Anaerobic Digestion Smallacale Dorothee Spuhler seecon gmbh Anaerobic

Anaerobic Digestion (Small-acale) Dorothee Spuhler, seecon gmbh Anaerobic Digestion (Small-scale)

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Find this presentation and more on: www. sswm. info. Contents 1. Concept 2. How can it optimise SSWM 3. Design principals 4. Treatment efficiency 5. Operation and maintenance 6. Applicability 7. Advantages and disadvantages 8. References Anaerobic Digestion (Small-scale) 3

Find this presentation and more on: www. sswm. info. 1. Concept Background Small-scale anaerobic biogas reactors are very common in agricultural regions in industrialised as well as developing countries. Because this plants not only allow the treatment of wastes (manure, green waste, toilet products) but also result in the on-site production of a renewable energy source, such plants have been widely disseminated by many rural developing programmes in the past 30 years. In Nepal for instance more than 200’ 000 such plants have been constructed in the past 20 years. The main features of small-scale anaerobic biogas reactors are: • Requires animal dung (rich in organic matter and high productions yields) to produced sufficient energy for the household • Can co-treat toilet products and kitchen or garden waste (green waste) • Depend on relatively high daily mean temperature as anaerobic digestion, the process which produces biogas slows down drastically with decreasing temperatures. Anaerobic Digestion (Small-scale) 4

Find this presentation and more on: www. sswm. info. 1. Concept Background On-site recycling of nutrients and energy Toilet, Kitchen and Garden Waste + Manure Adapted from: http: //www. seco. cpa. state. tx. us/energy-sources/biomass/images/manurebiogas. gif [Accessed: 30. 05. 2010] Anaerobic Digestion (Small-scale) 5

Find this presentation and more on: www. sswm. info. 1. Concept What are Small-Scale Anaerobic Digesters? … Airtight reactors, typically designed to produce biogas at the household or community level. Biogas is produced by the conversion of green waste by a process called anaerobic digestion. During anaerobic digestion, microorganism transform organic matter contained in the wastes into biogas The produced biogas can be used either directly for coocking, heating or lightening or be transformed into combined heat and power (CHP) in small cogeneration plants. With time the reactors fill up and digested sludge (sludge which organic fraction was already converted to biogas) accumulates in the bottom. Nutrients remain in the sludge, which is a well-balanced soil amendment. Toilets can be linked to the reactors and co-digested with the animal dung, but biogas production from human manure is only low and therefore animal dung and green wastes are required to cover a familiy’s needs. Anaerobic Digestion (Small-scale) 6

Find this presentation and more on: www. sswm. info. 1. Concept “The Ecocylce of biogas” What are Small-Scale Anaerobic Digesters? Coocking Cattle Dung / Manure Lightning Toilet Products (Excreta, Faeces) Biogas Heating Kitchen / Garden Organic Waste (Green Waste) Electricity Fuel Fertiliser Anaerobic Digestion (Small-scale) D. Spuhler (2010), Adapted from: www. kristianstad. se; http: //www. newseedadvisors. com/2009/09/10/invest/ ; http: //www. hydroharrys. com/hydroharrys_about_fertilizer. php and www. clker. com [Accessed: 02. 06. 2010] 7

Find this presentation and more on: www. sswm. info. 1. Concept Possible Benefits for Users: Under the right conditions a biogas plant yields several benefits to end-users • Social: ◦ Improved sanitation: reduction of pathogens, worm eggs and flies ◦ Reduction of workload: less firewood collection, better cooking performance ◦ Improved indoor air quality: less smoke and harmful particle emission of biogas stove compared to wood or dung fuels; • Environmental ◦ Production of green energy ◦ Reduction of greenhouse gas emission ◦ Organic fertilizer production • Economical: ◦ Better Health more work capacity ◦ Fertilizer, better crop yields, better Health ◦ Fuel substitution Anaerobic Digestion (Small-scale) 8

Find this presentation and more on: www. sswm. info. 1. Concept Possible Benefits for Users: Reduced indoor pollution Source: M. WAFLER Coocking with fuelwood Anaerobic Digestion (Small-scale) Source: M. WAFLER Biogas stove 9

Find this presentation and more on: www. sswm. info. 1. Concept What is Anaerobic Digeastion ? (1/3) Degradation of organic material by bacteria. In the absence of air (anaerobic). Four stages: • Hydrolisis ◦ Cleavage of a chemical compound through the reaction with water. ◦ Insoluble complex molecules are bracken down to short sugars, fatty acids and amino acids. • Fermentation (Acidogenesis) ◦ Products from hydrolysis are transformed into organic acids, alcohols, carbon dioxide (CO 2), hydrogen (H) and ammonia (NH 3). • Acetogenesis ◦ Organic acids and alcohols are converted into hydrogen (H 2), carbon dioxide (CO 2) and acetic acid (CH 3 COOH). Therefore, oxygen is consumed anaerobic conditions are created • Methanogenesis ◦ Methanogenic bacteria (methanogenesis), transform the acetic acid, carbon dioxide and hydrogen into biogas. Anaerobic Digestion (Small-scale) 10

Find this presentation and more on: www. sswm. info. 1. Concept What is Anaerobic Digestion ? (2/3) D. SPUHLER (2010) Anaerobic Digestion (Small-scale) 11

Find this presentation and more on: www. sswm. info. 1. Concept What is Anaerobic Digestion ? (3/3) Source: http: //water. me. vccs. edu/courses/ENV 149/changes/Feat 11_pi c. II-1. jpg [Accessed: 02. 06. 2010] Anaerobic Digestion (Small-scale) 12

Find this presentation and more on: www. sswm. info. 1. Concept What is Biogas ? Biogas is a mixture of methane and carbon dioxide. The properties of biogas are similar to the ones of natural gas. Biogas is the common name for the mixture of gases released from anaerobic digestion. Typically biogas is composed of: Methane (CH 4) Carbon Dioxide (CO 2) Hydrogen (H) Nitrogen (N 2) Hydrogen sulphide (H 2 S) 50 to 75 % 25 to 50 % 5 to 10 % 1 to 2 % Traces Sources: YADAV & HESSE (1981); FAO (1996); PIPOLI (2005); GTZ (2009 Source: MUENCH (2008) Methane is the valuable part of the biogas. Biogas that contains about 60 to 70 % of CH 4 has a calorific value of about 6 k. Wh/m 3 what corresponds to about half an L of diesel oil. (ISAT/GTZ 1999, Vol. I) Anaerobic Digestion (Small-scale) 13

Find this presentation and more on: www. sswm. info. 1. Concept Examples: Small-scale Biogas plants Source: M. WRIGHT, Ashden Awards Biogas plant for cow dung, Padli village (India) Anaerobic Digestion (Small-scale) Source: M. WRIGHT, Ashden Awards 14

Find this presentation and more on: www. sswm. info. 1. Concept Examples: Small-scale Biogas Plants Biogas lamp Source: M. WRIGHT, Ashden Awards Anaerobic Digestion (Small-scale) Adding greywater to the biogas reactor to optimise moisture conditionss 15

Find this presentation and more on: www. sswm. info. 1. Concept Examples Small-scale Biogas Plants The “Mudbooster” Plant Source: UNKNOWN Anaerobic Digestion (Small-scale) 16

Find this presentation and more on: www. sswm. info. 1. Concept Examples Small-scale Biogas Plants Source: C. RIECK (2009) Wet clay is used to fit the concrete lid of the manhole gas-tight. Source: Su. San. A Biogas outlet and manhole with remouvable cover from a underground biogas plant Installed by the NGO TED in Maseru, Lesotho (Susana) Anaerobic Digestion (Small-scale) Source: C. RIECK (2009) The manhole is filled with water to keep the clay sealing wet and gas tight. Gas leackage would be indicated by bubbles. 17

Find this presentation and more on: www. sswm. info. 2. How it can optimize SSWM Biogas plants can contribute to sustainable sanitation Biogas plants transform traditional manure management; reducing CH 4 and CO 2 emission Anaerobic Digestion (Small-scale) Biogas substitutes conventional energy sources, reducing reliance on fossil fuel and firewood (CO 2) Digested sludge can substitute chemical fertiliser D. SPUHLER (2010), adapted from: http: //www. terranet. or. id/mitra/dewats/photo/masukan 1256. jpg; http: //www. borda-sea. org/modules/cjaycontent/index. php? id=6; http: //whrefresh. com/wpcontent/uploads/2010/01/potato_field. jpg; http: //www. greenspec. co. uk/images/energy/CHP/chp 2. gif]; http: //peda. gov. in/eng/images/ruralbiogas-plant_179. jpg; [Accessed: 30. 05. 2010], BPO (2006) and BUNNY (n. y. ) 18

Find this presentation and more on: www. sswm. info. 1. Concept Examples: Biogas Appliances Biogas lamps K. P. Pravinjith Biogas cooking stoves Krämer (TBW) PBO (2006) M. Wafler Chang Mai Biogas generator Anaerobic Digestion (Small-scale) Biogas rice cooker Biogas boiler Source: UNKNOWN 19

Find this presentation and more on: www. sswm. info. 3. Design Principals Basics: Process Parameters Anaerobic digestion = Biological system of bacteria Optimal conditions required that bacteria feel wealthy… • Temperature ◦ Performance ◦ Retention time • p. H: Wide range, but methanogenesis requires neutrality (6. 5 -7. 5). (MES et al. 2003) • Total solid (TS) ◦ Solids for digestion (organics) - Liquid for fluidity of slurry. ◦ Optimal TScontent: 5 to 10%. • COD: Chemical oxygen demand: Methane production potential (SASSE 1988; NIJAGUNA 2002) Anaerobic Digestion (Small-scale) 20

Find this presentation and more on: www. sswm. info. 3. Design Principals Basics: Daily manure yield for different cattle Sources: OEKOTOP; WERNER et al. (1998) Anaerobic Digestion (Small-scale) 21

Find this presentation and more on: www. sswm. info. 3. Design Principals Basics: Gas yields for different feedstocks Sources: OEKOTOP; WERNER et al. (1998) Anaerobic Digestion (Small-scale) 22

Find this presentation and more on: www. sswm. info. 3. Design Principals Basics: Biogas Guideline data Suitable digesting temperature 20 to 35 °C Retention time 40 to 100 days Biogas energy 6 k. Wh/m 3 = 0. 61 L diesel fuel Biogas generation 0. 3 – 0. 5 m 3 gas/m 3 digester volume per day Human yields 0. 02 m 3/person per day Cow yields 0. 4 m 3/Kg dung Gas requirement for cooking 0. 3 to 0. 9 m 3/person per day Gas requirement for one lamp 0. 1 to 0. 15 m 3/h Adapted from WERNER et al. (1998); ISAT/GTZ (1999), Vol. I; MANG (2005) Anaerobic Digestion (Small-scale) 23

Find this presentation and more on: www. sswm. info. 3. Design Principals Types of Digester: Bag or Rubber Balloon Biogas Plants (1/2) Huge common plastic bag (e. g. PVC): sludge settles on the bottom and biogas is collected in the top. Gas is transported by the pressure from the elasticity of the balloon (can be enhanced by placing weights on the balloon). • Most simple design, easy and low-cost ( if material locally available) • Temperature enhanced when exposed to sun • Simple to clean but lifespan generally limited Plastic bag Gas pipe To reuse or further treatment (e. g. drying bed) Biogas accumulates in the top of the bag Leveled surface Inlet Layer of compacted backfill Anaerobic Digestion (Small-scale) Source: adapted from FAO (1996) Batch mode: emptying once every few years Plug-flow reactor: the slurry moves through continuously much like a train a tunnel 24

Find this presentation and more on: www. sswm. info. 3. Design Principals Types of Digester: Bag or Rubber Balloon Biogas Plants (2/2) Underground plugflow reactor bag biogas plant ( ) and balloon biogas collection chamber ( ). (Philippines, Garry Baron) Source: http: //www. habmigern 2003. info/biogas/Baron-digester. htm [Accessed: 02. 06. 2010] Anaerobic Digestion (Small-scale) 25

Find this presentation and more on: www. sswm. info. 3. Design Principals Types of Digester: Fixed-dome Biogas Plants (1/3) Airtight underground reactor out of concrete or brick work (most often round), with a fixed (also airtight) dome in which gas is collected. Gas pressure is absorbed by the slurry which is displaced into a compensation tank. • Most widely disseminated • Long life-spam • Underground: safes space and protect from temperature changes • Construction must be supervised Anaerobic Digestion (Small-scale) 26

Find this presentation and more on: www. sswm. info. 3. Design Principals Types of Digester: Fixed-dome Biogas Plants (2/3) Biogas collection Inlet Fixeddome Seal Removable cover Biogas accumulates in the dome Slurry Overflow tank / compensation chamber Source: adapted from http: //peda. gov. in/eng/images/rural-biogas-plant_179. jpg [Accessed: 02. 06. 2010] Anaerobic Digestion (Small-scale) 27

Find this presentation and more on: www. sswm. info. 3. Design Principals Types of Digester: Fixed-dome Biogas Plants (3/4) Source: K. P. PRAVVIJITH Anaerobic Digestion (Small-scale) Source: K. P. PRAVVIJITH

Find this presentation and more on: www. sswm. info. 3. Design Principals Plastic dome Any pit can be filled with organic waste and covered airtight with a plastic sheet in order to collect biogas Source: ISAT/GTZ (1999, Vol. I) Anaerobic Digestion (Small-scale) 29

Find this presentation and more on: www. sswm. info. 3. Design Principals Floating-drum Biogas Plants Floating-drum plants consist of an underground digester and a moving gasholder (mostly of made out of steel). The gasholder floats either directly on the fermentation slurry or in a water jacket of its own. The gas is collected in the gas drum, which rises or moves down, according to the amount of gas stored. The gas drum is prevented from tilting by a guiding frame. • Easy to and to control operation • Material costs are high • High risk of corrosion and rusting (short lifespam). Anaerobic Digestion (Small-scale) Inlet Biogas Outle t Slurry 30

Find this presentation and more on: www. sswm. info. 3. Design Principals Floating-drum Biogas Plants Different design of floating drum plants Open gasholder MUELLER (2007) Anaerobic Digestion (Small-scale) Floating drum plant with inlet from the NGO BIOTECH (India) 31

Find this presentation and more on: www. sswm. info. 3. Design Principals Toilet linked Biogas Reactors Co-digestion of toilet products (nightsoil or blackwater) is a sustainable solutions for • Hygienically safe on-site treatment of toilet excreta • Production of fertiliser • Production of renewable energy The mixing of animal dung with blackwater increases its fluidity and results in optimal moisture conditions for the anaerobic digestion. Human manure has a lower content in organic matter and thus a limited biogas yield. Anaerobic Digestion (Small-scale) 32

Find this presentation and more on: www. sswm. info. 3. Design Principals Toilet linked Biogas Reactors Source: ? ? ? Anaerobic Digestion (Small-scale) 33

Find this presentation and more on: www. sswm. info. 3. Design Principals Toilet linked Biogas Reactors Inlet for animal waste Pourflush toilet Source: adapted from WELL (n. a. ) Gas outlet pipe Link of toilet Baffle to mix influent with tank contents Anaerobic Digestion (Small-scale) Biogas reactor Removable cover annual desludging Collection and expansions chamber 34

Find this presentation and more on: www. sswm. info. 3. Design Principals Toilet linked Biogas Reactors Manure and green waste mixing chamber http: //www. ashdenawards. org/files/imagecache/large/fi les/images/biogasnepal 05 a. jpg [Accessed: 02. 06. 2010] Source: M. WAFLER Pour-flush toilet Sludge drying bed Expansions chamber Biogas reactor Anaerobic Digestion (Small-scale) 35

Find this presentation and more on: www. sswm. info. 4. Treatment Efficiency Health aspects Anaerobic digested sludge are generally pathogen free. Pathogen removal depends temperature and retention time. Generally , at more than 55°C pathogens are killed after a few days. At normal temperatures (mesophilic digestion), longer time is required. Source: SASSE (1988) In reality, fresh sludge is always mixed with new sludge and it is very difficult to control retention times. Therefore, caution needs to be taken when emptying and handling sludge manually. Source: WERNER et al. (1998) Anaerobic Digestion (Small-scale) 36

Find this presentation and more on: www. sswm. info. 4. Treatment Efficiency Nutrients Anaerobic digestion only removes organics, and the main mineral material and almost all nutrients remain in the bottom sludge. Biogas slurry • Phosphorus: almost 100 % = Fertilisers • Nitrogen (ammonium): and 50 to 70 % (JOENSSEN et al. 2004) èBiogas Slurry = Fertiliser Further treaments to increase the safety (pathogen removal) • Composting • Drying beds / Humification Anaerobic Digestion (Small-scale) 37

Find this presentation and more on: www. sswm. info. 5. Operation and Maintenance (O&M) Start-up Seeding with living sludge form other anaerobic reactor required. The establishment of the complex biological conditions for anaerobic digestion and biogas production may takes some weeks to months. Operation No skilled operator is required but households should be trained to understand the system. Regular maintenance includes • Checking for foaming or scum formation • Checking for air/gas- tightness • Checking for rusting (e. g. floating-drum reactor) Anaerobic Digestion (Small-scale) 38

Find this presentation and more on: www. sswm. info. 6. Applicability Small-scale biogas digesters can transform almost any biodegradable waste into biogas. Household or community scale. Most often used for biogas production in rural areas from animal dung. Green wastes (kitchen, garden, etc. ) can be added. If toilets are linked: safe and sustainable sanitation solution. Underground construction provided: can also be constructed in urban areas. As anaerobic digestion is limited to moderate to high temperature, only in areas where temperature does not fall short of for any substantial length of time. Anaerobic Digestion (Small-scale) 39

Find this presentation and more on: www. sswm. info. 7. Pros’ and Cons’ Disvantages: Advantages: • Experts are required for the • Low-cost design of the reactor and skilled • Generation of biogas and labour is required for the fertilizer construction of a gastight tank • Combined treatment of animal, • Substrates need to contain high human and solid organic waste amounts of organic matter for • Low operation and maintenance biogas production • Underground construction (low • Slurry may has to be further space requirement and high treated before reuse (e. g. acceptance) composting) • Low risk of odours • Resistance against shock loads • Below temperatures of 15°C, • Long life span if maintained and biogas production is economically operated correctly not interesting (heating required) • Reduces the amount of wood fuel • Requires seeding (start-up can be and improves indoor air quality long due to the low growth yield of anaerobic bacteria) Anaerobic Digestion (Small-scale) 40

Find this presentation and more on: www. sswm. info. Thank you for your attention! Source: ? ? ? Anaerobic Digestion (Small-scale) 41

Find this presentation and more on: www. sswm. info. 8. References BPO (2006): Support Project to the Biogas Programme for the Animal Husbandry Sector in some Provinces of Vietnam. BP I Final report. Hanoi: Biogas Project Office (BPO) Hanoi BUNNY, H. , BESSELINK, I. (n. y. ): The National Biodigester Programme in Cambodia. In Relation to the Clean Development Mechanism. National Biogidgester PRobramme and NV Netherlands Development Organisation FAO (1996): Biogas Technology - A Training Manual for Extension. Consolidated Management Services Nepal (P) Ltd. and Food and Agriculture Organization of the United Nations (FAO) Available at: http: //www. fao. org/docrep/008/ae 897 e 00. HTM [Accessed: 19. 04. 2010] GTZ (2009): Biogas sanitation for black water or brown water, or excreta treatment and reuse in developing countries. Draft Version. (=Technology review). Eschborn: German Agency for Technical Cooperation Gmb. H (GTZ) and Sustainable Sanitation Alliance (Su. San. A) Available at: http: //www. gtz. de/en/themen/umwelt-infrastruktur/wasser/9397. htm [Accessed: 11. 03. 2010] ISAT/GTZ (1999): Biogas Basics. (=Biogas Digest, Volume I). Information and Advisory Services on Appropriate Technology (ISAT) and German Agency for Technical Cooperation Gmb. H (GTZ). Available at: http: //www 2. gtz. de/dokumente/bib/04 -5364. pdf [Accessed: 19. 04. 2010] JOENSSON, H. , RICHERT A. , VINNERAAS, B. , SALOMON, E. (2004): Guidelines on the Use of Urine and Faeces in Crop Production. (= Eco. San. Res Publication Series, Report No. 2004 -2). Stockholm: Stockholm Environment Institute (SEI) MANG, H. -P. , (2005): Biogas Sanitation Systems. (=Ecological sanitation course, Norway, 15. -20. August 2005). Beijing: Chinese Academy of Agricultural Engineering MES, T. Z. D. de, STAMS, A. J. M, REITH, J. H. , ZEEMAN, G. (2003): Chapter 4. Methane production by anaerobic digestion of wastewater and solid wastes. In: REITH, J. H. , WIJFFELS, R. H. , BARTEN, H. (Eds. ) (2003): Biomethane and Biohydrogen. Status and perspectives of biological methane and hydrogen production. Dutch Biological Hydrogen Foundation and the Netherlands Agency for Energy and the Environment (Novem). Available at: http: //gasunie. eldoc. ub. rug. nl/FILES/root/2003/3339875. pdf [Accessed: 25. 04. 2010] MUELLER, C. (2007): Anaerobic Digestion of Biodegradable Solid Waste in Low- and Middle-Income Countries. Swiss Federal Institute of Aquatic Science (EAWAG), Department of Water and Sanitation in Developing Countries (SANDEC) http: //www. eawag. ch/organisation/abteilungen/sandec/publikationen/publications_swm/downloads_swm/Anaerobic_Digestion_high_resolution. pdf [Accessed: 27. 04. 2010] MUENCH, E. (2008): Overview of anaerobic treatment options for sustainable sanitation systems. In: BGR Symposium „Coupling Sustainable Sanitation and Groundwater Protection“ 14 – 17 Oct 2008, Hannover, Germany. Eschborn: German Agency for Technical Cooperation (GTZ) Gmb. H Available at: http: //www. gtz. de/en/dokumente/en-bgr-conference-biogas-ecosan-muench-2008. pdf [Accessed: 23. 04. 2010] NIJAGUNA, B. T. (2002): Biogas Technology. New Delhi: New Age International (P) Ltd. PIPOLI, T. (2005): Feasibility of Biomass-based Fuel Cells for Manned Space Exploration. In: Proceedings of the Seventh Eurpean Space Power Conference, Stresa, Italy. 9 to 13 May 2005. SASSE, L. (1988): Biogas Plants. German Appropriate Technology Exchange (GATE) and German Agency for Technical Cooperation (GTZ) Gmb. H Available at: http: //www. borda-net. org/modules/wfdownloads/viewcat. php? cid=5 [Accessed: 25. 04. 2010] WELL (n. y. ): Using Human Waste. (=WELL Technical Briefs, No. 63) Loughborough: Water and Environmental health at London and Loughborough (WELL) Available at: http: //www. lboro. ac. uk/well/resources/technical-briefs. htm [Accessed: 26. 04. 2010] WERNER, U. STOEHR, U. , HEES, N. (1998): Biogas Plants in Animal Husbandry. German Appropriate Technology Exchange (GATE) and German Agency for Technical Cooperation (GTZ) Gmb. H Available at: http: //www. scribd. com/doc/27434211/Biogas-Plant-in-Animal-Husbandry [Accessed: 25. 04. 2010] YADAVA, L. S. , HESSE, P. R. (1981): The Development and Use of Biogas Technology in Rural Areas of Asia (A Status Report 1981). Improving Soil Fertility through Organic Recycling. (=Project Field Document No. 10. ). Food and Agriculture Organization (FAO) and United Nations Development Programme (UNEP) Anaerobic Digestion (Small-scale) 42

“Linking up Sustainable Sanitation, Water Management & Agriculture” SSWM is an initiative supported by: Compiled by: Anaerobic Digestion (Small-scale) 43