Liyuan Chai - ASEF Advances on Treatment Technology of... · Advances on treatment technology of...

Advances on treatment technology of

heavy metals - wastewater in China

Liyuan Chai

Central South University National Research Center for Heavy Metal

Pollution Control and Engineering

E-mail:[email protected],13974807632

1. Technical advances on the treatment of

heavy metals - wastewater

2. Plans and advices on the reduction of

wastewater from heavy metal smelting

Outline

1. Technical advances on wastewater treatment

of heavy metal in nonferrous industry

Definition of heavy metal ?

Ten heavy metals in nonferrous industry: Cu, Pb, Zn, Cd, Hg,

Sn, Sb, Bi, Ni, Co

Five toxic heavy metals in environmental area: Pb, Cd, Hg,

As, Cr

Discharged quantity of heavy metals from nonferrous

industry occupies about 70% of the whole in China

dust

Product

mineral deposit

ore（±1%Me）

metal（±99.9%Me）

concentrate（±50%Me）

metallurgy

gangue mining

Mineral dressing

processing

Tailings

Waste residue

waste

Wastewater Gas, dust

wastewater

Gas pollutants, wastewater and solid waste from smelting

account for 97% , 20%, 23% of industry waste, respectively.

Qingshuitang industrial

district

1. Smelting industry

2. Chemical industry

3. Combined sewage

4. Heavy metal polluted

soil

Shuikoushan mining district

1. Mines

2. Smelting industry

3. Leaching in slag dump

Cd and As discharge

amount in

Hengyang city

account for 50.2 %

and 54.2 % of the

total pollutant in

Hunan, respectively.

Hg, Cd, As, Cr, Pb, cyanide and

volatilization hydroxybenzene

account for 60 % of the total

industrial discharge value in

Hunan.

Urgent demand for

heavy metal treatment

in Xiang River

670 Km in Hunan, 8.54×104 square

kilometers (40.3 area% of Hunan),

cover 8 prefecture level cities. the basin

population accounts for 60% of the

total value of Hunan. GDP reaches to 76

% in Hunan.

High concentration, large fluctuation: concentration of As, Cd,

Pb, Zn in wastewater is in the range of 10 mg/L ~ 2000 mg/L;

Complex compositions: multiple heavy metal ions (As, Cd, Zn,

Pb), organic compounds (i.e., oily substances)

Abundant amounts of wastewater: more than 20,000 tons/day;

Many kinds of states: states like ionic, colloidal or particle

suspensions (the Hg in acidic wastewater).

Feature of wastewater of heavy metal smelting

Stricter

Integrated emission standard of air pollutants

GB16297－1996

Integrated wastewater discharge standard

GB8978－1996

Identification standards for hazardous wastes

GB5085.1～5085.3－1996

Original standard

Emission standard of pollutants for lead and zinc industry

GB25466-2010 New

standard

(1) Demand of new standard on pollution prevention

technique

Comparison of original and new standards on the discharge limit

of pollutants in wastewater

Pollutants Original standard GB8978－1996

New standard GB25466-2010

pH 6～9 6～9

COD 100 80

SS 70 60

Total Pb 1.0 0.5

Total Zn 2.0 1.5

Total Cd 0.1 0.05

Total Hg 0.05 0.03

Total As 0.5 0.3

Total Cu 0.5 0.5

Total Ni 1.0 0.5

sulfide compound 1.0 1.0

F compound 10 10

Require large amounts of chemical agents; create abundant

sediments and secondary pollution; hardly achieve deep

purification.

1) Chemical precipitation: the most common method to

treat heavy metal ions in wastewater, mature technology,

suitable to treat a wide range of wastewater, high efficiency,

easy operation.

Lime neutralization

Sulfide precipitation process

OH-+ Mn+ M (OH)n↓

S2-+ M2+ MS↓

Large amounts of

sediments

(2) Present technical situation

Technical bottleneck for advanced treating and recycling

smelter wastewater containing heavy metal

Smelter Wastewater Containing Heavy

Metal Standard

emission Lime Neutralization

◇ Difficult to be satisfied for new discharge standard(GB25466-

2010)。

◇ Due to lime，Ca2+ concentration is so high, resulting in that

purified water can not be reused

Traditional “standard

emission” cannot meet

the requirement of

reduction and recycling

2) Ion exchange method

交换对象

吸附性

大分子物质

无机阳离子或有机碱阳离子

无机阴离子或有机酸阴离子

选用阳离子交换树脂

选用阴离子交换树脂

强

弱

选弱酸或弱碱性树脂

选强酸或强碱性树脂

选择大孔树脂或交联度低的树脂

表5.1 树脂的选择

Selection criteria

Easy separation

Simple equipment

Easy regeneration

Enriching metal

xCreate abundant wastewater

during regeneration

xLong cycle time

xSalts corrupt pipes

xNot available for high

concentration wastewater

virtues drawbacks

There are microfiltration membrane (MF), ultrafiltration

membrane (UF), nanofiltration membrane (NF), reverse

osmosis membrane (RO).

Small floor area

Convenient operation

Easily automated process

control

x expansive x easily polluted x high energy consumption

3) Membrane technique

Activated

carbon Zeolite Metal Oxide Polymer

Agriculture

waste

Deep treatment method. wide range of adaptation, good

treatment effect, recovery of heavy metals, could be

repeatedly used.

difficult to separate, difficult to treat regeneration solution,

difficult to treat high concentration wastewater.

4) Adsorption method

reach drainage standard

Discharge reduction: ~500 tons heavy metal in every billion

ton of wastewater.

Zero discharge

Satisfy standard CJ3020-93(mg/L ）： Zn:1, Pb:0.05, Cu:1, As:0.05, Cd:0.01, Hg:0.001

Discharge standard GB8978-1996(mg/L)：

Zn:5, Pb:1, Cu:1, As:0.5, Cd:0.1, Hg:0.05

Direct deep

treatment

Highly urgent: deep wastewater treatment of heavy metal smelting

Metal ions Stable

complex Solid

New idea?

Cu2+

Cd2+

Cd2+

Cd2+

Hg2+ Zn2+

Zn2+

Zn2+

Hg2+

Zn2+

Pb2+

Cu2+

Hg2+ Cu2+

OH-

OH-

OH- OH-

OH-

OH-

OH- OH- OH-

OH-

OH-

OH-

OH- OH-

OH-

OH-

OH-

OH-

Cu2+

Cd2+

Cd2+

Cd2+

Hg2+

Zn2+

Pb2+

Zn2+

Hg2+

Pb2+

Zn2+

Cu2+ Cu2+

-CO-

OH-

OH-

OH-

-SH

-COO-

-COO-

-SH

-SH

OH-

OH-

OH-

OH-

-SH

-SH

-SH

-SH

-SH

-COO-

-COO-

-COO-

-SH

-SH

-CO-

-CO-

-CO-

-CO-

-CO- -CO-

New idea:

Multiple ligands

Traditional method:

single ligands

precipitate transform

1） Biological-agent-based new technology on the

treatment of waste acid wash of Pb-Zn smelting

gas;

2）Deep treatment of heavy metal wastewater by

biological method and new recovery technology.

(3) Technical advances on wastewater

treatment of heavy metal smelting

Production technology of biological agent

② CdCOO+ ① CdOH+ ③ CdNHCOCH3 ④ CdSH+

HO

MO

LU

MO

△E↑, complex stability↑, heavy metal removal↑

OH

OH

O

OH

O

OH

O

HO

OH

OH

O

O

O

OH

O

OH

O

HO

HS

O

OHS

O

O O

HO

O

O

OH

O

酯基化

巯基化

酰基化

Microorganisms

culture

Metabolism

products

component

design

Biological

agent

Other compounds

579.89

706.04

1043.70

1246.71

1449.80

1531.10

1652.21

2862.16

2925.96

3301.87

445.06

573.35

1158.70

1286.531375.46

1517.04

1634.93

1733.21

2563.71

2925.87

3341.10

62

64

66

68

70

72

74

76

78

80

82

84

86

88

90

92

94

96

%Transmittance

1000 2000 3000 4000

Wavenumbers (cm-1)

Design of pilot-scale product line of biological agent and industrialized production

Design of effective reactor， establish product line (10,000 tons/year)

1）A novel process of Hg-containing acidic wastewater

treatment using biologics

Species analysis of Hg

The content of Hg in suspended particles is 20~60%；

The content of colloidal Hg is 30~70%；

The content of other ionic Hg is 10~30%

0 2 4 6 8 10

2

4

6

8

10

Initial concentration of 9.31mg/L

Initial concentration of 36.0mg/L

Settling time/h

Hg

co

ncen

trati

on

in

su

pern

ate

(m

g/L

)

28

30

32

34

36

Hg

co

ncen

trati

on

in

su

pern

ate

(m

g/L

)Hg in suspended particles

-2 0 2 4 6 8 10 12 14 16 18 20 22

0

10

20

30

40

50

60

70

Migration rate

Zeta potential

Hg concentration mg/L

cond m

s/cm

-10

-8

-6

-4

-2

0

zeta

mv

Colloidal Hg

Acidic wastewater

Coordination

Separation

Supernate

Coordinating slag

(raw materials in Hg smelter)

Hydrolysis

Separation Overflow Discharge with

standard level Sludge

plate-frame

pressure

filtration

Filtrate Hydrolzing slag （Disposition）

Calcium carbide slurry

Biologics, Hg remover

Process flows of Hg acidic wastewater treatment using biologics

Solving the problems of

advanced purification of heavy

metal wastewater, removal of

atomic state Hg, and secondary

pollution of H2S.

Reducing a pH

buffer area and cost.

Increase the grade

of Hg in sludge and

recovery value. Homogenization

Pilot scale test——complete equipment

Coordinating basin and hydrolyzing basin

Dosage bunker, secondary coordinating basin ,and hydrolyzing basin

Overflow

Elevated tank for biologics, flocculant et al.

Removal of Hg in homogenization process:

23日 25日 27日 29日 1日 3日 5日 7日 9日 11日 13日

-5

0

5

10

15

20

25

30

35

40

Hg concentration in acidic wastewater (mg/L)

Date

Hg concentration before homogenization

Hg concentration after homogenization

Effect of homogenization

on Hg concentration

23日 25日 27日 29日 1日 3日 5日 7日 9日 11日 13日

0

5

10

15

20

25

30

35

40

45

50

55

60

Hg content in acidic wastewater, %

Date

Hg content before homogenization

Hg content after homogenization

Hg content in acidic wastewater

before and after homogenization

29.52% Hg was removed by homogenization.

Results of Industrial Test

Removal of Hg in

coordination process

15日17日19日21日23日25日27日29日1日 3日 5日 7日 9日11日13日

0

5

10

15

20

Hg

conc

entra

tion

in a

cidi

c w

aste

wat

er (m

g/L)

Date

Hg concentration

before coordination

Hg concentration

after coordination

The removal efficiency of Hg by coordination is 28%~94.83% (mean 62.4%).

Removal of Hg in hydrolysis process

15日17日19日21日23日25日27日29日1日 3日 5日 7日 9日11日13日 --

-16

-14

-12

-10

-8

-6

-4

-2

0

2

4

6

8

10

12

14

16

Hg concentration

after coordination

Hg concentration

after neutralization

Hg concentration

after filter pressing

Date

Hg

conc

entra

tion

afte

r coo

rdin

atio

n (m

g/L)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Hg concentration in treated w

ater (mg/L)

Steady operation stage: Hg concentration in treated water is 0.013-0.03 mg/L.

Removal efficiency of Cu, Zn, Pb, Cd


-1

0

1

2

3

4

5

Cu concentration

after homogenization

Cu concentration


Cu concentration


Date

Cu c

oncentr

ati

on a

fter

hom

ogeniz

ati

on (

mg/L

)

-0.1

0.0

0.1

0.2

0.3

0.4

0.5

Cu c

oncentra

tion in

treate

d w

ate

r (mg/L)


-180

-160

-140

-120

-100

-80

-60

-40

-20

0

20

40

60

80

100

120

140

160

180

Zn concentration


Zn concentration


Zn concentration


Date

Zn c

oncentr

ati

on a

fter

hom

ogeniz

ati

on (

mg/L

)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

Zn c

oncentra

tion in

treate

d w

ate

r (mg/L

)

Treated water: Cu<0.1；Zn<0.5 ；Pb<0.5；Cd<0.02mg/L


-20

-15

-10

-5

0

5

10

15

20

Cd concentration


Cd concentration


Cd concentration


Date

Cd c

oncentr

ati

on a

fter

hom

ogeniz

ati

on (

mg/L

)

0.00

0.05

0.10

0.15

0.20

0.25

0.30

0.35

0.40

Cd c

oncentra

tion in

treate

d w

ate

r (mg/L

)


-4

-2

0

2

4

6

8

10

12

14

16

18

Pb concentration


Pb concentration


Pb concentration


Date

Pb c

oncentr

ati

on a

fter

hom

ogeniz

ati

on (

mg/L

)

0

1

2

3

4

5

Pb c

oncentra

tion in

treate

d w

ate

r (mg/L

)

Removal efficiency of As, F, Cl


0.000

0.005

0.010

0.015

0.020

0.025

0.000

0.005

0.010

0.015

0.020

0.025

As

conce

ntr

atio

n (

g/L

)

Date

As concentration


As concentration


As concentration



0.00

0.05

0.10

0.15

0.20

0.25

0.6

0.8

1.0

1.2

1.4

1.6

1.8

0.00

0.05

0.10

0.15

0.20

0.25

0.6

0.8

1.0

1.2

1.4

1.6

1.8

F c

once

ntr

atio

n (

g/L

)

Date

F concentration after homogenization

F concentration after neutralization

F concentration after filter pressing

15日17日19日21日23日25日27日29日 1日 3日 5日 7日 9日11日

0.0

0.5

1.0

1.5

0.0

0.5

1.0

1.5

Cl

concentr

ati

on (

g/L

)

Date

Cl concentration after homogenization

Cl concentration after neutralization

Cl concentration after filter pressing

The average remov

al efficiency of Cl is

about 21%.

The removal efficiency

of F is higher than 97%.

The As

concentration is far

below the standard.

The removal

efficiency of As

reaches 97.5%.

F

As

Cl

Hg anti-shock loading capability

0 40 80 120 160 200 240 280-400

-300

-200

-100

0

100

200

300

400

500

No.

Hg

in

acid

ic w

ast

ew

ate

r，m

g/L

Standard

0.00

0.05

0.10

0.15

0.20 Hg

co

ncen

tratio

n in

treate

d w

ate

r，m

g/L

Acidic

wastewater

Treated water

The Hg

concentration in

acidic wastewater

fluctuated in

the range of 1-450

mg/L.

The Hg

concentration in

treated water are

all lower than 0.03

mg/L.

Slag quantity and

distribution equilibrium of Hg

Slag quantity and Hg distribution equilibrium in slag

Quantity of

Hg in acidic

wastewater,

521.2kg

Slag type Quantity of

dry slag，ton

Hg quantity in

slag，kg Ratio，%

Homogenizing

slag

0.405 115 22.1

Coordinating

slag

0.778 311.4 59.8

Hydrolyzing

slag

369.7 93.6 17.76

Treated water 24000m3 1.2 0.24

•The results in this table is agreed well with speciation study.

•By backstepping, the Hg average concentration in acidic

wastewater is 24.38 mg/L. This value is close to the real value,

indicating the accuracy of analysis.

o ●

o o

o

√ √ √

√ √

× ●

×

√

√ √ o

o

√

√

√

√

√

√ √

√

√

√

√ √ √

● ●

×

× o

× ×

√

√ √

√

√

√ PbSO4

● PbO

O Na3(Ga3Ge3O12)(H2O)4 ×

AlGe2O·0.13NH4·0.17H2O

Hg content analysis in Coordinating

slag: Hg content >22%

Element Wt% At%

C 9.74 33.12

O 12.27 31.32

As 1.35 0.74

Al 1.64 2.48

Si 2.58 3.75

S 9.36 11.92

Pb 27.50 5.42

Cl 1.54 1.78

Ca 0.30 0.30

Fe 1.02 0.74

Zn 4.22 2.64

Hg 28.49 5.80

Sheet Al2(SO4)3 and hexagonal

PbO. Amorphous Hg is in the

Flocs.

Element content，%

Hg 22.06

Pb 21.26

Zn 1.16

Cd 0.214

As 0.06

Cu 0.02 EDX analysis

In line with EDX results. Hg

is in the form of atomic state

and can be used as raw

material in Hg smelting.

XRD

analysis

Component

analysis

Main element in

coordinating slag:

Hg 28.4%, Pb

27.5%.

10 20 30 40 50 60 70 80

2-Theta(°)

x10^3

2.0

4.0

6.0

8.0

10.0

12.0

14.0

Inte

nsity(C

PS

)

[1.raw]

√ CaSO4.2H2O

● CaCO3

o Ca6Fe(SO4)2[B(OH)4]12.26H2O

× CaF2

o o

o o

o

o

●

√

√

√

√

●

√

√ ●

√ √

√ × √ √

●

● ●

×

o o

o √ √ √

element content，%

Hg 0.017

Pb 0.06

Zn 0.46

Cd 0.36

As 0.06

Cu 0.0036

The total content of

heavy metal is only

0.96%.No need to

recycle But need safe

treatment.

Element Wt% At%

C 8.54 16.02

O 34.14 48.04

F 4.84 5.73

Na 1.25 1.22

As 0.86 0.26

Al 0.91 0.76

Si 1.69 1.35

S 8.60 6.04

Cd 1.66 0.33

K 0.11 0.07

Ca 32.55 18.29

Fe 3.88 1.57

Zn 0.96 0.33

Main element is Ca. The

removal effect of As, Cd

and F is significant.

Main element is Ca.

The removal effect of

As, Cd and F is

significant.

EDX analysis

XRD analysis

Component

analysis

Hg content analysis in

Hydrolyzing slag

2）Method for direct advanced treatment for heavy

metal wastewater with biological agent

Heavy metal

wastewater

Coordination

Hydrolysis

Decalcification

Treated water

Flocculation

Residue

（Reuse） (Recycle)

A novel technology for

heavy metal smelting

wastewater treatment:

multi-groups

coordination-

hydrolysis-

decalcification-

flocculation and

separation.

Coordination between biologics and

wastewater by pipeline

1# and 2# reaction basin

3#, 4#, 5# reaction basin Inclined board settling basin

On-site industrial test: 600 m3/h

Application example Mobile and modular pilot plant system for heavy metal

wastewater treatment using biologics

Waste

water

Coordina

tion

Hyd

rolys

is

Separ

ation

Advanced

treatment

Waste

water

Coordina

tion

Hyd

rolys

is

Separ

ation Reuse

Waste

water

Coordina

tion

Hyd

rolys

is

Separ

ation

Recyclin

g

Dec

alcif

y

Dec

alcif

y

Memb

rane

1）2400m3/d acidic wastewater treatment using

biologics project in Zhuzhou Smelter

Floor plan of trial project Production site（2009.11）

Batching system

2）Largest Zn smelter in China

Production site Process control system Treated water

Equalizing basin Batching system

• Daily treating capaci

ty: 14400m3;

• Emission standard

of pollutants for lead

and zinc industry

(GB 25466-2010)

• Treated water

reused

3） Largest Pb smelter in China

Reaction basin

Plate sedimentation tank

• Daily treating capacity:

6000m3

• Emission standard of

pollutants for lead and

zinc industry (GB

25466-2010)

• Totally reused

4）Emergency Accident

Treatment for Tl wastewater

Reaction Basin

Sedimentation basin

• Wastewater quantity: 30000m3

• Thallium < 0.05mg/L

• Zn, Cd, Pb: Emission standard of

pollutants for lead and zinc

industry (GB 25466-2010)

• Pollution risk has been solved

• As the future treatment method

Technological advantages

Heavy metals in purified water meets the National Standard

（GB25466-2010）；

Concentration of Ca2+ is less than 50mg?L, reuse rate of

purified water increases from about 50% to more than 90%

The content of heavy metals in sludge increases about 30%, the

amount of sludge decreases 15%；

The discharged amount of heavy metals decreases more than

80%；and the treatment cost of waste water decreases 15%.

The Technology has been applied to over 30 enterprises, annual

reuse amount of purified water reaches 4000m3, and reduced

amount of heavy metals, including Pb, Hg, Cd, Ad, Zn, Tl, is

over 200 000 kilogram.

1、Set up expert system for network optimization of

industrial water

Collecting information of using and draining water

& Setting up a database

Water cycling and water balance research

Set up expert system for network optimization of water

Water resources optimization and control

构建工艺与设备用水对水质要求、排污、水流向等多目标集成模型，优化全厂用水、排污分质分类体系

2、 Several Suggestions for heavy metal wastewater in nonferros industry

2、Technical proposal for recycle-circulation of water —优化用水排污循环回用技术方案及用水调配网络

生产工序

Production

water

Living

water

Treated

waer

Waste

water

reuse

Internal

recycling of

wastewater

Backwater

pipe network

Recycled

water pipe

network

Sewage pipe

network

Treated water

pipe network

Rainwater

Pipe network

Setting up discharge

channel and

cofferdam

Transport sewage in pipeline to master station

Wastewater

sedimentation

tank （Simple treatment)

Monitoring and

measurement

Wastewater multi-circulation

• Rain and

sewage diversion

• Clean and dirty

water diversion

• Dual water

supply

Production process

Wastewater

sedimentation


Wastewater

sedimentation


实现用水管理、分质供水、废水深度处理与回用

3、Solving the technical bottleneck of advanced water using and

saving in lead and zinc system section

解决系统工段内先进用水与节水技术瓶颈，源头实现废水减排

Recycling and reuse of filtering water in Zn leaching

process: To solve the problem of system volume

expansion and bad water quality caused by completely

recycling of wastewater containing Zn (1-2 g/L).

Comprehensive treatment of wastewater from Pb

smelting: To solve the problem of high acidity and SS in

dedusting water for its recycling and reuse.

Reuse of Zn electrolytic wastewater: To solve the

problem of economic recovery and water balance of high

concentration Zn (10 g/L).

Integration of “Water saving management-Reuse based on

water quality-Advanced treatment and reuse”.

Total management of water using and discharge in

smelters according to cleaner production to reduce

wastewater quantity, recycle water resource, and reduce

quantity of pollutant discharged.

Through emission reduction in whole process, wastewater

discharge amount decrease by >70% and the water

repeating utilization factor is higher than 95%.

4、Optimization and integration of reuse technologies

based on the quality of wastewater generated from

nonferrou industry

优化集成有色企业废水分质回用技术

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