Anaerobic Digestion Basics

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1 Anaerobic Digestion Basics Stanley (Jay) Solomon, Jr. Extension Educator East Peoria Center Ted Funk, PhD, PE Dept of Agric. and Biological Eng. University of Illinois at Urbana- Champaign

2 Manure Happens Make the Best of It

3 Types of manure treatment Physical Chemical Biological

4 Phases of treatment Primary Secondary Tertiary

5 What is Anaerobic Digestion? an aer o bic (Merriam-Webster on-line) Function: adjective 1 a : living, active, occurring, or existing in the absence of free oxygen <anaerobic respiration> <anaerobic bacteria>

6 What is Anaerobic Digestion? di ges tion (Merriam-Webster on-line) Function: noun b:the process in sewage treatment by which organic matter in sludge is decomposed by anaerobic bacteria with the release of a burnable mixture of gases

7 REAL BASIC anaerobic digestion an extension of the gut First Phase: Liquefaction Second Phase: Gasification Biogas Complex organic material (manure) Low odor effluent Acid-forming bacteria Methaneforming bacteria

8 Engineered Storage Products Inc.

9 The Neighbor Factor

10 Benefits possible with digester Less farm odor Better fertilizer Source of revenue Heat source Recycled bedding material (dairy) Pathogen reduction Weed seeds killed Other

11 Biodegradability Ultimate is about 40-60% of volatile solids, or 0.32 to 0.48 m 3 CH 4 /kg VS. Limited by hydraulic retention time.

12 Biogas Content Methane Carbon dioxide Water Hydrogen sulfide Nitrogen

13 Biogas Yields* Swine 150 lb. Dairy 1,400 lb. Beef 1,100 lb. high energy diet Lb VS/day Max yield ft 3 /day Energy/day therm 60:40 CH 4 :CO *60% conversion of VS to CH 4, mesophilic conditions

16 Biogas use

17 Biogas Quality (CH 4 -CO 2 ratios attained) usually CH 4 % with CSTR up to 87 CH 4 % with attached-film

18 Lagoon Batch Fed-batch Sequencing batch Completely-mixed Plug-flow Staged Attached-film Reactor designs

19 Collection for high-solids, plug flow system Collection via Manure Scraper

20 Liquid/solid separation primary and/or tertiary treatment?

21 Solids Separated Another waste stream? Or economic opportunity?

22 Fundamental Challenges in Digester Design Hydraulic retention time longer retention is better but bigger higher solids manure is harder to pump but smaller digester needed Microbial washout how to keep the bugs in the digester

23 Continuous v. batch digestion

24 How to keep the bugs in the digester attached film

25 Fundamental Challenges in Digester Design Settling and clogging mechanical failures and reduction of reactor volume capacity Constant temperature control heat requirements in winter

26 What happens to the energy produced energy budget Mixed digester may use 15% for mixing Heated digester may use up to 100%+ in winter for heating digester, heating influent feedstock (especially frozen manure)

27 Fundamental Challenges in Digester Design Digestive upsets full-scale die-off of the microorganisms you need Mixing to get incoming feedstock warmed and inoculated quickly to reduce settling

28 Extra care needed to make digester work Avoid microbe killers antibiotics, heavy metals, Rumensin Frequent feeding, fresh manure

29 Does Bedding Digest?

30 pumps liq/sol separation storages surge tanks Extra stuff needed for digester system

31 Post-digestion collection/transfer pit

32 Gen-set, gas cleaning, and heat recovery for Hunter Haven Dairy

33 Lagoon for digester effluent

34 Dairy digester effluent, no liquid/solid separation used

35 Effects of Digestion on Manure Lower odor potential Weed seeds killed Pathogens greatly reduced Water pollution potential (BOD) reduced Nitrogen, phosphorus, and potassium concentrations in the liquid are virtually unchanged Plant-available nitrogen somewhat different Liquid volume virtually unchanged

36 Effluent and solids use

37 Where does anaerobic digestion fit? Manure stabilization Odor reduction Energy production waste heat, biogas, electricity via engine genset or fuel cell Carbon trading

38 Haubenschild Dairy Manure Digester, Princeton, MN AgSTAR Charter Farm

39 Swine manure digester, Hunan Province, PRC

40 Potential for Digesters in Illinois CAFOs about 870 (swine, beef, dairy, poultry layers) of scale even remotely of interest today for digester installation

41 Potential for Digesters in Illinois Beef: 200 operations, about 210,000 head on feed Dairy: 80 large operations, 29 % of total cows in this group, 103,000 head state total or 30,000 head Swine: 74% in the size group 2,000+ head; 590 operations, 4.2 million head +/- Poultry: very small number of large operations

42 Illinois Biogas Yields* Potential Swine 150 lb. Dairy 1,400 lb. Beef 1,100 lb. high energy diet Lb VS/day Max yield ft 3 /day x 4.2 million x 30, x 210,000 *60% conversion of VS to CH 4, mesophilic conditions

43 Swine 150 lb. Dairy 1,400 lb. Beef 1,100 lb. high energy diet Illinois Biogas Potential 75 million Therms/yr.? Lb VS/day Max yield ft 3 /day Energy/yr 60:40 CH 4 :CO 2, No losses e6 49,000, e6 6,000, e6 20,000,000 *60% conversion of VS to CH 4, mesophilic conditions

44 Leefer Beef Unit Carlinville, IL, May 1981

45 Principle is the same the names have changed

Farm Digesters and Digestion 101 by Mark Moser

Farm Digesters and Digestion 101 by Mark Moser A Promising Solution - Anaerobic Digestion Technology Anaerobic digestion is one of the few manure treatment options that reduces the environmental impact