Enhanced Biological Phosporous Removal by Anaerobic and Aerobic/Anoxic processes

Università degli Studi di SalernoDipartimento di Ingegneria CivileDipartimento di Ingegneria Civile

Laurea in Ingegneria per l’Ambiente ed il Laurea in Ingegneria per l’Ambiente ed il Territorio in Territorio in Impianti di trattamento delle acque reflue IIImpianti di trattamento delle acque reflue II

ENHANCED BIOLOGICAL PHOSPHORUS ENHANCED BIOLOGICAL PHOSPHORUS REMOVAL BY ANAEROBIC, AEROBIC/ANOXIC REMOVAL BY ANAEROBIC, AEROBIC/ANOXIC

PROCESSESPROCESSES

AllievoAllievoPaolo SianoPaolo SianoN.Mat. 06205-N.Mat. 06205-000160000160

Relatore:Relatore:Prof.Ing. Luigi RizzoProf.Ing. Luigi Rizzo

Correlatore:Correlatore:Prof.ssa. Maria Ascensão ReisProf.ssa. Maria Ascensão Reis

: : Enhanced Biological Phosphorus Removal by anaerobic, aerobic/anoxic processes : : 29 April 2011

FrameworkFramework

Background Objectives Materials and methods

Wastewater sampling

Batch test

Chemical Analysis

ResultsPhosphorus in Beirolas WWTP

Anaerobic-Aerobic and Anaerobic/Anoxic batch tests

Conclusions


BackgroundBackground



World Resource institute (www.wri.org)



World Resource institute (www.wri.org)



Parameter Power plant in terms of population equivalent

D.E. 91/271/CEE

10,000 – 100,000 >100,000

Concentrazione

% di riduzione

Concentr. % di riduz.

Total P (P mg/l) ≤ 2 80 ≤ 1 80

Total N (N mg/l) ≤ 15 70-80 ≤ 10 70-80World Resource institute (www.wri.org)

Chemical Chemical RemovalRemovalChemical Chemical RemovalRemoval

Biological Biological RemovalRemoval

(EBPR)(EBPR)

Biological Biological RemovalRemoval

(EBPR)(EBPR)

PRECIPITATIONPRECIPITATION

ADDITION OF METAL SALTS

ENHANCEENHANCE


: : Enhanced Biological Phosphorus Removal by anaerobic, aerobic/anoxic processes : : Presented on the 29 April 2011

ANAEROBIC/AEROBIC

PROCESSES

promoted byPoliphosphate Accumulating

Organisms(PAOs)

Much lower operating costs Reduced sludge production Reuse processed sludge

Phoredox [A/O]Phoredox [A/O]

ANAEROBIC CONDITIONSliquid phase

energy

O2

liquid phase

O2

AEROBIC CONDITIONS



energy

liquid phase

NO2

NO3

Phoredox 3-stage [A2/O]



energy

O2

University of Cape Town (UCT)

Bardenpho

Combined nitrogen and phosphorus removal schemes

Virginia Initiative Plant [VIP]

A2/O





Carvalho et. al. (2007) observed

difference in anoxic P-uptake and

proposed hypothesis that different

Accumulibacter clades have

different metabolic capabilities.

***

Flowers et al., (2009) confirmed

that two different clades have

affinities to nitrate: type I

Accumulibacter, hereafter refered

as PAOI, seems having the ability

to denitrify using nitrate, contrary

to Type II Accumulibacter,

hereafter PAOII. Although anoxic

conditions with nitrate seems to

favor PAOI over PAOII, they seem

be able to co-exist.

The aim of the study has been the optimization of the Enhanced Biological Phosphorus Removal

(EBPR) through:

ObjectivesObjectives

Reproduction of the EBPR

process at lab-scale and

evaluation process

efficiency;

Estimation of the

microbial composition of

Beirolas UWWTP through

chemical analysis,

according to the method

proposed by Meinhold et

al. (1999).



ExperimentalExperimental

Materials and methods: wastewater Materials and methods: wastewater samplingsamplingActivated sludge was collected from

Beirolas UWWTP (Loures, Portugal)


Beirolas UWWTP

Materials and methods: wastewater Materials and methods: wastewater samplingsampling"Barden-pho" BPR unit configuration based on 3-

stages


• Anaerobic zone

(4.3% of total);• Anoxic zone

(21.3% of total);

• Aerobic zone(74.4% volume total).

Materials and methods: wastewater Materials and methods: wastewater samplingsampling

5 L 5 L of sludge from aerobic tank of sludge from aerobic tank to arrange biological batch tests.to arrange biological batch tests.


Materials and methods: wastewater Materials and methods: wastewater samplingsamplingAdditional samples from :Additional samples from : biological unitsbiological units (Anaerobic, anoxic and (Anaerobic, anoxic and aerobic tank);aerobic tank); primary and secondary settling. primary and secondary settling.

In order to characterize the plant.In order to characterize the plant.



Materials and methods: batch testMaterials and methods: batch test

Batch test conditionsBatch test conditionsAcetate as carbon source

Temperature of 22°C (±2°C)

pH in the range 6.5÷7.5

ANAEROBICANAEROBICREACTORREACTOR

AEROBIC AEROBIC REACTORREACTOR

ANOXIC ANOXIC REACTOREACTO

RR

Volume 1.5 L

Volume 0.6 L

Volume 0.6 L

SPLITSPLIT


Chemical AnalysisChemical Analysis

Phosphorus, Acetate, Nitrate Phosphorus, Acetate, Nitrate Hight Pressure Liquid Chromatography Hight Pressure Liquid Chromatography

(HPLC)(HPLC)IonPac® AS9-HCIonPac® AS9-HC

PhosporusPhosporusAscorbic acid methodAscorbic acid methodSkalar 5100Skalar 5100

AmmoniaAmmoniaAmmonia gas sensing combination electrode Ammonia gas sensing combination electrode Thermo Orion, NH4/95-12Thermo Orion, NH4/95-12

Total and Volatile Suspended Total and Volatile Suspended Solids Solids (TSS, VSS)(TSS, VSS)

Membrane Filtration MethodMembrane Filtration Method


ANAEROBIC ANAEROBIC REACTORREACTOR

Time (min)Time (min)

Conc

. of P

Conc

. of P

~ ~ 120120 ~ ~ 360360

Max release of PMax release of P

anaer.anaer. aer./anox.aer./anox.

Carbon comsuptionCarbon comsuption

Results: Results: Anaerobic-Aerobic and Anaerobic-Aerobic and Anaerobic/Anoxic batch testsAnaerobic/Anoxic batch tests


AEROBIC REACTORAEROBIC REACTORMax release of PMax release of P

Max aerobic Max aerobic uptake of Puptake of P


Conc

. of P

Conc

. of P

anaer.anaer.

~ ~ 120120 ~ ~ 360360

aer./anox.aer./anox.

Carbon comsuptionCarbon comsuption



ANOXIC REACTORANOXIC REACTORMax release of PMax release of P

Max anoxic Max anoxic uptake of Puptake of P


Conc

. of P

Conc

. of P

~ ~ 120120 ~ ~ 360360


Carbon comsuptionCarbon comsuptionNitrate Nitrate

comsuptioncomsuption




Batch test for B4 samples. Initial Acetate concentration 25 ppm; Initial concentration of P 20ppm; Initial NO3 25ppm.

Anaerobic condition

Aerobic/Anoxic

condition



Batch test for B6 samples.Initial Acetate concentration 30 ppm; Initial concentration of P 20ppm; Initial NO3 25ppm.

Anaerobic condition

Aerobic/Anoxic

condition



Batch test for B7 samples. Initial Acetate concentration 40 ppm; Initial concentration of P 20ppm; Initial NO3 25ppm.

Spiking of P

Anaerobic condition

Aerobic/Anoxic

condition

Aerobic condition




Anaerobic condition

Aerobic/Anoxic

condition

P Ae (on Ax)




Anaerobic condition

Anoxiccondition

Aerobic condition



n° Batch

Initial

Hac

P-release rate

An. P/HAc ratio

Ae P-uptake

rate

Ax. P-uptake

rate

Ax/Ae P uptake

rate

[-] [mg/L][mgP/gVSS/

h][molP/

molHAc][mgP/gVSS/

h][mgP/gVSS/h] [%]

B4 25 9.73 0.37 7.40 3.68 36.45

B6 30 11.63 0.19 3.87 1.50 28.44

B7 40 6.68 0.18 8.57 3.55 45.34

B8 40 9.98 0.22 6.51 1.88 49.40

B5 50 8.61 0.22 n.r. n.r. n.r.avarage

>>9.33 0.23 6.59 2.65 39.91

stand.dev.>>

1.83 0.08 2.00 1.12 9.36

Summary of the anaerobic-aerobic-anoxic activity batch tests results carried out

According to other studies


Results: Results: Assessing PAO/DPAO activityAssessing PAO/DPAO activity


Conc

. of P

Conc

. of P

~ ~ 120120 ~ ~ 360360


Anoxic Anoxic uptakeuptake

Aerobic Aerobic uptakeuptake Anaerobic releaseAnaerobic release

Aerobic uptakeAerobic uptakeAnoxic uptakeAnoxic uptakeAcetate consuptionAcetate consuptionNitrate consuptionNitrate consuption

XDPAO

XPAO

DPax

DPox =

Relative activity of DPAO

in EBPR systems(Meinhold et al.,1999)


XDPAO

XPAO

DPax

DPox =

Relative activity of DPAO

in EBPR systems(Meinhold et al.,1999)

Results: Results: Assessing PAO/DPAO activityAssessing PAO/DPAO activity


Results: phosphorus in Beirolas WWTPResults: phosphorus in Beirolas WWTP

Efficiency

92%

?“secondary”

P-release


Results: Results: WWTP & Batch testsWWTP & Batch tests


ConclusionsConclusions

EBPR process at lab-scale was reproduced and typical trends of phosphorus, nitrate and acetate were observed;

The batch tests results obtained suggest that phosphorus removal is due to two type of PAOs: PAOs type I (also called DPAOs) that are likely to be able to reduce nitrate and PAO type II that cannot;

Relative chemical activity of PAOs and DPAOs was estimated, (Meinhold et al. 1999): DPAOs occurrence as high as 40% and PAOs occurrence as high as 60%;

Phosphorus removal efficiency at Beirolas UWWTP is quite variable, but under the investigated conditions a 92% removal was observed;

The higher the concentration of intracellular phosphorous in aerobic tank of UWWTP the higher the phosphorus release rate in the anaerobic phase of batch test.


ConclusionsConclusions

The knowledge of the microbial composition and its efficiency

is key factor to perform good P and N removals.


Education

Enhanced Biological Phosporous Removal by Anaerobic and Aerobic/Anoxic processes