REMOVAL AND RECOVERY OF PHOSPHATE ANIONS FROM

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(tensioactive agent). The optimal process parameters. (pH,. Ca2+/PO43- molar ratio, collector/PO43-molar ratio, ammonium and/or metallic ions influence and.

REMOVAL

AND

RECOVERY

WASTEWATER

Ligia

Stoica,

loana

1-University

The

anions

with

(tensioactive molar ratio, influence

flotation

analysis

at

species

presents

a by

time)

separated

from

study

were

were

the

concerning

the

down

phosphate (DAF)

without (pH, and/or

established The

4115365

flotation

for

by

in

collector Ca2+/PO43metallic ions

"model"

insoluble

characterized

vibration

Chemistry

+(401)

precipitate

solutions.

parameters and

Inorganic Fax:

process parameters ratio, ammonium

practical

electronic

Dept.

settling

optimal

FROM

Radu

Romania,

removal

down

for

optimal

Nicoleta

precipitate

settling

verified

and

major

the

the

and

and

Bucharest

paper

ANIONS TECHNIQUE

Bucharest,

7000

agent). The collector/PO43-molar

and

systems

The

Jitaru

(10•€1000-mg.l-1)

comparison

by

Str.,

PHOSPHATE

FLOTATION

"Politehnica"

1 Polizu

Abstract

OF BY

aqueous

species

isolated

differential

thermal

spectrometry.

foam

represent

basic-orthophosphate

as

a

compound.

INTRODUCTION

Eutrophication

of

surface

problem

caused

by

excessive

industrial

effluents

in

particularly

industry.

These

effluents

10•€1000mgmg l-1, compounds

the

Applying systems, fertilizer

same the

fertilizer can

be

legislation

applying

the Flotation

chemical

properties,

is

worldwide of

resulted anions

source

a

particularly

wastewater

technique and/or

1-3. High less for

flotation

be

that

may

from

in the

environmental phosphorus,

fertilizer

concentration

prove

to

from

phosphate

be

range

a

source

of

useful

of

these

time.

obtained

concentration,

inputs,

the

a pollution

materials

Romanian

to

phosphate

flotation

phosphate

continues

nutrient by

containing

represent at

water

for

raw

material

separation than

4

wastewater

removal for

efficiency mg/l

(the

which

is

phosphate the

manufacture

(R>98%)

maximum flown

in

anions

and limited

the

river

of the

decreasing

value 4-5)

phosphate

is

allowed

by

realized

by

method. a

separation hydrodynamic

method

whose

equilibrium

Phosphorus Research Bulletin Vol. 10 (1999), 466

achievements correlated

depend with

the

species

of

on:

physicostructure

and

the

possibilities

included

of ion recovery

in the

purification

recommend

it by comparison



diversity

Species solutions

methods

in nature

foam.

group.

and

Therefore

Some

of

the

flotation

flotation

can

be

characteristics

structure)

likely

to

be

separated

from

diluted

M)



flexibility and reliability of separation



possibility

of foam recovery

EXPERIMENTAL

the

with other methods:

(both

(10-2•€10-6

from

plants

as useful

compounds

PROCEDURE

Equipments: ・

Laboratory

apparatus



UV - VIS spectrophotometer



ORION



Electrical

were

of

same

"model" - 1000mg l-1

in the

reagents

suitable

settling and

collector

donor

atom.

(0.2

The meter

ORION IR

solution

of

Ca

research.

flocculent

quaternary

of H3PO4,

separation

%

realized

salt

a

were

a

concentration

precipitate

reagent

experiments N

500

C19H42NBr

using

Ca3PO4,

as

POLIAS

conditions

were

(OH)2 Flotation

(0.1

ammonium

having

used

solution)

solution)

plus

DAF

molar

excess

a N-

using

Ca2+/PO43-

Ca5(PO4)3OH

and having

established

different

the

ratio

precipitate

Ca3PO4). was

assured

with

a

glass

and

calomel

electrode

digital

pH-

type spectra using

potassium

bromide Phosphate by

molibden

systems

experimental

Ca(OH)2,

%

control

conditions,

performed

saturated

CaHPO4.2H2O,

to

pH

and

experiments

to

reported

practically

optimal

All

(corresponding

and

down

solid

The

methodology.

reagent

Jena

stirrer

10

used

Karl Zeiss

pH - meter

Aqueous range

DAF

were a

Karl in the

performed Zeis

Jena

range

anions

on

the

obtained

spectrophotometer,

400•€÷4000cm

physico-chemical

spectrophotometrically

samples

by

optimal

pelleting

separation

techniques

with

-1 analysis

methods

at

after

present reducing

in the

the

effluents

phosphorous

was at

blue

complex. The

data

obtained

performing

the

Phosphorus Research Bulletin Vol. 10 (1999), 467

precipitated

settling

down

process

are

presented in figures. 1,2, and 3. The separation principal stages

in PO43- aqueous

systems

recovery by

precipitate flotation method are presented in figure 4. The results of the study performed by precipitated flotation using homogenous aqueous systems are presented in figure 5 and 6 and the results of the study performed by precipitated flotation method on practically solutions are presented in figure 7, 8, 9 and 10. RESULTS AND DISCUTIONS 1. The results obtained for orthophosphate

anions removal by precipitate

settling down show: by increasing the molar ratio Ca: P, the PO43- concentration in effluents decreases, but a concentration less than admitted value (4 mg l-1, 2,8 mg/l represents the alarm level; for effluents which flow in the river) is not attended. In the industrial effluent after neutralizing by treatment with lime, the final concentration of orthophosphate

is about 10 mg/l. These conclusions make necessary a study of

removal and recovery of orthophosphate anions by flotation techniques (i.e. Dissolved Air Flotation) of the precipitate resulted after neutralizing the wastewater. 2. The results obtained for orthophosphate anions removal by precipitate flotation usina a model solution show: ■

phosphate

application

only By

and

1000

for

mg l-1

Flotation

Ca

pH

Collector

concentrations. 0 •€

5.10-1

level

orthophosphate

Phosphorus

in

are

to data

the molar

presented

effluents ratio

for

range

resulted

Ca

or

was

equal

Experimental

studied molar

can

5-10-2.

Research Bulletin Vol. 10 (1999), 468

free, 6

be

flotation

obtained

for

500

than

: P•†3

- orthophosphate collector

of

(Fig.5). are

data

level in the effluents

in figure which

possibility mg l-1

less

6•€12.

influence

a solutions

good

concentrations

alarm

collector

the

500 •€1000

(•† 1,66)

obtained

in the

concentration

corresponds

for

determine

having

ratio

less than

At different (0

molar

studied

value

Experimental alarm

results

was

a final concentration ■

: P

(Fig.5,6);

good

water

solutions

solutions

ma l-1

in

concentrated

increasing

200 ■

concentration

show

obtained for

a

obtained

in the POLIAS

concentration at

the

phosphate

range was value

optimum

in

for pH =12

different

ratio

in which

indicated

added). less collector

than -

Figure 1. Precipitate settling down at Ca:P molar ratio = 1

Figure 2. Precipitate settling down at Ca:P molar ratio =1.5

Figure 3. Precipitate settling down at Ca:P molar ratio =1.66

Phosphorus Research Bulletin Vol. 10 (1999), 469

Figure 4 Separations scheme of dissolved air flotation (DAF) process for orthophosphate

Phosphorus Research Bulletin Vol. 10 (1999), 470

Figure 5. Phosphate precipitate flotation separation (model solution) at Ca:P molar ratio =1,5

Figure 6. Phosphate precipitate flotation separation (model solution) at Ci = 200 mg/l

Figure 7. Phosphate precipitate flotation separation (practical solution) at Ca:P molar ratio =1

Phosphorus Research Bulletin Vol. 10 (1999), 471

Figure8. Phosphate precipitateflotation separation (practicalsolution)at Ca:P molarratio =1,5

Figure 9. Phosphate precipitate flotation separation (practical solution) at Ca: P molar ratio =1,5

Figure 10. Phosphate precipitate flotation separation (practical solution) at 25% excess Ca(01-1)2

Phosphorus

Research Bulletin Vol. 10 (1999), 472

3. The following influencing factors were studied on practical solutions in the same concentration orthophosphate



Ca:P

anions

flotation

pH



collector

concentration results

intervention

level

concentration

but

excess

above

obtained

( the

final

In

and

level

effluents

and

is

a

POLIAS is not

good

pH=9,74•€11

anion

which

in

added

insoluble

+

were

was

soluble

practical

molar

generally

Using

obtaining)

in

pH

=9

25

the

same is

indicated - 10,

Ca

stoichiometrical

systems trimethil

by

paper

and

by

6-7. The

obtained

isolated

at

different

collector

correspondingly

in

elemental

to

No

ammonium

citrate

foam)

a

that

-

solutions

citric

optimal analysis

separated

with

phase

at

thermal

in solid

interactions

in solid or

obtained

analysis,

indicate

compound. contained

the

chemical

data

phosphorus

proposes

precipitate

Very

good

results

calculated

in

reagent

(POLIAS)

and

is

orthophosphate

variant)

phase

collector

separated

and/or

in

the

foam

acid.

with

19

obtained

for

pH

molar

of

recovery using

species

rapport at

orthophosphate

(DAF

bromide

reagent

Optimal

an

flotation

ammonium

: P

values.

CONCLUSIONS

The

%

effluent

data

for

the

reagent.

studied (0

in a

the

Experimental level

than

solutions

in

under

- 510-2.

less

ratio.

of precipitate

were 0

).

alarm

excess

species

major

The

in water

1,66

level than

has

studied

Ca(OH)2

found.

25%

range

(i.e.

spectrometry

Ca3(PO)4

alarm

solutions the

for

is

POLIAS)

sublate

conditions

=

effluents

concentrations

less

collector

the

orthophosphate

the

for

the

ratio

:P

orthophosphate

in the

flotation

in obtained

Ca

tricalcium

under

molar

infrared

to

are

at

is situated

orthophosphate

separation

mg l-1

values

precipitate

The

+1000

level)

very

ratio

free,

alarm

range,

Orthophosphate

collector

the

500

concentration molar

concentrations

corresponding

concentration

= 1 ,66

(orthophosphate

range

Ca(OH)2.

concentration

molar ratio



Good

the

ramie:



as

carbon = 9

510-2

- 11,

Phosphorus Research Bulletin Vol. 10 (1999), 473

in the

from

reagents

aqueous

the

hexadecil

in structure.

and

25 in

collector

concentrations

collector

atoms

tricalciumortophosphate, ratio

method

the

%

excess presence

precipitation of

floculant

- orthophosphate. wasterwater

is situated

in the

range 500 -1000 mg/I.Orthophosphate

species, which are present

in aqueous

systems, were insolubilized as tricalcium phosphate and then interacted with flocullant and collector reagent. The results show the possibility of orthophosphate separation recovery (% R = 97 - 99%) and the foam processing by recycling the solid product in the manufacture of phosphate fertilizer type single or concentrated superphosphate.

REFERENCES 1. Ligia Stoica The separation and the concentration of ions by flotation, Doctoral Thesis, Politechnical Institute, lasi,1978, Romania 2. Ligia Stoica, Magdalena Diculescu, Carmen Plapcianu, Water. Research ., 32, 10, 3021 - 3030, 1998 3. P. Mavros, K.A. Matis - Innovation in Flotation Technology, Nato ASI Series, vol.208, 490 - 492 4. NTPA 001 - Romanian environmental legislation 5. Aurel Varduca - Hydrochemical and chemical pollution of water, edited by Jean Pierre Carbonel H.G.A, Bucharest, Romania, 1997 6. Nakamoto K. Infrared Spectra of Inorganic Coordination Compounds , Wiley I nterscience Publications, New - York, London, Sidney, Toronto, 1970 7. Richard A. Nyquist and Ronald O . Kagel - Infrared Spectra of Inorganic Compounds

Phosphorus

Research Bulletin Vol. 10 (1999), 474

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