Close-recycling of industrial liquid waste

Desalination,67 (1987) 299-326 Elsevier Science Publishers B.V., Amsterdam -

CLOSE-RECYCLING

Xu Jing

-

1.

Senior

2.

Chief

I.

of

Environment

Engineering

Command,

Shanghai

Bao

Shan

Iron

Co.

demand

urban

supply water

is

used

in

oonsumption. heat waste

the

the

water

70-802

of

the

to

the

washing

transferred

pollutants

liquid

Industrial

despite

of

and

is

more

yet

About

systems

systems,

and

and

are

discharged

equivalent

to

world

the

into

the

amount

of

used.

problems

pollution In

the

Tienjin tons

wastewater

is

environment

already

scant

days

removing

of

as

or

laid

the

allowable

toxic

maximum below

Cadmium. phosphorus,

ohromium(

VI),

mercury,

below

0.05

0.0005

polychlorinated (see

0.01

ppm;

ppm;

ppm; biphenyl,

substances Fig.

1).

in

as

some

drought.

is

short

industrial

in

wasting

of

and

resulting

treatment,

severe

a large attention

part

in

specifying

arsenic,

the

effluent

following

non-detectable; below

below

methyl-mercury.

0.1

0.05

ppm; ppm;

non-detectable;

non-detectable. in

from

laws

concentrations cyanide,

was

of pollutants

anti-pollution

lead,

exist

of

China

of

souroes

non-detectable;

below

toxic

down

while

grip

resources.

usually

substances.

limits:

well

wastewater

pollutants

the

there,

water

Governments

organio

complicated

discharged

pressing

shortages,

of

the

face

in

a million

stipulating

these

water

city

wastewater.

major

and constantly

the

early

on

the

day

city’s

focused

are

example,

of

the

pollution

regions

yet

municipal

in

every

an and

oountries

water

or

take

water

many

of

countries

whioh

more

proportion

oooling

processes.

producing

Nowadays

and

in

cooling

as place,

a small

human

used

risen

taken

only

washing

water,

has has

for is

In

processes.

water

water

increase

supply

water; the

for

development

population

of

Institute

General The

of

Shanghai

Sciences

Steel

and

To

WASTE

Engineer Engineer,

Consultant.

and

LIQUID

uen

Protection 3.

OF INDUSTRIAL

299

Printed in The Netherlands

wastewater

The

states are

fairly

In

300

complex ion state:

water soluble State

cPJPb(OR)*]+, [HgS$; EDTA-Pb salt etc.

HgClz . R-M-R h+e muddy diffusion states solid state,

state:

metal qowder,oxides.carbonate. hydroxide, Pb.Cd-metal soap,PbS04, sulfide.chromateo Lcokoidal state: colloid metal,

1non-soluble in Water state

sulfide.hydroxibe. .enitiisioe State: oiWsubstance. emuiaion of organic phosphrous compound, organic metal. metal soappb-metal soap organic metal compound -oil state organic phosphorus.

Fig. 1. States of toxic substancs in waste II.

water

Treatment methodology Liquid waste can generally be divided into three

categories: organic, inorganic Pollutants

in

substances, of

wastewater

colloids,

these.

The

which

wastewater treatment The or

usually to

solids

be

cannot agent

be

biological

and

wastewater processes.

treat

wastewater

pollutants

suspended

substances,

colloids

methods

can

be

the

size

depending

on

from

wastewater

specific

substances,

particles is

Organic

applied

by

gravity,

or

of

to the

suspended

particles,

sedimentation by

or

filtration

through

membranes.

Colloidal fine

removed using

mesh

combinations

difficult. both

two.

very

inorganic to

are

various are

physicochemioal

used

they

separation

flotation. fine

whether

(l-100pml: can

only

the

suspended

matter.

Physical they

involves are

or

involves while

of

as

treatment

mainly

methods

soluble

pollutants

processes.

following

according

matter

of

makes

treatment

physicochemical

a mixture

classified

soluble

components

sophisticated,

and

are

with

easily generally

the

mostly same

collected added

or so

from

lnm

electric sedimented,

that

the

to

charge. fine

lpm, and

are

very

as

they

a flocculation particles

form

301

suspended solids. After that, sedimentation or filtration devices can be used, or reverse osmosis filtration by semi-permeable membrane can be carried out. Soluble substances

(
particles in the ion state, and cannot be removed by general methods such as filtration or settling unless these are preceded by bioflocculation form non-soluble flocculates

or special chemical reactions to (heavy metals). Other methods

such as adsorption, ion exchange, electrodialysis distillation

and

are also used to separate soluble substanoes

from wastewater. At present wastewater

treatment involves three main

processesr namely primary, secondary and tertiary treatment. Primary treatment will remove grits and suspended solids of coarse granules from wastewater by screening, sand filtering and settling, etc. Secondary treatment removes fine suspended solids first. and then soluble components; after secondary treatment the outflow will generally meet effluent standards. Organic wastewater

is treated biologically by means of the

activated sludge process, and inorganic wastewater by neutralization

flocculation,

physicochemical

oxidation-reduction

and

processes. In the event that after secondary

treatment the different component concentrations

are still

higher than the limits set for industrial use, then tertiary treatment should be employed to avoid any environmental pollution and ensure the water is fit for recycling (see Fig. 2). After secondary treatment of municipal wastewater by a biochemical

process. various kinds of tertiary treatment can

be employed; some results of applying this treatment are shown in Table 1. From Table 1 it can be observed that only the turbidity of treated wastewater by flocculation-

is improved signifioantly

settling and sand filtering. Adsorption

treatment with activated carbon greatly lowers the chemical oxygen demand (COD) and biochemical

oxygen demand (BOD)

indexes, and the majority of soluble substances would be eliminated after eleotrodialysis

and reverse osmosis

treatment. In those closed water systems where eutrophication

occurs.

the main objective of treatment is to eliminate phosphorus

I

gavity

I

I

flotation

ressure flotation

-4

fig. 2

-omFion

S

methane fuhmentatiom

for waste weter

incineration

sludge treatment

I

activated sludge trllckling filter disc

Three grades treatment

eletrolytiC

oxidation wet method

air

centrifugal filtration

vaccum fil*ration

pressure filtration

treatment neutre1izetion

inorganic fbcculatinn high polymar agents

[~~

treatment

treatment ______

secondary

primarytreetmm

__-._.._-___

I

_

a-

cond&tivity

NH4-N

1

73.6

4.5

74

4.3

570

74

4.2

12

1.0

Tab.?. comparison of water quality

!

9

‘.3

6.4

o

17.3 1, 18?_

0

7.3

19557 1 -

0.005.

1

I

8.3

0.5

(mm>

J

I

f

304 and

nitrogen.

To

eliminate

floOCUlatiOn-settling electrodialysls III.

The

result

and

origins

Close

of

reuse

in

are

discharge of

wastewater recover

as

the

of

the

production

raw

material

either

in

of

material

raw

the

wastewater

same

production.

If

industry

would

above

not

offers

minimum

consumption

water,

it

promises

profits.

anti-pollution of

The

an

and

importance

of

in

the

reused

any

in

were

applied,

effluent

waste not

materials,

energy lower

component and

an

advanced

and industrial

productivity,

many

recovery

chemical

be

technology,

development

treatment; process

wastewater

important

production

researoh

IV.

is

and

by

production,

methods

raw

maximum

to

wastewater

After

industrial

the

desirable

physical. can

produce

of

reduces

production

during

and for

eliminates

Is

elsewhere.

it

use

developed.

from

the

a

production

system

technology in

mentioned of

It

It

as

in

wastewater

other

possible

water that

about

been one

the

further

so

So close-recycling

greater

or

basically

also

of

significant.

material

of

line. as

reused

undergo

the

and

cooling

treatment

has

control

regeneration be

factory

and

should

biochemical

all.

and then

raw

production:

from

can

came

now a complete

the

wastewater

recovery

effect

very

innovations

production in

much

material

The

also

water and

until

industrial

domestic

is

flow-charts,

etc., phases

during

amount

osmosis

industrial

industrial

two

employed.

changes

methods,

There

means

of

technical

production

the

Is

close-recycling

technological

installations, water

reverse

recycling

of

phosphorus,

process

at

only and costs

and

of important

field

countries.

close-recycling-treatment

of

industrial

wastewater From

an ecological

population in

river

of

the

and water

water

equilibrium

perspective

its

density

way

beyond

and over

resulting

problems.

necessary

to

this

has areas,

eliminate

traces

of

should

therefore

organic

have the

vast To

led

to

natural

led

to

in

the

pollutants

urban building

assimilation in

ecological

being

one

eoologlcal

equilibrium,

phosphorus. and

tertiary

a breakdown

nitrogen, germs.

before

of

the

it

coloring

Municipal

treatment

up

capacity

eutrophication

restore

substances undergo

increases

is

agents,

wastewater reuse.

305 In

cases of a shortage o? freshwater

The development industrial municipal

when

discharge

of of

taken

to

have a situation resource

water

wastewater

increase

the

already

one

of

supply

look

to

can

fresh

(flash to

be

all

In

on

the

which

water.

an answer

only by

at

measures

in

demands

polluted

desalination as

Increase

Recycling. the

of

etc.)

the

strenuous which

is

upstream. is

and made

supplies,

electrodialysis,

fresh

industry

the

treatment.

countries and

urban

consumption

water

aggravated levels

of

water

three can

be

fact.,

many

distillation the

shortage

of

water.

With a view to tightening effluent controls As current waste can

be

avoided

wastewater heavy

by

has

effluent

therefore heavy

such

encourage Strict cases

water

with

which

heavy

other

wastewater

treated.

It

to

should

containing

chromium,

metals

actually

containing

wastewater

cadmium.

recover

they

of

waste,

being

discharge

etc..

from

so

as

wastewater

reuse. of

uastewater

technology and

(especially

would

economically

ensure

that

attractive.

neutralization,

heavy

conditions

causing why

discharge

was

of seepage from solid waste

certain

solids, popular

attention. organic

has

The and

are

may be

secondary

close-recycling

pollutants

metals)

there

hazardous

treating

V.

of

of

levels,

wastewater

of

cyanide.

to

flocculation

wastewater

Fig.

diluted

instead

as

control

After

reason

been

levels

quantities

amount cases,

with

discharge

greater

some

to

deal

total

an economic perspective

close-recycling

under

simply

companies

Prom

In

In

forbidden

metals

only

the

a given

standards

be

force

not

discharging with

pollution.

metals

meet

and

controls and

along

increases

to

effluent

concentration

been

some

but

seepage

from

these

pollution.

That

is

attracting

more

and

close-recycling

inorganic

in

solidified,

technology

wastewater

Is

one more

for

presented

in

3. Individual The

techniques

close-recycling

combination

of

many

of system

individual

the

close-recycling

of

wastewater

techniques.

process treatment Some

of

is these

a

306

It

I

307 teohnfques of

and

wastewater

1.

their

techniques

colloidal

particles

molecular

pattern

flocculation

of

since

repel

one

another

to

When

charge

(usually

of

they

have

some

all

colloida

counterthrust

force

of

takes

additives

are which of

salt

molecular

charge

I giving

Moreover.

it

with

minimum

consumption

efficient.

In

wastewater

this

is

needed

and

agent deuatering

of

of

pretreatment

with

i).

The

properties

are

shown

polymers produce

are high

rare,

molecular

of

or

a high

recommended, the

as

improved

settling

weight

is

high

links,

at

the

it

only the

is

also

is

a small

and

extremely amount

flocculation,

of

filtration

employed or

it

flocculation

molecular

treatment some

high

2.

Cationia

Table

acid quite

all

as

a

solid-liquid

effectiveness. of

in

metal hydrogen

molecular

complete

tertiary

metal

use

the

thus

some

colloidal are

particles

It

to

and

hydroxide)

and

treatment,

amazing

polymethylacrylic

of

colloida.

agents

size

colloidal

to

during

separation

The during

its

due

charge

(ferric

strongly

group

electric neutralize

the

those

is

because

a large

to

increases

force granule

opposite

added

produce

they

remains

hydrolysis

salt

agent adhesive

velocity.

to

through

in

charge,

flocculation.

hydroxide).

a large

the

2);

water

Because

particles

electric

Fig.

the

a aoattering

cm).

pattern,

achieve

ferric

(aluminum

a strong

reacts

To

have

pattern of

by but

chemical

surface

are

surface

in

flocculation

produces

here.

separated

10-4

particles

(See

soluble

-

scattering

place.

positive

ions

the

the

especially

aluminum

process

the

necessary

are

applicable,

treatment

desorlbed

flotation,

colloidal

charge)

among

oxides

in

10D7

a negative

or

force

by

scattering

a positive charge

or

1 nm which

these

their

electric

flocculation

the

are

nm are

separated

movement

gravitational

salts

than be

range

and

10

sedimentation

leas

have

Brownian and

stable.

for

metals

than

of

(flocculation

water

the

heavy

particles~blgger

traditional

the

applications

contains

by flocculation

Separation

Suspended

of

combined

whioh

and

amino

but polymers

the

molecular ester;

include

anionic

acrylamide should

flocculation

polymers

be

and

group mentioned.

non-ionic

which

can

By the

I pClyaCwlat2

CiFG&-CT~Z& --

9-1,

"above6

f---

ferric sulfLte ferrous chloride ferrous ~~_.__ gulphate.

agents

I G2P dose of jiCn -^, be avoid in abs r;;l;;ion sho*Jld 5 . I

if treatment Condition is not fa %r:~r?blc residue :'eand chromarid
I soae msin agent f,rnctionis avai-lable oolyvinyl lmine Ez cation aPPlicabi:chennegative electric charge is z 5. tfle Coa-polyvinyl pyridinetO acidic applied singly. !poly 8 g &an_ts. _ thiourea saries non-extrnon-ion e" type coa- poly acrylamide emes of acidic or -gulants ; alkaline

I

$ F vl type CCa 3 g gulants

anion

:. 5 ferro k" 2 r( -salt

1

categories

* 4 z

categoies and functLon of coagulant9

for I remarks coagulation J aluminum sulfate geneaally apolied'-jointly wiyh fe ___~. lumlnium 6-B rr0 sals to boost efficent of coa - __._r.. sodium QAation effective deckromation n .*.aluminate ~salt change in PH value of solution. alumi~um~.chlorJd~

Tab.2

309

side

link

cation

there

and

particles The

of

cost

is

of

raw

is

recover

acid

agent

from

the

silicon.

In

efficiency

be

to

complexity

of

its

easily adsorb

the them.

in

to

production

of

to

flocculation kinds

get

a high

and

and and

municipal

containing

poly-ion

and

charge high

because and

polynuclear

the

agents the

pA value

and

agents

can

compounds

particles

flocculation to

oxides. of

complex

suspended

molecular according

metals

hydrogen

flocculation

of

increase

flocculation

temperature

electric

the

also

heavy

by

molecular

Inorganic

flocculation

eliminate

wastewater

components,

to

molecular

sedimented

high

of

acid

we can

high

high

technology

molecular

sediment

and

by

density

sulfuric

a high

adding

agents.

inorganic

sedimented

recovery

wastewater

doses

of

treatment

by

while

varying

the

waste

applying

character.

produce

neutralize

fine

treatment.

quickly

to

neutralization

treat

changeable

added

by

inorganic

applied

anion,

flocculate

wastewater

membrane

flocculated

both

be

metallurgical

agents

can

Usually

its

used

significantly

flocculation

produce

in

many

can

pretreatment the

can

molecular

agents

silicon.

in

which

high

which

We have

oontaining

in

contains

flocculation

flocculants.

which effectively

low.

of

substances

molecular

used

also

wastewater

organic

to

substances

material

Application

Industrial

are

polymers

suspended

polyacrylamide ii).

a CONA2 group

non-ion

agents

nature

of

to

and can

be

the

wastewater. 2.

Exchange

Ion based

and

exchange on

the

hinge

and group

developments

in

involving special metals been

a kind hinge

to

serves resin

obtain the

chelating and dramatic

of

resins

oxidation-

of

of

have of

in

can

opened

the

into

Aere

the

the

exchanger.

Recent

up new horizons, acid

with

group hot

selectively

resins.

and

introduced

ion

weak

regeneration which

is

polymer

styrene

shape.

function

reduction

developments

molecular

group

resins

capable

high

a ball

research

double-function group

of

structure

a functional

moleoules

functional

alkaline

is

co-polymer

divinylbenzene, high

adsorption

resin

adsorb

Recently,

manufacture

and

weak

water,

of

there large

heavy have mesh,

310 multi-pore

resins

Colloidal balls (about

l-10 and

narrow

ion

affects

the

expand would

However,

as

pore

while

it

is

fine

surface

area

200-1400~.

for

be

rather is

(10 There

high

molecular

weight

adsorb

a high

and

desorb to

the

development

resin,

the

of

is

large of

following

expand

that

the

mesh,

more

and

it

has

in

resin

the

As

has

and It

resin

it

is Following

and resin

chelating in

containing

significant.

can

favorable so

by

the

heavy

The

proaess

has

applications:

a.

Condensation

b.

Elimination

and

recovery

of

high

of

low

of

metals

conaentrations

and of

reuse

impurities

of

water. in

wastewater. c. in

Elimination

wastewater d. e.

discharged

Treatment

fluctuations Seleotion

selectivity.

the

of

resin,

wastewater.

multi-pore

with

ions

adsorption.

and

wastewater

very

70.0005i).

aontraction,

organic

opaque

of of

organic and

of

a large

super-porous

expand

more

Large

groups

exchange-adsorption of

resin,

form

by

(average

and of

strength.

in

distribution

of

would

only

application. in

substances

treatment becoming

to

exchange

expansion

swell

ions

pore

easily of

treatment

function

close-recycling metals

can

resin strength

mechanical

in

hinge

greatly

mechaniaal

constituted,

colloidal of

applicable

hinge

formed

kind

freely

velocity

characteristics the

be

and

low

of

so

fine

another

can

is

and

239000-2301000P

structure

resin

would

the

of

loss

being

of

pore

its

limited

is

interstices

the

0.1

through

Modification

manufactured

particles, m2/g)

remain (below

place

resin

large

interstices

fine

there

and hinge

hard

non-consecutive

fine,

takes of

water

transparent

spaces area

usually

high

resin

fine

resin.

structure. of

surface

significant

would

its

small the

layers

very

structure in

multi-pore

balls,

the

in

without

a resin

that

characteristics;

reduced and

a co-polymer

adsorption

spaces

fine

of

numerous

a very

significantly be

mesh,

so

exchange

its

slightly such

with

fine

influences

basis of

together 11,

and

the

consists

squeezed

m2/g)

on

resin

of In

in

industrial

volume and

concentrations

and

separation

large

of

toxic

wastewater

subject

conoentration. of

substances

volumes.

metals

by

resin

to

large

311 Tab.3

Categories and characteristics of membrane and separation techniques membrane csteg3ries

electro-

dynznic function

characteristics

ion exchange

dialysis

membrane

ciiflusionperneation

permeation membrane

fine bltra;ioc

fine holl3:0.ess poly.:?r

membrane hollxnes

I,

of memxalk

ultra-filter l~~~f~~er 1

breDared

acraordarvI

o the siae moleular of-solution

V;aterselective psrma-dater permeation tian meTCrane DressuEeh d concentration dJff:er,ce 20-1C?%~/cm' f solution

1 chromium

regeneration agent NaOH

rinse water

neutralization sedimentation treated

( desalted fig.4

water water)

I I

312 f.

Elimination

of

3.

Hembrane

separation

Pending through the

permeation

a high

membrane

helps

to

separate

so In

substance

dynamic

change

of

easily Please

refer

is

as

the

in

to

Resin

in

high substances

and

pH.

The

production.

characteristics

of

esobange ions

various

aots

as

upon

the

the

is

size

resin

demonstrates

electric

oharge

while the

H+ and

those

ion

exchange

following

the

three

dynamic

resin

a high

molecules).

and

If

mind:

of

force

exchange

molecular

a molecular

water

easily, to

in

on

take

ooncentration the

is

through

introduced will

place.

osmosis,

membrane

of

By utilizing membrane

in

borne

are

osmosis

take

difference

depends for

solution

will be

permeate

permeate

of

difference

should

whioh

(easier

membrane

of of

temperature

diffusion

diffusion

exchange

permeation Ion

the

concentration

struotare

permeability;

treatment

separation

in

no

continuous

directly

the

separation

points

solution

radius

advantages:

the the

reused

3 for

of

applied

The

be

membrane,

and

fundamental

repelled.

of

or

techniques.

a result

is

for for

conaentrations of

permeability,

anionic

make kind

oamoaia

side

c.

to some

difference

following

fluotuation

Table

different

either

b.

of

to

membrane

we need

consumption;

and

can

to

the

suitable

by

separation

Diffusion

of

it

solution

membrane

hinge

components

pressure

membrane,

the

membrane

called

concentration

energy

solutions

influenced

a.

is

of

percolation

the

of

and

kind

technique

has

low

and

condensed

the

this

obtain

molecules

selectivity

concentration

through

separation

concentration

resin

solvent

the

the

difference,

phase;

operation;

place

and

difference).

Membrane

If

to

pass

wastewater.

utilize

this

(potential

pressure

solution

change

order

in

membrane,

we can

substances;

separation.

metals

techniques

of

molecular

solution,

the

organic

polymer

sieve: the

the

hydrophilic

seleotive like

enormous

diffusion

cationic

membrane

of

velocity ion

ionio

opposite of

for

membrane.

to

that

charge

of

coefficient to

Otl-,

the

are of acid

313

HNO,

radioactive waste water tank

NaOH

oh 10 edimentation * filteratio

starag

effluent (1)

trea&ent,of radioactive waste water with ion excange resin

primary purified water 990m30. 002-o. radioactive waste water 100!Z5 O.C2-0.25%

003%

lC-6micro-curie/ml

eletrodialysis primary purifie; solution secondary water 3 100~1~0.02-0.3X ;.‘2”-“o 3is lo-'micro-curie/ml 10-4mic;b_ curie/ml electfodialysis

c 'c 04 $:a

g&i% 1 ar g

?JZ IQ%

.&"E "G

treated water *9

80m' 0.0001% 10-8$licrOJ curuie/mL

l-4 namted wasteLiquid 1.2-1i'4% LO-2-LO-4microcurie/ml

,Oml 1.52.7% 10-3micro-cu.rie/mL ? / evapor&bi.on

(2) treatment of riadioactive waste water with membrane

fig.?. treatment of radioactive waste water with ion exchange resin and membrane

314 and alkali can be separated from other substances. This process is employed in olosa-recyoling

to recover acid and

alkali without consumption of eleotricity and it is very promising in application. The principle is as follows: If the concentration of the solution is greater on one side of the membrane and the size of the molecules smaller. molecules with an electric charge opposite to that of the membrane permeate through more easily. Greater physicoohemical

stability and a thinner

membrane make diffusion easier. The membrane is more efficient if the permeation pressure on the moving water is low and there is a favorable selective diffusion coefficient of the solvent molecules

(i.e. a high transport velocity and

segregation speed). Applications of diffusion-permeation a. To separate NiSO,, (CuSO,,) and recover APSO,, in metallurgical

works using the wet method.

b. To separate A12(S04) and recover P12S04 from aluminum oxide processing effluent. c. To recover chromium from electroplating d. To recover hydrofluoric

effluent.

acid and fluorosilicic

acid

from titanium and lead effluent. e. To recover hydrochloric acid from extraction or pickling liquid. f. To recover sulfuric acid from iron and steel pickling effluent. g. To recover sulfuric acid from gluaose processing liquid. In recent years. exchange-adsorption

and membrane

separation techniques have been recommended for the treatment of (a) electroplating

effluent containing chromium using ion

exchange resin (see Fig. 41; (b) radioaative liquid waste using ion exchange resin and membrane

(see Fig. 51; (c) iron

and steel work wastewater with ion exchange membrane

(see

Fig. 6); (dl Pb-wastewater with ion exchange resin and chemical process (see Fig. 71; (el cynamide wastewater with electrodialysis

process (see Fig. 8); (f) paper mill black

liquid by electrodialysis

(see Fig. 9); and (g) resin

regeneration wastewater by ion exchange resin (see Fig. 101.

315

4'residue liquid H2S04

a)g/l ti_+4+FeSO4 -Hi

FeSO4 12Og/i

&H+

I-Fe++-+ wai:er

I +

3

I

*H2S04+.

l-H2S04

c.EL2sop

l*2so4

( I' 2 %7 o+ ' 22: 16og/l 2 1 4. 2Wl 5 H2S04 ZOO-22Og/l 2 'B FeS04 180-2OOg/l

__ -+ "4 o I electrolytic

t. *cathode reac;on anode reaction y20f'H++OHH2S04~2H++S0;- ZH++SO-=-H SO 4-2 4 40H-r=0;+2H20+2 coagulant5 a-settling tank

suJp.huricacid reolenisbmut _.1 7 pickiing tank H2S04 3OOg/l FeS04 2Og/l

Fig.6. Close-recycle treatment of waste acid from iron and.steel work

_

organic Pb-waste M%fPP

-1

Fi.g.7.

Fe2(S04)3~1 roat

NaOH HCl

316

Fig.8. electrodailyaistreatment for cyamide waste water (closed system)

Cl

pH 4-6 -

b'g.9.Recovery of alkali from Paper 1~11 black liquid

317

cation exchange anion exchange resn regenerat- resin regeneration agent ion agent acid waste water (NCI+NaCI)

alkaline I waste water.I

l

'neutralization" R=N ~ discharge R=NHCI pH7.O+O low l~.~l volume weak alkali

I ~I R-COOH I SI

(NaOH+NaCl)I l weak acid lo ~i~I i.C E R

fig. i0. treatment of waste liquid from resin regeneration

--coagulant

waste water

I

*~ o

I

~a-i

Hsand

secondly treat~entF--1 c a g u ~ on

~filtrationJ I

NaOCI ]_I25U drum filtration

I HCI desalted wa~er (for reuse)

Fig.1 D m

'4

318 Tab.4.

eater 7il,zlity after electr~:~x!;al)rsi5 trc2tment

Tab.5.

Water quality

of permeated industrial water

(Pnm!

water

and

! Fe

319 4. Resin regeneration

in the treatment of wasteuater

Resin has been widely used in the production of pure water, but it has to be regenerated with acid and alkali (see Fig. 6). During the regeneration process and before discharge, wastewater neutralization

should be neutralized.

In the

process it is hard to handle pollutant

sediments without causing

environmental

some

pollution. In

order to avoid secondary polution. it is advisable to use weakly acidic resin in the treatment of neutralization effluent as it does not give any sediment in the discharge. VI. Examples of close-recycling 1. Desalination

and reuse of municipal wastewater

As municipal water supplies tend to be very tight, municipal wastewater has to be treated and reused; close-recycling

consisting of biochemical

by flocculation

and electrodialysis

treatment followed

is suitable for this

purpose, and can prevent much squandering of fresh water. In Tokyo, experimental

treatment of this kind was carried out on

over 250 m3/day of wastewater Wastewater

at the Southsand Street

Treatment Plant. the treatment capacity being

later increased (see Fig. 71. Pretreatment,

especially by 25 urn drum filtration,

eliminates microbic and ferric hydroxide pollutants and so avoids the membrane becoming clogged up, while at the same time sodium chlorate is added, and although some residue of ahlorine (about 0.5 ppm) would appear. it would not affect the membrane. Usually large pore polypropylene membrane is used and recycling with pH l-2 Cl every 30 minutes is necessary. This method is suitable for the secondary treatment of wastewater

containing 1000 ppm TDS or for the

treatment of industrial wastewater

containing 2000-4000 ppm

of TDS. In Japan this method was applied to relieve a shortage of about 900 million m3 of fresh water in the Kant0 District. 2. Vasterrater rrom chemical works Generally the wastewater

from chemical works contains

about 700-2000 ppm TDS and not a lot of organic or inorganic

320

---I

321

Tab.6. Result of ferrite treatment of Lavy metals

purifying tank

collection

industirial vater

I ultrafiltration

I

I

+

I

1-1

ion exchange

b-Iactive I

1

I

,

carbon/ 1

fig.12.

Tab.7.

result of ultra-filtration membrane treatment of eletronh3r~'ic coating material source liquid

pH

A.5

8.72

8.75

solid -_Tatter (%)___~-10 -_ amine(nor3al) conductivity $J/cm)

uf;tra-filtration reverse osmosis treated water tieated liquid

q-9 89.8

83.5

1690

2100 -

__.

..__..-!L?!.57.1 1440

322 substances

are

combination

present

of

techniques

is

organic

fresh

be

and

by fine

can

reverse

osmosis,

eliminated

be

rate

by

and

172,

membrane

after

organic

acid

3.

Wastewater

Large

so

the

(see

fror

volumes

of

from

from

processes

are

industries.

In

machinery jointly

applied

Central

Research

alkaline

containing eliminate to

water

and for

heavy

metals,

the reuse.

The

(see

Fig.

suspended water

11).

is

solids.

yeSO

is

the

added NaOB is

and

part

filtered pR value reverse micro-ohm

mixed to

with adjust

and

is

for

the sand

and

reuse of

are at

the

acidic

to of

and

is

applied is

to prior

a

by-product

process, to

and cm.

produce wastewater

electrodialysis Fe-0 acidic

and

eliminate

adjusted.

the

wastewater

neutralization,

the

wastewater

industries

electrodialysis

process

per

the

by

electrical

combined

osmosis

of and

metals,

alkaline

by

of

drop

regenerated

treatment

by

will

iron

heavy the

for

be

compounds

machinery

process

except

first

0.1

added

Fe-0

can divalent.

5).

water

are

technical

is

pollutants

treatment

the

overall

the

The

be

By

of

membrane

of

followed

by

being

the

metals,

the

generated

conductivity metals,

In

of

In

technique,

wastewater

Fe-O

exchange

year

the

and in

techniques

reuse.

heavy

close-recycling alkaline

ion

water

nitrogen

and

acidic

In

the

and

can

l/2.

salts 99% of

containing

treatment

by

one

4 and

Japan,

COD (Hn)

calcium,

generated

Institute.

osmosis pure

19%.

membrane

and

the

wastewater,

reverse extra

by

silicate,

electrical

boilers,

in

by

Tables

the

solids sand

and

After

to

by

solution

silicate

eliminate

suspended

filtration

ions.

wastewater

wastewater daily

total

years of

rinsings

by

elimination

mainly

substances,

oxalic

the

91% of

three

consist

and

eliminated.

of

to

possible

By flocculation, 2/3,

of

be

is

sedimentation,

monovalent

ions).

the

operation.

by

osmosis

possible

of

a

reverse

entirely

961

flocculation,

of

can

not

It

than

filtration.

NE4-N)

is

use

More

95-971

multivalent

it

Industrial

reduced

(95-961

(N03-N.

as

using and

eleotrodialysis.

for

eliminated

filtering

Close-recycling filtration

methods.

content

and

by

water

physicochemical aan

it.

recommended,

substances

obtain

in

flocculation,

and ion In

extra

the

seoonh

containing

pE value

pure

exchange.

to

its part,

heavy 10.

the

323

1

. watei resin coating matelrial

extra-filtration

/ reverse

1

1

osmosis

fig. 13.

F-on

electro-

plating tank

1

vacua condensatio cooling water

1

condensed liquid

sludge

9

chromium eletro?latin tank

cwles6er3

NiSO4

r-=

fig. 14.

recovery

/L

regematian

ion exchange

I

concentratedNISO,

I

Fig. 15.

324

temperature generate

Is

separation 6.

are

ferrite wave

out,

in

can

with

the

be

blown

can

used

in

to

solid-lfquid

shown

reduce be

in

and

results

to

produotlon

also

is

in

salt

carried

magnetia

Table

content out

body

to

and

or

the

electric

Yastewater from the automobile Industry

In the systems,

automobile where

separately. water the

motor

can

teohniques. tons

of

It

teohnologiaal in

suspended

solids of

eliminate part there

is

paints and

the

can

be

ratio

per

to

meet

12. in

is

5.

the

13).

aontains

is

the

suspended

and

13-331

Wastemater amount industry

organic are

the

in

the

of

heavy

metals

its

the

was

discharged

It

part

in (3)

treatment

its

which

it

BOD is solids,

pg

value

The

results

7,

which

ooating

soluble

is

its 6-9.

and

of shows

material

that

are

solids.

industry

industry contains. after

to

3;

electrophoretlc

Table

eleotroplatlng it

to

after

color,

from the eleetroplatlmg

from

used

coating;

non-volatile

in

total

is 30 in

osmosis

substances.

solids of

from

of a high

membrane

Ohm,

given

is

a lot with

example,

10s

The

eleotrophoretic

milky

1.000-2r000

recovery

are

totally;

reverse of

hundred

12,000-14,000

flotation

reused

For

two

treatment

BOD drops

from

a liquid

numerous

Wastewater the

Fig. it

only

ultrafiltration by

is

be

In

close-reoyoling

wastewater upward

as and

thousand

requirements.

there

and water

by

(see

(1)

domestio

treated

mg/l,

eliminated

part

can

is

wastewater

pressure

rinsing

recovered

and

of

the

this

substances,

resistance

99.82

In

High

material

treatment

day

for

mainly

contains

of

water

water

4.000-6.000

help

replenish

cooling

reused

the

reused

painting

fifty

consumption

two

treated

ultrafiltration.

to

Fig.

water

coating

With

is

and

manufactures

water

by

are

wastewater

after

Co.

oonoeyed

recycled,

necessary

BOD.

are

reused

and

day.

is

is

wastewater

is

micro

(2)

be

process

presented

water

Automobile

per

fresh

content

also

daily,

tons

wastewater industrial domestic

oooling

Nissan

vehicles

thousand

and

treatment,

water,

rinsing Japan,

Industry,

domestic

After

industrial

of

air

separation

absorption.

4.

for

‘,C,

magnet

electrodialysis

reuse

residue

60-70

then

carried by

ppm for

to

and

Desalination

(500

it

raised

ferrite,

is In

only

the

notorious early

neutralization

days

325 which

treatment, the

ion

caused

exchange

rinsing

water

has

been

reuse.

and

liquid

regeneration

undergoes

electrodialysis

or

interim

reverse

process

all

salts;

these

technological

wastewater

at

the

rinsing

wastewater

at

the

shifting

involve

a combination

diffusion

membrane

Recovery In Cr3+

the and

which

of Fe*+

membrane

while

Fe,

hydroxide the

will

also is

of

Reusing In

The

the

concentration

the

methods

generally

reverse vacuum

osmosis,

evaporation

and

be

high

concentration, to

the the

the

chromate

in by

anode

the

into

electroplating

tank

cathode,

and

Cr

Part 6+

vacuum

for

the

by

for

anode

chamber, react

tank

electroplating

in

will

eliminated.

the

isolated

cathode

solution

after

between

for

the

of

solution,

(cations) to

oxidized

rinsing

the

chamber

by

and

a residue

recycling

impurities

produced

to

chromium

liquid

membrane

generated will

is

concentration

concentration

process.

chromate

back

to

recover

whole

treatment. low

high

waste

the

the

ions

be

conveyed conveyed

and the

Recovery

replaced

and

Cu in

solution

conveyed water

Zn.

involves

accumulates

through

radical

compound in

tank

pass

close-recycling

electrodialysis.

regularly

electrolysis.

chamber

covering

electroplating

gradually

electroplating

crystallize

the

chromium from

be

to

exchange.

of

electrolysis.

chromium

should

treatment

membrane

a distillation-

at

and

Now

by

before

stage.

ion

the

from

mainly stage

of

permeation,

isolated

aimed

with

wastewater

in

waste

concentration

applied

are

pollution.

adopted

osmosis,

is

steps

process

Electroplating

environmental

process for

concentration

severe

of the

with

hydroxide 3+ Cr

the

anode

reuse.

and

Rinsing

concentration,

tank,

and

cooling

reuse

(see

Fig.

is water 14).

liquid electroplating condensed

by

process, vacuum

liquid

evaporation

of

low

or

I

1 H2S04 FeS04

the

Pig.16.

326

eleotrodialysis.

and

electroplating liquid)

is

reused

after

is

regenerated

to

ion by

condensed

while

conveyed

be

process,

the

tank

the

acid during

regeneration.

after

vacuum

evaporation

(or

tank.

the

See

desired)

flowchart

in

water

Fig.

salt

in

the

the

solution,

osmosis

to

oan resin

permeation

salt

reverse

conveyed

the

exchange

nickel

Nickel

after

is

Rinsing Cation

from

to

concentration

By a diffusion

solution

is

tank.

separated

waste

concentration

conveyed

(low

treatment. acid.

is

is

water

recovery

exchange sulfuric

sulfuric

liquid

cooling

if

a high

electroplating

15.

Acid reooverp tror an acid rinsing tank In falls

the

acid

due

to

solution.

The

separate

free

sulfate

is

membrane ions on

the

permeation

acid

ferrous to

on the

side

Fig.

method ion

(pure side,

and

gradually metals

can

be

in

used

solution.

cathode

membrane

(see

other

sulfate

metal the

efficiency and

Fe

Ferrous

iron)

by

isolated

sulfuric

sulfuric

the

to

radical

acid

is

collected

161.

Conolusion

they

close-recycling been

only

control

i.e.

technological

basis

manufacturing the

(closed)

ion

all

objectives

of are

membrane

of

greater realized.

the

made

easy. not

have

process),

relationship over

in

the

soda

(using sulfide),

soda

produotion

non-aqueous

electroplating

processes

etc. efforts in

to

Innovations all

sodium

grade

non-aqueous

close-recycling fully

and

manufacturing

(high

eleotroplating)t still

problems

as

technical

control. be

that

olose-recycling

instead

mercury

systems,

make

wastewater

into

paper alkali

exchange

static

to

only

though point

all task,

other

wastes”

research

without

dyeing

(ionizing us

and

many

analysis,

“three

pollution-free dioxide

been

organization,

continue

of

not

sophisticated

also

benefit and

processes

technology: chlorine

but

have

and

a technological

really

a very

above

treatment

from

has is

cost

recommended

wastewater

technical

production the

in

difficult

techniques

administration,

using

very

control

considered,

on

use

application

wastes”

world

to

seem

their

between

techniques

put

may not view,

“Three

Let

from

through

recently

be

acidic of

diffusion

transferred

anode

The

of

process

accumulation

electrolysis

pass

VII.

rinsing the

the

to

ensure

treatment

that of

the

industrial