Biogas at work in Uganda
Wednesday, 7 March 2012
Friday, 2 March 2012
Types of Anaerobic Digesters
Types of Anaerobic Digesters
Anaerobic digesters are capable of treating insoluble wastes and soluble waste-waters. Insoluble wastes such as particulate and colloidal organics are considered to be high-strength wastes and require lengthy digestion periods for hydrolysis and solubilization. Digester retention times of at least 10–20 days are typical for high-strength wastes. High-rate anaerobic digesters are used for the treatment of soluble wastewaters. Because these wastewaters do not require hydrolysis and solubilization of wastes, much faster rates of treatment are obtained. High-rate anaerobic digesters usually have retention times of less than 8 hours.
High-strength wastes are usually treated in suspended growth systems, whereas soluble wastewaters are usually treated in fixed-film systems. Several anaerobic digester processes and configurations are available for the treatment of insoluble wastes and soluble wastewaters (Table 1). Each configuration impacts solids retention time (SRT) and hydraulic retention time (HRT). Minimal HRT is desired to reduce digester volume and capital costs. Maximal SRT is desired to achieve process stability and minimal sludge production
BACTERIAL GROWTH—SUSPENDED Dome Biodigester
In suspended growth systems, the bacteria are suspended in the digester through intermittent or continuous mixing action (Figure ). The mixing action distributes the bacteria or biomass throughout the digester.
Because completely mixed anaerobic digesters do not incorporate a means for retaining and concentrating the biomass, the SRT is the same as the HRT.
Advantages and Disadvantages of Suspended Growth Anaerobic Digesters
Advantages
Suitable for the treatment of particulate, colloidal, and soluble wastes Toxic wastes may be diluted Uniform distribution of nutrients, pH, substrate, and temperature
Disadvantages
Large digester volume required to provide necessary SRT Treatment efficiency may be reduced due to loss of particulate and colloidal wastes and bacteria in digester effluent
Completely mixed anaerobic digesters are designed for relatively long HRTs. Feed sludge can be added to the digester on a continuous or intermittent basis. Advantages and disadvantages of completely mixed suspended growth digesters are listed in Table
BACTERIAL GROWTH—FIXED Dome Digester
Anaerobic fixed-film (sludge blankets) systems provide a quiescent environment for the growth of an agglutinated mass of bacteria (Figure 2). Because bacterial growth requires relatively long periods of time to develop, the media used in fixed-film systems hold the bacteria in the digester for relatively long periods and provide for long SRTs and short HRTs. The bacteria grow as fixed films of dendritic or “stringlike” masses on the supportive media or as clumps of solids within the openings or voids of the supportive media. Fixed-film systems usually use gravel, plastic, and rock as the supportive media. The openings make up approximately 50% or more of the media. Fixed-film systems operate as flow-through processes, that is, wastewater passes over and through a bed of fixed film of bacteria growth and through entrapped clumps of bacterial growth (Figure 23.3). Soluble organic compounds in the waste-water are absorbed (diffuse into) by the bacteria, whereas insoluble organic compounds are adsorbed (attach) to the surface of the bacteria. The flow of wastewater through fixed-film systems may be from the bottom to the top (upflow) or from the
top to the bottom .Because the bacteria (solids) in fixed-film systems remain in the digester for long
SRTs, the systems allow methane-forming bacteria to acclimate to toxicants such as ammonia, sulfide, and formaldehyde. Therefore, anaerobic fixed-film systems with long SRTs and short HRTs may be used to treat industrial wastewater containing toxicants. Numerous fixed-film systems are available for use in the digestion of municipal and industrial wastewaters and sludges . These systems are capable of treating a variety of wastewaters and sludges, provide good contact
biogas plant
Anaerobic digesters are capable of treating insoluble wastes and soluble waste-waters. Insoluble wastes such as particulate and colloidal organics are considered to be high-strength wastes and require lengthy digestion periods for hydrolysis and solubilization. Digester retention times of at least 10–20 days are typical for high-strength wastes. High-rate anaerobic digesters are used for the treatment of soluble wastewaters. Because these wastewaters do not require hydrolysis and solubilization of wastes, much faster rates of treatment are obtained. High-rate anaerobic digesters usually have retention times of less than 8 hours.
High-strength wastes are usually treated in suspended growth systems, whereas soluble wastewaters are usually treated in fixed-film systems. Several anaerobic digester processes and configurations are available for the treatment of insoluble wastes and soluble wastewaters (Table 1). Each configuration impacts solids retention time (SRT) and hydraulic retention time (HRT). Minimal HRT is desired to reduce digester volume and capital costs. Maximal SRT is desired to achieve process stability and minimal sludge production
BACTERIAL GROWTH—SUSPENDED Dome Biodigester
In suspended growth systems, the bacteria are suspended in the digester through intermittent or continuous mixing action (Figure ). The mixing action distributes the bacteria or biomass throughout the digester.
Because completely mixed anaerobic digesters do not incorporate a means for retaining and concentrating the biomass, the SRT is the same as the HRT.
Advantages and Disadvantages of Suspended Growth Anaerobic Digesters
Advantages
Suitable for the treatment of particulate, colloidal, and soluble wastes Toxic wastes may be diluted Uniform distribution of nutrients, pH, substrate, and temperature
Disadvantages
Large digester volume required to provide necessary SRT Treatment efficiency may be reduced due to loss of particulate and colloidal wastes and bacteria in digester effluent
Completely mixed anaerobic digesters are designed for relatively long HRTs. Feed sludge can be added to the digester on a continuous or intermittent basis. Advantages and disadvantages of completely mixed suspended growth digesters are listed in Table
BACTERIAL GROWTH—FIXED Dome Digester
Anaerobic fixed-film (sludge blankets) systems provide a quiescent environment for the growth of an agglutinated mass of bacteria (Figure 2). Because bacterial growth requires relatively long periods of time to develop, the media used in fixed-film systems hold the bacteria in the digester for relatively long periods and provide for long SRTs and short HRTs. The bacteria grow as fixed films of dendritic or “stringlike” masses on the supportive media or as clumps of solids within the openings or voids of the supportive media. Fixed-film systems usually use gravel, plastic, and rock as the supportive media. The openings make up approximately 50% or more of the media. Fixed-film systems operate as flow-through processes, that is, wastewater passes over and through a bed of fixed film of bacteria growth and through entrapped clumps of bacterial growth (Figure 23.3). Soluble organic compounds in the waste-water are absorbed (diffuse into) by the bacteria, whereas insoluble organic compounds are adsorbed (attach) to the surface of the bacteria. The flow of wastewater through fixed-film systems may be from the bottom to the top (upflow) or from the
top to the bottom .Because the bacteria (solids) in fixed-film systems remain in the digester for long
SRTs, the systems allow methane-forming bacteria to acclimate to toxicants such as ammonia, sulfide, and formaldehyde. Therefore, anaerobic fixed-film systems with long SRTs and short HRTs may be used to treat industrial wastewater containing toxicants. Numerous fixed-film systems are available for use in the digestion of municipal and industrial wastewaters and sludges . These systems are capable of treating a variety of wastewaters and sludges, provide good contact
biogas plant
 |
| Anaerobic fixed- dome 2 |
 |
| suspended growth systems 1 |
Anaerobic Digestion Stages
Anaerobic Digestion Stages
The anaerobic digestion process and production of methane is divided into stages. Three stages often are used to illustrate the sequence of microbial events that occur during the digestion process and the production of methane (Figure). These stages are hydrolysis, acid forming, and methanogenesis. The anaerobic digestion process proceeds efficiently if the degradation rates of all three stages are equal. If the first stage is inhibited, then the substrates for the second and third stages will be limited and methane production decreases. If the
third stage is inhibited, the acids produced in the second stage accumulate. The inhibition of the third stage occurs because of an increase in acids and, consequently, loss of alkalinity and decrease in pH. The most common upsets of anaerobic digesters occur because of inhibition of methane-forming bacteria—the third stage. The anaerobic digestion process contains different groups of bacteria. These groups work in sequence, with the products of one group serving as the substrates of another group. Therefore, each group is linked to other groups in chainlike fashion, with the weakest links being acetate production and methane production.
STAGE 1—HYDROLYSIS STAGE
STAGE 2—ACID-FORMING STAGE
STAGE 3—METHANOGENESIS STAGE
The anaerobic digestion process and production of methane is divided into stages. Three stages often are used to illustrate the sequence of microbial events that occur during the digestion process and the production of methane (Figure). These stages are hydrolysis, acid forming, and methanogenesis. The anaerobic digestion process proceeds efficiently if the degradation rates of all three stages are equal. If the first stage is inhibited, then the substrates for the second and third stages will be limited and methane production decreases. If the
third stage is inhibited, the acids produced in the second stage accumulate. The inhibition of the third stage occurs because of an increase in acids and, consequently, loss of alkalinity and decrease in pH. The most common upsets of anaerobic digesters occur because of inhibition of methane-forming bacteria—the third stage. The anaerobic digestion process contains different groups of bacteria. These groups work in sequence, with the products of one group serving as the substrates of another group. Therefore, each group is linked to other groups in chainlike fashion, with the weakest links being acetate production and methane production.
 |
| Anaerobic Digestion Stages |
STAGE 2—ACID-FORMING STAGE
STAGE 3—METHANOGENESIS STAGE
Thursday, 1 March 2012
Kenya National Domestic Biogas part 1
EXECUTIVE
The
Partnership Programme), funded by the Directorate General for International Cooperation (DGIS)
under the Netherlands Ministry of Foreign Affairs. ABPP is part of a broader objective of DGIS
targeting the provision of sustainable energy to 10 million people by the year 2015. It is being
supported by DGIS through two Dutch development NGOs, the Humanist Institute for Cooperation
with Developing Countries (Hivos) and the Netherlands Development Organisation (SNV).
The overall objective of the Programme is to contribute to the achievement of the Millennium
Development Goals (MDGs) through the dissemination of domestic biogas plants as a local,
sustainable energy source through the development of a commercially viable, market‐oriented
biogas sector. ABPP targets to facilitate the construction of about 70,500 biogas plants in the six
participating countries, providing about half a million people access to a sustainable source of
energy.
The
taken by the Kenya National Federation of Agricultural Producers (KENFAP), in its capacity as the
National Implementing Agency (NIA) for KENDBIP. Sector development implies the close
collaboration
levels:
as the “sector leader” tasked with the stimulation of commercial interaction between the biogas
households (potential customers), Biogas Construction Enterprises (BCEs) and Biogas service
providers.
sector
development of the domestic biogas sector in Kenya.
This PID proposes that KENDBIP be implemented based on private sector market oriented principles,
but relying on governmental support for a favourable regulatory and policy environment, as well as
general buy‐in promotion and extension. KENDBIP will stimulate the installation of 8,000 domestic
biogas plants country wide, largely of 6m3 to 12m3 capacity, over a period of 4½ years (July 2009 to
December 2013). It will establish biogas plants through over 100 biogas‐related enterprises engaged
in construction, appliances and parts.
The programme adopts and customizes the approach to biodigester dissemination developed by
SNV – the ‘multi‐stakeholders sector development approach’. This approach, which has been
successfully implemented in Asia, is based on the establishment, over time, “of a market for
domestic biogas installations and accessories, in which a well‐informed demand side – i.e. in which
clients who know what they want, recognize quality and value for money – links up with an equally
capable supply side that provides the market with quality products at competitive prices and with
adequate after sales services. Such a market should be able to reach a volume that allows a
significant number of constructors and credit providers to maintain an economically sound and
profitable level of turnover. In the process towards market development, the government, civil
society organisations, and other players in the public and private domain have a role to play in
addition to the main actors in the market.”1
KENFAP will operationalise a ‘Biogas Office’, which, once set up, will go through a participatory
envisioning process to ensure effective delivery of goods and services under KENDBIP. The Biogas
Office will be responsible for among others, promotion and marketing, training of Users and
Contractors,
monitoring and evaluation, quality assurance, sector coordination and subsidy management.
Depending on the need, existing organizations or institutions will be identified by KENFAP to take
responsibility for the sound execution of these functions.
KENDBIP
financial facilitation by SACCOs, MFIs, banks, formal and informal groups, and end‐users’ capital
from savings, current income, donations, family remittances, etc.
Promotion and dissemination will prioritise high potential regions identified by the Kenya Biogas
Feasibility Study2. Rural development NGOs as well as governmental and private agricultural and
livestock extension services are integrated in the programme plan.
To reduce the investment cost barrier of domestic biogas installations, the programme will provide
an investment subsidy, with each biogas plant under KENDBIP being allocated a subsidy at a flat rate
of KES 25,000 (about EUR 240), irrespective of the size. The subsidy is critical in order to achieve the
right balance between cost of biogas plants and forecasted demand. Having a flat rate subsidy will
ensure that users of smaller biogas plants achieve a proportionately higher subsidy‐cost ratio.
In addition, financial institutions will be encouraged to partner in the programme to provide loans to
the end users and the government will be approached to offer investment incentives. Bio‐slurry
application in agriculture will be used to enhance economic benefits.
End users will be protected against construction errors through a Code of Ethics for Biogas
Contractors and documented biogas plant performance warranties and appliance guarantees lasting
up to three years. A quality control protocol will be put in place to ensure that 100% of complaints
and requests for repairs are solved during the first 5 years after completion and that 97% of
biodigesters are still in use when the programme terminates.
KENDBIP will utilise a total budget of EUR 10.443 million, out of which EUR 5.049 million or about
48% will be contribution from ends users, and EUR 4.939 million from ABPP (Hivos: EUR 3.498
million
will be approached to provide leverage of EUR 454,806 or more. Funds from Hivos will have three
components:
It is expected that KENDBIP will lead to savings of 37,388 tones of fuelwood, valued at KES 194.4
million3
EUR 2.4 million). An estimated 73,623 tonnes5 of CO2 equivalent emissions will be avoided, and the
health of over 15,000 men and women and over 38,800 children will be significantly improved.
Approximately 15 to 18 million6 hours per annum (equivalent to about 2,000 person‐years) will be
saved for women and children fetching firewood and other biomass sources for cooking and heating.
In
about 7,760 households, representing over 15,000 men and women and over 38,800 children7.
Employment
in addition to other direct and indirect employment in extension, promotion, credit, microfinance,
etc. – mostly targeting youth and incorporating women.
More Detail
Working of Biogas Plant Video Animation
Working of Biogas Plant Video Animation
This animation shall explain the biogas technique. You will be shown the process of a biogas plant Video animation · How to build a biogas plant · Gas of grass! Biogas to natural gas · Theory / basics · Biogas simple animation describing just how simple it is to build your own biogas digester
This animation shall explain the biogas technique. You will be shown the process of a biogas plant Video animation · How to build a biogas plant · Gas of grass! Biogas to natural gas · Theory / basics · Biogas simple animation describing just how simple it is to build your own biogas digester
Biogas News | Biogas digester picking up in Tsirang as well
Biogas digesterpicking up in Tsirang as well
 |
Biogas digesterpicking up in Tsirang as well |
Feb 24 2012Use of biogas digester in Tsirang is slowly, but absolutely building its way into the homes. Many farmers have now started replacing wood fed stoves with bio-gas. Our reporter, Pema Namgay, says the success of biogas digester plants in other Dzongkhags and its benefits are drawing the attention of the farmers.
Pema Wangchuk from Goserling Gewog in Tsirang built a big-gas plant last year. Pema Wangchuk,and four other farmers constructed the plants under the initiative of Bhutan Biogas digester project. They are the first group of farmers to start biogas digesterplant. And they are happy with the success of the project.
“The plant is benefiting us a lot. Firstly we no longer need to fetch firewood. Secondly the plant produces enough waste which can be used as fertilizer. And thirdly we no longer have to worry about the LPG shortage in the market. The four cubic metre biogas digester plant is enough for a family of five to cook throughout the day,” said Pema Wangchuk.
More farmers are now coming forward to construct their own biogas digester plants. Many more plants are expected to come up in the future. Til Bahadhur Nepal is one of those farmers who have decided to replace his wood fed stove with bio-gas. “Right now we are receiving help from the government. In future, the cost of biogas digester plant will increase. So I have decided to construct it now when government is helping us. It will be difficult later.”
Biogas digester is expected to become more popular in the Dzongkhag due to easy availability of raw materials and its multiple and economic uses. The masons, trained by the Bhutan Biogas digester project, are helping in the construction of the biogas digester plants.
Source:http://www.bbs.bt/news/?p=9930
Biogas production from oil palm waste is environment friendly
 |
| biogas production from oil palm waste is environment friendly |
Biogas Project Gives Positive Image For Oil Palm Industry, Says Musa
Sabah Chief Minister Datuk Seri Musa Aman is in no doubt that the biogas project being explored by the agricultural estate sector in the state, can create a positive image for the oil palm business.
He said it will be seen as an atmosphere friendly industry which gives serious thought to the safety of the environment.
He said the technology for biogas production from oil palm waste is not just environment friendly but also helps in the electricity generation for the plants and in the process, reduce the dependency on fossil fuel which is a source of air pollution.
"Previously, the disposal of waste from oil palm and the oil palm mills, posed a lot of problems for us. Now, it has become a source of electricity," he added.
Musa said this in his speech while officiating the opening of the Biogas Plant at the Sawit Apas Balung mill owned by Kumpulan Sawit Kinabalu here today.
He said it will be seen as an atmosphere friendly industry which gives serious thought to the safety of the environment.
He said the technology for biogas production from oil palm waste is not just environment friendly but also helps in the electricity generation for the plants and in the process, reduce the dependency on fossil fuel which is a source of air pollution.
"Previously, the disposal of waste from oil palm and the oil palm mills, posed a lot of problems for us. Now, it has become a source of electricity," he added.
Musa said this in his speech while officiating the opening of the Biogas Plant at the Sawit Apas Balung mill owned by Kumpulan Sawit Kinabalu here today.
Subscribe to:
Posts (Atom)