Energy and organic fertilizer from a diary cattle farm

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Centro Ricerche Produzioni Animali – C.R.P.A. S.p.A.

International conference

ManuREsource 2013 Manure management

and valorization

December 5‐6, 2013 Bruges, Belgium

Energy and organic fertilizer from a dairy cattle farm

S. Piccinini, L. Rossi, N. Labartino, G. Moscatelli, C. Fabbri

CRPA – Research Centre on Animal Production - Reggio Emilia - ITALY

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Energy and organic fertilizer from a dairy cattle farm

The Dairy cattle farm

Biogas plant

Stable House

The Agricola Antonio Farm is a dairy cattle farm (production of drinking milk) in the province of Bologna , Italy.

The dairy cows in production are about 200 (400 heads of cattle in total) and the agricultural area cultivated is 477 ha.

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fertilizer from a dairy cattle farm

Operational scheme of the farm

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Energetic enhancement: biogas production First plant

State system: Operating since 2009 Manufacturer: B.T.S. Italia

Substrates processed: cattle slurry, maize silage Process temperature: about 40 °C

Reactor type: CSTR

Digesters volume: 2 x 1900 m³

Covered storage tank volume : 4700 m³ Hydraulic retation time (HRT): 80 days

Engine: Jenbacher mod. JGS 320;

Elettric power installated: 1 MW_e

Production of electricity: total 8,400 MWh/y net 8,000 MWh/y Daily biogas production: 10,500 m³/day

( 55% CH4)

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First Biogas plant:

Organic load in the monitored period

Substrate processed:organic load 8908 t VS (in 16.3 months)

(%VS from each substrates)

Maize silage;

47,04%

Maize silage with onions; 24,84%

Cob maize silage;

0,10%

Mix of silages;

2,11%

Vegetable by-

products; 1,13% Cow manure;

24,77%

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First Biogas plant: production indices

Results (average values) of monitoring activity

(1) CHP maintenance (2) installation of a biomass extruder

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First Biogas plant: heat use

The surplus heat is partly used for drying hay (about 5000 t/y) and warm the house of the farmer (about 250 m

²

).

About 1,200 MWh

_th

/y

Forage drying

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The new biogas plant:

the farmer at the end of 2012, has built another biogas plant, within the same farm

State system: Operating since 2013 Manufacturer: B.T.S. Italia

Substrates processed: cattle manure, maize silage, straw and stalks

Process temperature: about 40 °C Reactor type: CSTR

Pre-tank, hydrolysis step: 470 m³ Digester volume: 1 x 3000 m³

Hydraulic retation time (HRT): 70 days Engine: Jenbacher mod. JGS 320;

Elettric power installated: 1 MW_e

Production of electricity: net 8,000 MWh/y

The vegetable matrices (maize silage, straw and stalks), before hydrolysis step, are chopped in an extruder.

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The valorisation of matter:

organic fertilizer production

After anaerobic digestion an innovative line of digestate drying was built, with a grant from the Rural Development Programme of the Emilia-Romagna region.

Input dryer: 22.2 t/day Output dryer: 2-3 t/day

(85-90%TS)

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The system uses the

residual heat of

cogeneration and is able

to also exploit the

residual heat potential of

the drying air to thicken a

part of the liquid fraction

of the digestate resulting

from the solid / liquid

separation.

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Layout of the new biogas plant

(Anaerobic Digestion + dryer +pelletizer)

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Raw digestate Dried digestate

pH ^[-] 7.9 ± 0.1 7.2 ± 0.7

[g/k g] 99.1 ± 8.2 870.6 ± 80.7

[%] 9.9 ± 0.8 87 ± 8

[g/k g] 75.8 ± 8.3 701.9 ± 62.6

[%TS] 76.4 ± 2.6 80.6 ± 1.4

[mg/k g] 6591 ± 717 18240 ± 2691

[%TS] 6.6 ± 0.7 2 ± 0.2

[mg/k g] 3758 ± 393 1976 ± 1293

[%TKN] 57 ± 1.8 10.7 ± 7.4

[mg/k g] 1376 ± 333 8456 ± 1693

[%TS] 1.4 ± 0.3 1 ± 0.1

[mg/k g] 4755 ± 608 28596 ± 24345

[%TS] 5.1 ± 0.4 3.2 ± 2.5

[%TS] ‐ 41.5 ± 3.1

C/N ‐ 21.2 ± 2.5

E.Coli ^{MPN/g (*)} ^‐ ^<10

Salmonella P/A in 25 g (**) ‐ Absence

Parameter

P K TOC

TS VS TKN NH₄⁺ - N

Measured data

(7 samples)

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The air, rich in water vapor, ammonia, and malodorous compounds, resulting from drying of the digestate, is treated in an acid scrubber with production of an ammonium sulfate solution that can be used to increase the Nitrogen content in the organic fertilizer or can be marketed as liquid nitrogenous fertilizer.

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The dried digestate is then subjected to pelletization, with production of organic fertilizer freely marketable under the Italian legislation

(Legislative Decree n. 75/2010)

Organic fertilizer production line with Pelletizer ( in the starting phase )

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Anaerobic Digestion Digestate drying system

Organic fertilizer

Digestate (65% of total):

8092 t/y TS 1010 t/y NTK 64.3 t/y

Dry fraction

Air with ammonia

Scrubber

^Nitrogen_liquid

fertilizer

Pelletizer

maximum organic fertilizer production

1188 t/y TS 1010 t/y NTK 35.7 t/y

434 t/y NTK 26 t/y

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Digestate drying system: nitrogen bilance

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Conclusions

• The multifunctionality and resilience of dairy farms also passes through the exploitation of energy and matter (organic fertilizer) of the manure;

• Anaerobic digestion is a reliable and

flexible process that enables this

exploitation of the manure.

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