Membrane technology as a tool to prevent dangers to human health by water-reuse

381

Desalination,67(1987)381-393

ElsevierSciencePublishersB.V.,Amsterdam-PrintedinTheNetherlands

MEMBRANE BY

TECHNOLOGY

A

TOOL

TO

PREVENT

DANGERS

TO

HUMAN

HEALTH

WATER-REUSE

R.F.

MADSEN

Director

5,

AS

A/S

of Research,

P.O.

17,

Box

1001

De

Danske

Copenhagen

Sukkerfabrikker,

K.

Langebrogade

(Denmark)

SUMMARY The paper gives a discussion of the health risks in reusing domestic sewage water as drinking water after purification. the transmission of viral diseases The potential risk of through a recycling water system can be reduced 5-7 logs by memrisk of transmission of, branti filtration, thus mimimizing the for example, hepatitis A, and increasing the safety beyond the level of traditional waterworks. Membrane filtration connected with denitrification will secure for the transmission of bacterial diseases. the water systems Membrane filtration reduces bacterial counts 7-9 logs. Membrane filtration will reduce the need for chlorination, and membrane filtration is a safe because colloids are removed, barrier for eggs of nematodes, helminths, etc.

INTRODUCTION Membrane increase 1) 2)

filtration safety

of

It

can

be

a

It

can

be

an

the

world

more

and

drinking

used

by

part

have

or

specially

a

ration

or

microfiltration)

can

ways: the

of

correctly, operation

consumer.

the

is

water

i.e.

is risk

purification

system

at

not of

always being

patients

without

too1

of

CONSUMER even

safe

(ref.

case

western

pathogenic

microorganisms

if

used

on

wounds

1, 2, 3)

direct

stop

the

from

from

at

increasing

of

in

free

pathogenic

aftercontamination in

though

and free

microfiltration

excellent

sterilization

OOll-9164/87/$03.50

THE that

normally

susceptible

or

BY

recognized

potential

an

and

FINISHER

water

Ultrafiltration offers

AS more

water

drinking

which

point

two

integral

FILTRATION is

germs,

by

finisher

in

waterworks.

MEMBRANE It

(ultrafilt

water

and of

O1987ElsevierSciencePublishersB.V.

the

consumption

security,

if

with

continuous

operation.

used

382

Microfiltration

for

and,

at

safe

preparing

Microfiltration logs, tion

will

paper.

decrease

growth

water

make

it

waste

water

in

example

and

be

cleaning

more

to

assessments

the

at

depend

need

waste water

a

and

in

this

WATERWORKS on

drinking

where

drinking towns

river,

urban

of

we

as

to

for

be

able

The

systems.

it

is

more

as

the

reuse.

methods

need

a

for

comsumptions

biotope

water

is

placed

where

natural

safe

water

are

but

situation

risk

purification

IN

methods

as

the

find

water,

later

demands

where

the

the

8

water.

on

to

around

concentra-

removed.

find

water

along

arrive

of

viral

TREATMENT

to

world

eliminating we

on

increased

waste

hopeless

of

WATER

drinking

intervals

procedure

THE

as

for

unsafe

household

count

used,

described

and

of

more

is

necessary

of

small

completely

reuse

and

rinse

OF

is

safety.

as

be

tool

water

bacterial

logs,

areas

areas

Consequently, direct

in

reused

short

more

more

and

more

many

with we

PART

urban

indirect

reality

grow,

AS

of

can

Today,

6

excellent

developing

filter

will

an where

increased

reduction

protozoa

also

places

strongly

give

around

and

is

at

ultrafiltration

FILTRATION

The

to

gives

an

Amoebae

MEMBRANE

is

systems

if

consumer water

China

example,

microfiltration

and

the

drinking

an to

risks

almost

make

we

risk

have

are

twofold: 1)

Pathogenic

2)

Toxic The

but

germs,

substances. risk

it

is

assessment

certainly in

Although, regarded this

so

does

free

pathogenic (ref. breaks Control

In other

give

of

a

difficult

1 the

years

similar

of

number to

factors

are

protozoa,

the a

the

of to

1972-1981.

disease potential amoebae,

can

is

developed

(ref.

etiology

reported

it

to

make,

unknown factors risk bacteria,

4,

normally

safe

5,

6).

In

US

today

Olson

et

disease

Center

addition

be

drink, is

caused

are

water-borne the

to

world

outbreaks

water

have

water

that

epidemic

drinking

Table

addition

helminths,

is

drinking

that

where

etiology

the

germs

germs

however,

in

in

world,

pathogenic

mean,

known

in

breaks,

in

germs

4)

western

incidents

from

pathogenic

required.

the

low

not

of

of

to

by al. out-

Disease

these

out-

etiology. in in

the some

and

table, places,

virus.

a

number including

of

383

TABLE

1

Etiology

of

Reported

'to CDC,

Water-Borne

Disease

Outbreaks

Number of Outbreaks

Etiology Giardia

lamblia

Shigella Hepatitis

A

Norwalk-like

agents

31.5 14.8

10

6.7

10

6.7

Salmonella

Salmonella

typhi

4

jejuni

Enterotoxigenic

E.

cholerae

2.0

1

0.7

1

0.7

01

1 chemicals

can

risk

what

the

into in

chlorine

no

In

a

2)

Risk

be

to

sure

analyse

the

outbreaks

have

a very

the water

that

at

least

not

to

increase

diseases?

find

supply

known

large of

par-t of

waste

systems, in

incidents

and

see

been.

entrainment

mistakes

systems,

we

risk

following Risk

is

with

also

failures

going

1)

and

endemic

filter

the

water

either

outbreaks

01‘ untreated

due

to

pressure

operation

or

failure

of

have

in

waterworks

dosing.

However, where

we

drinking

water

or

for

this,

connected

water

water

step

reasons

doing

be

water

reuse

epidemics

important

In

loss

we

of

One

can

100.1

149

How the

0.7

28.2

42

Total

5.4

2.7

3 coli

Rotavirus Miscellaneous

Etiology

Percentage of Total

22

Nontyphoid

Campylobacter

Known

47

8

Vibro

of

1972-1981

find

were

assessment into

risk under under

outbreaks

which

come

observed. where

treatment

in

we

look

only

a waterworks,

at

the

we

risk

have

from

to

waste

assess

the

factors: normal

conditions

epidemic

with

conditions

well-functioning with

equipment.

well-functioning

equip-

ment. 3)

Risk

of

dosing.

operation

failures,

e.g.

filters

and

chlorine

or

ozone

Under

normal germs

which

give

can

relationship

It

is

large

obvious

L,

of

I

I

risk

sure

data

gives

that

in a number on

the

fecal

coliform,

2.

have

to

be

exists

diseases

be

of

present

at

a very

Salmonella

in

a

small

is existing

IO-lOO/litre.

I

I

IO0 IO' IO2 SAlMONEllA/lITER

I

7)

1 and

the

to

consumer

virus,

coliforms

and

litre,

of

for

Figs.

viral

have

to the (ref.

risk

see where

per

we

pass

Mechalas

risk

I

IO

to

disease

that

the

at counts

0 000

able

diseases.

of virus

already

not

Salmonella,

number,

number

are

between and

coliform,

conditions

operation

pathogenic

I

J IO4

to3

I

I

I

IO3

IO4 IO5 IO6 IO' loa COLIFORM(MPN/l00ml) I t I I I I 4.9x10* 5 BxlO'6 5x1047 oxlo57.zxlo67.1xlo7 FECAL COLIFORM lMPN/l00mll

Fig. 1. Relationship and fecal coliforms

If

we

move

where

the

capable egg,

of

a

larva,

tion,

and It

other

can

or

of

one

well

a

known

are

and 7))

scale

viruses,

that

long

time

that

nematodes,

we have in a water

one

passing fairly

coliforms,

of pathogenic

worm),

copepod

means

cercaria

creatures for

of the (guinea

This

encysted

survive

risk (ref.

infected

man.

These

is also

end

Dracunculus

infecting

disease.

8).

the as

existence

cause

7,

to

such

helminths,

between disease (after Mechalas

single the

resistant

in drinking

germs,

a parasite system

is

fertilized

waterworks to water

crustacean

can

chlorina(ref.

5,

copepods,

385

etc.

art?

during

ideal

hiding

chlorination

present

waste

in

for,

being

risk

the

Naturally,

8).

places

without

of

water

for

example,

pathogenic

pathogenic

different very

depends

Vibrio

Cholera

themselves

on

much

(ref.

germs

1,

being and

geography

climate.

0 014 z

0.012

-

2 0.010

-

y 2

0 008 -

0.006 B ~0004

-

n

-

-

0.002

I 2

OO

I

I

I2

14

I 60

I 70

I

I

IO 8 VIRUS (PFU/LITER) I I I I 50 30 40 20 COL I FORM I IO” MPN/ I OOml1

I IO

I 0

I

I

6

4

I

I

I

I

I

I

I

I

I

0

5

IO

I5

20

25

30

35

40

FECAL

COLIFORM

L103MPN/100mL)

and Fig. 2. Relationship between disease risk forms, and fecal coliforms (after Mechalas (ref.

The

can

1)

Viruses,

2)

Bacteria

3)

Protozoa, Each

be

summarized

e.g.

of

are

potential

of

coli-

risk

in

of

the

as

hepatitis

helminths, these

which

organisms,

pathogenic

water,

salmonella 7))

A

and

Norwalk

agent

etc.

subjects

has

to

be

treated

individually.

VIRUS It

seems

pathogenic (ref. of

4,

1000

reasonable viruses,

7,

9),

viruses

even

to such

as

though

ingested

believe

it

causes

that

only

hepatitis must

be

A,

one can

believed

a disease.

of cause

that

some a only

disease one

out

It

is

impossible

hepatitis

A

whether water

they will

all

be

than

one

will

be endemic

other

have

If and a

true for

have

1000

l/year,

consume drinking Of

water

number

by

is

l-3

can

sewage

give

the

ducing

the

count

If

the

one-virus

total

frequency

though

a

eases,

would

been

between

values means

below that

treatment value

and

100,000.

an addition methods

with

diseased

5

all

no

out

of

can

only

stages

of

virus

up

of

reduces give

this

around

reduction.

to

be

2

Strong

conventional

a 7-9

l/1000, be

are

have

log

capable

water

reduction,

re-

when

using

a

with

people

some

the

viral with

in

membranes

with

experimental

count

year

dis-

systems

reduction

reasonable per

viral

reducing

membrane

filtration viral

all

to water. of

our the

2 gives

give

counting

related

tested

of membrane

1 million

of

is correct, this would give a -3 ) or clearly unacceptable, al-

of

risk,

numbers

log

directly would

to10

Table

we

various

treatment

they

content

and

in

people if

virus/litre.

logs

would

disease

best

a disease,

water

flocculation

experiments,

7

the

reduction.

membranes

In

whether

100 million

drinking

sewage

difficulty

We

take

causes

of

varying

1-2

going

10-l

out

measure,

and

assumption

significantly.

bacteriophages.

4 log

with

Ultrafiltration count

to

filtration

frequency

only

less

systems

assess

only

reduction

Normal

10-'-10-3

of

disease

to

that the average -8 10 virus/litre.

contains

reduction

to

only

drinking-water

from

is

virus

6).

was

epidemics.

viruses

one

around

Coagulation

water

treatment,

demand

of

sand

or

Drinking

infects

can

1000

impossible

4,

logs.

of only

disease

water

(ref.

chlorination

disease

the

Sewage

reduction,

If

viral

experience

106/litre

out that

be only

this

by

purification.

log

a

the

cases.

one

should

course,

calculate

to

that

with

and

We

of

water,

transmission.

difficult

today.

such

example,

should

sewage

part

drinking

patient

It is extremely

prevent

is

A

certain

from

in connection

hepatitis

transmission

to

a

come

or direct

through

only.

we want,

year

food

only

one

whether

today

from

patient

such

it

come

where

precautions

estimate

existing

suspected

Conditions

we

to

cases

to the close

drinking

has

cut-off

data.

This

conventional to

security

count

the

of only

this

water.

safe one

387

TABLE

2

Bacteriophage

rejection

Ultrafiltration

on

DDS

Strain

GR61PP

membranes

count broth/ml

Count permeate/ml

Ratio

T

even

E.

coli

9 x

10 7

100

0.9

x

10s

T

even

E.

coli

7 x

10 7

10

7.0

x

106

For the

diseases

main

will

cause

than

one

more

We

or

it

the

3)

One

out

4)

Only

3%

for

other

of

can

through

of

other

the

the

one

drinking

disease

case.

disease

than

If

can

other

it

be

water,

in

average

causes

caused

case,

more by

the

one

outbreak

humans,

not

causes

viruses

the

drinking

water

of

is

outside, disease,

consumed,

the

rest

is

used

purposes.

a

in

normal

person

has

should

be

each

case

to

be

mot-e

of

by

then

not

-6

from the

than

3

drinking

cause

outside

more

10

is

system,

spread

will

probably counts

number

recycling

diseased

viral

infection,

in

consumed

for

but

that

cause

1000

epidemic

since

less

only

reduction

large,

one of

assumptions

the

average

case

out.

take

water

than

causes

only

one

outbreak

1) Only one virus multiply 2) Viruses

If

transmitted

whether less

an

If

die

are

is

case,

infected. will

that

question

water

another

case.

the range which 6 10 /g stool are

than

stool

to

drinking

production from each 10 10 viruses x if an only,

since

in

This

figure

is

may

be

often

expected,

measured

on

patients. It the

is

obvious

normal

recirculation preventing calculation.

that

waste

water

of any

waste

chance

the

addition

and water of

of

a

membrane

water-purification

the

as

drinking

spread

of

filtration

system water

epidemics

would

completely based

to make safe,

on

this

388 BACTERIA The

normal

bacteriological

determination that

not

showing

in

a

plication

cases the

p

of the

tions.

The

strains

main

obtained

on

a number

TABLE

of

coli

E.

units

our

are

fermentation

made

multi-

is,

there-

the

determinaof virus.

membranes

on

Table

or

gives

operation

of results

broth.

have

of

equipment

normal

a number

organism

water

determination

under

the

stool.

picture

industrial

results

but

human

ultrafiltration

in

is

a problem

possibility

whole

the

is

through

Fortunately,

than open

log

products,

The

virus.

easier

from

a

water it

indicator-

spread

also

body.

with

8

can

but

with

part

on dairy

a pollution

membranes

around

drinking However,

is a safe

which

human

is much

for

water.

bacteria

has

than

filtration

of

the

dying,

microfiltration

reduction

from

this

water

complex

of bacteria

test

in

bacteria

outside

Membrane 0.1

coli

chance

more

tion

E.

pathogenic

only

fore,

all

whether

Most not

of

lactobacillus have

3

also

gives

been

results

of applications.

3

Bacterial

rejection

Membrane

Strain

Count fermentation broth/ml

DDS

E. coli

3.0

15

2.0

x 108

E. coli Lactobacillus

2.1 x 5 x 10 9

230 12

0.9 4.0

x 108 x 10 8

UF

GR61PP

DDS

a

condi-

0.1~

When

Lactobacillus

4 x 10 8

4

1.0 x 108

8 x 10 9

8

109

Lactobacillus Lactobacillus

4 x 10 9 6 x lo 8

30 2

it

is

I

doubt

the

8

log

up that

units

ultrafiltration

are

possible

microfiltration, but

x 10YO 10

Ratio

Lactobacillus

experiments

control,

Count permeate/ml

in we

to

made to

the

obtain 12

practice have

plants.

in

found

log

the

as

laboratory

larger units

it will the

1.3 x 108 3.0 x 10 8

be

under

reduction

strict

factors

by

described

as

sterility,

possible

to

come

in

industrial

most

usual

above

389

It able

must to

be

noted

measure

that

all

bacterial

microfiltered

experiments

counts

made

are

the

of

the

rather

on

where

strain

we

have

been

ultrafiltered

or

fermentation

concentrated

broths. In

literature

you

In

we

permeate.

cases

the

concentrate

100

ml.

In

has,

these

often have

find found

been

however, our

cases,

results

showing

reported,

the

only

equipment

in

the

would

sterility

bacterial range

also

of

give

of

count

on

104-106/

a

"sterile"

permeate. Normal

water in

decrease without

chlorination

population,

but

Domestic of

many

such

continues If

a

to

is

safe

water

be

decrease

as

a medium waste

necessary

If

for

water

the etc.

bacterial

a

great

a

BOD, are

removed,

operation.

6

SUPPl Y I

domestic

bacterial

for

nitrogen

a safe

+

of

and

to have

of bocterLo and tox;ns + ChlorLnotLon or ozonizotion + Remov$200; ?;pL US

reuse

not

log

count. medium

a scheme

Removol

for

COD,

2-3

the

growth comwater

growth.

treatment

3. Scheme

good

in

reused,

0

Fig.

a

treatment

change

bacterial

is

Waste water

Water

gives

Waste-water

be

should

in order

4).

in

produced

ammonia,

urea,

chlorination

(ref.

normally

strains.

as

domestic 3

not

waste

without count

gives

bacterial

pounds,

Fig.

treatment

bacterial

water.

as shown

in

390

The

various

stages

in this

process

scheme may be different

processes. The removal of ammonia, urea, and the last part of COD or BOD are processes which in the normal process today are left to

the

natural

performed

biotope.

by membrane

relatively

In

principle,

filtration,

these

processes

but the membrane

can be

has to be a

and it is a justified

tight reverse osmosis membrane,

method only when other methods are impossible. The removal of bacteria, organic colloids, and large molecular size toxins is a process which can be performed with rather open ultrafiltration

membranes, and it is in this stage of the process

that

filtration

membrane

has

a

future

in

the

treatment

of

drinking water for large urban areas. A challenging BOD, NH the

3'

opportunity

is to combine

the removal

of rest

urea, etc. with the removal of bacteria. In this case,

cleaned

water

from

sewage

treatment

is going

into

a bio-

logical reactor digesting the impurities, and the water from this reactor

is going

directly to membrane

filtration.

In this case,

the scheme will be as shown in Fig. 4.

+ Sewage

treatment

+ Woter treatment

.

Removal rest BOD NH3 - PO43- ect.

v

Removal of bocterLa and toxins 9 Chlorination or

ozonization + Remo;$ $ ;ypluS + SUPPLY L

Fig. 4. Scheme for logical reactor.

reuse

of

domestic

water,

including

a bio-

391

One it

problem

today

is to

is' economically

solved,

although

The urea, The

bacterial

used

The and

from

the

The

and

where

will

be

side.

give

BOD,

NH

3’

level. will

be

chlorination

low

a degree

problem

expensive

today

permeate

as

major

the

for

lower

or

many

is

type

problem

helminths,

drinking

will

be

water

that

that

same

from

system

sense

the

eggs

entering the

count

treating

as

is

to

this

is on the

function

before

prevents

doubt,

bacterial

in the

water

demand

protozoa

the

count

process

in

process can

process

think,

or as

low

ozonization,

sources

of

as and

surface

today.

Without ing,

this

I

at a satisfactory

treated

chlorine

water

the

reactor

phosphate

normally the

today

biological and

develop

feasible.

5-8

nematodes,

water

safe

lower

system.

if it is well

leaving

logs

copepods,

the

function-

waterworks

than

has

conventional

a

plants

of water.

is whether

this

makes

the

water

more

safe

at

consumers'. The

that

main

even

problem

almost

the

sufficient,

if

pathogenic

germs.

The

to

of

If the

turbidity

in

HELMINTHS, Some diseases

the

makes

act

as

also

in

the a

This

means

waterworks

growth

these

cases

is not

medium

for

to take

all

depend

on

aftergrowth.

system

be

as

a

or the

increased

water.

This

safe

system

membrane chlorine

gives

NEMATODES,

pathogenic

if only

This

aftergrowth.

will

filtration demand

possibilities

fail,

the

and

increasing

of

fast

moni-

system.

PROTOZOA, of

necessary

reactor

will

the

of the

can

is

leaving

equipment.

biological result

here

in water

possible

the

monitoring

immediate

toring

is

prevent

success

adequate

assess

water

it

Consequently, precautions

to

sterility

one

COPEPODS

organisms

organism

it necessary

within

these

groups

cause

is ingested.

that

drinking

water

is free

from

these

organisms. Due

to

treatment

the

entrainment the

are

danger

of

almost

always

organisms

potential

sizes

gives

eggs

exist often

as

well

quantitative by very

as

backflushing, chlorine

in conventional

organisms,

removal,

however,

etc.

resistant,

systems.

normal

water

the

risk

of

of filters,

and

as

this

is always

a

392

Membrane

filtration

and

the

only

are

so

large

Some

of

tional can

that

they

have

water

purification

for

example,

organisms

a very

is broken

non-pathogenic

these

water

offers

risk

the

hide,

of

real

safe

no

chance

are

able

live

to

they,

(ref. and

1).

danger,

particles membranes.

a problem

because

Cholera

the

penetrating

create

systems,

of this

because

of

organisms

Vibrio

removal

membranes,

in conven-

dead

or

alive,

Furthermore,

reproduce

some

in

drinking-

direct

entrain-

systems.

Membrane ment

of

filtration

these

prevents

growth

to

a tool

is

organisms

into

the

to

prevent

the

drinking-water

degree

to

which

systems,

food

is

but

it only

removed

from

the

solution

to

water. Membrane this

filtration

problem,

because

but

the

alone

it will

organisms

will

remove

are

probably

not

the

health

prevented

from

be

risk

a

of this

being

problem,

present

during

chlorination.

TOXIC

COMPOUNDS some

For

toxic

reality

possible

whereas

other

treatment In be

compounds

from

distillation

are

a water

practice, to

is

by

or

removed

waste by

water

is

reverse

efficiently

by

in

osmosis, the

normal

procedures.

able

way

removal

compounds, only

to

remove

all

prevent

treatment

types

toxic

at

of toxic

material

a reasonable

cost

material,

the

from

and

entering

the

will only

not safe

waste-water

system. Chlorination carcinogenic minimize

is

tinued,

but

cals

have

ation

of

of

high some

more

of

against ids

it

and

pounds.

concern

because it

Consequently,

of

waste

may

also

contents household

directly

drinking

role

special

is

of

it

may

produce

utmost

concern

should

be

to

chlorination.

Chlorination

The

of

compounds.

water,

we the

ultrafiltration toxic

compounds

microorganisms

water be

as

used

widely

a problem

that

of hypochlorite

and

many

household

give

a heavy

disconchemichlorin-

wastes. use more or

the

municipal

important

waste

will

this

microfiltration

will which,

be

in if

the

in

removal

chlorinated,

water

as a source

question

be.

The

increased

safety

of organic

collo-

give

toxic

com-

393

REFERENCES R.V. Levy, R.D. Cheetham, Applied and Environmental

J. Davis, G. Microbiology,

Wirier, and F.L. Hart, May 1984, Vol. 47 No.

5, pp. 889-894. Gerald L. Mandell, R. Gordon Douglas Jr., and John E. Bennett, Principles and Practice of Infectious Diseases, 2. Edit., Wiley & Sons, 1985. H.-M. Just und R. Michel, Infektionsgefahrdung durch Bakterien, Pilze und Am6ben in KGhlund Sp6lwasser zahnarztlicher Einheiten, Dtsch Zahnzrztl Z 39, 60-64 (1984). Betty H. Olson and Laslo A. Nagy, Advances in Applied Microbiology, 1984, 30, PP. 73-132. Guidelines for Drinking-Water Quality, Vol. 2, WHO, WHO Geneva, 1984. Committee Report (1979), Viruses in Drinking Water, J. Am. Water Works Ass., 71, 441-444. An investigation into recreational water J.M. Mechalas, 1972, quality data book, Vol 4, EPA 18040, DAZ 04/72, United States Printing Office, Washington DC. E.B. Small, P.A. West, M.I. Huq, R. Rahman, and R.R. A. Huq, Applied and Environmental Microbiology, Jan. Colwell, 1983, Vol. 45 No. 1, pp. 275-283. Virus Transmission by the Water Vehicle, Health G. Berg, Laboratory Science, 3:86-89 (1966).