During the last decade some so called ‘dry fermentation’ prototype plants were developed for anaerobic digestion of organic material containing 15-50 % total solids. These plants show added advantages com-pared to slurry digestion plants: Less reactor volume, less process energy, less transport capacity, less odour emissions. However on-farm dry fermentation plants are not common and rarely commercially available. This paper reports about an innovative two phase prototype biogas plant designed for continuous digestion of solid dairy cattle manure

Evers, Lars

Granstedt, Artur

Lehto, Marja

Schäfer, Winfried

Sorvala, Sanna

Teye, Frederick

English

Organic Eprints

Ekologiskt lantbrukKonferens 22–23 november 2005Ultuna, UppsalaCentrum för uthålligt lantbruk Sammanfattningarav föredrag och postrar312 ekologiskt lantbruk • konferens • ultuna • november 2005tyder på att populationsprocesser på både lokal och landskapsskala är viktiga för arters fortlevnad i jordbrukslandskapet.Vi kommer också att inom projektet undersöka vilka mekanismer som gör att ekologisk odling gynnar biologisk mångfald. Tillsammans med våra beﬁ  ntliga resultat ger detta strategier för att utveckla den ekologiska odlingen så att effekten för biologisk mångfald blir maximal och det geograﬁ  ska läget optimalt. Projektet är en del av FORMAS’ (Forskningsrådet för miljö, areella näringar och samhällsbyggande) forskningstema ”Den ekologiska pro-duktionens landskapsekologi: växtskydd och biodiversitet”.  1. Rundlöf, M. & Smith, H. G. 2005. The effect of organic farming on biodiversity depends on landscape context. Submitted. 2. Nilsson, H. 2005. Farming practice and landscape effects on bum-blebee diversity and abundance. MSc-thesis, Lund University. 3. Edlund, M. 2005. Will biodiversity of vascular plants increase on two different scales in organic farming? MSc-thesis, Lund University. Two phase continuous di-gestion of solid manure on-farm: Design, mass and nutrient balanceIntroduction/Problem During the last decade some so called ‘dry fermentation’ prototype plants were developed for anaerobic digestion of organic material containing 15–50 % total solids. These plants show added advantages compared to slurry digestion plants: Less reactor volume, less process energy, less trans-port capacity, less odour emissions. However on-farm dry fermentation plants are not common and rarely commercially available. This paper reports about an innovative two phase prototype biogas plant designed for continuous digestion of solid dairy cattle manure.MethodologyManure of a dairy stanchion barn is shifted by a hydraulic powered scraper into the feeder channel of the hydrolysis reactor. The manure is a mixture of faeces, straw and oat husks. From the feeder channel the manure is pressed via a feeder pipe to the top of the 30° inclined hydrolysis reactor of 53m3 capacity. The manure mixes with the substrate sinking down by gravity force. After 22–25 days retention at 38 °C, the substrate is discharged by a bottomless drawer from the lower part of the reactor. Every drawer cycle removes about 0.1 m3 substrate from the hydrolysis reactor to be discharged into the transport screw underneath. From the transport screw the substrate Winfried Schäfer1, Lars Evers2, Marja Lehto1, Sanna Sorvala1, Fre-derick Teye1, Artur Granstedt2, 1 Agricultural Engineering Re-search (VAKOLA), MTT Agrifood Research Finland,e-mail: winfried.schafer@mtt.ﬁ  ,2 Biodynamic Research Institute, Skilleby gård, Järna, e-mail: sbﬁ  @jdb.se313Postersammanfattningarpartly drops into a down crossing extruder screw where it is separated into solid and liquid fractions. The remaining material is conveyed back to the feeder channel and inoculated into the fresh manure. The solid fraction from the extruder screw is stored at the dung yard for composting. The liquid fraction is collected into a buffer and from there pumped into the methane reactor with 17 m3 capacity. Liquid from the buffer and from the methane reactor partly returns into the feeder pipe to improve the ﬂ  ow ability. After 19–21 days retention at 38 °C the efﬂ  uent is pumped into a slurry store covered by a ﬂ  oating canvas. In 2004 we took three times samples from the input manure, solid fraction, efﬂ  uent, straw, and oat husks. Total solids and nutrient content was analysed by HS Miljölab Ltd. in Kalmar, Sweden and Novalab Ltd. in Karkkila, Finland. Volatile solids were analysed at the laboratory of MTT/Vakola. The gas yield of each reactor was measured by a gas meter (Actaris G6 RF1) and the reading was daily recorded. ResultsThe plant produced in average 52 m3 biogas d-1. Maximum yield was 91 m3 d-1 biogas or 0.17 m3 methane kg-1 VS . The solid fraction contained 73±2 % of input VS and the efﬂ  uent 10±2 %. In average 76.3 % of produ-ced methane was used for process heating. Up to 305 kWh d-1 or 56 % of the produced energy was available for heating the farm estate. Composted solid fraction and efﬂ  uent together contained 70-81 % of the total input nitrogen and 94-111% of input NH4. Mass and nutrient balance is shown in the table below.26. October2004FM TS VS Norg Nsol Ntot NH4 NOx K Pkg/d kg/d kg/d kg/d kg/d kg/d kg/d kg/d kg/d kg/dFaeces 2175 199 176 6.05 1.63 7.68 1.08 0.56 10.02 1.40Straw 57 44 37 0.23 0.01 0.24 0.01 0.31 0.05Oat husks 197 181 162 0.56 0.04 0.59 0.01 0.03 1.09 0.20Sum input 2429 424 375 6.83 1.68 8.50 1.09 0.58 11.42 1.65Solid fraction 1189 317 282 3.65 0.75 4.40 0.52 0.23 4.63 0.84Efﬂ  uent 1176 45 31 1.65 1.29 2.94 1.18 0.12 3.76 0.60Biogas 64 62 62Sum output 2429 424 375 5.29 2.04 7.34 1.70 0.34 8.40 1.44Conclusions The two phase prototype biogas plant in Järna is suitable for digestion of organic residues of the farm and the surrounding food processing units. The prototype put many recent research results into practice. But there is still a lack of appropriate technical solutions in terms of handling organic material of high dry matter content, and process optimisation. The inno-vative continuously feeding and discharging technique is appropriate for the consistency and the dry matter content of the organic residues of the farm. It is probably not suitable for larger quantities of unchopped straw or green cut.  

Two phase continuous digestion of solid manure on-farm: design, mass and nutrient balance

Jukuri

Ekologiskt lantbrukKonferens 22–23 november 2005Ultuna, UppsalaCentrum för uthålligt lantbruk Sammanfattningarav föredrag och postrar312 ekologiskt lantbruk • konferens • ultuna • november 2005tyder på att populationsprocesser på både lokal och landskapsskala är viktiga för arters fortlevnad i jordbrukslandskapet.Vi kommer också att inom projektet undersöka vilka mekanismer som gör att ekologisk odling gynnar biologisk mångfald. Tillsammans med våra befi ntliga resultat ger detta strategier för att utveckla den ekologiska odlingen så att effekten för biologisk mångfald blir maximal och det geografi ska läget optimalt. Projektet är en del av FORMAS’ (Forskningsrådet för miljö, areella näringar och samhällsbyggande) forskningstema ”Den ekologiska pro-duktionens landskapsekologi: växtskydd och biodiversitet”.  1. Rundlöf, M. & Smith, H. G. 2005. The effect of organic farming on biodiversity depends on landscape context. Submitted. 2. Nilsson, H. 2005. Farming practice and landscape effects on bum-blebee diversity and abundance. MSc-thesis, Lund University. 3. Edlund, M. 2005. Will biodiversity of vascular plants increase on two different scales in organic farming? MSc-thesis, Lund University. Two phase continuous di-gestion of solid manure on-farm: Design, mass and nutrient balanceIntroduction/Problem During the last decade some so called ‘dry fermentation’ prototype plants were developed for anaerobic digestion of organic material containing 15–50 % total solids. These plants show added advantages compared to slurry digestion plants: Less reactor volume, less process energy, less trans-port capacity, less odour emissions. However on-farm dry fermentation plants are not common and rarely commercially available. This paper reports about an innovative two phase prototype biogas plant designed for continuous digestion of solid dairy cattle manure.MethodologyManure of a dairy stanchion barn is shifted by a hydraulic powered scraper into the feeder channel of the hydrolysis reactor. The manure is a mixture of faeces, straw and oat husks. From the feeder channel the manure is pressed via a feeder pipe to the top of the 30° inclined hydrolysis reactor of 53m3 capacity. The manure mixes with the substrate sinking down by gravity force. After 22–25 days retention at 38 °C, the substrate is discharged by a bottomless drawer from the lower part of the reactor. Every drawer cycle removes about 0.1 m3 substrate from the hydrolysis reactor to be discharged into the transport screw underneath. From the transport screw the substrate Winfried Schäfer1, Lars Evers2, Marja Lehto1, Sanna Sorvala1, Fre-derick Teye1, Artur Granstedt2, 1 Agricultural Engineering Re-search (VAKOLA), MTT Agrifood Research Finland,e-mail: winfried.schafer@mtt.fi ,2 Biodynamic Research Institute, Skilleby gård, Järna, e-mail: sbfi @jdb.se313Postersammanfattningarpartly drops into a down crossing extruder screw where it is separated into solid and liquid fractions. The remaining material is conveyed back to the feeder channel and inoculated into the fresh manure. The solid fraction from the extruder screw is stored at the dung yard for composting. The liquid fraction is collected into a buffer and from there pumped into the methane reactor with 17 m3 capacity. Liquid from the buffer and from the methane reactor partly returns into the feeder pipe to improve the fl ow ability. After 19–21 days retention at 38 °C the effl uent is pumped into a slurry store covered by a fl oating canvas. In 2004 we took three times samples from the input manure, solid fraction, effl uent, straw, and oat husks. Total solids and nutrient content was analysed by HS Miljölab Ltd. in Kalmar, Sweden and Novalab Ltd. in Karkkila, Finland. Volatile solids were analysed at the laboratory of MTT/Vakola. The gas yield of each reactor was measured by a gas meter (Actaris G6 RF1) and the reading was daily recorded. ResultsThe plant produced in average 52 m3 biogas d-1. Maximum yield was 91 m3 d-1 biogas or 0.17 m3 methane kg-1 VS . The solid fraction contained 73±2 % of input VS and the effl uent 10±2 %. In average 76.3 % of produ-ced methane was used for process heating. Up to 305 kWh d-1 or 56 % of the produced energy was available for heating the farm estate. Composted solid fraction and effl uent together contained 70-81 % of the total input nitrogen and 94-111% of input NH4. Mass and nutrient balance is shown in the table below.26. October2004FM TS VS Norg Nsol Ntot NH4 NOx K Pkg/d kg/d kg/d kg/d kg/d kg/d kg/d kg/d kg/d kg/dFaeces 2175 199 176 6.05 1.63 7.68 1.08 0.56 10.02 1.40Straw 57 44 37 0.23 0.01 0.24 0.01 0.31 0.05Oat husks 197 181 162 0.56 0.04 0.59 0.01 0.03 1.09 0.20Sum input 2429 424 375 6.83 1.68 8.50 1.09 0.58 11.42 1.65Solid fraction 1189 317 282 3.65 0.75 4.40 0.52 0.23 4.63 0.84Effl uent 1176 45 31 1.65 1.29 2.94 1.18 0.12 3.76 0.60Biogas 64 62 62Sum output 2429 424 375 5.29 2.04 7.34 1.70 0.34 8.40 1.44Conclusions The two phase prototype biogas plant in Järna is suitable for digestion of organic residues of the farm and the surrounding food processing units. The prototype put many recent research results into practice. But there is still a lack of appropriate technical solutions in terms of handling organic material of high dry matter content, and process optimisation. The inno-vative continuously feeding and discharging technique is appropriate for the consistency and the dry matter content of the organic residues of the farm. It is probably not suitable for larger quantities of unchopped straw or green cut.  

Two phase continuous digestion of solid manure on-farm: design, mass and nutrient balance

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