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University of Trento Department of Civil, Environmental And Mechanical Engineering Soluzioni integrate per il post-trattamento digestato: Case Study BIOGAS IN AREE ALPINE KLIMAENERGY 26-28 Marzo 2015 Prof. Dr. Gianni Andreottola Ing. Michela Langone, PhD Ing. Alice Limoli

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Page 1: Dicam post-trattamento_case study

!

Dipartimento di Ingegneria Civile Ambientale Meccanica

Corso di Laurea Magistrale in Ingegneria per l’Ambiente e il Territorio

Indagine sperimentale sui processi di rimozione dell’azoto dal digestato di origine zootecnica

Relatore Laureando Prof. Dott. Ing. Gianni Andreottola Alice Limoli

Correlatrice Dott.ssa Michela Langone

Anno Accademico 2013-2014 ! !

University of Trento Department of Civil, Environmental

And Mechanical Engineering

Soluzioni integrate per il post-trattamento digestato: Case Study

BIOGAS IN AREE ALPINE KLIMAENERGY 26-28 Marzo 2015

Prof. Dr. Gianni Andreottola Ing. Michela Langone, PhD Ing. Alice Limoli

Page 2: Dicam post-trattamento_case study

UNITN research fields

Anaerobic digestion and Co-digestion

OFMSW pre-treatment

Phytodepuration

Reduction of sewage sludge production

Respirometric techniques

Conventional biological treatments for carbon, phosphorus and nitrogen removal:

SBR, MBR, MBBR, etc

Innovative biological treatments: Partial Nitritation, Anammox, sulphate

reduction, autotrophic denitrification

Ammonia removal chemical processes: conventional and

nonconventional air stripping

Improvement of Sludge biodegradability for AD: Hydrodynamic cavitation system

Page 3: Dicam post-trattamento_case study

Aim

CASE STUDY: • Monitoring a post-treatment plant of manure

digestate • The current post-treatment produces compost and

a liquid fraction applied to agricultural land • Collaboration with AlpiBiogas, Atzwanger

(improvement of post-treatments), Univeristy of Bozen and Innsbruck (management of the DENI-DEMON pilot plant)

Page 4: Dicam post-trattamento_case study

AGENDA

• Anaerobic digestion plant description

• Characherization of digestate

• Digestate post-treatment plant description

• Results and efficency of the current post-treatment

• Increase of ammonia removal efficiency proposal

• Introduction to DENI-DEMON pilot plant

Page 5: Dicam post-trattamento_case study

ANAEROBIC DIGESTER

Cow manure

Cow slurry

Pig slurry

Poultry manure

Ingestate

Digestate

Biogas

INGESTATE

Biomass Type ST

(%TQ) SV

(%ST) Biogas

(m3/t SV) Methane

(%) TKN

(% ST)

Cow manure 12 82 300,0 55,0 2,5

Cow slurry 8 68 400,0 55,0 4,3

Pig slurry 3,5 70 700,0 55,0 8,0

Poultry manure 25 56,8 644,0 57,1 7,9

Page 6: Dicam post-trattamento_case study

ANAEROBIC DIGESTER

• CHP potential power 400kW • 1.550.000 m3

biogas/year • 865.000 m3

CH4/year • Electric energy: 3270 MWhel/year • Thermal energy: 3230 MWhth/year

Cow manure (29,0%)

Digestate

Biogas

AD Cow slurry (29,7%)

Pig slurry (29,7%)

Poultry manure (11,6%)

Ingestate

Cow manure (28%) Cow slurry (21%) Pig slurry (16%) Poultry manure (35%)

865.000 m3CH4/year

Page 7: Dicam post-trattamento_case study

CHARACTERIZATION OF DIGESTATE

DIGESTATE

Parameters value

ST (g/L) 73

SV (g/L) 46

CODtot (mg/L) 189.690

CODsol (mg/L) 39.350

TKN (mg/L) 6.803

N-NH4 (mg/L) 5.258

Norg (mg/L) 1.545

CODsol /N 7,48

Page 8: Dicam post-trattamento_case study

DIGESTATE USES

• Monitored land application Only if the ingestate is composed of animal wastesaters or waste of fruit and vegetables industry Nitrates directive

• Composting Production of organic fertilizer that can be sold according to the provisions of law 75/2010

• Sewage treatment In sewage system or surface water

Page 9: Dicam post-trattamento_case study

• Screw press • Oxidation tank • Centrifuge • Equalization tank • DAF (dissolved air flotation)

POST-TREATMENT PLANT SCHEME

• Compost • Liquid fraction to agricoltural land

Two valuable products:

Page 10: Dicam post-trattamento_case study

Digestate treatment plant scheme

Solid fraction removal efficiency

SCREW PRESS CENTRIFUGE DAF

ηST real 22% 48% 58%

ηST theoretical 32-35% 62% 60%

POST-TREATMENT PLANT EFFICIENCY

14.500 ton/year of solid fraction sent to composting plant

High use of coagulant (FeCl3)

Page 11: Dicam post-trattamento_case study

Digestate treatment plant scheme

Nitrogen Removal efficiency

OXIDATION TANK WHOLE TREATMENT

PLANT

ηTAN 21% 51%

ηTKN 17% 59%

POST-TREATMENT PLANT EFFICIENCY

600 ha/year in NVZ (170 kgN/ ha year) 300 ha/year in OZ (340 kgN/ha year )

Page 12: Dicam post-trattamento_case study

POST-TREATMENT PLANT EFFICIENCY

• Low nitrogen ( 20%) removal efficiency in the biological reactor, mainly due to ammonia stripping:

High solid content in the biological reactor (45 gTS/L) and high temperature (30°C) allow cell lysis, that increase the pH of the reactor up to 8,5

The high pH and the high temperature causes the ammonia gas formation

NH4+ NH3(gas)

+H+

The mixing and aeration conditions in the biological reactor cause

ammonia stripping

• Ammonia removal in the in the whole system is higher than in the biological reactor, due to ammonia stripping during the separation phases

Indagine!sperimentale!sui!processi!di!rimozione!dell’azoto!dal!digestato!di!origine!zootecnica!

!

!52!

!

Figura!3.!20!Aspetti!biochimici!e!termodinamici!dei!sistemi!ATAD!

!

La! Figura! 3.! 20! rappresenta! in! modo! schematico! le! reazioni! che! avvengono! all’interno! di! un!

reattore!ATAD.!

Per! mantenere! il! regime! operativo! microaerobico! è! necessaria! un’elevata! efficienza! di!

trasferimento! dell’ossigeno.! In! caso! di! trasferimento! troppo! basso! di! ossigeno! si! rischia! la!

formazione!di!condizioni!anaerobiche,!mentre!in!condizioni!di!eccessiva!aerazione!si!può!avere!un!

eccessivo!abbassamento!della!temperatura.!

Il! rilascio! in! atmosfera! di! anidride! carbonica! è,! nel! caso! della! digestione! termofila,! maggiore!

rispetto!alla!digestione!aerobica!standard;!questo!effetto!è!dovuto!alla!temperatura!di!esercizio.!

La! popolazione! microbica! vitale! è! detta! termofila! per! la! capacità! di! resistere! alle! temperature!

raggiunte!nel!reattore.!Un’analisi!molecolare!più!dettagliata!rivela!che!le!forme!presenti!sono!sia!di!

carattere!aerobico!che!anaerobico.!

Parte!dell’ammoniaca!passa!dalla!fase!liquida!a!quella!gassosa.!Grazie!agli!elevati!valori!di!pH!nel!

fluido!l’ammoniaca!tende!a!strippare;!questo!fenomeno!è! favorito!dalle!alte!temperature!e!dalla!

presenza!di!una!vasta!interfaccia!fluido]gas,!dovuta!all’aerazione!con!micro!bolle.!Altri!fattori!che!

contribuiscono!al!rilascio!di!ammoniaca!in!atmosfera!sono!l’accelerata!idrolisi!delle!proteine!con!

trasformazione!dell’azoto!organico!in!azoto!ammoniacale!e! l’inibita!nitrificazione,!effetto!dovuto!

alle! alte! temperature! (Staton! et! al.,! 2001).! Il! quantitativo! di! ammoniaca! presente! nell’effluente!

risulta,!tuttavia,!circa!uguale!a!quello!influente,!fenomeno!dovuto!alla!combinazione!di!lisi!cellulare!

che!ne!aumenta!la!concentrazione!e!di!strippaggio!che!la!diminuisce.!

E’!possibile!applicare!il!processo!ATAD!per!il!trattamento!di!reflui!ad!elevato!contenuto!di!sostanza!

organica!in!quanto!è!la!lisi!a!determinare!l’innalzamento!della!temperatura.!Il!digestato!ha!invece!

perso! gran! parte! della! sostanza! organica! durante! il! processo! di! digestione! anaerobica,! per! tale!

motivo!non!è!dunque!possibile!applicare!un!trattamento!di!digestione!termofila!autotermica!!a!valle!

di!un!digestore!anaerobico.!

!

• Low efficiency of solid remove in the centrifuge and a high use of coagulant (FeCl3)

that consume alkaninity

Page 13: Dicam post-trattamento_case study

EFFLUENT FROM FLOTATION PROCESS

Parameters value

SST (g/L) 11

SSV (g/L) 6

CODtot (mg/L) 18.800

CODsol (mg/L) 2.560

TKN (mg/L) 2.813

N-NH4 (mg/L) 2.450

N-NO2 (mg/L) 0,4

N-NO3 (mg/L) 0

Norg (mg/L) 363

CODsol /N 1,04

Alcalinity (mgHCO3- /L) 3.875

POST-TREATMENT PLANT EFFICIENCY

Page 14: Dicam post-trattamento_case study

PROPOSAL FOR HIGHER AMMONIA REMOVAL EFFICIENCY

PILOT PLANT Experimentation University of Innsbruck, Trento & Bozen

AIM: Reduce the agricoltural land necessary to application or Discharge in sewage system

HOW? : Innovative biological treatment Partial Nitrification and Anammox

process

NH4+ NO2

- NO3- 1.5O2

0.5O2

AOB Autotrophic Bacteria

NOB

NH4+

NO3-

N2

Autotrophic Bacteria

1.32NO2 -

< 60% Oxigen consumption

Less sludge production

PARTIAL NITRIFICATION

ANAMMOX

Page 15: Dicam post-trattamento_case study

INNOVATIVE BIOLOGICAL PROCESSES PILOT PLANT Experimentation University of Innsbruck, Trento & Bozen

DENI – DEMON Process applied to the liquid fraction of digestate (output of centrifuge or flotation) • DENI tank where denitrification

is performed to remove the residual COD

• DEMON reactor where Partial Nitrification

and anammox are performed to remove NH4

• Discharge tank

DEMON DENI DISCHARGE TANK

Page 16: Dicam post-trattamento_case study

INNOVATIVE BIOLOGICAL PROCESSES PILOT PLANT Experimentation University of Innsbruck, Trento & Bozen

DENI – DEMON Process monitoring December 2014 - January 2015

DEMON DENI DISCHARGE TANK

Page 17: Dicam post-trattamento_case study

INNOVATIVE BIOLOGICAL PROCESSES PILOT PLANT Experimentation University of Innsbruck, Trento & Bozen

DENI – DEMON Process applied to the liquid fraction of digestate (output of centrifuge or flotation)

TAN removal efficency TN removal efficency 18.12.2014 93% 92,7% 7.01.2015 86% 86,2%

14.01.2015 85% 84,5% 22.01.2015 81% 80,6%

TAN removal efficency TN removal efficency 18.12.2014 63% 63%

7.01.2015 44% 43% 14.01.2015 36% 34% 22.01.2015 51% 47%

Nitrogen Removal Efficiency DENI-DEMON process

Nitrogen Removal Efficiency DEMON process

Page 18: Dicam post-trattamento_case study

INNOVATIVE BIOLOGICAL PROCESSES PILOT PLANT Experimentation University of Innsbruck, Trento & Bozen

DENI – DEMON Process • Several biological processes are involved simultaneously both in the

DENI and in the DEMON reactor: denitrification, anammox and Nitritation, as can be observed from monitoring data.

• The biological processes involved did not reach a steady state and Nitrite accumulation occurred in the DEMON reactor

• Disease causes: - high solid concentration in the effluent to treat, that accumulate in

the reactor - low alkalinity content, that limit biological processes due to ferric

chloride use in the centrifuge

• Possible improvement to the treatment scheme: • Replace the centrifuge with a membrane module, avoiding the

utilization of polyelectrolyte. This can ensure a lower solid content and a higher alkalinity content in the effluent to treat.

Page 19: Dicam post-trattamento_case study

PROPOSAL FOR HIGHER AMMONIA REMOVAL EFFICIENCY

AIM: Reduce the agricoltural land necessary to application Discharge in sewage system

HOW? : Integration of sequential technological solutions Two steps process

WHICH? : First step: Conventional or nonconventional air stripping (N removal efficiency 80-90%)

+ Second step: Conventional or Innovative Biological treatment (N removal efficiency 60-90%)

Page 20: Dicam post-trattamento_case study

AIR STRIPPING First step

Lab - Experimentation at the University of Trento CONVENTIONAL AIR STRIPPING

applied to the liquid fraction of digestate Lower solid content=15g/L “Packing” air stripping column pH=11.5 T=20°C Recycles n. 8 Ammonia efficiency average = 50-60% NONCONVENTIONAL AIR STRIPPING applied to the raw digestate Higher solid content=50g/L “Sequencing batch reactor” with a mixed phase pH=10-11 T=20-30°C HRT=3days Ammonia efficiency average>90%

Page 21: Dicam post-trattamento_case study

BIOLOGICAL TREATMENT Second step

CONVENTIONAL BIOLOGICAL TREATMENT

NITRIFICATION + DENITRIFICATION + with external carbon sources Disadvantages High oxygen consumption; High sludge production; External carbon source required.

NONCONVENTIONAL BIOLOGICAL TREATMENT

PRE-DENITRIFICATION + PARTIAL NITRITATION + ANAMMOX DENI - DEMON PROCESS

Advantages Low oxygen consumption, as the nitrification is stopped to nitrite; Low sludge production, mainly autotrophic processes; No external carbon source required.

Page 22: Dicam post-trattamento_case study

CONCLUSION

The DENI-DEMON process directly applyed to the

liquid fraction of the digestate did not reached the

stability due to the alkalinity limitation and the high

solid content. Further experimentation is needed.

Dewatering system and N-removal have strong

interaction.

In order to reach a high ammonia removal efficiency

(>90%) a sequential two step process is proposed,

composed by stripping and biological process.

Page 23: Dicam post-trattamento_case study

THANKS FOR THE ATTENTION!

QUESTIONS?

CONTACT: Prof. Gianni Andreottola [email protected] Ing. Michela Langone, PhD [email protected] Ing. Alice Limoli [email protected]

http://www.ing.unitn.it/~lisa/

BIOGAS IN AREE ALPINE KLIMAENERGY 26-28 Marzo 2015

Page 24: Dicam post-trattamento_case study

• Mass balance

• Membrane

• Pilot plant monitoring • Pilot plant analyses

• New plant scheme

Page 25: Dicam post-trattamento_case study

MEMBRANE

• CERAMIC FILTER DISC 312 Kerafol

• Membrane pore size 0,5μm; • Diameter 312 mm • Thickness 6 mm; • Filtering surface 0,14 m2 each

disc

Economic sustainability is verifying

Page 26: Dicam post-trattamento_case study

DIGESTATE TREATMENT PLANT MONITORING

Digestate treatment plant scheme

DIGESTATE

Samplingdata Massbalancedata

ST 74,9 65,1 g/l

TKN 6802,8 5058,6 mg/l

TAN 5258,4 4451,4 mg/l

SCREWPRESSLIQUIDFRACTION

Samplingdata Massbalancedata

ST 58,5 48,0 g/l

TKN 6902,2 5263,7 mg/l

TAN 5236,6 4463,1 mg/l

Norganico 1665,5 800,6 mg/l

OXIDATIONTANK

Samplingdata Massbalancedata

ST 45,4 50,0 g/l

TKN 5717,5 5265,5 mg/l

TAN 4151 4445,0 mg/l

Norganico 1566,5 1220,5 mg/l

CENTRIFUGELIQUIDFRACTION

Samplingdata Massbalancedata

ST 31,0 22,0 g/l

TAN 3043 4205,1 mg/l

EQUALIZATIONTANK

Samplingdata Massbalancedata

ST 27,5 22,0 g/l

TAN 3445,0 4205,1 mg/l

DAFLIQUIDFRACTION

Samplingdata Massbalancedata

SST 11,4 10,0 g/l

TAN 3020,3 3418,2 mg/l

Page 27: Dicam post-trattamento_case study

PILOT PLANT MONITORING

(1)Feed

pH T Alk-tot NH4 NO2 NO3 CODsol SST SSV TKN CODtot

Date

[°C] [mMCaCO3][mgN/L]

[mgN/L]

[mgN/L]

[mgO2/L]

mgSST/L %SST[mgN/L]

[mgO2/L]

18/12/14 54,57 2.090 <0,01 0,85 2.568 266 55

07/01/15 6,94

20,31 2.750 11,05 1,68 1.182 259 66 2.443 1.980

14/01/15

46,53 3.190 3,02 0,94 2.868 63 52

22/01/15 7,30 17,20 61,29 2.624 <0,01 0,83 1.998 252 56 2.780 2.238

(2)Denipre-recirculation

pH T Alk-tot NH4 NO2 NO3 CODsol SST SSV TKN CODtot

Date

[°C][mM

CaCO3][mgN/L] [mgN/L] [mgN/L] [mgO2/L] mgSST/L %SST [mgN/L]

[mgO2/L]

18/12/14 13,1 580 <0.01 0,40 870 2.440,00 57

07/01/15 8,00

12,6 915 1,01 0,64 824 2.200,00 56 908 3.080

14/01/15 7,90

10,3 788 0,37 0,42 698 nd 63

22/01/15 7,70 10,4 13,3 1.070 1,92 0,26 856 2.290 20 759 1.698

(4)DEMONinsettling(endofcycle)

pH T Alk-tot NH4 NO2 NO3 CODsol SST SSV TKN CODtot

Date

[°C] [mM] [mgN/L] [mgN/L] [mgN/L] [mgO2/L] mgSST/L %SST [mgN/L] [mgO2/L]

18/12/14 2,29 214 <0.01 0,72 684 1.880 54

07/01/15

2,36 511 10,56 1,28 632 960 61 520 1.960

14/01/15 7,00

2,09 508 14,84 0,70 582 nd 56

22/01/15 7,10 23,10 2,36 523 46,55 2,15 716 990 27 487 1.148

Page 28: Dicam post-trattamento_case study

PILOT PLANT MONITORING

(5)DEMONinmixing

pH T SST SSV TKN CODtot

Date

[°C] mgSST/L %SST

18/12/14 11.100 51

07/01/15

9.400 60 908 10.060

14/01/15

6.930 56

22/01/15 7,0 24,6 10.400 46 725 6.760

(6)DISCHARGETANKafterDEMONdischarge

pH T Alk-tot NH4 NO2 NO3 CODsol SST SSV TKN CODtot

Date °C [mM] [mgN/L] [mgN/L] [mgN/L] [mgO2/L] mgSST/L%SST [mgN/L] [mgO2/L]

18/12/14 1,90 152 <0.01 0,14 666 71 69

07/01/15 7,70 2,20 380 1,29 0,22 534 27 44 365 614

14/01/15 7,50 2,64 494 0,76 0,14 564 46 80

22/01/15 7,50 5,10 2,42 500 9,11 0,69 670 40 12 361 856

(7)DEMON(endoffirstaerationphase)

pH T Alk-tot NH4 NO2 NO3 CODsol

Date

[°C] [mM] [mgN/L] [mgN/L] [mgN/L] [mgO2/L]

22/01/15 7,00 25,20 2,48 569 48,94 2,34 728

Page 29: Dicam post-trattamento_case study

PILOT PLANT MONITORING Number Name Description Sampling time Analyses

1 TQ Influent TQ As weekly feeding indifferent SST, SSV, *

1 F Influent F As weekly feeding indifferent N-NH4, N-NO2, N-NO3, COD, Alkalinity

2 TQ Deni pre-recirculation TQ Sampled before recirculation 09:10:00 - 09:20:00 SST, SSV, *

2 F Deni pre-recirculation F Sampled before recirculation 09:10:00 - 09:20:00 N-NH4, N-NO2, N-NO3, COD, Alkalinity

3 TQ Deni post-recirculation TQ Sampled after recirculation 09:40:00 - 10:00:00 SST, SSV, *

3 F Deni post-recirculation F Sampled after recirculation 09:40:00 - 10:00:00 N-NH4, N-NO2, N-NO3, COD, Alkalinity

4 TQ DEMON in settling TQ Mid-end of settling phase 15:15:00 - 15:20:00 SST, SSV, *

4 F DEMON in settling F Mid-end of settling phase 15:15:00 - 15:20:00 N-NH4, N-NO2, N-NO3, COD, Alkalinity

5 TQ DEMON in mixing TQ during first

aeration phase During mixing/ventilation phase

09:40:00 -15:00:00 SST, SSV, *

in ventilation

6 TQ Discharge tank TQ After DEMON discharge 15:35:00 SST, SSV, *

6 F Discharge tank F After DEMON discharge 15:35:00 N-NH4, N-NO2, N-NO3, COD, Alkalinity

7 F DEMON F end first aeration (pH

7.88) DEMON end first aeration (pH 7.88) 12:20:00 N-NH4, N-NO2, N-NO3, COD, Alkalinity

*TKN and COD 2° and 4° sampling

Page 30: Dicam post-trattamento_case study

PILOT PLANT MONITORING

TAN removal efficency

TN removal efficency

18.12.2014 93% 92,7% 7.01.2015 86% 86,2%

14.01.2015 85% 84,5% 22.01.2015 81% 80,6%

TN=TAN+N-NO2+N-NO3

-

500

1.000

1.500

2.000

2.500

3.000

3.500

mg

/L

DENI - DEMON - DISCHARGE TANK

N-NH4 in

N-NH4 out

CODsol_in

COD sol_out

N-NO2 out

N-NO3

Page 31: Dicam post-trattamento_case study

DEMON REACTOR MONITORING

TAN removal efficency

TN removal efficency

18.12.2014 63% 63% 7.01.2015 44% 43%

14.01.2015 36% 34% 22.01.2015 51% 47%

-

200

400

600

800

1.000

1.200

mg

/L

DEMON

N-NH4 in

N-NH4 out

CODsol_in

COD sol_out

N-NO2 out

N-NO3

TN=TAN+N-NO2+N-NO3

Nitrite N-NO2=46 mg/l

Page 32: Dicam post-trattamento_case study

NEW PLANT SCHEME

• Membrane separation system

• Stripping treatment

• DENI-DEMON treatment

• Thermal drying treatment of the solid fraction

Page 33: Dicam post-trattamento_case study