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Elisabeth v. Münch – UNESCO-IHE Institute for Water Education

Heinz-Peter Mang – CAAE-IEEP

Georg Schultes – Waldmichelbacher Hof

Arne Panesar - akwasser-BBU

Ten years of operational experiences with the ecosan-biogas

plant at a family-owned farm and restaurant in Germany

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Waldmichelbacher HofWaldmichelbacher Hofwww.waldmichelbacher-hof.de

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Overview of farm sizeOverview of farm size

Location: Bavaria, Germany Farm of 200 ha, 170 ha grazing land and

fruit trees, 30 ha fodder crops 280 hornless cattle and 20 horses (LSU) Restaurant with 250 seats Slaughterhouse processing one cattle per

week Four families (14 persons) live and work

on/from the farm & restaurant

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Wastewater management options in 1991

Wastewater management options in 1991

Starting point: New slaughterhouse; no public sewer

Option 1: On-site wastewater treatment plant

Option 2: Pipe to closest sewer (2.5 km) Option 3: Ecosan-biogas plant

Option 3 was selected based on practical considerations and cost

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Overview of ecosan-biogas process

Overview of ecosan-biogas process

Aim of the closed-loop “ecological sanitation biogas concept“ was to improve the financial return of farm and restaurant, based on a sustainable reuse of nutrients and water

Sewage of the farmhouses and restaurant together with animal manure, organic waste from kitchen, slaughterhouse and destillery are sanitised (anaerobic digestion)

Fertiliser, heat and electricity is produced

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Concept design componentsConcept design components

Low flush toilets for all buildings Wastewater storage tank of 100 m3 (gravity flow

– 2,500 m3/year) Manure collection and mixing channel under the

cattle shed Heated, insulated and fully mixed anaerobic

digester with 280 m3 volume (40-44°C) Anaerobic storage digester with 1500 m3

Two combined heat and power generator sets with 37 kW (electricity) and 74 kW (thermal energy / heat) each

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Concept schematic of closed-loopConcept schematic of closed-loop

“Ecosan- Biogas Plant”

Fertiliser (“digested manure”)

Anaerobic digester (heated)

Biogas

Restaurant, shop,

distillery

Collection channel: Manure and ww storage tank effluent

Households

Barn and stable (in winter)

Cattle

Farmland Fodder

Horses

Slaughter- house

Cogeneration plant

Meat

Electricity exported to

the grid

ww storage

tank

E

H + E

H + E

M W

W

W W

W

OSW

E

BG

BG

F

F

DM

DM

W

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Cattle shed, showing gaps in floor for manure transfer to collection channel (under the shed)

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Anaerobic digester no. 1 (insulated, heated, mixed & covered)

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Gas bladder of anaerobic digester no. 2 (not heated, not mixed)

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MilestonesMilestones

1991: Consulting, planning and design

1993: Construction 1994: Start-up 1995: First optimisation 1995 – 2004: Ongoing

improvements of the system

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Key resultsKey results Total investment costs of 200,000 € Annual savings in operating costs:

– 20,000 €/year for not needing to purchase fertiliser– 23,400 €/year due to electricity produced on-site (more

than 50% of the electricity demand covered)– Heat for all residential houses and restaurant, and hot

water (100% of total demand in summer, 20% in winter)– 5,300 €/year is the income from selling excess

electricity to the grid Valuable liquid fertiliser (digested manure) produced from

digestion process; non-odorous Sanitation of sewage by mesophilic digestion and long

retention times

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Spreading of digested manure on the fields

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Lessons learntLessons learnt

Based on the experience gathered, a new design could be realised for 50% of the investment costs

Recommended future work:– Detailed nutrient balance over the agricultural land– Detailed study on pathogen removal in anaerobic

digesters– Work towards streamlining legislation in Germany to

encourage this type of reuse