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TABLE OF CONTENTS (Con’t) Chaoter m 9 Instrumentation and Controls for Biogas Equipment Introduction Gas Composition Gas Caloric Value Gas Density Gas Flow Pressure Ambient Exposure Potential Biogas Safety Considerations Introduction Toxicological Dangers Flammability Dangers Physical Dangers Safety Equipment Recommended Safety Practices References IO Appendix A - Alphabetical Listing of Equipment Suppliers Appendix B - Listing of Companies by Product or Service
Methane Digesters For Fuel Gas and Fertilizer With Complete Instructions For Two Working Models
by L. John Fry Santa Barbara, California
"Methane Digesters" is also published, independently, as Newsletter No. 3, Spring 1973, by The New Alchemy Institute, Box 432, Woods Hole, Massachusetts 02543,
Inspiration: L. John Fry Contributors: L. John Fry, Richard Merrill Editors: Richard Merrill, Yedida Merrill Artwork: Beth Amine Thanks to: Earl Barnhart Kim Mitchell
Installation of Balaji Biogas System and its Application with Purification and Bottling Biogas Unit
Introduction At present our country is facing various problems which become more serious in next coming years. Demand of petroleum products is increasing, India has spending a big budget for importing these products and on the other hand our country faces serious problems like environmental pollution, disturbance in weather & global warming. India is an agriculture-based country and there is abundant availability of resources but these are not properly used and commercialized. In spite of all the developments and technologies are available yet the rural people facing the shortage of energy. The prime challenge for the country is to provide the minimum energy services to allow the rural people to achieve decent standard of living. The biogas plant is a boon to the Indian farmers. The two main products of the biogas plants are enriched compost manure and methane where as compost manure helps to meet the fertilizer requirements of the farmers in a more economical and efficient manner and boost agricultural production. Biogas is used for cooking and lighting purposes and in larger plants , as motive power for driving small engines.Indian government have installed gobar gas plants, which are approximately 12,00,000small, 3,40,000 medium, and 4,000 big gobar gas plant. If 20,00 gobar gas plants of 120 M3 hasbeen installed then approximately 6842 Lakh Rs. of diesel/petrol can save, but this project isfailed in few years no body have think that why this project is failed.Few years back KVIC & other agencies related to installation of bio gas plant installedtwo types of Biogas plant one was fixed dome and second was floating dome. Fixed domedigester was covered by concrete gas holder while floating dome digester was made up of metal(iron) sheet gas holder. Fixed dome digesters require one month for installation. After sometimes these types of digesters faced problem of scum deposition on upper surface which can notremoved easily, ultimately biogas production effected. In these plants high maintenance costwas required for removing scum. On the other hand floating gas holder (metal sheet) wascorroded due to contact with water and hydrogen sulfide. Second problem was that at the timefeeding few amounts of mud particles was present with feed, gradually this mud deposited in thelower surface of digester. Due to these problems digestion and gas formation is effected.Following problems keeping in mind we designed a low cost, easy and quick to install, durable,easy to maintain and anti corrosive type of biogas plant.
This manual contains a complete set of training materials on various topics around the large-scale dissemination of domestic (agricultural) biogas systems, including a system approach to biogas technology, biogas programmes, reuse of slurry, subsidy and institutional financing, quality standards and monitoring and evaluation issues.
This book is the first in a series on Urban Solid Waste Recovery, and represents an attempt to document the experiences of recycling activities in cities around the world. It covers the whole waste chain from municipal or agricultural generation of organic waste to different treatment methods, such as composting, co-composting, anaerobic digestion with production of biogas, and briquetting.
This chapter is part of a publication, commissioned by the Netherlands Agency for Energy and the Environment (Novem) on the status and perspectives of research and development in the field of high-tech biological production of methane and hydrogen. Chapter 4 gives a short but precise introduction the technological aspects of waste treatment by anaerobic digestion and the reuse of the produced biogas.
This paper outlines the processes of anaerobic digestion, reviews the current technology available for the anaerobic digestion of municipal organic wastes and proposes the adoption of the technology in the United States, beginning with commercial waste in New York City. The greatest concerns for New York are space and transportation, indicating that the most appropriate system is one using solid waste near the site of waste generation. A demonstration plant was constructed to show the improvement of local environmental conditions, job creation, and electricity generation in order to achieve support at policy level.
ISAT (Editor); GTZ (Editor) (1999): Biogas Basics. Information and Advisory Services on Appropriate Technology (ISAT) and German Agency for Technical Cooperation GmbH (GTZ) . URL [Accessed: 19.04.2010]
The information service on biogas technology has been developed and produced on the behalf of the GTZ project Information and Advisory Service on Appropriate Technology (ISAT). Volume I tells you all you need to get an overview on biogas sanitation systems, from history over process and operation parameters to social, political and cultural issues.
This information service on biogas technology has been developed and produced on the order of the GTZ project Information and Advisory Service on Appropriate Technology (ISAT). Volume III discusses the micro- and macro-economic viability of biogas sanitation systems.
ISAT (Editor); GTZ (Editor) (1999): Biogas - Country Reports. Information and Advisory Services on Appropriate Technology (ISAT) and German Agency for Technical Cooperation GmbH (GTZ). URL [Accessed: 19.04.2010]
The information service on biogas technology has been developed and produced on the behalf of the GTZ project Information and Advisory Service on Appropriate Technology (ISAT). Volume IV summarises over 20 case studies from biogas sanitation as an appropriate technology in developing countries.
ISAT (Editor); GTZ (Editor) (1999): Biogas - Country Reports. Information and Advisory Services on Appropriate Technology (ISAT) and German Agency for Technical Cooperation GmbH (GTZ). URL [Accessed: 19.04.2010]
The information service on biogas technology has been developed and produced on the behalf of the GTZ project Information and Advisory Service on Appropriate Technology (ISAT). Volume IV summarises over 20 case studies from biogas sanitation as an appropriate technology in developing countries.
Naturgerechte Technologien (Editor) (2000): Anaerobic Methods of Waste Treatment. German Agency for Technical Cooperation GmbH (GTZ) and German Appropriate Technology Exchange (GATE). URL [Accessed: 20.04.2010]
This technical factsheet describes the treatment of wastes through anaerobic digestion and biogas production at large-scale in a very comprehensive way. The treatment of different wastes, including sewage sludge, agricultural and industrial wastes or solid municipal wastes, is emphasised.
TUHUS-DUBROW (2008): Waste? Not. In: The Boston Globe. URL [Accessed: 21.02.2010]
Critical article on conventional end-of-pipe wastewater approaches, introducing some alternatives such as biogas digester, arborloos or the fossa alterna.
Decentralized anaerobic digestion is a promising technology to handle the large organic fraction of the municipal solid waste with the additional benefit of producing biogas as well as fertilizer. In this study a market level biogas plant in Thiruvananthapuram, South India and constructed by a NGO called BIOTECH is monitored and evaluated.
This article talks about new treatment options for the anaerobic digestion of organic household waste in developing countries to improve waste management and provide households and institutions with biogas — a renewable, clean source of cooking energy.
VANDEVIVERE, P.; BAERE, L. de (2002): Types of anaerobic digesters for solid wastes. In: MATA-ALVAREZ, J. (Editor) (1999): Biomethanization of the Organic Fraction of Municipal Solid Wastes. London, 336 - 367. URL [Accessed: 30.05.2010]
This chapter presents and explains most common anaerobic digesters for solid waste. The different technologies are compared in respect to biological and technical performance as well as reliability. It was distinguished between one-stage, two-stage, and batch systems.
This book is the first in a series on Urban Solid Waste Recovery, and represents an attempt to document the experiences of recycling activities in cities around the world. It covers the whole waste chain from municipal or agricultural generation of organic waste to different treatment methods, such as composting, co-composting, anaerobic digestion with production of biogas, and briquetting.
BIOTECH is a nodal agency of the Ministry of Non-Conventional Energy Sources in Kerala, South India (MUELLER 2007). BIOTECH has been developing and installing biogas plants that generate biogas from domestic biodegradable waste like cooked food waste, vegetable waste and waste water from kitchen (1 m3 for a 3 to 5 member family meets about 50 % of cooking needs, MUELLER 2007) (see picture above). BIOTECH has also developed reactors for the decentralised anaerobic digestion of organic market waste or municipal solid or slaughterhouse waste. The electricity generated from the decentralized plants for market wastes is used for street lightning and distributed to households.
Schematic plan of a BIOTECH market level plant. The sketch is not drawn to scale, but the proportions have been considered as far as possible. a) Inlet tank for feedstock. b) Digester tank. c) Effluent tank. d) Effluent storage tank. e) Effluent pump. f) Gasholder drum. The drum is stabilized by a guide pole in the middle and is floating in a water jacket outside the digester. g) Biogas pipe. h) Gas Scrubber. i) Biogas generator j) Drainage connection for excess effluent Source: HEEB (2009)
As the ARTIs, the BIOTECH market level plants are based on a floating-drum design including a recirculation loop to optimise moisture content (HEEB 2009). The feedstock (often market wastes) is put in the inlet tank from where it is flushed into the main digester tank for anaerobic digestion (3 m diameter and 3 m depth, HEEB 2009). To increase the retention time for solids, there is a baffle in the middle of the tank and orthogonal to the flow direction. The baffle holds back unsuspended solid compounds of the waste, whereas liquids can easily flow over (much like septic tanks or biogas digesters, see also factsheet (see also small scale digesters or biogas settlers). This leads to an increased retention time for unsuspended solids and therefore to an improved decomposition of this compounds. The digested liquor (digestate) flows into the effluent tank from where a pump, run with electricity of the produced biogas, transports it up into an overhead storage tank. From the tank, the digestate is then used to flush the feedstock from the inlet tank into the digester tank avoiding the need of fresh water for flushing (HEEB 2009).
Large-Scale Wet Digestion of Municipal Organic Waste
Digester and gas storage at the Rayong Municipality Cogeneration plant, Thailand. Source: MUELLER (2007)
In Thailand, the development of alternative energy sources is critical, as the government has set 2011 as the target date for 8% of the nation’s total energy reduction (MUELLER 2007). This has given large rise to various large-scale biogas projects. The Rayong Municipality has constructed a wet fed-batch high-solids plant for the treatment of the organic fraction of the municipal solid waste. The plant is comprised of two systems; a process that converts waste to biogas and fertiliser and a biogas-fired cogeneration process (CHP). Additional to the organic solid waste from the municipality, the Rayong plant uses food, vegetables and fruit wastes and night soil as waste materials. The plant has a capacity to handle 60 tons of waste per day turning out into an output of 5800 tons organic fertiliser and electricity of about 5 million kWh (MUELLER 2007).
The ARTI household digester in Dar es Salaam, Tanzania (Left) and a similar model from BIOTECH. Source: VOEGELI & LOHRI (2009) and HEEB (2009)
ARTI stands for Appropriate Rural Technology Institute, which has developed the ARTI compact biogas plant in 2003 for the treatment of organic waste at the household level (1 to 2 Kg of food waste per day). The plant is sufficiently compact to be used also by urban households. Approximately 2000 such plants are currently in use in Maharashtra, India, in both urban and rural households (WRAPAI 2009). In Africa, only few ARTI biogas plants have been installed so far (Tanzania, VOEGELI & LOHRI 2009; VOEGELI et al. 2009).
ARTI compact biogas plants are based on a simple and low-cost floating-drum design applying a wet digestion process. The plants are made from conventional polythene water tanks (two tanks, with volumes of typically 0.75 m3and 1 m3, MUELLER 2007) and standard plumber piping. The smaller tank is the gasholder and is inverted over the larger one, which holds the mixture of decomposing feedstock and water (LOHRI 2009). An inlet is provided for adding feedstock, and an overflow for removing the digested residue. The overflow liquid can be mixed with the feedstock and recycled back into the plant to maintain optimal moisture condition for a wet digestion process (MUELLER 2007). A pipe takes the biogas to a collection balloon or directly to the kitchen.
You can make biogas energy with a DIY methane generator.
Producing methane from manure using your own small scale waste to energy biogas digester is feasible for many small farms. What is Biogas Energy?Biogas energy is fueled by burning methane produced by the decomposition of organic wastes.
Small scale biogas generator
Methane is a gas – chemically CH4. It is colourless, odourless and, of course, flammable. Methane is widely used as the main constituent of mains natural gas. Whenever organic materials are decomposed by bacteria anaerobically (i.e. in the absence of oxygen) methane and carbon dioxide are produced. Small scale manure-to-energy methane generator plans are available here. Sources of Biogas Energy Just about any organic waste can be decomposed as a methane generator - plant (soft material is better than woody material) and animal wastes, and even human waste. On a municipal level, rubbish tips act as biogas digesters and are prodigious methane generators. Even in Perth, Australia, companies are actively harvesting this methane to produce climate friendly biogas electricity. In fact, because un-burnt methane released into the atmosphere is a powerful greenhouse gas, 10% of our personal impact on the climate comes from the food refuse we put in our garbage bins that ends up decomposing under landfill. In a small scale waste to energy situation it is possible to generate methane from manure or even sewerage. And biogas energy is constantly being manufactured in digestive systems like yours and your cow’s… yes, farts are methane too! Check out this video to see how to make a simple home digester:
Pros and Cons of Methane Generator Systems Advantages • Makes good use of organic wastes. You can obtain fuel from sewage sludge and animal slurries first, and prevent runoff and methane emissions at the same time – and you still get fertiliser at the end of the process. • Is a clean, easily controlled source of renewable energy. • Uses up methane, a powerful greenhouse gas. • Reduces pathogen (disease agent) levels in the waste. • Residue provides valuable organic fertilizer. • Simple to build and operate. • Low maintenance requirements. • Can be efficiently used to run cooking, heating, gas lighting, absorption refrigerators and gas powered engines. • No smell (unless there’s a leak, which you’d want to know about and fix immediately anyway!). Disadvantages • Most practical to be generated and used at the source of the waste. This is because the energy needed to compress the gas for transport, or convert it into electricity is excessive, reducing the efficiency of biogas energy production. • For safety, basic precautions (see below) must be adhered to. Small Scale Waste to Energy Methane Generator Systems Biogas Energy Each kilogram of biodegradable material yields around 0.4 m³ (400l) of gas. So in practice, in small scale waste to energy systems, if you have some livestock, plus kitchen and human waste you can meet your cooking and lighting needs easily: • 2 gas rings for a couple of hours a day will use between 1-2 m³ • Gas lights need around 0.1 m3 (100l) per hour. Driving any kind of engine (eg a generator or a pump) is, however, way beyond the domestic-scale. (Better to go for algal biodiesel!)
What Size Methane Generator is Needed? If generating methane from manure, collect dung for several days to determine average daily dung production. On this basis, the appropriate size biogas digester plant can be calculated. For example, where 55 kg of dung a day is available a 8 m3 plant is warranted; where it’s only 6 kg of dung a day, a 1 m3 plant will suffice. For a family of 8 with a few animals (say 8-10 cows), a 10m³ digester is a commonly used size in India, with 2 m³ gas storage. Ideal Temperatures for Producing Methane from Manure How long you leave the material in a batch digester depends on temperature (2 weeks at 50°C up to 2 months at 15°C). The average is around 1 month – so gauge how much material you will add each day, and multiply it by 30 to calculate the size of the digester. While anaerobic digestion occurs between 32° F (0°C) and 150° F (65°C), the optimum temperature range for methane generating microbial activity is 85°F (29°C) to 95° F (35°C). Little gas production occurs below 60°F (16°C). In colder climates placing the digester in a greenhouse, and perhaps using some of the methane to warm the system, are possible strategies. Methane Generator Systems • The biogas digester is the system component where the animal, human and other organic wastes are introduced, usually as a slurry with water, to break down anaerobically. • A storage container is used to hold the gas produced, from which it is piped for burning as a fuel. Variable volume storage (i.e. flexible bag or floating drum) is easier, cheaper and more energy efficient than high pressure cylinders, regulators or compressors. • When the digester is emptied, the spent effluent is dried for later reuse as a fertilizer. Types of Biogas Digesters The two main digester types of digesters are the continuous and the batch. Continuous digesters have a constant throughput of material, and batch digesters extract the gas from a contained batch of material, which is then emptied and a new batch added. As firewood for cooking has become scarce, millions of small scale continuous digesters are in use in developing countries, especially India and China. Digesters tend to be larger-scale in developed countries, taking animal slurries and human sewage. Methane Generator Design The Indian cylindrical pit design has become a popular choice around the world due to its reliability and simplicity. It comprises two basic parts: a slurry tank and a covered by a gas cap or drum to capture the gas released from the slurry. Domestic Scale Batch Biogas Digestor
Small experimental biogas digester at Redfield. Waste material is put into the oil drum, neoprene cover rises when full of gas, gas is tapped into container (upside-down plastic drum with water seal) which rises as more gas enters. When full, gas can be tapped off and used with the little gas ring.
Batch digesters based on a container (see photo, above) are feasible on the domestic scale. Mini Methane Generator Project Instructions to make a mini methane generator (suit education project) are in the "Methane-Biogas Production Guide" which, along with heaps of other free eBooks on sustainable living, can be accessed free here.
Methane Safety Like electricity and other energy systems, safety is usually assured so long as the risks are understood and sensible precautions are followed. Fire or Explosion Risk Methane is obviously flammable, and can even be explosive. With this in mind... • The methane generator digester area must be well ventilated to prevent the accumulation of trapped gases. • In the vicinity of a digester no naked flames are permitted, electrical equipment must be of suitable quality, normally "explosion proof", and other sources of sparks are any iron or steel tools or other items, power tools, normal electrical switches, mobile phones and static electricity kept a safe distance away. A flame trap should be incorporated in the supply line, which must be of a minimum of 20 m long. Instructions on building a flame trap can be found here.
Asphyxiation Risk Biogas displaces air, reducing the oxygen level so any digester area needs to be well ventilated. Disease While the spent slurry has lost a lot of its pathogens, there’s a lot of microbial activity at work in producing biogas energy! So avoid contact with the digester contents and wash up thoroughly after working around the methane generator (especially before eating or drinking).
What is Biogas Energy?Biogas energy is fueled by burning methane produced by the decomposition of organic wastes. 
