Download Designing a Swine Waste Treatment System for Organic Cacao Farming in Mayapan, Belize and more Study notes Civil Engineering in PDF only on Docsity! 1 Mayapan, Belize Swine Waste Treatment System SML Engineering Inc. Statement of the Problem Design a system to treat pig waste for use as fertilizer for organic cacao crops – Government funded – Limited technology – Treatment system smaller than others built Mayapan, Belize Soil and Pig Waste Characteristics 10 to 25 Pigs Expected Waste is 10% Solids C:N:P:K = 7:1:0.38:0.53 Produce 4 to 13 pounds of Waste per Day Rainforest Soil is Devoid of Virtually All Nutrients Cacao grown is Organic Cacao Two Harvest Peaks: Jan-Feb; Mar-June Ripe Pod Contains about 40 Seeds Seeds are Dried and Fermented to Cocoa Beans Future Conditions Current design for 1 organic cacao farmer – 10 total farmers in Mayapan – 3 are successful at organic cacao farming Total crop area not expected to increase 2 N P K Ideal Nutrients for Cacao Trees 39% 4% 57% Raw Solid Pig Waste Nutrients 6.6% 2.5% 3.5% Standard Store Bought Fertilizer 30% 10% 10% Product Goals Product Goals Pathogen Destruction – Main route of destruction through elevated temperature – Other physical and chemical disinfectants not feasible because of energy, money or other reasons Using Bacteria to Make Fertilizer “Good” bacteria that treat waste are not the same as “bad” pathogenic bacteria Types of Bacteria – Aerobic – Anaerobic • Methanogens Constraints and Criteria Non-cost Criteria (50%) 1. Quality of resulting fertilizing agent (10%) 2. Long-term effectiveness/ reliability (9%) 3. Protection of human health and environment (7%) 4. Community acceptability (7%) 5. Maintenance effort (7%) 6. Expandability of the treatment unit (5%) 7. Positive byproducts such as biogas (3%) 8. Odor (2%) Cost Criteria (50%) 1. Capital Cost (30%) 2. Operation and maintenance over lifetime (20%) Alternatives Anaerobic Digestion Anaerobic/Aerobic Digestion Composting Anaerobic Batch Reactor Anaerobic Digestion Reactor 1 Homogenization Reactor 3 Anaerobic Digester Reactor 2 Anaerobic Digester Pigpen Methane Recovery Fertilizer 5 Uses of Biogas Cooking on Biogas Stove Run a Biogas fueled generator to create electricity Operational and Startup Information The system startup should be seeded with cow manure 20% of the biomass should be left behind after each cycle The system should be mixed at least twice a day for ten minutes The waste will need to be diluted by an equal amount of water Final Capital Cost Materials Total Cost 2" PVC Pipe $7.88 4" PVC Pipe $1.22 Pipe fittings (caps, etc)* $126.00 1250 L (330 Gallon) Tank $2,520.00 Shovel/Scoop $20.00 Heavy-duty Wheelbarrow $50.00 Methane Recovery System $500.00 Total $3,225 Schedule 2-5 Days for Construction 2 months to fine tune residence times, percentage of recycle, and dilution factor Vampire Bat Problems Vampire bats in Mayapan often bite the pigs The pigpen needs to have a physical barrier from the bats Total Cost $270 Additional Considerations The system would be experimental as the smallest system we found in research had a 10,000 liter reactor. In a co-op system the benefits would be much greater as electricity production could be considered. For a co-op system much larger reactors built of concrete would need to be designed, however design principals previously discussed would still be valid 6 Questions ? SML Engineering Inc.
