3. technical options of phosphorus removal in wwtp_matthias barjenbruch

7/24/2019 3. Technical Options of Phosphorus Removal in WWTP_Matthias Barjenbruch

1/30

Technical Options of Phosphorus Removal in

Wastewater Treatment plant (WWTP)

M. Barjenbruch, E. Exner

FG Siedlungswasserwirtschaft, TU BerlinGustav-Meyer-Allee 25, D - 13355 Berlin

Phone: +49 / (0) 30 / 314 72246; Fax: +49 / (0) 30 / 314 72248e-mail: [email protected], [email protected]


2/30

Importance of phosphorus12. frequent element of the crust of earth

Phosphorus is a chemical element. Symbol Pordinal number 15 and has a specific weight of 31 g/mol

Greek - lichttragend, given by the shining of the white

phosphorus in the reaction with oxygen. P was discovered in 1669 by Hennig Brand, a German pharmacist

and alchemist.

Phosphorus is essential important for all organism.

P-compounds are parts of DNA- and RNA-molecules

The phosphorus containing compounds ADP/ATP are playing and

important parts in the energy metabolism of all cells.

A man with 70 kg contains about 700 g phosphorus, from which 600 gis bound in the bones

Important nutrient for the growth of plants and essential fertilizer

Main resources come from: Morocco, South Africa, Russia, China and

USAResource remain only according WHO only about 60-80 years


3/30

Objectives of the P-elimination

Prevention of the eutrophication of water bodies. P effects in water bodies

eutrophication already in the lower range of microgram especially in:

Lakes, dammed or tide influenced water bodies, Northern Sea of Baltic Sea

Factor of minimum for the growth of plants: N : P = 7:1.

Classification of lakes:

Eutrophic; nutrient rich lakes, in depth about 0-30%,

O2-saturation, only 2 m sight in depth, high production of algae,tot. P~ 45 - 85 g/l

River according the German Surface water ordinance

50 g P/l large rivers in the middle mountain; inlets to the Baltic Sea

50/100 g P/l all other rivers

Surveillance value of WWTP according wastewater ordinance

10,000 - < 100,000 PE: 2.0 mg P/l

> 100,000 PE: 1.0 mg P/l Special regional restrictions!


4/30

Examples of Eutrophication


5/30

Origin and estimation of the specific P-load in municipal

sewage [in g P / (Ed)]

1,6

05)

0,246)

0,054)

1,6

2,252)

0,752)

0,42)

Metabolism products1)

Washing powder for textiles

Household detergents/washing-up liquid

Other P-sources3)

1,95,0Sum, related to PE

6,915,7Average Concentration (mg/l)9)

1,27)1,28)Industry/trade/settlement aeras (as PE)

20051975Origin of phosphorus

Concentration in Germany: 5,6 - 14 mg P/l


6/30

Phosphorus in the sewage

Main part of the total phosphorus (ca. 68%):

In an inorganic solved status, mainly orthophosphate and

possible condensed phosphates

Smaller part of the total phosphorus:

organic solved and none solved mode (phosphonate, hardly

degradable organic P-compounds from textile industry andfrom heat-/power-production)

Condensed and organic parts of phosphorus will mainly

tranfered into ortho phosphates Only ortho phosphate can be removed from the water

by precipitation and following separation!


7/30

Processes of phosphorus elimination

Phosphorus can not be transferred like as nitrogen into thegaseous status and eliminated to the air.

Phosphorus compounds must be removed from the wastewater ina stable (solid) aggregated status bounded in separateble particlesvia the sludge path.

Processes of chemical P-elimination

Me3+ + PO43-

Me(PO)4 + Me (OH) metals: Fe3+, Al3+

Pre-, simultaneous- and final pr, Nachfllung, or combinationprecipitation

Influence parameters for the efficiency of the precipitation

Dosage

-relation factor pH-value

Ca2+

Particle separation

Processes of biological P-elimination (Bio-P)

Combination of Bio-P and chemical P-elimination


8/30

Processes of the chemical P-elimination

SF TF/ATPS SS

PAPre-precipitation

= 2-3CPe

2 mg/l

Combined

precipitation

= 2 2,5

ATPS SS

PAPA PA PA

CF < 0,5 mg/l= 0,3 mg/l

= 1,2 1,5

Simultaneous

precipitation

= 1,2 1,5 1-1,5 mg/l

z.T. < 1,0ATPS SS

PAPA PA

PA

PA: preciptation agent


9/30

-value: relative amount of precipitant with the unit [mol Me/mol XP,Prec]

with:

XMe necessary amount of precipitant (metal) (mg Me/l sewage),

XP,Fll phosphorus to be precipitated (mg P/l sewage),

AMMe atomic mass of metal (mg/mmol),

AMP atomic mass of phosphors (mg/mmol)

and the atomic mass AM: (P) Phosphor: 31; (Fe) iron 56 ; (Al) aluminium 27

= 1,0 stochiometric dosage

= 1,5 50 % over stochiometric dosage

Calculation of the amount of the precipitant

]/[/

/

,

PmolMemolAMX

AMX

PFllP

MeMeprec

BioPPDNPBMPoutPInPprecP XXXCCX ,,,,,,

According the kind of bounded P in the sludge:

XPBM = 1,0 % (nitrification, COD Elimination)

XPBDN = 0,5 % (denitrification)

XPBioP = 1,0 % (anaerobic tank)


10/30

Concurrent reactions

Parallel to the precipitation reaction several concurrent

reactions appear:

Hydroxyd development

Me3+ + 3OH- Me(OH)3

Carbonate development

Ca2+ + CO32- CaCO3

Komplexierung of organic substance

Different reaction of adsorption

Follow ups of by-reaction

Higher consumption of precipitation agent

Increase of the sludge production


11/30

Amount of additional sludge

The phosphate, hydroxides and all other flucculated

compounds formed by the precipitation agents produce

a higher amount of sludge (Dry solids (DS)) 2,5 g DS/g Fe (about 5,0 g DS/g P),

4 g DS/g Al (about 4,0 g DS/g P).

If you apply calcium products you have to calculate with1.35 amount of flocculant as an increase of sludge:

pH-value at 9,5 about 50 g DS/(PE d),

pH-value at 11 about 200 g DS/(PE d).

Theses additional amounts of sludge have be regarded

in the planning of the sludge treatment process!


12/30

Jar-tests with iron-(III)-chloride

Example

-value 0 1,2 2,0 2,8 3,6


13/30

Common precipitants

Product description Chemical formu typical

delivery form

density or

bulk density

[t/m3]

storage and

dosage

effective kation

for

P-precipitation

common

active substances

per kg

delivery form

pH

from

(saturated)

dilution

aluminium chloride AlCl3 dilution

1,3

reservoir

acid-resitent pump

Al3+

58 60 g/kg

2,2 mol/kg 1

Iron (III)-chloride FeCl3 dilution

1,41 1,43

reservoir

acid-resitent pump

Fe3+

135 138 g/kg

2,4 2,5 mol/kg 1

Iron (III)-chloridsulphate FeClSO4 dilution

1,43 1,52

reservoir

acid-resitent pump

Fe3+

123 g/kg

2,2 mol/kg 1

iron(II)-sulphate FeSO4 7 H2O residual damp

(green-) salt

1

Einsumpfbunker

acid-resitent pump

Fe2+

Fe3+

178 195 g/kg

3,2 3,5 mol/kg2

Sodium aluminate NaAl(OH)4 dilution

1,3 1,5

reservoir

pump

Al3+

62 105 g/kg

2,3 3,9 mol/kg 14

Calciumhydroxid

White lime hydrate

(extinguihedr lime)

stabilisied lime milkj

(20 %ig)

Ca(OH)2 powder

0,45

suspension

1,15

Silo

Schnecke

Tank

Exzenterpumpe

Ca2+

376 g/kg

9,4 mol/kg

75 g/kg

1,9 mol/kg

12,5

polyaluminium-(hydroxid)-

chloride (PAC)

[Al(OH)3-xClx]n dilution

1,2 1,37 reservoir

acid-resitent pump

Al3+

70 90 g/kg

2,6 3,3 mol/kg 1 3

According DWA 2011


14/30

Requirements on the an die pureness of

the flocculation agent

Parameter [mg/mol ESMe]

Lead (Pb) 15

Cadmium (Cd) 0,2

Chromium (Cr) 15

Copper (Cu) 15

Nickel (Ni) 20

Mercury (Hg) 0,15

Zinc (Zn) 50

AOX 5

Guidance values in flocculation agents to protect theenvironment against heavy metal discharge

According DWA 2011


15/30

Dosage of the precipitation agent

at locations with by flow increase turbulence

in short distance of the storage tank

hydraulic direct jumpIncrease of the cross section,

absorption chamber of weirs,

Drop constructionjunction of part flows

Installation of mixer with a high frequency

Installation of screens and static mixers Archimedes screw (e.g. filtration)

Pressure side turbulence of pumps

Aerated flow section (Fe2+)

Protection pipe


16/30

Example of good location for the dosage of

precipitations agents

Cnannel

Sewage

blast pipe

Precipitation agent

Break, bendVenturi Flow breaker


17/30

Examples of location for dosage

Bad solution bad mixing of the flocculant

durch Randlage kaum B nearly no

contact to the complete water surface

good solution Dosage into the change of flow direction

but better would be over the whole

cross-section


18/30

Examples of location for dosage

Good mixing conditions special injections form different side of

the pipe

Against the flow direction

also good mixing conditions

but danger of corrosion


19/30

Storage of the flocculation agent

Sealed filling place

Separated catchment of

losses of the flocculation

agent


20/30

Principle of the enhanced biological P-elimination

PO4 -P

A

C

Time

luxery uptake

ANAEROBIC AEROBIC

P-Release P-Up-take

B


21/30

Biological P-elimination

Advantages:

No additional agents (flocculants) necessary

Decrease of salts in the effluent of a WWTP

Lower additional sludge production

No additional heavy metals in the sludge

No disturbances possible for the nitrification process

DisadvantagesHigher investment cost for the construction

of the anaerobic tank

A little bit more instable process, so often additional chemical dosageis required

In winter time higher tendency of bulking sludge


22/30

DimensioningContact time and Detention time

Detention time

VAN

tR = QIn

Contact time

VANtc =

(Qrs + Q In)

Dimensioning (biological P-elimination) DWA A 131 anaerobic tank: > 0,5 to 0,75 h

Regarding the maximum dry weather flow and the flow of the

return sludge

Bi P


23/30

Bio-PPhoredox-process (Detention time: 0,5 to 0,75 h)

Effluent

Aeration

Secondary Settler

Return sludge

Excess Sludge

anoxic zone

denitrification

aerated zone

COD-elimination

& nitrification

Internal recirculation

Inlet

anaerobic

zone = 1,2 1,5

PA1-1,5 mg/l

z.T. < 1,0

CPe

2,0 mg/l

E l


24/30

ExampleWWTP Lbeck-Priwall


25/30

Modified-UCT-Process

effluent

Aeration

Secondary

settlerReturn slduge

Excess sludge

Anoxic zone

denitrificationaerated zone

COD-elimination &

Nitrification

interanl recirculation

Inlet

Anaerobic

zone

ISAH


26/30

ISAH-process

Effluent

Aeration

Secondary

SettlerReturn sludge

Excess Sludge

Anoxic zone

denitrificationAerated zone

COD-elimination

& nitrification

Internal recirculation

Inlet

Anaerobic

zone

Returnsludge

Denitrifcation

P elimination in Germany and DWA North East


27/30

1,70

1,20

1,00 1,000,90

1,000,90

0,80 0,80 0,80 0,80 0,80 0,80 0,78 0,75 0,75 0,75

3,5

2,4 2,4

0,8 0,80,7

0,640,76

0,64 0,660,75

0,63 0,67 0,63

1,70

0

0,5

1

1,5

2

2,5

3

3,5

4

1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009Jahr

Pges.-

Ablaufwert[mg/L]

Pges.-Abl. D[mg/L]

Pges.Abl-Nord-Ost

P-elimination in Germany and DWA North-EastPtot- mean values in WWTP effluent 1992 to 2009

Effluent:

1.0 0.49 mg P/l

Inlet:

14 5.6 mg P/l

DWA, 2010

Pto

t-Effluent

values[m

g/l]

Year

Effects of PA-consumption on P -effluent


28/30

Effects of PA-consumption on Ptot-effluent

with lower Ptot-Effluent value higher amount of precipitant is needed

0

5

10

15

20

25

30

35

40

45

50

55

60

Bio-P Deni Chem-P

KP

[molMe

/kgP]

CP,AN 0,5 mg/l CP,AN 1,0 mg/l CP,AN 2,0 mg/l

26

44

107

73

14

38

14

1510


29/30

0

5

10

15

20

25

30

35

40

45

50

55

60

Bio-P Deni Chem-P

KP

[molMe/kgP]

Zulauf Biologie Rcklaufschlamm Ablauf Biologie Mehrfachdosierung

23

6727

108

318

7

12

13

12

11

Influence of the dosage location

Inlet to activated tank has the highestfloccucation agent demand 20-25%


30/30

1. Biologische StufeBio-P-Becken

Thank your

for attention

3. technical options of phosphorus removal in wwtp_matthias barjenbruch

Documents