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Biogas in Ethiopia Video



Deforestation is an important cause for climate change. We believe that in order to tackle some of the worlds biggest problems, we have to build on local solutions. Scaling these up is the key to making a difference. One way to stop deforestation is by using biogas.

Ethiopia is characterised by very low energy consumption, with the vast majority of the rural population having no access to electricity. As a result, the dependency on woody biomass has created an over-exploitation of the natural resource base, which in turn leads to lower agricultural production.

Continued interest in domestic biogas as one of the solutions to address rural energy, combined with SNVs experience with the promotion of domestic biogas and the commitment of national and regional stakeholders, led to the formulation of a Programme Implementation Document for a National Biogas Programme in Ethiopia in partnership with the Ethiopian Rural Energy Promotion & Development Centre (EREDPC). Implementation started in May 2008 with the construction of 100 demonstration biogas plants in 4 regions (Tigray, Oromia, Southern region and Amhara). In an initial phase (2008-2013), constructing a total of 14,000 biogas plants is targeted.
Biogas Plant Design

 Biogas Plant Design (Chapter 3)

2          Plant design
biogas plant formula
A simple plant design similar to the designs in Vietnam (KT), Cambodia (modified Dheenbandu) or Tanzania (modified Camartec) is used for this example.

Plant Layout
In this hemi-spherical design, the digester volume is the volume under the lower slurry level(LSL), and the gas storage volume is the volume between the lower and higher slurry level (HSL).

For all plants with internal gas storage, the gas storage volume in the plant is equal to the volume of the compensation volume

2.1        Total plant volume
Dome Radius
digester volume dimensions
As pic 1 shows, part of the dome volume, over the higher slurry level, is not used by a well functioning installation. The volume, often referred to as “dead volume” is required, however, to accommodate the floating layer on top of the slurry. In addition, when gas production is less then nominal (cold seasons) or when gas is slowly leaking, the higher slurry level can rise (up to overflow level). For that reason, the total plant volume used for dimensioning should be higher than the plant size range volume results. For this example, 20% addition is allowed for this dead volume. Hence, taking plant size 1 for the example, the total plant volume (digester + gas storage + dead volume) arrives at 3.90 x 1.2 = 4.68 m3.

Plant size range calculations (Chapter 2)


1.2 Plant size range calculations

1.2.1     For the smallest plant size (“size 1”) in the range:

i.          The minimum daily substrate feeding (min sub fee1) is equal to the minimum required gas production for the smallest installation divided by the specific gas production:min sub fee1 = min gas prod1 / spec gas prod.
Or: min sub fee1 = 1.00 / 0.040 = 25 [kg dung day]

ii.          A feeding of dung of 25 [kg dung / day] requires with a 1:1 dung to water ratio an equal amount of water. The minimum feeding(min fee1) to the plant thus arrives at 50 [ltr / day].

iii.         For the situation in which the daily feeding corresponds with the minimum feeding amount for which the plant will be designed, the hydraulic retention time is maximal (HRT max). The required digester volume (dig vol1) is equal to the hydraulic retention time multiplied by the daily feeding: dig vol1 = HRTmaxxmin fee1.

Or: dig vol1 = 60 x 50 = 3,000 [ltr]


Biogas plant opening Bad Salzdetfurth
On the 15th of April 2011 the official opening of the BIOGAS NORD plant in Salzdetfurth took place.
17 farmers signed two thirds of the shares, one third was signed by Stadtwerke Bad Salzdetfurth. prime contractor is BIOGAS NORD . In June 2010 the construction started and all further steps happened in an incredible pace. “Ca.  18. 000 tonnes of maize is produced by 15 farms in a local area on ca. 350 ha. Together with 8.000 tonnes of cattle and pig manure, they produce ca. 8 million kilowatt hours, which can be used to power circa 1600 households”, said Curd von Lenthe, manager of the participating farmers. The gas will be used for the home required heat as well as for the local heat grid and  a saline bath in Detfurth. In the future the supply of more consumers is planned.
Joachim Korth from the planning office Energie + Konzept: “ This plant has the advantage to give heat to the saline bath throughout the year and in addition reduce more 5000 tons of CO2”. Mayor Schaper said: „this is a successful relationship between the local farmers and the city“ and „ an important day for the whole region and the city. County commissioner Wegner acknowledged the operators:  “ Due to the rising prices and energy problems, we have to take new paths.”
Wesselns mayor Burkhard Helfenbein: „One can say the building is really beautiful. It´s blending in the landscape in a very good way."

Curd von Lenthe (left), Heiko Räther (right),
Dirk Wöhler BIOGAS NORD (middle)

Biogas plant Bad Salzdetfurth
Fotos:  Martensen
Design, construction and maintenance of a biogas generator (download PDF )
Design, construction and maintenance of a  Design, construction and maintenance of a  biogas generator

Biogas  generators can  be used  at  household  or  community  level  to  produce  usable fuel  and  fertilisers from human and animal waste.  This  document  covers  many  of  the  technical  aspects  of  designing,  constructing  and  maintaining  a  biogas generator however does not explore the cultural, social and education facets of the project. These should be researched separately with reference made to the case studies within this document.  
  
Introduction

Biogas  generators  extract  by-products  from  organic waste  (including  human  and  animal  excreta,  food stuffs,  etc)  which  can  be  used  to  replace  traditional fuels and fertilisers. Biogas generators produce 2 useful
products:

1.  Biogas – biogas is a natural gas which can be used directly  as  a  fuel  for  cooking  and  heating  or  used to  run  a  converted  generator  for  electricity production. 
2.  Fertiliser – digested sludge from the bottom of the biogas generator and over-flow effluent water  can be used as a fertiliser for crops  The  benefits  of  biogas  generators  are  explicitly  listed below  and  should  be  made  clear  when  suggesting  the construction  of  the  biogas  generator  to  users  in  order to improve speed and likelihood of acceptance:
1.  Biogas  generators  provide  a  safe  and  cleaner  way of  storing  excreta  and  subsequently  bring  about related advantages linked to safe sanitation
2.  Biogas  generators  provide  free  fuel  for  cooking, heating and lighting
3.  Biogas generators provide fertiliser for crops
4.  Biogas  requires  far  less  time  and  effort  to  collect than other fuels (e.g. wood)
5.  Biogas  reduces  the  need  for  wood  and  therefore reduces deforestation and the burden on women of collecting wood
6.  Biogas  creates  no  smoke  and  therefore  reduces health  problems  caused  by  burning  other  fuels indoors
7.  Biogas  is  environmentally  friendly  and  does  not release  as  many  greenhouse  gases  when  burned compared to other fuels 
8.  Dangerous  bacteria  in  faeces  are  killed  during digestion in the biogas generator 




Biogas production

Literature states that the biogas production rate of human excreta  is  0.02-0.07m3/kg/day  however  the  data  varies greatly  and  is  dependent  on  many  variables  (diet,  food intake, water intake, climate, etc). Similar  variance  is  apparent  in  human  waste  production data.  Literature  suggests  that  an  average  adult  can  be expected  to  produce  1-1.3kg  of  urine  and  0.2-0.4kg  of faeces  per  day  [7]  (if  local  figures  are  available  then  use these instead).  GTZ suggest the following production rates of biogas from wastes  of  different  animals  per  day  in  warm  climates  (in addition  to  human  excreta  other  organic  waste  such  as cattle  dung  can  be  added  to  the  generator  to  increase biogas production)



 Design, construction and maintenance of a  biogas generator


Download PDF Design, construction and maintenance of a  biogas generator (download PDF )



Organic Farming Part I - 'Organic Farming'




Organic Farming Part II - 'Cow dung to biogas' 

 



Like many organic farmers, Jose Elanjhimattam is both a practical and abundantly resourceful man. Starting with cow dung, Jose has created an ingenious system that simultaneously captures and separates nitrogen-rich organic manure and methane gas. Unlike dried cow dung, which tends to lose nitrogen throughout the drying process, the liquefied organic manure produced through Joses slurry provides soil with far higher levels of nitrogen. Additionally, the methane gas removed is used as a form of fuel. Jose estimates that the dung from two cows is sufficient to provide enough biogas to support the cooking requirements of a family of four. Resourceful, intelligent, simple great stuff!

Biogas
Biogas is one of the renewable sources of energy. It can be used for domestic and farm use.

What is biogas?
It mainly comprises of hydro-carbon which is combustible and can produce heat and energy when burnt. Bio-gas is produced through a bio-chemical process in which certain types of bacteria convert the biological wastes into useful bio-gas. Since the useful gas originates from biological process, it has been termed as bio-gas. Methane gas is the main constituent of biogas.
BIOFUELS/Alternative Energies/Green Energies
BIOFUELS/Alternative Energies/Green Energies
As we have been discussing many BIOFUELS/Alternative Energies/Green Energies, but we are neglecting the vital importance of BIOGAS with value to Industry as well as on domestic spheres. Bio Gas is not considered a today’s phenomenon, but has been utilized across the world for many centuries, particularly in the Indian Sub-Continent, where it is known as Gobar Gas in the rural regions. In today’s article, I am not putting spot light on its Domestic Importance but on its Industrial Implications, as Pakistan is suffering from worst Energy Crisis, as many Industries, who have Gas Fired Generators are not availing Natural Gas in the winter, ultimately enduring huge loss for Country’s GDP and hurdle in achieving Export Targets.
Biogas typically refers to a gas produced by the biological breakdown of organic matter in the absence of oxygen. Biogas is produced by anaerobic digestion or fermentation of biodegradable materials such as biomass, manures, sewage, municipal waste, green waste, and plant material and energy crops. This type of biogas comprises primarily methane and carbon dioxide. Biogas can be used as a low-cost fuel in any country for any heating purpose, such as cooking. It can also be used in modern waste management facilities where it can be used to run any type of heat engine, to generate either mechanical or electrical power. Biogas can be compressed, much like natural gas, and used to power motor vehicles. But in Pakistan, It can also be used to operate Gas Fired Industrial Generators (10KW-4MW) as well. According to statistics, there is little difference between composition of Biogas and Natural Gas; therefore, Biogas can be used in typical Gas Fired Generators.
Rationale of the Project
Germany is the largest producer of BIOGAS Plants and their Energy Production comprises on BIOGAS is more than 4,000 MWs. Besides, India and China are also exploring their horizons in this renewable energy and forming joint venture with German Companies to manufacture BIOGAS Plants in their home countries to explore the untapped potential. Within Pakistan’s Perspectives, Pakistan has one of the largest numbers of Milking/Meat Animals and Chicken. Thus, it has abundant Cow/Buffalo/Chicken’s Dung to be used for producing BIOGAS to operate typical Gas Fired Generators. In this regard, I researched, and one of the leading biogas plants manufacturers claimed that we (Pakistani Industrialists/Farm Owners) can generate 1 MW of electricity on GE JENBACHER Gas Fired Generator by utilizing biogas on their BIOGAS Plants.
For 1 MW Generation, about 150 Tons Manure/Day; Cow/Buffalo with 70% and Chicken’s Dung with 30% is required to operate 1 MW Gas fired Engine. Around 2000 Cows are required to produce 150 Ton Manure (i.e.; 75KG/COW/Day). Special Enzymes/Catalyst can be used to enhance the plant production/pressure by 20%. That kind of Biogas Plants cannot merely produce BIOGAS but also produce Soil Conditioner/Bio-Fertilizer as their by-products, which can be sold to many farmers.
Last but not the least; I do opine that Pakistan has enormous potential in this regard, so Govt. and Entrepreneurs should come up with new innovative ideas to produce Biogas for Electricity as well as to produce Biogas Plants utilize here as export it at large. Indigenous Industrialists in any field can exploit this fabulous technology by installing Biogas Plant in their premises and availing Feedstock; Manure from nearby areas to operate their usual Gas Fired Engines
that may lead to achieve more production and export targets. This project is feasible, because feedstock is easily available at very cheap prices, and its by-product; Bio-Fertilizer can also be sold at good price. Just one time cost is required to install biogas plant, and it can be operated with few personnel. Therefore, Local Business People can earn and save a lot from local untapped resource.

Source:BIOFUELS/Alternative Energies/Green Energies
Biogas Purification:  H2S Removal using Biofiltration
by 
Mary Elizabeth Fischer

H2S Removal using Biofiltration

A thesis
presented to the University of Waterloo in fulfillment of the thesis requirement for the degree of Master of Applied Science in Chemical Engineering



AUTHOR'S DECLARATION
I hereby declare that I am the sole author of this thesis. This is a true copy of the thesis, including any required final revisions, as accepted by my examiners. 
I understand that my thesis may be made electronically available to the public.

Abstract
Biogas, composed principally of methane, has limited use in energy generation due to the presence of hydrogen sulphide (H2S). Biogas cannot be burned directly in an engine as H2S present causes corrosion in the reaction chamber. There currently exist various technologies for the removal of H2S from a gas stream, but most are chemically based, expensive, and are limited in use. 
The purpose of this study was to determine a biogas purification technique suitable for a small scale farm application; including using a technology inexpensive, efficient, robust and easy to operate. As such, biofiltration was investigated for H2S removal from biogas. Factors considered in the design of  the biofiltration system included the source and conditioning of inoculum, type of packing material, and general operating conditions including inlet gas flow rate and H2S loading rate to the biofilter.  Activated sludge conditioned in  A. ferrooxidans  media was an effective inoculum source. This was tested for growth support compatibility with gravel packing material, to be used in the biofilter. The inoculated packing material was loaded into the biofilter initially during start-up and acclimatization.  In this study, synthetic biogas (49.9%volCH4, 49.9%volCO2, 2000ppmv H2S) mixed with air (totalling 4%vol O2) was added at 5-10L/hr to a biofilter of 0.4L gravel packing inoculated with conditioned activated sludge. Baseline H2S removal studies in a non-inoculated biofilter were performed with anticipated operating conditions, including an inlet gas stream at 7.5L/h (25oC, 1atm), resulting in 31-56% H2S removal. A factorial test performed found that air content in the inlet gas stream was the significant factor affecting the removal of H2S in the non-inoculated biofilter. 
Operation of the biofilter with biogas was done for 61 days, including 41 days for start-up and acclimatization and 20 days of H2S loading tests. Start-up and acclimatization with biogas resulted in complete H2S removal after 2 days, with an average overall H2S removal of 98.1%±2.9 std deviation over 34 days. Loading tests performed on the system ranged 5-12.4L/h (25oC, 1atm), with a loading rate of 27.8 to 69.5gH2S/m3
h of filter bed. Throughout this test the average H2S removal rate was 98.9%±2.1 std deviation over 20 days. Although complete H2S breakthrough studies were not performed, these results indicate that biofiltration is a promising technology for H2S removal from biogas in a small scale application. 
BIOGAS PURIFICATION USING WATER SCRUBBING SYSTEMS  (DOWNLOAD PDF )


BIOGAS PURIFICATION USING WATER SCRUBBING SYSTEMS Diagram



Introduction


Biogas is the result of the anaerobic digestion process, and has a promising use in energy generation
with 40-70% methane present in the gas. Using biogas in energy production is useful not only as a
renewable energy source, but also because it captures and uses green house gases normally emitted
into the atmosphere. Biogas is presently used in heating and in turbines for electricity production.
Anaerobic digestion is the process in which organic materials are degraded by anaerobic bacteria
completing methanogenesis, and creating methane. This process is present in landfills, sewage sludge,
and biomass digesters. The resulting biogas contains 55-70%vol methane (CH4), 30-45% vol carbon
dioxide (CO2), and 0-1.5%vol hydrogen sulphide (H2S); the exact composition depending on the
feedstock and the anaerobic digestion conditions.
Biogas has limited use in energy generation due to the presence of H2S. The H2S present converts to
sulphuric acid when combusted, and creates corrosion in the combustion chamber, especially with
levels in excess of 100ppm H2S in the biogas. By removing the H2S present, the use of biogas can
expand from heating and generators, to applications such as diesel engines.


  1. Download PDF File 

  1. BIOGAS PURIFICATION USING WATER SCRUBBING SYSTEMS  PDF
  2. Siloxane adsorption by solids in biogas purification (pdf)
  3. The Purification of Biogas (GTZ, 1985, 33 p.) (pdf)
  4. The Purification of Biogas (GTZ, 1985, 33 p.) (HTML)
  5.  

Biogas purification plant

Biogas purification plant

 

at the inauguration of  new biogas purification plant in Lund. No ribbons were cut. Instead, a sample was played through the PA. Please feel free to have a listen yourself: 

Starting now, the biogas from the local sewage treatment works gets purfied in this new facility, and then distributed and sold as vehicle fuel.

Photo Source: http://www.flickr.com/photos/p1r/4658876315/

 

 More subsidy for biogas plants sought


Biotech, a Thiruvananthapuram-based agency recognised by the Union Ministry of New and Renewable Energy, is set to give a proposal to the State government seeking higher subsidy for setting up biogas plants generating energy through waste treatment.
The proposal, coming as it does at a time when the Union government is seriously considering the possibility of restricting subsidy for cooking gas, aims at drawing attention to biogas plants as an attractive mode of generating alternative energy, while addressing the issue of waste treatment.
“As of now, local bodies are permitted by the State government to grant a subsidy of up to Rs. 3,000 for biogas plants.
“This is inadequate. We want the government to grant at least half the cost of setting up the plants as subsidy,” A. Sajidas, director of Biotech, told The Hindu .
The limit imposed by the State government restricts many local bodies, which may otherwise be willing to give more assistance for the plants. Mr. Sajidas said that the ideal situation would be to permit local bodies to grant higher subsidy, as they deemed fit, taking into consideration the garbage issue in their limits.
As of now the Central government grants a subsidy of Rs. 4,000 and Biotech offers an additional Rs. 4,000 as carbon credit for setting up biogas plants.
Biotech is planning widespread demonstrations across the State to drive home the advantages of adopting biogas plants in the prevailing uncertainty over the continuance of subsidy for cooking gas. Applications are being invited from parties interested in holding demonstrations.
Special focus will also be given to holding demonstrations and awareness classes in schools, as it is the best way to get the message to individual households. “Experts from Biotech will visit the place and hold demonstrations. Besides, training will also be imparted to interested parties in setting up and operating biogas plants, as faulty methods could result in a negative fallout,” Mr. Sajidas, who has a doctorate in solid waste treatment, said.
He said that plants developed by Biotech alone are recognised and provided subsidy by the Union Ministry of New and Renewable Energy in the State.
Protection of vital sources of water from pollution through the operation of centralised waste treatment plants is another advantage of adopting biogas plants. The pollution of Kadamprayar near the solid waste treatment plant at Brahmapuram in Ernakulam is a case in point.
A biogas plant of one cubic metre with the capacity to treat 2 kg of food waste and 20-30 litres of waste water is ideal for a normal household of five members.
Out of the total cost of Rs. 21,000, the beneficiary would have to raise Rs. 13,000 after the Rs. 8,000 offered as subsidy by the Union government and Biotech.
 Camartec appeals for massive biogas production

Sisal Biogas Plant at Hale Tanzania

The Centre for Agriculture Mechanisation and Rural Technology (Camartec) has appealed for more government budget allocation to boost biogas production that could help many power users cope with the current energy crisis.
Biogas which is pollution-free and clean gas is seen as an option for rural and peri-urban low and medium income earners as it can easily produce energy for their daily domestic needs, such as cooking, heating and lighting.
Camartec is implementing biogas project across the country, and so far a total of 12,000 biogas plants are to be constructed under the first phase of the project set to cost euro 16 million to completion 2013.
“But budget constraints remained a challenge to spread the biogas technology across Tanzania especially for rural-based communities,” Camartec director general Evarist Ng’wandu said.
Speaking to media practitioners here recently, engineer Ng’wandu stressed the need to allocate more financial resources in the Ministry of Industry, Trade and Marketing.
“This will help to boost the biogas sector in Tanzania which is affordable and simple in rural and peri-urban households,” he said.
The official noted that despite its economic and environmental significance, the 29-year-old centre is constrained with a number of challenges, one being shortage of funds.
Camartec is responsible for carrying-out different researches as well as promoting improved household stoves, community stoves, biogas and solar energy facilities, he noted.
“But all these couldn’t be reached if there are no funds to accomplish all these responsibilities,” he said.
“Our centre has increased services to 11 regions and managed to train technicians to install over 500 biogas plants in those areas,” Ng’wandu said
He added that agriculture alone will not succeed without industrial development; hence the need to allocate more funds in the sector remained crucial.
He however commended government efforts in developing biogas technology, whereby in five-years between 2007 and 2013, the centre plans to install about 12,000 biogas plants across the country.
Started in 1982, the centre was meant to produce and disseminate agricultural implements such as harrow planters, nutshells, oil press machines, wheelbarrows, pulling and oxen carts, water harvesting tanks and brick making tools.
Among other things, Camartec also pioneered to develop biogas technology, the innovation intended to be among the responses to skyrocketing oil prices in the world market in 1970s.
A plant used to produce biogas, also known as a biodigester, is an anaerobic digester that treats farm wastes or energy crops. This has been mostly the case in the developed countries where in recent years the technology has assumed new importance because of advanced methods of waste treatment.
In most developing countries, however, domestic biogas plants convert livestock manure into gas. The technology has been feasible for smallholders with livestock producing at least 50 kgs of manure per day.
Recently, Camartec launched a large-scale production of biodigesters that could help many families cope with the crisis.
The project, as a component of the African Biogas Partnership Programme (ABPP), known as Tanzania Domestic Biogas Programme (TDBP), is funded by The Netherlands, through its directorate of international cooperation.
Programme coordinator Lehada Cyprian Shilla, once expressed optimism over its potential to alleviate current energy woes as it would provide cleaner and safer energy solutions at a household level.
When it was officially inaugurated by Vice President Mohamed Gharib Bilal, a total of 1,439 units had been constructed under the programme in various regions  giving Tanzania a lead ahead of other nations where the initiative is being undertaken in Africa.
“Besides, providing an alternative source of energy to households currently faced with rising kerosene prices and worsening electricity crisis, the programme is expected to stimulate the private sector’s participation in the development of biogas technology and sale of a gas “that is affordable and simple in rural and peri-urban households,” he said.
By Lusekelo Philemon, The Guardian
 
Source: http://in2eastafrica.net/tanzania-camartec-appeals-for-massive-biogas-production/

 Biogas to be produced from poisonous algae?




Swedish researchers are now gathering poisonous alga with the help of oil sump pumps. The aim is to use this system to save sensitive shores and at the same time use the alga soup in the production of biogas. The current project is led by Fredrik Gröndahl, associate professor at KTH in Stockholm.
The Baltic Sea is one of the most polluted in the world. In the last 50 years it has suffered from over-fertilisation and during this process the poisonous algal blooms have become more common.
The new method is currently tested on alga in the St Anna archipelago outside Norrköping.  

Source: blog.paksc.org


Methane – biogas – production guide 


Basic properties of methane 
Methane – biogas – production guide

 
Methane is a colourless, odourless, flammable1 gas and the main constituent, 85% to 90%, of the pipe natural gas that we use in our homes in  the UK, Europe and the USA.  Its chemical symbols are CH4  and its is a hydrocarbon.  The theoretical methane yield can be shown  to be 5.6 ft3/pound (lb) of chemical oxygen demand converted, but the exact recoverable yield depends on a number of environmental conditions. The ultimate yield of  biogas depends on the  composition and biodegradability of the organic feedstock, but its production rate will depend on the population of microorganisms, their growth conditions, and fermentation
temperature.  Methane produced by the anaerobic digestion process is quite similar to natural gas2 that is extracted from the wellhead  and piped to our homes. However, natural gas contains a  variety of hydrocarbons other than methane, such as ethane, propane, and butane. As a result, natural gas will always have a higher calorific value than pure methane. Depending on the digestion process, the methane content of biogas is generally between 55%-80%. The remaining composition is primarily carbon dioxide, with trace quantities (0-15,000 ppm) of corrosive hydrogen sulfide and water.
Methane – biogas – production guide
The average expected  energy content of pure  methane is  896-1069 Btu/ft3; natural gas has an energy content about 10% higher because of added gas liquids  like butane. However, the particular  characteristics of methane, the  simplest of the hydrocarbons, make it  an excellent fuel for certain uses.  With some equipment modifications to account for its lower energy content and other constituent components, biogas can be used in all energy consuming applications designed for natural gas.
 The gas made using the suggested ideas contained in this document will be made up
of methane plus other gasses or ‘diluters’ and have a typical value of 600 BTUs per
cubic foot. 
Anecdotal evidence indicates that biogas was used for heating bath water in Assyria during the10th  century BC and in  Persia during the 16th  century. Jan Baptita Van Helmont first determined in 17th  century that flammable gases could  evolve from decaying organic matter. Count Alessandro Volta concluded in 1776 that there was a direct correlation between the amount of decaying organic matter and the amount of flammable gas produced. In 1808, Sir Humphry Davy determined that methane was present in the gases produced during the anaerobic digestion of cattle manure.
The first digestion plant was built at a leper colony in Bombay, India in 1859. Anaerobic digestion reached England in 1895  when biogas was recovered from  a ‘carefully designed’ sewage treatment facility and used to fuel street lamps in Exeter. The development of  microbiology as a  science led to research by  Buswell5  and others in the 1930s to identify anaerobic bacteria and the conditions that promote methane production.

                                              
 Methane will not ignite and burn without the presence of oxygen 2 The name natural gas was used to distinguish it from town gas made from coal or oil. Town gas was distributedaround the UK until the discovery of natural gas in the North Sea. It comprised  a whole range of gases includingmethane and carbon monoxide.



Methane gas also occurs naturally  as swamp gas produced from murky stagnantwater. Lightning could ignite this gas and has been said to be the origin of Willow theWisp. Indeed the term swamp gas is  often  used as methane gas produced  by anaerobic digestion. Landfill gas is also made up of a high proportion of methane andis a good example of the commercial use of  methane production where the gas is often used to drive a gas engine and electric generators.

Gas made with a digester is also commonly called biogas.

Anaerobic digestion

Anaerobic digestion is one of the most common chemical processes in nature.Anaerobic means the decay or breakdown in the absence of air or more specifically oxygen. The process is similar to fermentation as the transformation is brought about by micro-organisms (bacteria) called anaerobes. Like with  the production of alcohol (ethanol) digestion takes place in two stages. First, in the medium of digestion certain micro-organisms break-down the materials into simple  sugars, alcohol, glycerol and peptides. When these  components are present in the correct amounts and the conditions are correct,  a second group of micro-organisms converts these simpler molecules into methane gas. The micro-organisms are particularly sensitive to environmental conditions including temperature and acidity.

Anaerobic  digestion occurs between 32o 

F and 150o
 F. However  the optimum
temperature which promotes activity of the  micro-organisms and consequently
produce more methane gas is between 85o
 and 95o
F. In colder climates this is
difficult to  maintain but worthwhile trying to achieve.  Below 60o
F little gas is
produced.

Methane – biogas – production guide
Acidity is also important with a desired pH of between 7 and 8. With a low acid content the  - high pH  - the fermenting slows down until the bacteria produce enough acid (acidic carbon dioxide) to restore the balance. Acidity can be measured using litmus paper.

Carbon and nitrogen are the other two components for a digester  and are both required for the micro-organisms to live. However, the bacteria consume the carbon at about 30 times faster than the nitrogen. This 30:1 ratio produces the maximum amount of gas. If the ratio is not correct the bacteria will usually compensate creating the right balance within the digester.

As mentioned earlier the gas produced in a  digester is  not pure methane and is usually 75% methane and carbon dioxide (CO2  ) with trace amounts  of hydrogen, nitrogen and other gases characteristic of the original materials used in the digester.
The slurry that is left after the digestion process is complete is mainly  composed of organic humus, with small amounts of nitrogen and phosphates. This final product of gas production makes an excellent fertiliser and soil conditioner.

It should be noted that the time in starting the digester and producing gas can be as long as four weeks – but sometimes as short as two weeks. This is because the bacteria will first need time to breakdown the slurry into alcohols and sugars, before the second group of bacteria, the gas producing ones, can adjust the carbon/nitrogen mix and the acidity level for reasonable amounts of gas to be produced.


Methane – biogas – production guide

Modest experiment in methane gas production

Having read the first part of this guide many readers may want to build a methane digestion plant now and power up their houses. However, while you are waiting to build a digester large enough to process your household waste and other peoples’ waste from down the street into enough methane to heat the house, you may wish to try a simple, low cost experiment.  This will help familiarise you with the fuel's production and some of its characteristics.  
Here is how to put together one of the simplest and least expensive methane production experiments of all. You will need only a gallon cider jug, some sort of gas holder (a recycled, heavy-duty plastic bag) and, from the chemistry lab, some rubber tubing, a couple of tubing clamps, a two-hole rubber stopper, glass tubing and a glass "Y". 

Your first step in constructing a mini-methane-generator will be to make a manometer. This is a U-shaped tube, partly filled with water, that will let you know when your little digester is producing gas, indicate the pressure of that gas and act as a safety valve (since excess pressure will blow the water out of the manometer). Any chemistry student should be able to show you the proper way to heat and form your
glass tubing. 

The four inch manometer dimension shown in the drawing should be considered a maximum for both practical and safety reasons. Filling the tube with water to such a depth will give you eight inches of pressure ( eight inches water gauge is about the same pressure  as the gas in a UK home)  and therefore more than sufficient. Gas appliances usually operate on pressures of less than eight inches and there is no reason for you to risk blowing your jug apart with gas compressed beyond this amount.
Once your manometer is completed, you should make a "burner tip" by drawing out a piece of glass tubing in the approved manner (again, any chemistry student should be able to help you if you have never formed glass tubing before). The tip should be quite long as a precaution against the possibility of a back flash. Then attach the stretched-out burner to one arm of your glass "Y" with a short piece of rubber tubing on which a clamp is placed to act as a valve.  
The other branch of the "Y" feeds directly to your gas collector through a longer section of rubber tubing (also fitted with a clamp). The experiment that wrote this

article3  made a collector from a polyethylene milk bag taken from a cafeteria-type dispenser. The cardboard cartons that fit inside such dispensers are thrown out after one use and you will find that each box contains a bag-liner. Fully inflated, the bags are somewhat larger than a king-sized pillow. Wash one out, roll it up to expel the air
inside and hook it to the "Y".

Now you are ready to place some manure in the jug. The best type appears to be a mixture of droppings and litter from chickens but, if you can not get that, try something else such as straight horse manure. As mentioned earlier in this guide the very most efficient formula is 30 parts of carbon to one part nitrogen. 

                                 
 This section of the gude was taken from a Mother Earth publication written by Robert C. McMahon


Mix the manure with water to form slurry and pour it into the jug. Fill the jug to about four inches below the stopper (there will be some initial foaming and you want to keep it out of the tubing).  Once again the most efficient generation of methane takes place at 90 to 100°F and, if your slurry's temperature drops much below 80°, the gas production will be slow or non-existent. You will have to provide a sufficiently warm environment for your jug, then, if you want it to make gas. Bear in mind, though, that methane—carelessly handled—can explode so take suitable precautions in setting up your apparatus.  Never place the experiment near a naked fire or burner. Never use a jar or tin to collect the gas in as it will contain air and therefore an explosive mixture will be made. Always use a bag or something similar from which all the air can be expelled.


Start your generator working with all its valves (clamps) closed and, after a couple of days, the water being "pushed" up the long arm of the manometer will indicate that August 2006  7 Methane – biogas – production guide some pressure is beginning to build in the jug. This first production is mostly carbon dioxide, which will not burn. (Test the gas by holding an ignited match at the tip of the burner and opening its clamp. The amount of gas in the manometer is sufficient for such a trial, although—as stated—the carbon dioxide will not burn.) 

Continue the tests until a match held at the burner tip does ignite the escaping gas. This may take a couple of weeks or more depending upon the acid conditions of the slurry in your jug.
Eventually, incorrect acidity levels will correct themselves and your model generator will begin to produce methane. When you are satisfied that such production is underway, open the clamp to the gas collector and you're in business. Methane production—depending on temperature—should last for from one to three months. 

And what can you do with the gas? You can burn it off through the burner tip as a graphic demonstration that decomposed organic matter really does produce usable fuel. The quantity is too small for much else. To increase the pressure of the escaping gas (and, thereby, the spectacular nature of the resulting flame), place one or more weights on the collector bag. The manometer, of course, will faithfully indicate the pressure your gas reaches during such a demonstration.  
Once the thrill of watching the flame passes, disconnect the collector bag, take it outside and expel the remaining methane. Remember the residue left in the jug is an excellent fertiliser and you can use the liquid and some of the solids to seed your next batch of waste (and thereby hasten its production of gas). 

The author also suggests a couple of untried refinements. If you have a fish aquarium heater available, you might try putting your jug in a bucket of water warmed by the element. This would be a significant improvement in maintaining the digesting slurry at optimum working temperature. You can also improve the burning qualities of the resulting methane by bubbling it through a lime water solution to remove carbon
dioxide and passing it over ferric oxide (rust) to remove hydrogen sulphide.
Although the above experiment is imprecise and yields only a small quantity of methane, it will familiarise you with the digestion process and, possibly, encourage you to investigate the construction of larger-scale  generators that will produce usable quantities of gas.

Simple anaerobic digester

A larger digester can be made very simply. The main component required to make a simple digester is the  vessel that will contain  the slurry. The vessel must allow a method of filling as well as a way of extracting the gas.  The diagram below is  a simple digester show  for demonstration purposes only, and is not meant for
construction in its exact state as, although correct in concept it does not allow for the safe storage of the gas produced.

Gas storage

Once the gas has been produced  a practical  and safe means of storing the gas  is essential. As discussed earlier the storage container must not contain air and there must be no way for air to enter the storage vessel.  Therefore the vessel must have absolutely no air in it before the gas is introduced. If not an explosive mixture will be reduced. It is never adequate to allow a gas air mixture to be formed and rely on there being no source of ignition. Sources of ignition can arise from static electricity, for example, and therefore there is always a potential source of ignition nearby.
This basic digester will produce a modest amount of methane gas.  Once again it is a good model to try out in order to become familiarised with the process of methane production.  This type of digester is  known as a batch feed system, where slurry is introduced into the digester through a service door that is then sealed closed. After a few weeks once the conditions are right, fermentation begins. An airspace at the top of the vessel to allow the first group of bacteria some oxygen to breakdown the slurry into simple molecules and to help prevent foam produced during  the digestion process to travel into the pipes. After a couple of months the batch will no longer produce gas. At this point the drain valve is  opened and the decomposed matter
removed. The vessel may be flushed through but a small amount of slurry should be kept to help start the next batch.

Batch digester construction

This little digester will provide enough free gas to provide heat to cook one meal a day. Modest applications like lighting small rooms with gas lanterns and cooking are ideal for this system. It can also be a low cost build.  A simple inner tube from a large tyre such as a tractor will make a perfect container for the gas as it:
•  Is relatively inexpensive and easy to obtain •  May be purged of air relatively easily by rolling tightly
•  Automatically creates pressure for feeding the appliance •  Is about the right volume for the size of the digester.



Purging the container  or pipe means to remove all air from it. It cannot be emphasised enough that at no time must air be aloud to mix with the methane.The container used in this system is a standard 44-gallon oil drum. Try and get one
that is relatively clean with no rust whatsoever.  Safely remove any residues in thetank with soap and water and then clean water. Oil drums  are used to  store a very wide range of chemicals and oils so find out what was stored in it before you flush out the contents. If in doubt look for  another container that has been used for a safer

product.

A stable and secure base can be  made out of a few concrete bricks  or slabs. The drum when full will be very heavy. The container agould be kept off the ground to prevent rusting where  possible. The drum should also be high enough to allow draining into a suitable container.
There are normally two vent holes  at the top of the drum.  It is best to try and use  these to fill the vessel. They will need to be closed afterwards and be gas tight. If a larger access hole is required one suggestion is to use an air filter cover form an old  car  - some like fords had large metal air filters with one or two bolts to secure them and a rubber gasket to provide an air tight seal. After cutting out the right size hole a
cross bar could be fitted across the hole with bolts aligned to fit the air filter cover.  Last, drill a snug fitting ¾” hole into the top of the drum and install the gas outlet pipe. A further hole should be drilled near the bottom of the drum so that  a drain can be fitted with a valve. The materials for these pipes can be iron or copper. Plastic pipe
could be used for the drain. However some  times this pipe can go brittle when exposed to sunlight.

For larger outputs two  units can be constructed in series. Indeed as the units are simple and cheap to build you may wish to build even more

Suggested parts list

44 gallon oil drum
air filter housing for service door- optional
Concrete bricks for base
¾” copper piping
‘T’ joint with ½” copper reducer
Valves
Large tyre inner tube
Tyre hose – screw on type
Iron work for service door
Copper fittings- compression fittings are not recommended
PTFE tape, jointing compound, etc.
Solder and propane blow torch.
August 2006  10
Methane – biogas – production guide



Digester operation


The composition of the slurry will to a large extent determine the success of your
digester. To get the 30:1 ratio of carbon and nitrogen animal manure appears to be
best.  Adding grass cuttings and leaves maybe acceptable but they contain little or no
nitrogen. But trial and error may help you find the right mix. 

On a farm manure is readily available but in the city less so. It is then possible to mix
leaves and grass clippings with organic waste from the kitchen.  This can include fruit
and vegetable peelings but not cooked food, meat, paper or cardboard.

Ideally the slurry that works best in the digester comprises:

•  3 to 4 gallons of liquefied manure
•  10 gallons of water
•  Enough grass cuttings and leaves (50:50 ration) to fill the vessel within 1 foot of
the top.

August 2006  11
Methane – biogas – production guide
The mixture should be stirred well and should produce gas after about 2 weeks with
peak production after about 8 weeks. There will be little production after 12 weeks. 

When gas is being produced – try bubbling the output through some  water rather
than into the storage vessel  - leave it to produce gas for several days until you are
certain that all the air has been expelled. DO NOT LIGHT THE GAS. The vessel and
pipe work may still contain air and therefore you might cause an explosion.

Then take the inner tube and remove the tyre valve. Roll the tube very tightly pushing
all of the air out of the tube. When this is complete replace the valve and screw the
valve onto the ‘T’ joint. The system should now be free of any air and ready to accept
an appliance.

You must also purge all pipes that are added to the system at this point as they will
have air in them until the gas passes through. You can let the appliance run for a few
minutes before lighting when it is first connected.  Do not do this in an enclosed area
where the venting gas can build up. 

Digester performance

This type of batch feed system does offer some drawbacks as will probably need the
gas each day rather than waiting for two weeks. One solution is to use two digesters
and aim for one to reach peak performance whilst the other is fermenting and starting
to produce gas.  

Continuous output digester

A fairly large digester can be built from two 275-gallon boiler oil tanks. One can be
used for the digester and one for the holding tank.

A feed chamber can be placed at the end of the digester, with an airtight valve at the
top and bottom of its column.

The exhaust tube can be placed up near the top of the tank, but low enough so that
the level of the used slurry flows out of the digester (about 8 gallons) will come out.
On the other hand a pipe too low will be exhausting slurry that is still digestible.  A
simple way  of setting the correct height is to add exactly  8 gallons of liquid slurry
when filling at the point when the slurry just starts to overflow out of the exhaust pipe.
Close the valve and add 8 more gallons.

The holding tank should be equipped with a pressure valve measuring up to 50 pisg.
The pressure of the gas should be monitored closely and any excess gas vented or
consumed.

The holding tank cannot of course be collapsed. Therefore, a displacement method
must be used to purge it of air. Filling the tank with water to the very top ensuring that
there is no air present can do this. Once the feed line from the digester is purged –
let it run for a few days after fermentation like the drum digester – it can be attached
to the holding tank. The methane will then displace the water that will flow out of the
exhaust tube. Once all  the water is removed, the valve to the exhaust tube on the
holding tank can be closed. The tank is now purged and ready for use.

August 2006  12
Methane – biogas – production guide
Parts
Two 275-gallon oil tanks
¾” copper tubing and fittings
50psig pressure gauge
Length of plastic hose for a site tube
Hose clamps
Valve to fit 4” copper pipe
Length of 4” copper pipe for fill tube
Funnel to aid filling   


Operation of continuous output digester
1.  To start the digester close all valves
2.  Open valves (g) (c) and (d)
3.  Fill the low pressure chute with slurry until the sight level tube shows slurry near
the top in the tank ( one foot space form the top). The slurry will seek its own level
therefore there will still be slurry in the fill chute up to the level of the slurry in the
digester. The slurry should be allowed to pre-ferment. A cover maybe fitted to the
top of the chute if desired. Remember to close valve ( c)  after initial filling and
after daily filling.
4.  As gas passes through valves (d) and (g) the system is purged and air is
displaced. Fit a hose to  the purge fitting and place the other end of the  hose in
water to check for bubbles of gas. Purge for  a few days once the system is
fermenting. Make sure no air is present in the line.
5.  Open valve  (f) fill the holding tank full with water making sure to expel all of the
air. Then close valve (f).
August 2006  13
Methane – biogas – production guide
6.  Open valves (a) and (e) and let gas enter the holding tank and thus displace the
water. It will be forced out of the water displacement tube. An optional extension
may be placed on top  of this tube, however make sure that the pipe  passes
above the top of the tank since the water will seek its own level.
7.  A hose may be fitted to the water fill pipe, and the gas  consumed by opening
valve (f). Close valve (e) once all water is displaced.
8.  Monitor the pressure gauge daily. If the pressure is high in the system gravity will
not be enough to push  the slurry down the fill  chute. A circulation pump would
then have to be installed. However  of the pressure is within the specified range
up to 50psig then there should be no problem. To refill  daily, close  all valves.
Open valve (b) and let 1/30th
 of the slurry come out (this slurry is already
digested). Then close  valve (b) and replace  the 1/30th
 of the slurry volume
through the fill chute.

Methane – biogas – production guide
.
E-Books available

Methane Production Guide - how to make biogas. Three simple anaerobic digesters for home construction (Jemmett Engineering Energy Guides) 






Methane Production Guide - how to make biogas. Three simple anaerobic digesters for home construction (Jemmett Engineering Energy Guides)
biogas cowtec television program enjoy sub english



Thai research result generated "COWTEC", the artificial Cow... Good Genius for Manure, Bio Extract from by-product in farming or organic rubbish. Rapidly create ready product within 24 hours and beneficially generate biogas for cooking or as clean power source to substitute solar oil.

"COWTEC" provides convenience, shorten time in fertilizer manufacturing, support production process, save production area, and manpower. The daily generating manure is efficiency and truly save production cost but productive for farming.

Biodigestors Improve Quality of Life while Protecting the Environment



BCrowfoot-Moo1-250Traditional providers of milk, meat and fertilizer can also be grazing fuel factories. Credit: Betsy Crowfoot
Biogas has been collected for years by major first-world agricultural entities, landfills and manufacturers, but now families in developing countries and environmentally at-risk sites also are finding the collection of methane gas byproduct can fuel lamps, ovens, and hope.
Moses and Miriam Sabiika live 20 miles from the Ugandan capital of Kampala, and the shores of Lake Victoria. Nearly a dozen years ago they received a gift of livestock via a Heifer International program, to supplement the crops that barely sustained them, their five children, and two grandchildren.
Within a few years their cattle had multiplied, leaving them in the enviable position of having excess manure. Enviable, because the Sabiikas knew about the biogas collection technology which has become popular in small agricultural and peri-urban settings, not only in Africa, but across the world.
Improved-Biodigester-Honduras-250Improved biodigester, Honduras. Courtesy: Heifer International
In late 2009 a biogas ‘digester’ was installed near their home by Heifer International and the Uganda Domestic Biogas Program (UDBP) partnership, and within a month they started collecting gas.
Prior to the use of biogas, Mrs. Sabiika said, cooking with firewood was “a nightmare” – particularly during rainy season. Women and children will traditionally spend long hours collecting firewood – contributing to the deforestation of habitat, and detracting from their ability to attend schools or get jobs. Cooking over a fire is also hazardous, because of the noxious smoke, and open fires prove dangerous to small children.

How it Works

Chinese-biodigester-250Chinese biodigester. Courtesy: Heifer International
Dung is fed into a containment chamber – in Honduras it might be a heavy-duty plastic structure; in China, a domed concrete over brick repository – called a digester. In this oxygen-free environment bacteria breaks down the organic waste creating a mixture of gases, predominantly methane, which is combustible. The gas is captured and converted into energy, used for cooking, lighting and heat.
“I could not believe when I had the gas coming,” said Mr. Sabiika. “I immediately got a match box to test and to my surprise, the gas could cook and light.” The biogas, he added, cooked quickly and cleanly; and although customarily men in his culture do not cook, he bucked that tradition and made himself a cup of tea.
Taiwan-biodigester-250Taiwan biodigester. Courtesy: Heifer International
Biogas is beneficial for so many reasons. It improves the quality of life and economic condition for the families involved; eliminates harmful smoky wood and coal fires from their homes; and diverts methane gas from the environment. The process destroys germs that exist in the fecal matter, and helps reduce water pollution from runoff waste.
Added UDBP Engineer Kato Christopher, “Owing to the increasing energy demand and increased deforestation, this program is a timely action taken towards encouraging the general public to reduce the energy demand through efficient use of the existing energy sources.”
Another byproduct of the byproduct? An organic fertilizing slurry that helps families grow more vigorous crops.
Improved-oven-ecologic-250Improved oven (ecologic). Courtesy: Heifer International
“I used to think the only thing cows produced was milk,” said Juan, a Honduran farmer who now hosts a bio digester. “My cow gives me milk, calves, it can give me meat, organic fertilizer and something I never imagined: fire for my stove!”
Switching from firewood to biogas has helped save trees and eliminate odor and pollution produced by smoky fires, he added. “Sometimes people aren’t thinking about the environment and they are wasting their resources and contaminating the environment. Bio digesters have really helped to save trees and help protect the environment.”


source: http://ecology.com/ecology-today/2011/08/11/biogas-digestors-improve-quality-of-life-while-protecting-the-environment/

Design of a mechanism to mix biogas with air in compression internal combustion engine

Ahmad Hazury, Hamid (2010) Design of a mechanism to mix biogas with air in compression internal combustion engine. EngD thesis, Universiti Malaysia Pahang.
[img]PDF
900Kb

Abstract

Internal combustion engines burn fuel to create kinetic energy. The burning of fuel is basically the reaction of the fuel with the oxygen in the air. The amount of oxygen present in the cylinder is the limiting factor for the amount of fuel can be burnt. If there’s too much fuel present, not all fuel will be burnt and un-burnt fuel will be pushed out through the exhaust valve. When building an engine, it’s very important to know the air-fuel ratio at which exactly all the available oxygen is used to burn the fuel and all the fuel is burnt completely. This ratio is called the stoichiometric air-fuel ratio. This project has successfully design a venturi mixer and analyze design of pressure regulator that perform accurate state estimation achieving desired outputs with certain parameters setting. It helps identify the current operating state of the system on which, on certain condition can generate the accurate output.
Item Type:Thesis (EngD)
Uncontrolled Keywords:Internal combustion engines
Subjects:T Technology > TJ Mechanical engineering and machinery
Faculty:Faculty of Mechanical Engineering
ID Code:1507
Deposited By:Syed Mohd Faiz
Deposited On:03 Aug 2011 11:31
Last Modified:03 Aug 2011 11:31

Design of biogas digester (Indian type)

Mohd Ayub , Adnan (2010) Design of biogas digester (Indian type). EngD thesis, Universiti Malaysia Pahang.
[img]PDF
1215Kb

Abstract

This project deals with designing and fabricating a biogas digester which is focusing on Indian type. The objective of this project is to design a biogas digester that can produces biogas with specific flow rate. The digester that uses floating roof will produces constant pressure biogas. The specifications for the design will meet the type and specifications of the diesel engine that will run the generator. The fabrication of lab size digester was done by using 200 litres barrel. Biogas, a clean and renewable form of energy could very well substitute (especially in the rural sector) for conventional sources of energy (fossil fuels, oil, etc.) which are causing ecological–environmental problems and at the same time depleting at a faster rate. Utilization of biogas has gained importance in recent years, mainly due to the availability of cheap raw materials and environmental compatibility. Further, with an increase in the cost of petroleum products, biogas can be an effective alternative source of energy for cooking, lighting, food processing, irrigation and several other requirements. In essence, a biogas digester involves anaerobic fermentation process in which different groups of bacteria act upon complex organic materials in the absence of air to produce biogas. The efficiency of anaerobic digestion essentially depends on intensity of bacterial activity, which is influenced by several factors such as ambient temperature, temperature of digester material, loading rate, retention time, pH value of digester content etc. Therefore, for efficient performance of a biogas plant, it is necessary to regulate all the factors suitably. The rate of biogas production also depends on the ambient temperature of a particular region.
Item Type:Thesis (EngD)
Uncontrolled Keywords:Engineering design, Biogas, Renewable energy sources
Subjects:T Technology > TA Engineering (General). Civil engineering (General)
Faculty:Faculty of Mechanical Engineering
ID Code:1832
Deposited By:Syed Mohd Faiz
Deposited On:09 Aug 2011 12:23
Last Modified:09 Aug 2011 12:23
 Biog & Puxin Biogas Plants
 Biog & Puxin Biogas Plants


Puxin Biogas Plants superiority in consummate hydraulic pressure biogas system and convenient construction solutions, as we have developed a new type gas plant featuring easy operation, easy maintenance, fast
initial gas producing. Our plants are well reputed in the biogas industry with durable quality of products,
excellent safety and the low cost.
 The following are the biogas system.

1. Puxin medium size biogas system: The medium size biogas system is composed of one or a group of
100 m3 biogas plants formed into a unit, the pipes system, the gas purification system and the appliances or electricity generator. The medium size biogas system is mainly applied to the livestock (pig, cow, etc.) plants to treat the waste, or applied to public buildings (hotel, apartment, etc.) to treat sewage and organic food waste. 
2. Puxin family size biogas system: The family size biogas system is composed of one or several 10 m3
biogas plants formed into a unit, the pipe system, the gas purification devices and the appliances. The
family size biogas system is mainly applied to family house to treat sewage and organic food waste. 
For those two type biogas systems we sell all the equipments and products needed to build the biogas system to our customers, train the technicians for them, and we or our customers can build the biogas application system themselves.
Our products for building a biogas plant include: the steel mould that is equipment used to build the concrete digester of the 10m3 biogas plant, the glass fiber gasholder that is a component of the 10m3 Puxin biogas plant, the pipeline, the biogas appliances (stove, water heater, rice cooker, lamp etc.) and small power biogas generators.  
The steel mould is composed of a number of steel mounding boards. By using a steel mould a 6 or 10 m3 biogas digester can be build in two days, or 150 in a year. The steel mould is reusable and can be used over 2000 times and lasts over ten years.   The glass fiber reinforced plastic gasholder is 1.0-1.2
m3 that is one of the main components of the Puxin biogas plant, and it can last over 10 years.

The Structure

Puxin  Biogas  Plant  is  of  the  hydraulic pressure  biogas  plant  type,  and  is composed  of  a  concrete  digester  and  a glass  fibre  reinforced  plastic  gasholder. The  digester  has  a  capacity  of  6  or  10 cubic  meters,  and  is  constituted  by  a stomach,  a  neck  an  inlet  and  an  outlet. The gasholder  is 1.6 m in diameter, 1 or 1.2  cubic  meter  in  capacity.  The gasholder  is  installed  within  the  digester neck,  fixed  by  a  component;  the gasholder and the digester are sealed up with water.
 Biog & Puxin Biogas Plants
 Comparing with the traditional fixed dome type hydraulic Biogas plant, Puxin Biogas

Digester has the following distinct advantages:   Easy to build and 100% success rate: The construction of Puxin Biogas Plant is exempt from the difficult airtight craft, so the technical difficulty is greatly decreased, and the construction perriod is greatly shortened. To build a Puxin Biogas Digester successfully, the constructers are only required to master how to assemble and disassemble the steel mould. Any workman can learn to
build Puxin Biogas Digester within a day and with 100% success rate

Download PDF : http://www.biog.as/puxin.pdf

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