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Characteristics of anaerobic-digested manure Anaerobic digestion : A way to enhance nutritional performance of animal manure. Torben Ravn Pedersen National Specialist Biogas and Slurry Separation. Subejcts. Danish Agricultural Advisory Service Manure handling in Denmark Biogas in Denmark
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Characteristics of anaerobic-digested manureAnaerobicdigestion: A way to enhancenutritional performance of animal manure Torben Ravn Pedersen National Specialist Biogas and Slurry Separation
Subejcts • Danish Agricultural Advisory Service • Manure handling in Denmark • Biogas in Denmark • Nutritient value in treated manure
Biogas Biogas rests on tree legs Energy Agriculture Environment
Agricultural advantages • Improved fertilizer value of nitrogen • Balanced P and K-balance in slurry • Homogeneous and light fluid • Full declaration of nutrients • Bacteria-free and seedless • Reduced costs for transportation of slurry
Environmental advantages • Reduced nitrate leaching • Reduced odour problems • Reduced green house gas emission • Controlled recycling of organic waste (turns waste into valuable fertilizer)
Mixing and digesting slurry change the characteristic of the slurry
Ammonia evaporation in spring barley 50 -N 40 30 -loss, % of spread NH4 20 10 NH3 0 2002 2003 Untreated pig slurry Digested pig slurry
Improved fertilizer effect of nitrogen- trials in winter wheat Digested slurry, trailing hoses Pig slurry, trailing hoses Cattle slurry, trailing hoses Digested slurry, injected Pig slurry, injected Cattle slurry, injected 0 20 40 60 80 100 N-utilization, % (fertilizer equivalent)
Fertilizer plan for nitrogen for 1 ha grass Per hectare Cattle slurry Digested slurry N-requirement, kg 250 250 N in slurry, kg total 170 170 N-utilization, % 40 60 N- in slurry, utilized, kg 68 102 Mineral fertilizer 182 148 Saved, kg Saved, Euro - - 34 27
N, P, and K in mineral fertilizer Prognosis
N-application in Denmark 450 400 350 300 250 1,000 tonne of N per year 200 150 Fertilizer 100 Manure 50 0 1940 1950 1960 1970 1980 1990 2000 2010
Digested slurry is low on bacteria 6 Test results from Ribe Biogas, bacteria per ml. slurry (1998) Log10 germs per ml. slurry 3 Date Before After Mar. 18 May 13 July 15 Sept. 9 Nov. 11 1,300,000 140,000 690,000 9,000,000 62,000 <5 <5 <5 <5 <5 5 10 Time, weeks Slurry tank, 6-8°C Mesofile biogas, 35°C Thermofile biogas, 53°C
Slurry separation –on treated manure Foto: Bigadan A/S. Foto: Westfalia