AD as an integral part of

manure management Michael Köttner

Train-the-Trainer WS 2, Kleve, 29 April 2015

2

Contents:

• 1. Enivormental Aspects

• 2. Application of Digestate

• 3. Digestate Processing

• 4. Treatment Costs - Profitability

• 5. Legal Aspects

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1. Enivormental Aspects

4

Miehe et al. 2008

Digestate production depending

on installation size

5

Biology – properties of different manures

Liquid manure typepH –

ValueC/N Properties

Cattle liquid manure 6.8 – 7 10 – 17• Good buffering capacity

• Rich in methane bacteria

Pig liquid manure approx. 7 5 - 10

• Good buffering capacity

• High proportion of heavy

metals (Zn 700-2000;

Cu 250-760 [mg/kg DM])

Poultry liquid manure 7 – 7.3 approx. 7• Good buffering capacity

• Strong sediment accumulation

Direct digestate application

6

S ubstrate D igestate0

200

400

600

800

1000B ov ine s lurry

Organic

As hes

Water

Kg

/tfr

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as

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28

93

25

S ubstrate D igestate0

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400

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800

1000C orn s ilag e

Organic

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Kg

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S ubstrate D igestate0

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400

600

800

1000Wheat (all c rop s ilag e)

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As hes

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Kg

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42

77

5

18

S ubstrate D igestate0

200

400

600

800

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Kg

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s15

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29

89

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49

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41

Fuchs and Drosg, 2010

Modification of composition for different substrates after passage

through a biogas installation (Peretzky 2008)

7

Environmental friendly (ecologi-

cal) liquid manure management

S&H Umwelt GmbH & Co.

Very big quantities of liquid manure lead to:

Odor impacts during treatment and production Spreading of pathogenic germs Damage of the botanical composition and building of a typical

“Liquid Manure Flora” in the available grassland Worsening of the soil properties Contamination of the ground and surface waters

Biogas technology can not substantially reduce liquid manure quantities. It

OFFERS HOWEVER, different solutions for this problem, thanks to its positive

energy balance from the production of biogas.

8

Impact of selected substrate on

digestate composition Parameter Impact on digestate

Substrate influence

Energy Crops High DM

High organic residue fraction [oDM/DM]

Bio wastes Lower DM

Lower organic residue fraction [oDM/DM]

High slurry fraction High azotic concentration

High NH4-N/TN

High slaughter house waste

fraction

High azotic concentration

High NH4-N/TN

Fuchs and Drosg, 2010

9

Substrate DM oDM N P

Biogas

production Masse loss

[%] [DM%] [kg/t] [kg/t] [m³/t FM] [%]

Agricultural dung

Cowshed slurry 8-11 75-82 2,6-6,7 0,5-3,3 20-30 2-4

Pig slurry approx. 7 75-86 6-18 2-10 20-35 2-4

Cowshed manure approx. 25 68-76 1,1-3,4 1-1,5 40-50 5-6

Pig manure 20-25 75-80 2,6-5,2 2,3-2,8 55-65 7-8

Hen manure Approx. 32 63-80 5,4 - 70-90 9-11

Energy Crops

Corn silage 20-35 85-95 1,1-2 0,2-0,3 170-200 22-27

Rye 30-35 92-98 4,0 0,71 170-220 22-28

Sugar beet 23 90-95 2,6 0,4 170-180 22-23

Fodder sugar beet 12 75-85 1,9 0,4 75-100 10-13

Beet leaves 16 75-80 0,2-0,4 0,7-0,9 approx.70 9

Grass silage 25-50 70-95 3,5-6,9 0,4-0,8 170-200 22-26

Handreichung Biogasgewinnung und -nutzung (2006)

Nutrients content and mass loss fordifferent Substrates

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Parameter Impact on digestate

Process influence

High fresh water fraction

Higher quantity of produced digestate Lowering of salt concentration Generally less DM

High recyclated fraction

Lower quantity of produced digestate Increase of saltconcentration Increase of DM

Hight inert materials fraction (e.g. sand)Increase of total Dry matter fraction, Decline of oDM/DM

Short residence time

High fatty acid valueHigh organic residues fraction [oDM/DM]Lower NH4-N/TN fraction

One phase or two phases process No significant impact on digestate composition

Fuchs and Drosg, 2010

Impact of selected process on

digestate composition

11

Odor reductionReduction of the odor causing substances (humid acids, Phenols,

Phenol derivate)

Decomposition of organic substance

Decomposition rates oDM: of up to 40%

The fermented liquid manure can pumped and sprayed better compared to

the raw liquid manure

The agitation is reduced before the application on land

Sanitization

The degree of the sanitization depends on retention time, temperature

and applied procedure

Positive changes of liquid manure

properties through fermentation

12

Hydraulic retention time (days)

Rela

tive c

oncentra

tion (%

)

Odor reduction depending on retention time

13

Destroying the weed seeds

The longer the seeds in the liquid manure are exposed to the process and

the higher the temperature is, the more rapidly decreases the germination

capacity

Avoidance of plant corrosion

Improvement of the fertilizer value

The fermented liquid manure has a better short term N-Fertilizer effect

Positive changes of liquid manure

properties through fermentation

14

Reduction of pathogenic germs

1,00E+00

1,00E+01

1,00E+02

1,00E+03

1,00E+04

1,00E+05

1,00E+06

1,00E+07

1,00E+08

1,00E+09

GKZ EBA GCF FCF FKS

Keimart

Rohgülle

Biogasgülle

93,75%

99,90%

Anlage: Laukenmann

Temp.: 38°C

VWZ.: 80 Tage

Typ: Betonfermenter

Datum: Juni 1993

99,98%

99,70%

Messung durch

Institut für

Tierhygiene,

99,98%

Plant: Laukenmann

Temp.: 38°C

HRT: 80 days

Type: Concrete digester

Date: June 1993

Raw l. manure

Biogas digestate

Measurements by the institute for animal hygiene, University of HohenheimGerms Type

Am

ount in

CBU

/g

CBU=Colony Building Units

15

Cattle liquid manure

Biogas digestate

Source: Saxony Regional Office for Agriculture FB LB, Jäkel

Kg/m

3

DM (%) Nitrogen Ammonium Phosphor Potassium Magnesium Calcium pH-value

Mean values of some samples from

cattle liquid manure & biogas digestate

Oberlungwitz biogas plant study case

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Heavy Metals can not be reduced by the biogas process

Cadmium (Cd)

Chrome (Cr)

Quiksilver (Hh)

Plumb (Pb)

Copper (Cu)

Nickel (Ni)

Zinc (Zn)

Because drymatter content is lowered during biogas-process, in the

corelation the heavy metal concentration rises

After seperation most of the heavy metals content remains in the solid

phase.

Heavy Metal load

17

Certain Antibiotics can be reduced by the biogas process:

Sulfadiazin

Sulfamethazin

Chlortetracyyclin

Oxytetracyclin

Tetracyclin

In a field test in 15 biogas plants an elimination of antibiotics between

digester entrance and exit could be proven.

In the case of Chlortetracyclin the antibiotically inactive Iso-

Chlortetracyclin was confirmed as the main product of elimination.

Antibiotics Degradation

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Digestate can be spread on the fields

- no hygiene restrictions with animal slurry and plant material

Improved Fertilizer

- avoids nutrient losses

- reduces burning effect on plants

- improves flowing properties

- improves plant compatibility

- improves plant health

- reduces germination ability of weed seeds

Environmentally sound

- reduces the intensity of odor

- reduces air pollution through methane and ammonia

- reduces the wash out of nitrate

- sanitizes liquid manure

- recycles organic residues (co-fermentation)

- can avoid connection costs to a central sewer

5

Use of biogas digestate

19

2. Land Application of

Digestate

20

Digestate storage

After the anaerobic treatment of liquid manure and during the storage nitrogen

losses occur in form of ammonia

Digestate land application

During the application nitrogen losses can be presented in gaseous form

(ammonia) and in mineral form (nitrate)

Liquid digestate processing and

fertilization

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Trailing Hose Trailing-shoe Injection Splash Plate

Distribution of slurry Even Even Even Very uneven

Risk of amonia volatilization Medium Low Low or none High

Risk of cropcontamination Low Low Very low High

Risk of wind driftMinimal after

applicationMinimal after

application No risk High

Risk of smell Medium Low Very low High

Spreading capacity High Low low High

Working width 12-28 metres 6-12 metres 6-12 metres 6-10 metres

Mechanical cropdamage None None High None

Cost of application Medium Medium High Low

Amount of slurryvisible Some Some Very little Most

adapted from Birkmose, 2009

Example from Denmark summarising the characteristics of

four digestate and raw slurry application methods

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Fertilizer distributor tractor: strong smell and ammonia emissions, wind-

sensitively

Drag hose tractor: precise fertilization, around 41% lower NH3 emissions

Land application techniques

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No excessive agitation before the application

Deploy cooled substrate from the final storage

Spread using emission-reducing techniques (drag hose

tractor, etc.), and

Processing the digestate

To prevent the nitrate leaching by liquid digestate fertilization other

measures, besides the type of treatment must be taken into account:

Sufficient storage capacity (at least 6 months)

Periods of application

Quantity of liquid digestate (and thus N-quantity) to be applied

Spreading technology

Measures during liquid

digestate application

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Sept.-Dec.

Jan.-Feb. March April May June/July August

Inflow in m³ for a daily production of 19,2 m³

2339 1131 595 575 595 1170 595

Taking out in m³ 0 0 1400 4080 0 882 638

Proportional filling in m³ 3179 4310 3505 0 595 883 840

Filling of the endstorage in % with storage capacity of 3500 m³ (=182 days or 6 months)

91 % * 123 % 100 % 0 % ** 17 % 25% 24%

Filling of the endstorage in % with storage capacity of 4800 m³ (=250 days or 8,3 months)

66% 90% ***

73 % 0% ** 12 % 18% 17%

* Around middle December the endstorage would be already 100% full

**Once a year the storage is emptied (+/- 20 m³)

*** 10% buffer for rain water, that accumulates in the silo, and in case

of unfavorable weather conditions at the beginning of march no

digestate can be spread

Example filling level in percent of the total end storage capacity

25

80

155

March-May

July-August

September

Suggestion for digestate distribution in

percent during the course of one year

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3. Digestate Processing

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Reasons for processing

digested slurry Saves storage volume (liquid phase)

Surplus of nutrients or lacking area for land spreading Export of nutrients required

Digestate contains 70-90 % of water Removing water saves transport costs

Reduced costs for land spreading

Reduced environmental impacts

Nutrients release in the liquid phase

Reduction of volatile air pollutants

Odor reduction

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Basic principles of digestate

processing Physical Liquid-solid separation

Membrane technology

Vacuum evaporation

Chemical Flocculation

Precipitation (MAP, Phosphate)

Anaerobic digestion

Composting (aerobe)

Activated sludge process (aerobe)

Nitrification, denitrification

Biological

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solids: 15 %

microfiltration-concentrate: 20 %

(recirculation into the biogas plant)

reverse osmosis-concentrate: 15 %

(utilisation)

permeate: 50 %

digestate: 100 %

Accumulation of further residues /

side streams

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1. Partial separation 2. Complete separation

C, P2O5, Norg

N, P

N, K

N,P,K

Elimination of P2O5 Elimination of P2O5 + N

C, P2O5, Norg

Processing strategies

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Liquid-solid separation

• Screw press

• Decanter centrifuge

• Drying

Membrane technology

Vacuum evaporation

Applied Technologies

32

Liquid solid separation – partial

processing

20-80 % Ptot

10-20 % Ntot

Removal of:

plus: Production of compost

humus balance

Separation of solid contents

always the 1st processing step!!!

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Nutrient distribution

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Parameters Unit

Liquid phase after solid phaseseparation

COD [mg/l] 15 000 – 80 000

BOD5 [mg/l] 1 000 – 15 000

TN (total nitrogen) [mg/l] 3 000 – 8 500

NH4-N [mg/l] 2 500 – 7 500

TP (total phosphorus) [mg/l] 100 – 1 000

PO4-P [mg/l] 50 - 800

DM [%] 1,5 -7

Fuchs and Drosg, 2010

Spectrum of liquid phase composition after solid phase separation from digestate

Example of a waste digestion plant

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Partial processing

Centrifuge – WLV

Goal: P2O5 elimination

Type of nutrients to

eliminate leads to choice

of technology/ strategy:

P2O5: partial processing

N: complete processing

Source: WLV-Service GmbH, 2006

N: 78000 kg = 100%P2O5: 40234 kg = 100%K: 42843 kg = 100 %

N: 23288 kg = 30%P2O5: 27984 kg = 70%K: 42843 kg = 39 %

N: 55217 kg = 70%P2O5: 12250 kg = 30%K: 25940 kg = 61 %

Examplary nutrient distribution

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15-20 % DM

approx. 5 % DM in liquid

phase

Removes:

Simple device – often applied

Required coarse material for efficient operation

Wearing part: screen (depending on input matter)

Investment costs:

20.000 - 50.000 €

Liquid-solid separation - screw press

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30-40 % DS

approx. 1-3 % DM in liquid

phase

Removes:

Higher removal rate

Suitable for subsequent

complete nutrient elimination

Digestate’s properties =

criterium for device selection

Investment costs:

150.000 - 250.000 €Source: www.huber.de

Liquid-solid separation - Decanter centrifuge

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Liquid-solid separation - Decanter centrifuge

Decanter separation of the mixture digestate/ fats

Value and efficiency of nutrients and liquid manure

Source: Danish agrarian research

Raw manure Fat waste Digestate (fermented

liquid manure) Solid fraction Liquid fraction

Weight portion (%) 97 3 100 7 93

DM content (%) 5,2 41,4 4,2 33 2,3

P (kg/t) 1,2 0,3 1,3 13,4 0,3

N-total (kg/t) 4,8 1,3 4,6 11,7 4,0

NH4-n (kg/t) 3,6 0,4 3,6 3,0 3,6

Org. N (kg/t) 1,2 0,9 2,3 2,6 2,3

NH4-n portion (%) 75 28 79 26 89

Source: Hengdal fermentation gas/Danish agrarian research

FertilizerEfficiency nitrogen

(%)Increase in value per t liquid

manure €

Pig liquid manure 60 - 70 -

Digestate (fermented manure) 65 – 85 0,30 – 0,60

Separated biogas digestate 80 - 90 0,60 - 1,20

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Water

Partial N-losses

Removes:

Simple technology – mainly applied for sewage sludge

Combined utilisation of solar heat and waste heat

Requires complex control system

Investment costs:

approx. 300.000 €

(digestate from 450 kWel. Plant)

Liquid-solid separation - Solar drying

40

Heat coupled microgas turbine in combination with a solar supported digestate

drying process at the Farm at Karle, Fuessbach, Germany

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Complete nutrient separationElimination of P2O5 + N

Complex processes, requires

sophisticated technology

High energy demand

Economically viable only at big biogas

plants > 700 kWel

C, P2O5, Norg

N, P

N, K

42

Complete separation - Membrane technology

Anaerobic digestion = best

preparation

Requires good removal of coarse &

fibrous material (DM content ≈ 1 %)

The better AD and solids separtion

were, the better performe the

membranes!

Quelle:www.haase-energietechnik.de 2007

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Example:

3-MW biogas plant

Vacuum evaporation

source

: ww

w.a

quasy

stem

s-tech

.de

Complete separation –(Vacuum-) Evaporation

44

Complete separation – What isimportant?

High energy demand for generating pressure or heat

utilisation of surplus heat ??

Digested slurry might form crusts on the device

choose technology adapted to digested slurry

Complete removal of particulate substances (> 0,2 mm) before

entering membrane technology or vacuum evaporation

Inaccurate solids removal increases rate of failure

Cleaning & Repair might take days and leads to

increased costs!

45

Output costs depending on

transport distance

Tractor truck with 2 hanger (load capacity every 14t)

Tractor truck with 2 hanger (load capacity every 14t) + 2,5 €/m³ output

cost

Motor truck (25t)

Motor truck (25t) + 2,5 €/m3 output cost

Self-propelled unit for output + retrieval vehicule

Tractor truck with vacum baril

25

20

15

10

5

0

Sp

ecific

co

sts

[€/m

³]

0 20 40 60 80 100

Transport distance [km]

46

Separated material – and now ???

1 substance 2-4 different material flows

Concentrated nutrients might contain high salt loads

Concentrated nutrients allow specific fertilizer mixing

Utilization on own farm (partial nutrient removal)

Marketing?

Marketing channels?

Quality assurance and control

Requires good planning &

strategic partners

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4. Treatment Costs /

Profitability

48

Technology Energy (kWh/t) Costs (€/m3) Application

Composting of solid manure

5 -50 (for conversion

w. aeration system) 12,4 – 37,2No limitation on

farm size

Composting of poultry dung with pine bark n.s. 8,1 (€/t) Test stage

Anaerobic ponds low n.s. Limited

Biological treatment of pig liquid manure 16 (5,6 % DM) 6,1 Large farms

Ventilation of liquid dung 10 - 38 0,7 - 4Extensive

Experience

Mechanical separation 0,5 – 4 (kWh/m3) 1,4 – 4,2Extensive

Experience

Incineration of chicken dung production 18 (€/t)>130.000

BroilerEvaporation and drying process of Chicken manure 30 (kWh/m3 H2O) > 2,3 Test stage

Additives with pig liquid manure production0,5 – 1

(€/animal) Routine

Treatment costs of animal excrements

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Treatment costsThe total costs for a decanter separation are about 1,- € per t according todata of a Danish biogas manufacturer. This price in Denmark is profitablefor many large cattle farmers.

A further separation in the evaporator is more expensive (approx. 3.40 €per t). This expenditure should be paid back by saved transport costs andby a better utilization of fertilizer as well as by the improved spreading.

Long distances transportation of manure for the fraction which cannot beused in the surroundings of the enterprise would be more profitable

Economic value of digestate is indicated either as 10 € per LU per year orrelated to the nutrients also e.g. (2008):

55 €/ t N, 56 €/ t P,28 €/ t K.

50

Partial separation - profitabilityFertilizer value inprovement (Source KTBL 2010):

Nitrogen Phosphate Potassium

Cost of nutrients (€/kg) 0,60 0,45 0,35

NutrientsAmount C1

(kg/t)

Value C1

(€/t)

Amount C2

(kg/t)

Value C2

(€/t)

Δ Value C2 – C1

(€/t)

N 9,69 5,81 11,5 6,90 1,09

P2O5 4,97 2,24 13,82 6,22 3,98

K2O 5,29 1,85 8,35 2,92 1,07

Σ =6,14

C1: unseperated digestate; C2: seperated digestate

In areas where P2O

5 is not required, the one step treatment and

external transport make sense and could be profitable.

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Fuch

s a

nd

Dro

sg

, 20

10

52

Fuch

s a

nd

Dro

sg

, 20

10

53

Fuchs and Drosg, 2010

54

Conclusion

Nutrients = problem (surplus) nutrient separation & export

might be the only solution

But: calculate carefully (expensive technolgy) and be aware that you

might need to market nutrients

Also: which nutrients do you need to get rid off – where are they?(nutrient distribution between liquid and solid phase)

Complete nutrient removal is only viable at big biogas plants - not for

plants < 1 – 1,5 MWel

Rising demand and increasing sizes of biogas plants might lead to

decreasing technology prices

55

Michael Köttner

International Biogas and Bioenergy Centre of Competence IBBK

Am Feuersee 6 • 74592 Kirchberg/ Jagst • Germany

phone: +49. 7954. 926 203 • fax: +49. 7954. 926 204

info@biogas-zentrum.de • www.biogas-zentrum.de

Thank you for your attention!

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