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Anaerobic Digestion of DairyManure Influenced by the WastedMilk from Milking OperationsX. Wu, C. Dong, W. Yao, J. ZhuDept....
Introduction• Milking parlor generates milk contaminatedwater ending up in manure lagoon• Milk has high COD (190,000 mg/L)...
Objectives and procedures• Investigate the overall response of co-digesting dairy manure with milk using lab-scale batch a...
Objectives and procedures• Fresh dairy manure was collected from adairy farm equipped with a scraped manurehandling system...
Results• Increasing milk content increasescumulative biogas production
Results• Increasing milk content increasescumulative biogas production0200040006000800010000120000 2 4 6 8 10 12 14 16 18 ...
Results• Maximum biogas production rate for eachtreatment can be obtained by the slopes of thevolume curves.10141822260 3 ...
Results• Milk effect on COD reduction and TKNThe average values of COD and TKN for the batch digestion process with differ...
ConclusionThe following conclusions can be reached based onthe data from this study.• Added milk will increase biogas volu...
Dairy Manure Digestion Influenced by Wasted Milk from Milking Operations
Dairy Manure Digestion Influenced by Wasted Milk from Milking Operations
Dairy Manure Digestion Influenced by Wasted Milk from Milking Operations
Dairy Manure Digestion Influenced by Wasted Milk from Milking Operations
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Dairy Manure Digestion Influenced by Wasted Milk from Milking Operations

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Proceedings available at: http://www.extension.org/67645

Anaerobic digestion has many advantages both environmentally and economically. First, it produces renewable energy in the form of methane, a renewable energy source, which leads to a steady increase in the number of anaerobic manure digesters in the United States. According to the report from the World Dairy Expo held in Madison, Wisconsin in 2009 (Expo'09, 2009), the US dairy industry is taking the lead in adopting anaerobic technology because the majority (over 75%) of operating US manure digesters is installed on dairy farms. It is anticipated that this trend will continue as the country has determined to reduce its reliance on ever diminishing fossil-based energy resources.

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Dairy Manure Digestion Influenced by Wasted Milk from Milking Operations

  1. 1. Anaerobic Digestion of DairyManure Influenced by the WastedMilk from Milking OperationsX. Wu, C. Dong, W. Yao, J. ZhuDept. of Bioproducts and BiosystemsEngineeringUniversity of Minnesota
  2. 2. Introduction• Milking parlor generates milk contaminatedwater ending up in manure lagoon• Milk has high COD (190,000 mg/L)• Lagoon digesters are the commonly usedtype on current dairy farms• What will be the impactof milk on digesterfunction in terms ofbiogas production?
  3. 3. Objectives and procedures• Investigate the overall response of co-digesting dairy manure with milk using lab-scale batch anaerobic digesters• Milk was added to manure at 7 differentlevels, i.e., 1, 3, 5, 7, 9, and 14%• Evaluation was basedon total biogas volumeproduced, methanecontent, and otherchemical variables
  4. 4. Objectives and procedures• Fresh dairy manure was collected from adairy farm equipped with a scraped manurehandling system• Raw milk for the experiment was obtainedfrom another dairy farm close toWaseca, MN• One control digester without milk additionwas run side by side with the milk treateddigesters• Biogas composition was determined foreach digester every two days using a GC
  5. 5. Results• Increasing milk content increasescumulative biogas production
  6. 6. Results• Increasing milk content increasescumulative biogas production0200040006000800010000120000 2 4 6 8 10 12 14 16 18 20Totalbiogasproduced(mL)Percent of milk added (%)
  7. 7. Results• Maximum biogas production rate for eachtreatment can be obtained by the slopes of thevolume curves.10141822260 3 6 9 12 15 18 21Biogasproductionrate(mL/h)Percent milk added (%)
  8. 8. Results• Milk effect on COD reduction and TKNThe average values of COD and TKN for the batch digestion process with different milk content1Milk content COD (mg/L)*TKN (mg/L) C/N ratio2Initial Final Reduction Initial Final Reduction Initial Final3(%) (%)40 (Control) 14500 7300 49.7 2794 2742 1.9 5.19 2.6651% 15561 7700 50.5 2817 2792 0.9 5.52 2.7663% 17683 7300 58.7 2863 2840 0.8 6.18 2.5775% 19805 8100 59.1 2909 2794 4.0 6.81 2.8987% 21927 8300 62.1 2955 2908 1.6 7.42 2.8599% 24049 7600 68.4 3002 2970 1.0 8.01 2.561014% 29354 7800 73.4 3117 3080 1.1 9.42 2.531119% 34659 7700 77.8 3232 3206 0.8 10.7 2.401213*COD – chemical oxygen demand; TKN – total Kjeldahl nitrogen1415
  9. 9. ConclusionThe following conclusions can be reached based onthe data from this study.• Added milk will increase biogas volumetricproduction and the maximum biogas productionrate as compared to the control (7 and 18% vs. 1and 3%).• Added milk will reduce the methane content in thebiogas produced, thus increasing CO2 production.To avoid excessive CO2 production, the milkcontent in the digester liquid should be ≤ 3%.• Added milk will increase COD removal efficiencyfrom 49.7% (no milk) to 77.8% (19% milk)

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