Optimal design for membrane networks

.

Solvingdrought

Ultrasound effect on

problems in Eastern Enqland

crossflow filtration

Due

yothe

recent

investigated

the

alternative

water

Anghan,

together

a mobile a series

out

performance

have designed

pilot

followed

by RO

the North

was

directly were

water

hollow

fibre

carried

our

from

of

UF

The the

the

design

/otrrnal

(September

a can

design

The

is

on

design

permeator

model

programming workers

is used

of possible

superstructure

allows

optimizes

the

permeator

operating

conditions.

approxtmates studies in

natural

number

and discrete proposed multi-stage

and to that

of COI/CH, and

mixtures

enhanced

oil

Permeator for

a

different

areas.

It is claimed

provides the

membrane

an

preliminary separation

the

efficient design

of

systems

for

gas mixtures. of Membrane

(September

Science

I 998)

Membrane Technology No. 102

148,

to

the

123 -

135

71 -

89

membrane

VOC’s

during

French

feed.

Workers

at

have

operation

by raising

drinking

the

water

solvent

Researchers

the

Chemistry

previously

this

pressure

and

this process distillation

process

should

have

temperatures.

Changchun

published

to

processes.

at high

have written

of

of

technological

resistance at

that

with fractional

used in this

Membranes

flux

the operating

chemical

at

of the

Academy

the

It was reported

directly

Institute

of

a review of 25

papers on this subject.

Membrane Science and Ecbnolo~y 18, No.4,

vacuum (HOV’s)

of

the

influence

of

and

selectivity

using

4 -

Intermittent crossflushing of UF systems the effect

of backwashing

looked

at

such as

conditions

pressure and duration on the net flux per cycle in hollow

fibre UF systems.

It was

found

turbidity

of

backwashing effectiveness

that

monitoring

the

backwash

efficiency time

the

flux

water

than

of backwashing

pressure.

and

showed

was more dependent

process two

experiments

and downstream

productivity

in terms

the permeate flux

pressure

on the

of selectivity

concentration

of

treated

in this process).

to

and also water

(the

It is concluded

that

seems to be a good way to remove HOV’s

at low concentrations

from water, particularly

trichloroethylene,

for

chloroform

and

tetrachloroethylene. Desalination 117, 233 - 245 (September

1998)

Hydrodynamic behaviour in a membrane bioreactor Korean researchers have investigated the hydrodynamic

behaviour

of

anaerobic

biosolids

in membrane-coupled anaerobic bioreactors. approach

to predict flux decline was

made taking in to account

on crossflushing

low

was the

and The study also looks at the influence

A theoretical

study

at very

during crossflow ultrafiltration of digestion broth

8 (in Chinese)

recent

membrane for removal

flux

equivalent

VMD

of

production.

looks promising

VOC’s

characterisation

of

has been put

from water. Also studied

of temperature

markedly

point

Chinese

1998)

for the removal

say

(VMD)

concentrations

process

of the feed solution

enhanced

could be integrated

good

is

the boiling

consumption

distillation

researchers

simulation.

new way of

the surface of the membrane above

of backwashing

permeate

forward as a new process

concentrate

the vapour

and

to increase the

Vacuum membrane distillation

of halogenaced

Science 148,

and

in

(v -; 1.6

and system down time are reduced

distillation

to pervaporation.

backwashing journal

in

in concentration

is a relatively

Sciences

This

stages for both continuous

cleaning,

characterise

Applied

process cost. Case

derived

membrane for

a

is designed

investigated. are

of

function

treatment

approach

methodology binary

This

of separation

The

configuration

the total annual gas

large

simultaneously

objective

were

configurations

development that

for the separation

recovery

a very

and chemical

Vacuum

also

the increase

attributed

dehydration

to

velocity

hollow fibre ultrafiltration

Vapour

phase

by

that crossflushing

the frequency

Gas drying with vapour permeation

simplify

system

configurations.

the

strategy

an

permeator

The

because

approaches:

temperature.

nonlinear

strategy.

to embed

network

design

minimize

approximate

solution

that a general

superstructure

MINLP

an

and a mixed integer

(MINLP)

report

number

based

for

of dead-end,

systems

different

a temperature

have

strategy

networks.

researchers

1998)

permeation

achieved was found

regime

can be employed

on

contacts

an

the

weight

layer near the membrane.

In this process,

developed

be

of Membrane

different

State University

membrane

can

Crossflushing

parameters

gas

at Louisiana

increased

that showed

of bulk transfer

the

with

1938)

Researchers spiral-wound

JJux

that

Optimal design for membrane networks optimal

permeate polarization

seawater.

Desalination 118, 1 - 4 (September

evidence

on the that

in

the UF performance

on the filtered

presented

by crossflushing be

Desalination 118, 1’5 - 188 (September

until

molecular The

be achieved

ultrasound

found

significantly

solutions.

the

1 wt%

kPa

was irradiated

of different

dexttan

efficiency

UF cell and the

It was

irradiation flux

of the

is now underway,

water.

enhancement

plant

It is revealed

results showing

(MW)

results

RO

in

say

l‘hen,

could

m/s). It was also reported

from

30

alone.

pressure pulsing

researchers

under

1%

the fibre was in the turbulent

with

out by permeating

with 45 kHz of frequency cell

and

reinforced

of Technology

was preceded

t

In general,

could

be more effective when the crossflush

polyacrylonitrile

flux was obtained.

permeate

water

increase

solutions

ultrasound

the

for

was carried

UF

Beach

challenge

to

membranes.

be maintained

using

the expected

phase of testing

current

well;

as “excellent”.

little

due

at a used

sea. The

membranes.

>25%

prototype

the

described

well with

output second

a beach

filtration

the

flux

94.5

backwashing

(UF) membranes.

Japanese

dextran

while

the

describes

was set in crossflow

steady-state

‘The pilot trials were

from

provided

performed

study

the first phase

using

University

membrane

in

permeate

being

cloth.

Nagaoka

to produce

pilot plant installed

in Suffolk.

phase

obtained

have

Sea. The

solute

membranes

non-woven

fibre

abstracted

abstracted

and

of

on

(PAN) and ultrafiltration

and

of hollow

out in two phases:

second

plant

ultrasound

rejection

an

of the combination from

of

Science

by the use of crossflushing.

* 1% flux restoration

when backwashing

published

of Membrane

effect

The

a small mobile

seawater

as

the

site at Fehxstowc carried

de&nation

to establish

water

involved

in has

of trials

membranes

potable

of

with Norit

constructed

well

Water

supply.

carried UF

conditions

Anglian use

communication

/ownal

drought

England,

Eastern

A short

improved 99.9

on The

was significantly

mechanism interactions. reduction dechne

at the initial

prevents biosolids could

size

offered an exponential

flux

stage, as the biomass

cake

by the deposition

with back-transport

the flux, The optimal surface

transport and surface

It was found that the continuous of biosolids

layers being formed particles

the biosolids

based on hydrodynamics

velocities

operating

deposition

be predicted

of smaller less than

condition,

which

onto the membrane by the evaluation

of

critical flux. Water Research 32, (November

No.

1I. 3387

-

3397

1998)

0