From river water to high quality process water

Global demandfor

high quality or ultrapure process water is

high, making it a huge marketfor

thefiltration

and separation

industry Therefore, there is a constant drive to develop purfication processes that are more eficient,

more cost-efective

and more

riendly than exisitng technologies. In this article

environmentallyf

Axiva GmbH, Frankfurt am Main, Germany, explains why its new processfor the direct treatment of surface water meets these criteria.

From river watw

R

feed water raw water trast,

everse

osmosis

hcen the leading technology

scale.

drinking

bvater and also for direct water

al methods

of Iwars.

new

as an alternative

poor.

multistage,

complex

processes

employed

ment.

For example,

tinely

used to precipitate

has to hc carefully

wr-

to meet

precipita-

stream

compared

is relatiwl\i

In contrast,

chemicals

are rou-

and gardia,

controlled

the rcquircments

water

.

cay

* .

no chemical

design

and the

quality;

to automatc;

tlexibility

those

organisms

on mem-

the construction

advantages:

high pure

??

based

enable

that have a simple

follo\ving

suspended

processes

technology

of plants

to

in its pretreat-

at the same time the water

to conwntion-

such as ozoni/ation,

of ri\ cr \vater

such as crvtospordium

UF can now

chlorina-

hranc

solids and to kill waterborne

been

of

coagulation, filtration.

rescviors

are commonly

and process treatment

from

Therefore,

In con

and has only recently

bc used to purify

water

prctrcatrd

(UF) is relatively

used on an industrial

The quality

water,

L\ atcr and boiler

for a number

ultrafiltration

tlocculation,

tion and gravel

in the produc

tion of ultrapure drinking

tion,

has

edge

from conventionally

to this sector

fact

(RO)

to high water

because

of modular

treatments,

for cleaning

design;

apart

from

the membrane\;

and

but

chcmistrv

permeate

??

free from

microorganisms,

in o&r

fouling

of tlown-

in less bio

or recontamination

qucnt

RO.

Qiruses and other

resulting

in subsc-

stages.

In the past,

the use of UF for the direct

-!

treatment

Process Water Production from River Water

of river

economical.

I

large,

unreliable

gy-intensive. opcd

water

Turbiditv > 20 NTU

that combines

m i,

Reverse Osmosis

I Cond. < 30 @/cm

-

I

d

STUDY venture

company

of the Hiichst

effective

with the kvater suppI>

tested pilot-scale

particles

reliably

throughout

demonstrated

removed

the trial period

24

July/August

2000

that

suspend4 from

qualit)-

and met the requirements to the RO plant.

process

from the River

and microorganisms The permeate

and

and cost-

ultrafiltration of \vater

Main. The pilot study the process

Park,

developed

an efficient

for the treatment

water.

Industrial

the company

successfully Cond 2OOQ @/cm Turbidity < 0,05 NTU

ultra-

~2atcr.

In a joint

Frankfurt,

Conditioning

has devel-

the benefits

of RO to produce

from river

PILOT

ClPlRinsing

too

or too encr-

Now Axiva GmbH

a process

water

were

in operation

of UF with those pure

was not deemed

The UF systems

the

xvas very high (< 0.05

NTU)

for teed Lvatcr

The permeate

floxv Mas

Filtration+Separation

passed

through

an

150 pm coarse filter. This is a backwashable ter, which cleaned

fil-

Before

the

as to ensure

reliable

raw water

ia

to the next

2),

comprises

principle. of each

arranged

water from

of the venture

feed water. The aim

is to acquire

operating

expe-

riencc

with the plant over a period

of three

years,

and then use the information

to

develop

a full-scale

in

existing

conventional

plant technology

the production

of ultrapure

Membrane

Plant

in

water.

which

trolled

yield (ratio

Figure

initially

backwashing,

layout

the ra\v water

Filtration+Separation

is

because

primarilv

by the concentrate,

of permeate

,

princi-

with

plants

matical1.r washing

pumps

en orgy 1

production waters tional

to

process

design direct,

Lvatcr from surface

combinations,

there

is that its modular

is no riced to complete-

ly shut dobvn the plants cleaning

to convenand largcl?

of tvaste. Another

of the process

means

feed and

compared

avoids the formation

end system

auto-

and

of UF and RO for the

of ultrapure

saves energv

advantage

for

cleaning

of the UF and RO units.

The combination less

Both mem-

and washed

unit and the individual

that of a dead

prior

arc cleaned

using a central

circulation

a

flow to feed flolv)

of up to 90% can bc achieved.

on a

of

design. ‘The RO unit is con-

brane

for maintenance

or

purposes.

to a desalt-

flows as pure

into an intermediate

remain

in the concentrate

at regular

intervals

wash. As part

in-line,

industries

a

years

has been

developing

membrane

separa-

for a wide range

including

of

pharmaceuti-

cals, specialty

chemicals,

biotechnology

and agriculture.

dyes,

back-

chemical is meterrd

the contamination

and the remaining

of

concen-

with substances

that

organic

halogen

comas a con-

pounds.

The concentrate

is taken

tinuous

bleed

the loop of the

flow from

using

than twenty

a suitable

backwashing

raw water

GmbH

tion technology

is removed

by the permcatc

hypochlorite

preventing

adsorbable

and form which

For more Axiva systems

for

constituents

of this operation

such as sodium

tank,

taken

Th e raw \vater

the permeate

of the

modules

of manufacturers

(approximatelx

permeate

layer on the membrane,

form

1 shows the schematic In the first stage

also has the

at a low flow rate

Lvherc it is periodically

trated

plant.

of this type of

The syslcm

its standardisrd

vertically

but also permits

biocidallcleaning

plant that will replace

benefit

of using memhranc

operate

USC of ultrafiltration

The resultant

has now commis-

cess, as well as boiler

of the stanin series and

ing stage.

pilot plant for the

pro-

The major

parallel,

comparable

will be used in the production

mod&s

type 8040 arranged

from varictv

consumption

lvhich

spiral wound

of sevcon-

density.

specific

from the River Weser,

3) consists

concentrations,

flexibilt,.

considerable

of water

(Figure

packing

mod-

operates

treatment

is provided

high-pressure

membrane

cross-flow

Germany,

pressure

the four end

is

ple. The process

a large-scale

The 110 plant

in parallel.

a

is it has a high volume-specific

0.2 m/s)

in Breman,

through

to the RO unit.Thc

module

fibre)

sioned

operating

taining

ules (holloM

water

necessary

dardised

of the UF units

river

(Sgm)

era1 units of graded

and

The heart

pretreating

is passvd

fine filter

pumps.

and operate

so

of thr RO umt. Thr

of water

in parallel.

These

rtc,

optimum

by the speed-controlled

of a closed

c,g. pH

control,

UF units arranged

bleed

LARGE SCALE PROJECT A major stainless steel manufacturer based

performance strram

(Figure

or

IS fed to

scaling

on the jeeJ

(0.3 kWh/m3)

the UF permeatr

adjustment,

loop,

reliable

further

prepu-

consist

\vith a yield of

as wastewater

be treated

plant.The

which

I/m2”h,

4% of the permeate

the RO unit it is conditioned,

plant

8 504.

accumulates

of the

ultrafiltration

of 64

(about

volume)

operation

passed

approximately

washing

to

concentrated.

without

rified

an average

be returned used in back-

that can either

can bc

interrupting

UF, and can normally the river. The tvater

July/August

2000

25