1 of 15 elisabeth v. münch – unesco-ihe institute for water education heinz-peter mang –...
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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