1 of 15 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

2 of 15 Waldmichelbacher Hof

3 of 15 Overview 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

4 of 15 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

5 of 15 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

6 of 15 Concept design components Low flush toilets for all buildings Wastewater storage tank of 100 m 3 (gravity flow – 2,500 m 3 /year) Manure collection and mixing channel under the cattle shed Heated, insulated and fully mixed anaerobic digester with 280 m 3 volume (40-44°C) Anaerobic storage digester with 1500 m 3 Two combined heat and power generator sets with 37 kW (electricity) and 74 kW (thermal energy / heat) each

7 of 15 Concept schematic of closed-loop

8 of 15 Cattle shed, showing gaps in floor for manure transfer to collection channel (under the shed)

9 of 15 Anaerobic digester no. 1 (insulated, heated, mixed & covered)

10 of 15 Gas bladder of anaerobic digester no. 2 (not heated, not mixed)

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12 of 15 Milestones 1991: Consulting, planning and design 1993: Construction 1994: Start-up 1995: First optimisation 1995 – 2004: Ongoing improvements of the system

13 of 15 Key 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

14 of 15 Spreading of digested manure on the fields

15 of 15 Lessons 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