http://www.tandfonline.com/page/terms-and-conditionshttp://dx.doi.org/10.1080/10643380091184165http://www.tandfonline.com/loi/best20

7/27/2019 10643380091184165

2/49

Copyright 2000, CRC Press LLC Files may be downloaded for personal use only. Reproduction

of this material without the consent of the publisher is prohibited.

1

Critical Reviews in Environmental Science and Technology, 30(1):148 (2000)

Membrane Separation Bioreactors forWastewater TreatmentC. Visvanathan, 1 R. Ben Aim, 2 and K. Parameshwaran 3 1Environmental Engineering Program, Asian Institute of Technology, P.O. Box 4, KlongLuang, Pathumthani 12120, Thailand; Email: [email protected]; 2Institute National desSciences Appliques de Toulouse, Complexe Scientifique de, Rangueil 31077, ToulouseCedex, France; 3Center for Membrane Science and Technology, The University ofNew South Wales, Sydney 2052, Australia

ABSTRACT: With continuing depletion of fresh water resources, focus has shifted more towardwater recovery, reuse, and recycling, which require an extension of conventional wastewater treat-ment technologies. Downstream external factors like stricter compliance requirements for wastewater discharge, rising treatment costs, and spatial constraints necessitate renewed investigation of alter-native technologies. Coupled with biological treatment processes, membrane technology has gainedconsiderable attention due to its wide range of applicability and the performance characteristics of membrane systems that have been established by various investigations and innovations during thelast decade. This article summarizes research efforts and presents a review of the how and why of their development and applications. The focus is on appraising and comparing technologies on thebasis of their relative merits and demerits. Additional facts and figures, especially regarding processparameters and effluent quality, are used to evaluate primary findings on these technologies. Keyfactors such as loading rates, retention time, cross-flow velocities, membrane types, membranefouling, and backwashing, etc. are some of the aspects covered. Membrane applications in variousaerobic and anaerobic schemes are discussed at length. However, the emphasis is on the use of membranes as a solid/liquid separator, a key in achieving desired effluent quality. Further, technol-ogy development directions and possibilities are also explored. The review concludes with aneconomic assessment of the technologies because one of the key technology selection criteria isfinancial viability.

KEY WORDS: membrane bioreactor, membrane technology, solid/liquid separation, membrane air diffusers, membrane fouling, backwashing, micro-porous membranes.

I. INTRODUCTION

The use of biological treatment can be traced back to the late nineteenth

century. By the 1930s, it was a standard method of wastewater treatment (Rittmann,1987). Since then, both aerobic and anaerobic biological treatment methods havebeen commonly used to treat domestic and industrial wastewater. During thecourse of these processes, organic matter, mainly in soluble form, is converted into

7/27/2019 10643380091184165

3/49



2

H2O, CO 2, NH 4+, CH 4, NO 2 , NO 3 and biological cells. The end products differ depending on the presence or absence of oxygen. Nevertheless, biological cells arealways an end product, although their quantity varies depending on whether it isan aerobic or anaerobic process. After removal of the soluble biodegradable matter in the biological process, any biomass formed must be separated from the liquidstream to produce the required effluent quality. A secondary settling tank is usedfor the solid/liquid separation and this clarification is often the limiting factor ineffluent quality (Benefield and Randall, 1980).

In recent years, effluent standards have become more stringent in an effort topreserve existing water resources. Recycling and reuse of wastewater for second-ary purposes is on the rise due to dwindling natural resources, increasing water consumption, and the capacity limitations of existing water and wastewater con-veyance systems. In both cases, achieving a high level of treatment efficiency isimperative.

The quality of the final effluent from conventional biological treatment sys-tems is highly dependent on the hydrodynamic conditions in the sedimentationtank and the settling characteristics of the sludge. Consequently, large volumesedimentation tanks offering several hours of residence time are required to obtainadequate solid/liquid separation (Fane et al., 1978). At the same time, close controlof the biological treatment unit is necessary to avoid conditions that lead to poor settleability and/or bulking of sludge. Very often, however, economic constraintslimit such options. Even with such controls, further treatment such as filtration,carbon adsorption, etc. are needed for most applications of wastewater reuse.Therefore, a solid/liquid separation method different from conventional methodsis necessary.

Application of membrane separation (micro- or ultrafiltration) techniques for

biosolid separation can overcome the disadvantages of the sedimentation tank andbiological treatment steps. The membrane offers a complete barrier to suspendedsolids and yields higher quality effluent. Although the concept of an activatedsludge process coupled with ultrafiltration was commercialized in the late 1960sby Dorr-Oliver (Smith et al., 1969), the application has only recently started toattract serious attention (Figure 1), and there has been considerable developmentand application of membrane processes in combination with biological treatmentover the last 10 years.

This emerging technology, known as a membrane bioreactor (MBR), offersseveral advantages over the conventional processes currently available. Theseinclude excellent quality of treated water, which can be reused for industrialprocesses or for many secondary household purposes, small footprint size of the

treatment plant, and reduced sludge production and better process reliability.The purpose of this monograph is to provide a comprehensive review of

membrane bioreactor technology. The application of membranes in different stagesof biological treatment processes, the historical development of membrane bioreators,

7/27/2019 10643380091184165

4/49



3

and factors affecting the design and performance of MBR processes are discussed.A number of case studies for each type of major MBR application along with somecost information on MBR processes is also presented.

II. FEATURES OF MEMBRANE APPLICATION IN BIOLOGICALWASTEWATER TREATMENT

As our understanding of membrane technology grows, they are being appliedto a wider range of industrial applications and are used in many new ways for wastewater treatment. Membrane applications for wastewater treatment can begrouped into three major categories (Figure 2): (1) biosolid separation, (2) biomassaeration, and (3) extraction of selected pollutants. Biosolid separation is, however,the most widely studied and has found full-scale applications in many countries(Table 1). Use of combined night-soil treatment and wastewater reclamation atplant scale operations in buildings in Japan are examples of some successfulapplications, and in these cases membrane-coupled technology is considered astandard process (Yamamoto and Urase, 1997). Solid/liquid separation bioreactorsemploy micro- or ultrafiltration modules for the retention of biomass for thispurpose. The membranes can be placed in the external circuit of the bioreactor or they can be submerged directly into the bioreactor (Figure 2a).

Asymmetric membranes consist of a very dense top layer or skin with athickness of 0.1 to 0.5 m, supported by a thicker sublayer. The skin can be placedeither on the outside or inside of the membrane, and this layer eventually definesthe characterization of membrane separation.

FIGURE 1. Number of studies published on MBR.

7/27/2019 10643380091184165

5/49



4

TABLE1

Commercial Scale Solid/liquid Separation MBRPlants

Commercial

Number

Capacity

Company

name

Country

Type of Waste

of Plants

(m 3

/d)

Ref.

Rhone Poulenc-TechSep

Dorr Oliver

Thetfort Syst

Kubota

MitsuiPetrochemicalIndustries

Zenon EnvInc.

Dorr Oliver

Membratek

SITA/lyonnaise desEaux

Membratek

Grantmij

Degrement

UBIS

MSTS

Cycle-LET

Kubota

Kubota

ASMEX

Zenogem

MARS

ADUF

France

U

SA

U

SA

Japan

U

K

Japan

C

anada

U

SA

R

SA

France

S

.Africa

G

ermany

France

Domestic

Domestic

Domestic

Domestic

Domestic

Human excreta

Industrial

Industrial

Industrial

Landfillleachate

Industrial

Landfillleachate

Industrial

>40 1 >30 8 1 >40 1 1 2 3 2 3 1

10643380091184165

Documents