MANURE TREATMENT

1. MANURE TREATMENT Klaas Castelyn Elke Declerck Sam Gielen Mathieu Goudeseune Kris Van de Vyvere

2. Wetgeving

3. Manure - Intro • 25,5 million chickens • 5,8 million pigs • 1,3 million beefs • 186.000 other animals • ------------------------------- • Total: 33 million animals • 16 million Kg N • 60 million Kg N • 80 million Kg N • 3 million Kg N • ------------------------ • 160 million Kg N/year Sam Gielen - Presentatie Milieutechnische Constructies

4. Manure - Intro Sam Gielen - Presentatie Milieutechnische Constructies

5. Manure - Applications  Organic Fertilizer Invention of artificial fertilizer leads to manure surplus and eutrofication  manure processing Sam Gielen - Presentatie Milieutechnische Constructies

6. Manure – Legal Issues European Community • A regulation is a legislative act of the European Union which becomes immediately enforceable as law in all member states simultaneously. • A directive is a legislative act of the European Union which requires member states to achieve a particular result without dictating the means of achieving that result. • Nitrate Directive (1991) – Nitrate level of 50 mg /L • Water Framework Directive, NEC Directive Sam Gielen - Presentatie Milieutechnische Constructies

7. Manure – Legal Issues Regional Level Flanders • Mestdecreet • Oprichting Mestbank • Emmisienormen (170 Kg/ha) • Nitraatresidu • Uitscheidingsnormen • Emissierechten • Mestverwerking Sam Gielen - Presentatie Milieutechnische Constructies

8. Manure - Solutions • Livestock Reduction Sam Gielen - Presentatie Milieutechnische Constructies

9. Manure - Solutions Sam Gielen - Presentatie Milieutechnische Constructies

10. Manure - Balance Sam Gielen - Presentatie Milieutechnische Constructies

11. Manure - Waterquality Sam Gielen - Presentatie Milieutechnische Constructies

13. Pre-treatment Pre- treatment can help to improve fermentation and reduce the volume. • Microwave pre-treatment • Ultrasonic pre-treatment • Heat pre-treatment • Acid pre-treatment • Caustic pre-treatment • …

14. Anaerobic Digestion? Breakdown of organic material by microbial population working together in an oxygen free environment. Biogas Methane: 55 – 65 % Carbon dioxide: 35 – 45 %

15. Goals Primary goals: • Energy production (electricity, hot water, steam) • Reduce the mass of solids Secundairy goals: • Pathogen destruction • Pretreatment for nutrient recovery • Reduction of odors • Reduced greenhouse gas emissions • Conversion to more available N (N to NH3). • Improved flow properties • Improved fertilizer efficiency

16. Digestion

17. Options Wet or dry digestion? • Wet: up to 15% DS • Dry: 20 – 40 % DS • Pig manure: 6 – 10 % DS • Chicken manure: higher, but little structure  dry digestion not possible Single or multi step digestion? • Multi step: methanogenesis seperated from hydrolyse, fermentation and acetogenesis  expensive

18. Controlling factors • The type of waste being digested • Its concentration • Its temperature • The presence of toxic materials • The pH and alkalinity • The hydraulic retention time • The solids retention time • The ratio of food to microorganisms • The rate of digester loading • The rate at which toxic end products of digestion are removed

19. Controlling factors Waste Characteristics • Lignin and other some other hydrocarbons • High nitrogen and sulfur concentrations • Watersoluble Dairy Manure Composition (Stafford, Hawkes et al. 1980)

20. Controlling factors Dilution of Waste • Reduce the concentration of inhibitory constituents • Stratification • Intense mixing Foreign Materials • Animal bedding, sand and silt

21. Controlling factors Toxic Materials • fungicides and antibacterial agents • small quantities of toxic materials Nutrients • C/N < 43 • C/P < 187 • Excreted manure: C/N ratio of 10

22. Controlling factors Temperature Psychrophilic AD: • T < 20 °C Mesophilic AD: • T: 30-35 °C • retention time: 15-30 days Thermophilic AD: • T > 55 °C • retention time: 12-14 days • able to destroy a larger number of pathogens • more costly and complicated

23. Controlling factors Hydraulic Retention Time (HRT) • The number of days the materials stays in the tank. HRT = V/Q • It establishes the quantity of time available for bacterial growth and subsequent conversion of the organic material to gas. Solids Retention Time (SRT) • digester stability • It is the quantity of solids maintained in the digester divided by the quantity of solids wasted each day.

24. Controlling factors Food to Microorganism Ratio • the key factor • the bacterial consortia can only consume a limited amount of food each day • F/M ratio: the ratio of the pounds of waste supplied to the pounds of bacteria available to consume the waste is the food to microorganism ratio • A lower F/M ratio: greater percentage of waste converted to gas

25. Controlling factors End Product Removal • adversely affect the digestion process • organic acids, ammonia nitrogen, and hydrogen sulfide. • lowering the influent waste concentration or elutriation pH • between 6.8 and 8.5 Digester Loading (kg / m3 / d) • diluted or concentrated? • size and performance?

26. Digester Types Low rate processes: • covered anaerobic lagoons • plug flow digesters • mesophilic completely mixed digesters High rate processes: • thermophilic completely mixed digesters • anaerobic contact digesters • hybrid contact/fixed film reactors

27. Digester Types Anaerobic Lagoons (Very Low Rate) • covered ponds • at psychrophilic or ground temperatures • low gas production rates • long retention time • high dilution factor • seasonal variations • lowcost

28. Digester Types Completely Mixed Digesters (Low Rate) • heated and mixed • mesophilic range • thermophilic range • intense mixing • reasonable conversion of solids to gas. • high cost of installation • energy cost

29. Digester Types • Plug Flow Digesters (Low Rate) • the least expensive • horizontal or vertical reactor • simple, economical system • heated • stratification • removing of solids

30. Digester Types Contact Digesters (High Rate) • separating and concentrating the solids in a separate reactor and returning the solids to the influent. • degradable waste can be converted to gas since • completely mixed or plug flow • thermophilic or mesophilic range • dilute and concentrated waste

31. Digester Types Sequencing Batch Reactors (High Rate) • digestion and separation in the same tank • separation gravity • a more dilute, screened waste is treated Contact Stabilization Reactors (High Rate) • more efficient • efficiently converting slowly degradable materials in a highly concentratedreactor

32. Digester Types not appropriate for digesting manure: • ‘High rate’ digesters which retain bacteria • Not effective in converting particulate solids to gas • Clogging

33. Summary of Process Attributes

34. Co-digestion Benefits of Co-digestion: • improved nutrient balance and digestion • equalization of particulate, floating, settling, acidifying • additional biogas collection • possible gate fees for waste treatment • additional fertilizer (soil conditioner) reclamation • renewable biomass (“Energy Crops”) disposable for digestion in agriculture.

35. Co-digestion Drawbacks of Co-digestion: • increased digester effluent chemical oxygen demand (COD) • additional pretreatment requirements • increased mixing requirements • high utilization degree required • hygienisation requirements • restrictions of land use for digestate • crop costs and yield

36. Co-digestion Primary Waste Streams that can be digested with Manure? • Energy crops • Remains of agriculture and horticulture products • Remains of food industry • Secundairy materials • Animal waste category II • Animal waste category III

37. Some examples: • Food Industry: • Breweries • Potato Processing • Sugar Beet Processing • Dairy Processing • Meat Processing and Rendering Facilities • Catering, Institutional, Domestic, and Restaurant Wastes • Grain Industry: • Ethanol Plants with Wet and Dry Distillers Grains • Damaged Grains • Biodiesel Plants • Soybean Processing • Grain Milling Wastes • Crop Residues: • Corn Stover • Alfalfa or other Legumes • Switch Grass and Small Grains

38. Capacity • In agricultural area: maximum 60 000 ton/y of which minimum 60 % homegrown manure en crops • In industrial area: no limitations

39. Energy Production

40. Energyproduction • function of the conversion of volatile solids to gas. • 1kg volatile solids destroyes = 2.81 m³ methane • 1 m³ methane = 1060 kJ • at conversion efficiency 35 %  1 kg of volatile solides = 0,29 kWh of energy

41. Loading rates: • Conventional Digesters: 2 – 10 kg/m³/d • Lagoon: 0.04 kg/m3/d Expected Percentage VS Conversion to Gas

42. Costs

45. Solids separation of animal manure • Goal • Methods • Gravity settling • Mechanical separation • Screen separators • Screw presses • Belt-filter presses • Centrifuge • Comparison • Flocculents and polymers • Summary

46. Goal liquid fraction • Raw manure solid fraction • Load reduction for subsequent processes • Making handle fractions (recovering of C, N, P, K, Mg, (water) • Odor reduction

47. Disadvantages: Large size requirement High construction costs Requires loader to remove solids Methods • Gravity settling The use of settling tanks or basin with sloped access area where solids settle by gravity Advantages: Treatment of thin sowmanure (< 6% d.s.) Stockage & sales costs ↓ Easy to operate/install

48. Methods • Mechanical separation “technical efficiency”: part of P2O5 & N in solid fraction (preferable as high as possible) • Screen separators • cheap and simple • perforated plate • d.s. in solid fraction 6-10% (vibrating screens  12-21%)

49. Screw presses • Rotatable screw supplies for increasing pressure • Closed design • Belt-filter presses • Two belts (support-sieving & pressure belt) • Adaptable pressure (kind of manure dependant) • Continu washing • Efficiency ↑ with polymers

50. Centrifuge • Density solid and liquid material! • Centrifugal force • Very efficient, ↑ with polymer (wetter cake) • Expensive