Black & Veatch Weftec09-controlling Magnesium And Phosphorus...

BUILDING A WORLD OF DIFFERENCE®

CONTROLLING MAGNESIUM AND PHOSPHORUS TO REDUCE STRUVITE PRECIPITATION IN PLANT PROCESSES AND INCREASE REVENUE

PETER SCHAUER, JAMES BARNARD : BLACK & VEATCH ROB BAUR : CLEAN WATER SERVICES, TIGARD, OR • AHREN BRITTON : OSTARA

WASSTRIP PROCESS are combined in release tank to release phosphorus and magnesium prior to digestion.

diverted in the centrate stream to the struvite recovery process in liquid after thickening.

Patent Pending/World-Wide Rights Reserved

Primary Treatment

Solids Treatment Process

BACTERIA BREAK DOWN ORGANICS

Lime Ca(OH) 2 ADDED

Sludge 1,370 lbs/d

C + O2

NO3-

BACTERIA INGEST ORGANIC WASTE

P

PO4 NH

NH

+ 4

P NH

P VFA

BACTERIA METABOLIZE ORGANIC WASTE

SO

+ 4

O2

O2

O2

+ 4

6

-2 4

H 2O

H 2O

O2 -2 SO4 O 2 (CHO)N O2 O2 - + NO3H H+ O2 O

MOST BACTERIA SETTLE OUT

2

OXYGEN PUMPED IN

7

ANAEROBIC + AEROBIC = BIOLOGICAL NUTRIENT REMOVAL

GRAVITY

UNIFIED FERMENTATION AND THICKENING (UFAT) PATENT 6,387,264 FERMENTER

THICKENER

SLUDGE

SLUDGE

PRIMARY SLUDGE

Mg Release per L of WAS, mg

200

o-PO4 150

Mg 100 50 0 72

Time, hours

96

120

25 20

CENTRATE HIGH AMMONIA AND PHOSPHORUS

15 10 5

75 mg VFA / L RAS

186 mg VFA / L RAS

374 mg VFA / L RAS

571 mg VFA / L RAS

NEXT STEPS

0 0

50

100

Time, min

150

200

Lab Data 10

■ Determine the overall impact to the treatment plant. ■ Overall economics.

Test #1 Test #2 Test #3 Test #4

20

Modeling Data 50

100

Model #1 Model #2 Model #3 Model #4

0

150

0

100

200

300

Time, min

release using WASSTRIP.

DEWATERING CENTRIFUGE

BIOSOLIDS

US patents are pending that protect the WASSTRIP system and process technological advances, and world-wide patent rights are reserved to Clean Water Services, Oregon, USA.

■ Impacts from pH. ■ Impact on Dewaterability.

0.006

0.0012

0.005

0.0010

0.004

0.0008

0.003

0.0006

0.002

0.0004

0.001

0.0002

0.000

0.0000 0.00

0.02

THIS POSTER WAS PRESENTED AT WQTC.07 FOR MORE INFORMATION WRITE

40

BACTERIA FERMENTS OR BREAKS DOWN THIS MATERIAL

CENTRATE HIGH AMMONIA AND PHOSPHORUS

CRYSTAL GREEN SLOW RELEASE STRUVITE FERTILIZER PELLETS 5-28-0 10% Mg

20

60

■ Appears to be an upper limit on impact that VFAs can have on phosphorus release rates. ■ Release rates anticipated using existing tankage will be adequate for phosphorus and magnesium

ANAEROBIC DIGESTION REDUCED STRUVITE

O S TA R A

®

30

80

PREDICTED FULL-PLANT IMPACTS

THICKENING CENTRIFUGE

MAGNESIUM

30

40

100

Time, hours

90% PHOSPHATE REMOVED

35

50

0

CHEMICAL SLUDGE

40

60

0

LOW P + Mg CAKE

250

120

ANAEROBIC P + Mg RELEASE TANK

HIGH P + Mg

20% AMMONIA REMOVED

48

WASSTRIP (Patent Pending)

VFA

0.25 mg magnesium/mg total phosphorus. ■ BioWin was used to model the results of the tests. The endogenous release testing indicated a lower anaerobic hydrolysis rate than used in default configurations, though a reduced parameter value is used under the separate anaerobic digester model within the software. ■ Modeling to describe testing with the addition of VFA required large changes to the sequestration rate for PAO, suggesting that the limiting factor for phosphorus release during the tests was not the concentration of VFA. 70

CO2

N2

H2 O + ORGANIC WASTE

Testing was conducted to accurately predict the impact and sizing of the phosphorus release tank, as well as the impact on the overall system. ■ How much VFA needed to strip phosphorus? ■ The rate of P and Mg release in the tank? ■ Production of ammonia? ■ Impact on downstream processes? ■ Can it be modeled with commercial modeling software?

Endogenous Release, mg/L

Secondary Treatment

SLUDGE SETTLES TO BOTTOM

TESTING

24

concentrations in the digester is less favorable for unintentional struvite formation in the digesters.

WASSTRIP

SLUDGE (50%)

0

■ Lower phosphorus and magnesium

[email protected] OR VISIT www.bv.com

0.04

0.06

VFA / VSS

0.08

0.10 Phosphorus Release Magnesium Release

33% REDUCTION IN MAGNESIUM COSTS 12% INCREASE IN STRUVITE GENERATION

©Copyright, Black & Veatch Corporation, 2009. All rights reserved. The Black & Veatch name and logo are registered trademarks of Black & Veatch Holding Company. Other service marks and trademarks may be registered trademarks or trademarks of their respective companies.

Effluent

■ Phosphorus and magnesium are

Phosphorus Concentration, mg/L

Liquid Treatment Process

■ WAS and VFA-rich fermentates

■ WAS and VFA-rich fermentates combined in release tank. ■ The ratio of release of magnesium versus the release of phosphorus was between 0.20 mg and

Mg release Rate per VSS, hr -1

removed with the daily waste activated sludge. ■ During anaerobic solids processing, phoshporus, magnesium and nitrogen are released in the Influent recycle streams. 1,400 lbs/d ■ Some metal phosphate precipitation in sludge. ■ Struvite precipitation in sludge. ■ Remaining released Mg, P and ammonia in return streams. ■ Approximately 20% to 30% of the phosphorus load of the activated sludge process is in the recycle streams. 500 lbs/d ■ Recovery of phosphorus. ■ Reduces phosphorus load in the effluent. ■ Prevents loss of valuable resources. ■ Serves as a source of income.

WASTE-ACTIVATED SLUDGE STRIPPING TO REMOVE INTERNAL PHOSPHORUS

Endogenous Mg Release, mg/L

■ Phosphorus accumulates in the cell mass, or is precipitated in chemical reactions, and is

MODELING RESULTS

P release Rate per VSS, hr -1

BACKGROUND