Anaerobic digestion of slaughterhouse waste in Sweden

Åke Nordberg

JTI - Swedish Institute of Agricultural and Environmental Engineering

Biogas

Anaerobic digestion of animal by-products:a sustainable treatment alternative

Presentation out-line

• Regulations for anaerobic digestion (AD) of animal by-products (ABP)

• Potential biogas substrates from slaughtered animals

• AD of slaughterhouse waste in Sweden

Regulation (EC) No 1774/2002, applicablefrom 1st of May 2003 in all member states

Category Material

Category 1 Specified Risk Material representing an increased risk for public health, animals and environment.

Not designated for AD

Category 2 – without preliminary treatment

Manure, digestive tract content, milk, colostrum

Category 2 – after sterilisation with steam pressure and marking (with smell)

Fallen animals, slaughtered but not intended for human consumption (everything not included in Category 1 and 3)

Category 3 – approved according to Article 15

(pasteurisation)

Material originating from animals fit for slaughter but not intended for human consumption. ABP from food production

Category 3 – approved according to national legislation

Catering waste (except from international transport)

Pig slaughtering facility

Manure

Digestive tract content

Pasteurisation<12 mm≥60 min≥70 °C

AnaerobicDigester

(According toarticle 15)

Digestive tract

Bones, slaughter by-products

Blood

Parts of slaughtered animals

Fallen animalsSterilisation≥ 133 °C≥ 3 bar≥ 20 min

(< 6 mm not covered byABP-regulation)

End productSalmonella: 0 CFU in 25 g (5 samples)Enterobacteriaceae: 3 samples < 10 CFU/g, 2 samples < 300 CFU/gPlacing on the market, trade, application to land (not pasture)

Cat. 2 – no required treatment

Cat. 3 - pasteurisation

Cat. 2 - sterilisation

Screenings andflotation sludge >6 mm

Bovine slaughtering facility

Manure

Rumen content

Pasteurisation<12 mm≥60 min≥70 °C

AnaerobicDigester

(According toarticle 15)

Rumen

Bones, slaughter by-products

Blood*

Parts of slaughtered animals

Screenings andflotation sludge >6 mm

Sterilisation/IncinerationNot intended for AD

(< 6 mm not covered byABP-regulation)

End productSalmonella: 0 CFU in 25 g (5 samples)Enterobacteriaceae: 3 samples < 10 CFU/g, 2 samples < 300 CFU/gPlacing on the market, trade, application to land (not pasture)

Cat. 2 – no required treatment

Cat. 3 - pasteurisation

Cat. 1SRM; vertebral columnand skull, intestines

(no SRM in blood stream)

Calculated methane potential from slaughter of cattle and pigs divided into different waste categories

(% of total methane potential) and the total amount(MJ or kWh per animal).

Rumen,stomach

andintestinalcontent(Cat. 2)

Cat. 3(excl. blood)

Blood(cat. 3)

Cat. 2 Cat. 1(SRM) Total

% of tot % of tot % of tot % of tot % of tot MJ/animal

kWh/animal

Cattle 9 62 5 3 21 1300 361

Pig 6 82 8 4 - 140 39

Potential value of gas and organic fertiliser from slaughterhouse

GasEuro/ton

FertiliserEuro/ton

Meat and bone fraction 65 18

Blood 10 4

Digestive tract +content 11 2

Sludge 22 5

Raw biogas: 3.3 Eurocent/kWhN: 0.76 Euro/kgP: 1.20 Euro/kgK: 0.33 Euro/kg

Slaughterhouse waste in Sweden-legislation background

• 1988 (SFS 1988:537)– Meat meal from carcasses not allowed in

animal fodder• 1991 (LSFS 1990:51)

– Use of low-risk animal by-products in ruminant fodder prohibited in 1991

Existing biogas plants approved

for ABP co-digestion

Borås

Skövde

Luleå

Swedish co-digestion plants treating animal by-products

Plant Temperature Digestate Gas utilisationHelsingborg Mesophilic Slurry organic fertiliser Heat, electricity, vehicle fuel

Kalmar Thermophilic Slurry organic fertiliser Vehicle fuel

Kristianstad Mesophilic Slurry organic fertiliser Heat, vehicle fuel

Laholm Mesophilic Slurry organic fertiliser Upgraded gas to grid

Linköping Mesophilic Slurry organic fertiliser Vehicle fuel

Uppsala Thermophilic Slurry organic fertiliser Vehicle fuel

Vänersborg Thermophilic Solid digestate Heat, vehicle fuel

Skövde Thermophilic Slurry organic fertiliser Heat, vehicle fuel

Borås Thermophilic Solid digestate Vehicle fuel

Luleå Mesophilic Slurry organic fertiliser Heat, electricity

Summary of capacity and treated waste in Swedish biogas plants* 2003

Treatment capacity 300 000 m3 100 %

Used capacity 220 000 m3 73 %

Planned increase of treatment capacity 125 000 m3 +42 %

Manure 68 000 m3 30%

Source-sorted household waste 12 000 m3 5 %

Source-sorted from restaurants, shops etc 2 200 m3 1 %

Slaughterhouse waste 101 000 m3 45 %

Waste from other food industry 27 000 m3 12 %

Other organic waste 6 000 m3 3 %

Water 7 500 m3 3 %

Total amount of substrate 223 700 m3 100 %

*10 ABP-approved biogas plants (Major part treated in 7 plants)

Concluding remarks• Animal by-products are suitable for anaerobic

digestion giving high gas yields and a nutrient rich organic fertilizer

• AD of slaughterhouse waste within the legislative framework 1774/2002 offers a safe and sustainable waste management solution

• Governmental subsidies for facilitating investments in AD of slaughterhouse waste is well invested money from a sustainable point of view