Get our free book (in Spanish or English) on rainwater now - To Catch the Rain.

Difference between revisions of "Practivistas Chiapas biodigester"

From Appropedia
Jump to navigation Jump to search
Tags: ANON EDIT. To be patrolled., n
 
(140 intermediate revisions by 11 users not shown)
Line 1: Line 1:
{{Template:Projectinprogress|August 12, 2010}}
+
{{HSU Chiapas header}}
 +
[[Image:Biodigester diagramed copy.jpg|thumb|right|500px| Demonstration Biodigester in San Cristóbal de las Casas, Chiapas, Mexico]]
  
[[File:Photo on 2010-07-10 at 18.48.jpg|thumb|right|500px|''' Team Biogas: Julia Balibrera, Gina LaBar, Garnet Empyrion, and Annie Bartholomew''']]  
+
[[Image:TeamBiogas.jpg|thumb|left|400px|Team Biogas and Biodigester  (photo: Lonny Grafman)]]
 +
[[Image:Photo on 2010-07-10 at 18.48.jpg|thumb|left|400px|Team Biogas: [[User:Julialibrera|Julia Balibrera]], [[User:Ginalabar|Gina LaBar]], [[User:Gge2|Garnet Empyrion]], [[User:Annie.bartholomew|Annie Bartholomew]]]]
 +
== Objective ==
  
 +
In the summer of 2010, a collaboration between students of [[Humboldt State University]] and the International Institute of Renewable Resources (IRRI) will seek the construction and dissemination of a biodigestion system, the Sistema Biobolsa, within the community of San Cristóbal de las Casas, Chiapas. The objective of this project is to promote the realization of further Biobolsa projects in the San Cristobal de las Casas area by constructing a successful Biodigester demonstration system in the eco-home of local builder and home designer Juan Hidalgo.
  
==Team Biogas==
+
== International Renewable Resources Institute-Mexico ==
*[[User:Julialibrera|Julia Balibrera]]
 
*[[User:Annie.bartholomew|Annie Bartholomew]]
 
*[[User:Gge2|Garnet Empyrion]]
 
*[[User:Ginalabar|Gina LaBar]]
 
==International Renewable Resources Institute-Mexico==
 
[[International Renewable Resources Institute-Mexico|Appropedia Page: International Renewable Resources Institute-Mexico]]
 
  
[http://www.irrimexico.org Website:www.irrimexico.org]
+
"IRRI Mexico is dedicated to promoting sustainable use of natural resources. We provide education, develop new technologies, and install systems that help low income families meet their basic energy, water, and sanitation needs in a sustainable way. Our projects aim to empower families, communities, and businesses to produce their own clean energy, obtain their own water, and manage their own resources and wastes in ways that benefit them and the environment simultaneously."<ref name="Eaton"/>
  
General Information: info@irrimexico.org
+
:Appropedia Page: [[International Renewable Resources Institute-Mexico]]
 +
:Website: http://www.irrimexico.org
 +
:General Information: info@irrimexico.org  
 +
:Executive Director Alex Eaton: {{email|alex|irrimexico|org}}
 +
:Coordinator Helene Gutiérrez: {{email|helene|irrimexico|org}}
 +
:Telephone: + (52) 55 52 56 56 86
 +
:Instituto Internacional de Recursos Renovables
 +
:A.C.
 +
:37 Amatlán, 1st Floor
 +
:Col Condesa, Mexico D.F. 06140
  
Executive Director Alex Eaton: alex@irrimexico.org
+
'''IRRI's Mission'''
  
Director of the Board Ilan Adler: ilan@irrimexico.org
+
<center>''"To promote programs and businesses that produce sustainable goods and services and help reduce reliance on fossil fuels. IRRI supports rural and low-income communities with the objective of improving the quality of life through generating, developing, and conserving local resources. IRRI’s vision is sustainable and equitable prosperity in a world without contamination."''<ref> http://www.irrimexico.org</ref></center>
  
Telephone: 011 (52) 55 3547 0221 or 011 (52 1) 55 1886 8210
+
== Biodigestion==
  
Instituto Internacional de Recursos Renovables, A.C. Tlacotalpan No. 6 Bis, Int 301, Col Roma Mexico D.F. 06760 (52) 55 3547 0221
+
In Chiapas, Mexico, mismanagement of animal waste is problematic for the health of the planet as well as its inhabitants.<ref>"38% of pig farms dispose of their wastewaters without any treatment directly into the nation's water bodies, which in turn has a severe impact on the environment"  Victoria-Almeida, et al. "Sustainable Management of Effluent from Small Pigery Farms in Mexico" Instituo de Ingenieria, Universidad Nacional Autonoma de Mexico, Cd Universitaria  04510 D.F., Mexico. </ref> The odors themselves can be harmful to human health, causing irritation of the eye, nose, throat, headache, nausea, vomiting. <ref name="Mackie"> Mackie et al "Biological Identification and Biological Origin of Key Odor Components in Livestock Waste" J Anim Sci 1998. 76:1331-1342. http://www.animal-science.org/cgi/reprint/76/5/1331 </ref> Raw, or partially digested, manure retains hazardous pathogens which can be spread to humans through premature composting, agricultural run off and contamination of the water table. <ref> Guan, Tat Yee and Holley, Richard A. "Pathogen Survival in Swine Manure Environments and Transmission of Human Enteric Illness" Dept. of Food Science, Faculty of Food and Agricultural Science, University of Manitoba, Winnepeg, Manitoba R3T 2NT Canada. http://jeq.scijournals.org/cgi/reprint/32/2/383.pdf </ref>Furthermore, surface runoff of manure contributes to the degradation of local ecology. <ref name="Mackie"/> Decomposition of animal manure releases gases, such as methane, into the atmosphere that can be environmentally destructive. These gasses are byproducts of fermentation. Methane is a greenhouse gas is approximately 21 times more potent than carbon dioxide. <ref> To convert a known mass of methane to the universal CO2 equivalent (tonnes CO2e) global warming potential, multiply the methane mass by 21 (UNFCCC, 2008). Eaton, A.B. (2009) "The Role of Small-Scale Biodigesters in the Energy, Health and Climate Change Baseline in Mexico" Masters Thesis, HSU Environmental Resource Engineering. </ref>
  
"IRRI Mexico is dedicated to promoting sustainable use of natural resources. We provide education, develop new technologies, and install systems that help low income families meet their basic energy, water, and sanitation needs in a sustainable way. Our projects aim to empower families, communities, and businesses to produce their own clean energy, obtain their own water, and manage their own resources and wastes in ways that benefit them and the environment simultaneously."[18]
+
One way to mitigate these effects is to install a biodigester. Biodigestion describes the biological process by which organic matter is digested by anaerobic bacteria over the course of time. In the natural world, biodigestion occurs in a variety of anaerobic (oxygen-free) environments that include: marshes, the ocean floor, the human body, and manure. A biodigester is a system which uses the metabolism of anaerobic bacteria in order to digest animal manure producing biogas, a clean, renewable fuel source, as well as effluent, an organic fertilizer which in the case of our Biobolsa system we call Biol. <ref name="Eaton"> Eaton, A.B. (2009) "The Role of Small-Scale Biodigesters in the Engery, Health and Climate Change Baseline in Mexico" Masters Thesis, HSU Environmental Resource Engineering.</ref>
  
'''IRRI's Mission'''
+
The Biogas produced in a biodigester system is a key incentive. Approximately 25% of rural populations in Mexico currently use wood as a primary cooking fuel. <ref> "One in four households use fuel wood for either all or part of their energy for cooking" [Masera O. 2005. From Cookstoves to Cooking Systems: The Integrated Program on Sustainable Household Energy Use in Mexico. Energy for Sustainable Development 9, no. 1: 25-36.]  </ref> Wood as a fuel has several drawbacks: it is labor intensive to collect, it contributes to deforestation, and upon combustion poses significant respiratory risks to users.<ref>"Visible improvement in rural hygiene: Biogas contributes positively to rural health conditions. Biogas plants lower the incidence of respiratory diseases. Diseases like asthma, lung problems, and eye infections have considerably decreased in the same area when compared to the pre-biogas plant times. Biogas plants also kill pathogens like cholera, dysentery, typhoid, and paratyphoid." [http://www.economywatch.com/renewable-energy/advantages-of-biogas.html Economy Watch (2010)] (July 11, 2010) </ref> The popular alternative to wood use is Liquid Petroleum (LP) gas and electricity, the both of which require elevated operational costs. <ref> "One in four households use fuel wood for either all or part of their energy for cooking (Masera, 2005). The remaining energy needs throughout the country are met largely with Liquid Petroleum (LP) gas and electricity at a large economic burden for much of the low_income rural population."[Eaton, A.B. (2009) "The Role of Small-Scale Biodigesters in the Engery, Health and Climate Change Baseline in Mexico" Masters Thesis, HSU Environmental Resource Engineering.] </ref> Biogas can be an alternative to shouldering such an economic burden by providing low cost energy and increasing energy security.<ref>"Before a biogas plant is built or a biogas program is implemented, a techno-economic assessment should be made. For this, two sets of cost-benefit analyses have to be carried out: · The macro-economic analysis (economic analysis) which compares the costs of a biogas program and the benefits for the country or the society. · The micro-economic analysis (financial analysis) which judges the profitability of a biogas unit from the point of view of the user. In judging the economic viability of biogas programs and units the objectives of each decision-maker are of importance. Biogas programs (macro-level) and biogas units (microlevel) can serve the following purposes: · the production of energy at low cost (mainly micro-level); · a crop increase in agriculture by the production of bio-fertilizer (micro-level); · the improvement of sanitation and hygiene (micro and macro level); · the conservation of tree and forest reserves and a reduction in soil erosion (mainly macro-level); · an improvement in the conditions of members of poorer levels of the population (mainly macro-level); · a saving in foreign exchange (macro-level); · provision of skills enhancement and employment for rural areas (macro-level)."[Habermehl Stefan, Kossmann Werner, Pönitz Uta, Biogas Digest:Volume III Biogas - Costs and Benefits and Biogas – Programme Implementation &lt;www.gtz.co.za/de/dokumente/en-biogas-volume3.pdf&gt;] (July 11, 2010)</ref>
  
To promote programs and businesses that produce sustainable goods and services and help reduce reliance on fossil fuels. IRRI supports rural and low-income communities with the objective of improving the quality of life through generating, developing, and conserving local resources. IRRI’s vision is sustainable and equitable prosperity in a world without contamination."[19]
+
Typically, biogas is composed of 55 - 65% methane, 35-45% carbon dioxide, a small fraction of hydrogen sulfide gas, and other trace gases. Of these impurities, the presence of H<sub>2</sub>S (hydrogen sulfide) is the most problematic. Although H<sub>2</sub>S constitutes less than 0.5% of the gas stream, it is extremely corrosive. Any metal equipment used within a biogas system to convert the gas to either direct heat applications (a boiler) or to more complex energy exchanges (a generator) will therefore degrade relatively quickly. <ref> Taylor, John Poe , Removal of Hydrogen Sulfide from Biogas, August 2003. http://www.cowpower.cornell.edu/project_docs/Thesis_jpt7.pdf  </ref> The larger the system, the larger the impact the presence of gaseous impurities will have on biogas production. As we are building a small, size 3 Biobolsa system <ref> http://sistemabiobolsa.com/ </ref>, the intended application of the biogas is relatively small and therefore will not require an industrial approach to gas scrubbing. In order to reduce the H<sub>2</sub>S in the biogas, our system uses a packet of non-stainless steel wool in the gas regulator; with this type of filter, the the H<sub>2</sub>S will corrode the non-stainless steel wool before it has a chance to degrade metal equipment interior to the biogas´s end-use.  
  
==Objective and Background==
+
Animal manure has its high macro-nutrient content. It confers considerable amounts of nitrogen, potassium and phosphorous to germinating crops and can critically improve soil health. <ref>"Animal manure is a valuable fertilizer as well, conferring inputs to the soil over and above the simple chemical nutrients of N, P and K. As an input into the crop cultivation systems, manure continues to be the link between crop and animal production throughout the developing world."  Rodríguez et al. "Integrated farming systems for efficient use of local resources" University of Tropical Agriculture-UTA, Finca Ecológica, College of Agriculture and Forestry,Thu Duc, Ho Chi Minh, Vietnam </ref>. However, research has proven that manure that has undergone biodigestion is a more effective fertilizer than raw, or fresh, manure. <ref>"The biomass yield, and content of moisture and crude protein, of Chinese cabbage was highest when fertilized with biodigester effluent and lowest when fresh residual solids from manure were used." Thy, San and Buntha, Pheng "Evaluation of fertilizer of fresh solid manure, composted manure or biodigester effluent for growing Chinese cabbage (Brassica pekinensis)" Center for Livestock and Agriculture Development (UTA-Cambodia), POB 2423, Phnom Penh 3, Cambodia</ref> Furthermore, the application of raw manure to soil can potentially contaminate agricultural products with hazardous pathogens. These pathogens are heat-sensitive, generally destroyed by temperatures of 36 degrees celsius or greater.<ref>Ingham, et al. "Escherichia coli Contamination of Vegetables Grown in Soils Fertilized with Noncomposted Bovine Manure: Garden-Scale Studies"  Department of Food Science,1 Hancock Agricultural Research Station,2 Lancaster Agricultural Research Station, 3 West Madison Agricultural Research Station, University of Wisconsin—Madison, Madison, Wisconsin (Received 5 March 2004/ Accepted 1 July 2004)- </ref> The active anaerobic bacterias of a biodigestion system are mesophilic, meaning that they thrive in temperatures of 15-47 degrees C, <ref>"Micro-organisms which live in temperatures of 40°C-80°C are "thermophiles" and those that live in 10°C-47°C are "mesophiles." Rose, A. H., and Wilkinson, J. F. (1979) "Advances in Microbial Physiology" Vol. 19, 1st Ed., New York, New York.  </ref> although many show the ability to produce diverse and productive colonies in temperatures as low as 10 degrees celsius. <ref>Ahn, JH and Forster, CF (2002) The effect of temperature variations on the performance of mesophilic and thermophilic anaerobic filters treating a simulated papermill wasterwater. Process Biochemistry, 37 . pp. 589-594. ISSN 0032-9592</ref> Biodigestion occurs optimally at 15-40 celsius.<ref name="Eaton"/> This means that the effluent produced is pathogen free.
  
In the summer of 2010,  a collaboration between students of Humboldt State University and the International Institute of Renewable Resources (IRRI) will seek the construction and dissemination of a biodigestion system, the Biobolsa, within the community of San Cristobal de las Casas, Chiapas. The objective of this project is to promote the realization of further Biobolsa projects in the San Cristobal de las Casas area by constructing a successful Biodigester demonstration system in the eco-home of local architect Juan Hidalgo.
+
=== Dissemination of Different biodigester Models===
  
In Chiapas, Mexico, wood is used as a primary cooking fuel in rural communities. <ref> "One in four households use fuel wood for either all or part of their energy for cooking" [Masera O. 2005. From Cookstoves to Cooking Systems: The Integrated Program on
+
Worldwide, the dissemination of different models of biodigestion systems has seen three general trends of biodigester design which are identified by their different countries of origin. <ref name="Eaton"/>
Sustainable Household Energy Use in Mexico. Energy for Sustainable Development 9, no. 1: 25‐36.]  </ref> Wood as a fuel has several drawbacks: it is labor intensive to collect, it contributes to deforestation, and upon combustion poses significant respiratory risks to users.<ref>"Visible improvement in rural hygiene: Biogas contributes positively to rural health conditions. Biogas plants lower the incidence of respiratory diseases. Diseases like asthma, lung problems, and eye infections have considerably decreased in the same area when compared to the pre-biogas plant times. Biogas plants also kill pathogens like cholera, dysentery, typhoid, and paratyphoid."
+
 
[http://www.economywatch.com/renewable-energy/advantages-of-biogas.html Economy Watch (2010)] (July 11, 2010)
+
==== China ====
</ref> For these reasons, biogas as an alternative to wood fuel can improve the indoor air quality and overall quality of life for consumers in select applications.  
+
 
The most common management practices for livestock manure in Mexico typically consist of large open manure lagoons. <ref>
+
From A CHINESE BIOGAS HANDBOOK <ref>Translated by Michael Cook,  edited by: Ariane van Buren "A Chinese Biogas Handbook" Published by: Intermediate Technology Publications, Ltd. London WC2E 8HN United Kingdom 1979 </ref> "Since the 1950s China has experimented with the production of biogas from agricultural wastes, a practice based upon an age-old Chinese tradition of composting human, animal and plant wastes to produce an organic fertilizer of high quality. The breakthrough came in 1975 when a process was developed to ferment the materials in an airtight and watertight container in order to produce methane gas." This "breakthrough" describes the innovation of the Chinese Fixed Dome biodigester, which has been reproduced in over 7 million systems around the world although the majority of these systems operate in China. The system is constructed of cement, thereby requiring skilled labor and an extensive installation time. In the field, the design has shown structural weakness in the low production of gas and the frequent occasion of gas leaks. <ref name="Eaton"/>
"The common practice for manure management at these large pig farms in Mexico is storage in open manure lagoons. These lagoons are anaerobic below the water level, and produce large amounts of methane that bubbles out of the surfaceof the lagoon." [Eaton, A.B. (2009) "The Role of Small-Scale Biodigesters in the Engery, Health and Climate Change Baseline in Mexico" Masters Thesis, HSU Environmental Resource Engineering.] </ref>   These practices result in the uncontrolled release of methane gas into the atmosphere. Methane gas as a greenhouse gas is approximately 21 times more potent than carbon dioxide. <ref> To convert a known mass of methane to the universal CO2 equivalent (tonnes CO2e) global warming potential, multiply the methane mass by 21 (UNFCCC, 2008). [Eaton, A.B. (2009) "The Role of Small-Scale Biodigesters in the Engery, Health and Climate Change Baseline in Mexico" Masters Thesis, HSU Environmental Resource Engineering.] </ref> The controlled decomposition of animal waste in a biodigester is one alternative to the existing management practices. Use of the Biobolsa system results in the sequestration of greehouse gases and conversion of the animal waste into a safe and effective fertilizer. (REFERENCES)
+
 
 +
==== India ====
 +
 
 +
The floating cover, or Indian, biodigester was designed to address the problem of gas leaks in the Chinese Fixed Dome. In this model, the gas storage mechanism consists of a floating cover, typically constructed of fiberglass, which rises in response to the generation of gas, therefore having a larger gas storage capacity. Although over 3 million have been constructed around the world, this system too is difficult to effectively demonstrate as the system consists of moving parts of high industrial cost (fiberglass). <ref name="Eaton"/>
 +
 
 +
==== Taiwan ====
 +
 
 +
The Taiwanese, or "tubular plastic", design is the most economical of the 3 models discussed. As a result of high installation costs and difficulty in replacing parts, a continuous flow digester contained within a plastic bag was developed in order to achieve 1) greater weatherability 2) more efficient gas production 3) cheaper and more uniform manufacture and 4) a shorter installation time. <ref name="Eaton"/>
 +
 
 +
Our project is based on this tubular plastic model for a biodigester. Specifically, we will be building a Biobolsa system, engineered by Sistema Biobolsa <ref>http://sistemabiobolsa.com/</ref>  
 +
 
 +
==== Mexico ====
 +
 
 +
*Current:
 +
**Of the approximately 250 industrial biodigester projects that the Clean Development Mechanism{{w|Clean Development Mechanism}} (a mechanism of the Kyoto Protocol{{w|Kyoto Protocol}}) has funded 200 of those are in Brazil and Mexico. Additionally, nearly 30% of all the 'waste gas recovery projects' are in Mexico making up about 110 projects of which the great majority are anaerobic digesters. <ref name="Eaton"/>
 +
*Future:
 +
**Anaerobic digester systems may not be possible in some areas of Mexico due to water shortages. <ref> Secretaría de Medio Ambiente y Recursos Naturales (2008) "Animal Waste Management  Methane Emissions" Presentation prepared for Methane to Market. &amp;amp;amp;lt;http://www.methanetomarkets.org/documents/ag_cap_mexico.pdf&amp;amp;amp;gt; </ref> However, in conjunction with the recently installed [[HSU Chiapas Rainwater Catchment]] system at Juan´s house, we foresee the functioning of our system without a considerable additional cost for water.
 +
 
 +
== Criteria ==
  
==Criteria==
 
 
{| class="wikitable sortable"
 
{| class="wikitable sortable"
 
|-
 
|-
! Criteria
+
! Criteria  
! Description
+
! Description  
 
! Weight
 
! Weight
 
|-
 
|-
|Level of Energy Generation
+
| Potential for Community Involvement
|Amount of Methane Produced
+
| Must be a demonstration biodigester designed for educating the community.
|align="right"| 7
+
| align="right" | 10
|-
 
|Level of Fertilizer Generation
 
|Amount of Fertilizer Bi-product Produced
 
|align="right"| 5
 
 
|-
 
|-
|Durability
+
| Cost
|Needs to withstand use with no more than of $5-10 yearly maintenance.
+
| Needs to have enough spending to support project but not so much to bankrupt the community
|align="right"| 8
+
| align="right" | 9
 
|-
 
|-
|Cost
+
| Level of Appropriateness
|Needs to have enough spending to support project but not enough to bankrupt the community
+
| Project must be able to be incorporated in the setting and to the appeal of client
|align="right"|9
+
| align="right" | 9
 
|-
 
|-
|Adherence to the Mission of IRRI
+
| Durability
|Meets IRRI's educational standards
+
| Needs to withstand use with no more than of $5-10 yearly maintenance.
|align="right"|8
+
| align="right" | 8
 
|-
 
|-
|Level of Cultural Appropriateness
+
| Adherence to the Mission of IRRI
|Project must be able to be incorporated in the cultural setting of client.
+
| Meets IRRI's educational standards
|align="right"|9
+
| align="right" | 8
 
|-
 
|-
|Potential for Community Involvement
+
| Level of Energy Generation
|Must be a demonstration biodigestor designed for educating the community.
+
| Amount of Methane Produced
|align="right"|10
+
| align="right" | 7
 
|-
 
|-
 +
| Level of Fertilizer Generation
 +
| Amount of Fertilizer Bi-product Produced
 +
| align="right" | 7
 
|}
 
|}
  
==Budget==
+
== Budget ==
  
 
{| class="wikitable sortable"
 
{| class="wikitable sortable"
 
|-
 
|-
!Materials
+
! Materials  
!Unit Price (Pesos)
+
! Unit Price (Pesos)  
!Quantity
+
! Quantity  
!Cost
+
! Cost
|-
 
|High Density Polypropylene Biobolsa (3000 liters) and Kit <ref>the IRRI Biobolsa system includes: the gas regulator system with sulfur filter, hose to connect to Biobolsa system and valve, a biogas reservoir bag and plastic net to suspend bag from roofing, a recycled PET plastic blanket to protect the Biobolsa, a repair kit for the Biobolsa and a use and maintenance manuel for the whole system. <http://sistemabiobolsa.com/> Manual de Instalación. </ref>
 
|$800
 
|1               
 
|$800
 
|-
 
|4" PVC pipe
 
|$35/m
 
|2 meters               
 
|$70
 
 
|-
 
|-
|4" PVC wye fitting
+
| High Density Polypropylene Biobolsa (3000 liters) and Kit <ref>the IRRI Biobolsa system includes: the gas regulator system with sulfur filter, hose to connect to Biobolsa system and valve, a biogas reservoir bag and plastic net to suspend bag from roofing, a recycled PET plastic blanket to protect the Biobolsa, a repair kit for the Biobolsa and a use and maintenance manual for the whole system. &lt;http://sistemabiobolsa.com/&gt; Manual de Instalación. </ref>
|$25
+
| $8000
|2               
+
| 1
|$50
+
| $8000
 
|-
 
|-
|3/8" flexible hose (gas)
+
| 4" PVC pipe
|$7/meter
+
| $35/m
|55 meters
+
| 2 meters  
|$385                                                                                     
+
| $70
 
|-
 
|-
|Cement
+
| 4" PVC wye fitting
|$115/bag
+
| $25
|2              
+
| 2  
|$230
+
| $50
 
|-
 
|-
|Chicken Wire
+
| 3/8" flexible hose (gas)
|$22/meter
+
| $7/meter  
|1               
+
| 55 meters
|$22
+
| $385
 
|-
 
|-
|nails
+
| Cement
|$0
+
| $115/bag
|1               
+
| 2
|$0
+
| $230
 
|-
 
|-
|4" PVC pipe (for drainage system)
+
| Chicken Wire
|$46/meter
+
| $22/meter  
|5meters               
+
| 1
|$232
+
| $22
 
|-
 
|-
|Printing of Interpretive Signs
+
| nails
|$2
+
| $50 / kilo
|6               
+
| found on site
|$10
+
| $0
 
|-
 
|-
|Laminating of interpretive signs
+
| 4" PVC pipe (for drainage system)
|$16
+
| $46/meter
|6               
+
| 5meters
|$96
+
| $232
 
|-
 
|-
|Glue (for PVC)
+
| Printing of Interpretive Signs
|$12.5
+
| $2
|1               
+
| 6
|$12.5
+
| $12
 
|-
 
|-
|Glue (for plastic sheeting)
+
| Laminating of interpretive signs
|$0
+
| $16
|1               
+
| 12
|$0
+
| $192
 
|-
 
|-
|Corrugated Plastic Roofing Sheets
+
| Glue (for PVC)
|$360/sheet
+
| $12.5
|9               
+
| 1
|$3240
+
| $12.5
 
|-
 
|-
|Post for roof (wooden)
+
| Corrugated Plastic Roofing Sheets
|$50/post
+
| $360/sheet
|6               
+
| 9
|$300
+
| $3240
 
|-
 
|-
|Buckets
+
| Post for roof (wooden)
|$15/bucket
+
| $50/post
|2               
+
| 6
|$30
+
| $300
 
|-
 
|-
|Cross Beams
+
| Buckets
|$30/beam
+
| $15/bucket
|3               
+
| 2
|$90
+
| $30
 
|-
 
|-
|Beams
+
| Cross Beams  
|$15/beam
+
| $30/beam  
|7               
+
| 3
|$105
+
| $90
 
|-
 
|-
|Plastic Sheeting
+
| Beams
|$45/5 meters
+
| $15/beam
|2               
+
| 7
|$90
+
| $105
 
|-
 
|-
|stove
+
| Plastic Sheeting
|$0
+
| $45/5 meters
|1               
+
| 2
|$0
+
| $90
 
|-
 
|-
|Total
+
| bricks
|
+
| found on site
|            
+
| 12-18
|$0
+
| $0
 +
|-
 +
| natural gas stove
 +
| $210
 +
| 1
 +
| $210
 +
|- 
 +
| Total
 +
|
 +
| $13270.5
 
|}
 
|}
  
==Poop Chute==
+
== Materials  ==
  
 
<gallery>
 
<gallery>
File:Sifting.jpg|Sand is sifted for concrete mixture.  
+
File:Shovels material.jpg| Shovels are a must-have on every job site.  
File:Rubble Compaction.jpg|Compacting bricks for base of waste chute.  
+
File:Bucket saw materials.jpg| From these materials, we see the beginnings of our overflow system. Using a saw, a length of 4.5 meter PVC, and a 20 gallon bucket (which ironically held pig lard prior to its reappropriation as a Biol receptacle), we constructed a mouth on the rim of the bucket to accept the PVC from which will flow the Biol towards the second drainage bucket.  
File:Chute1.jpg|Chicken wire is laid on top of crushed bricks for base.  
+
File:Pick tools.JPG| The pick necessarily served to break the high-clay content earth in the excavation of the trench.  
File:Chute2.jpg|Concrete and recycled brick is used to build the sides.  
+
File:Plastic sheeting.JPG| We used plastic sheeting in order to build insulated housing for the biodigester.  
File:Cutting PVC.jpg|PVC pipe is cut to connect to Bio Bolsa.  
+
File:Biodigester material.JPG| High-density polypropylene which is the primary material in the actual Biobolsa.  
File:Chute4.jpg|Pipe is inserted and held with concrete.   
+
File:Clay tiles material.jpg| Around the perimeter of the Biobolsa, we built a super adobe barrier which contained a reinforcing layer of brick tiles.   
File:Chute7.jpg|Bricks are covered and sealed in concrete.
+
File:Costales material.jpg| We used the costals to build our super adobe wall, first as earthen content and secondly as the structural basis itself.  
File:Chute8.JPG|Waste chute is connected to the Bio Bolsa.  
+
</gallery>  
</gallery>
 
  
==Rubble Trench Construction==
+
== The Site  ==
  
<gallery>
+
We built our biodigester, the Sistema Biobolsa, at the house of Juan Hidalgo, on Calle Tapachula #55 in San Cristobal de las Casas. In San Cristobal, daytime temperatures average from 19° C. (66° F.) in winter and 23° C. (73° F.) in summer. Overnight lows average from 5° C. (41° F.) in winter and 13° C. (55° F.) in summer. &lt; http://www.innvista.com/culture/travel/mexico/sclc.htm &gt; (July 11, 2010)
File:RubbleTrench1.jpg|
 
File:RubbleTrench2.jpg|
 
File:Rubble Trench3.jpg|
 
File:RubbleTrench4.jpg|
 
</gallery>
 
  
 +
The coordinates of the house are&nbsp;: 16° 44’ 27.46’’ N 92° 37’ 39.78’’, at an elevation of 2154 m.
  
[[File:Digging Trench.jpg|thumb|right|500px|]]  
+
The house of Juan Hidalgo is a demo-house, in which the property itself seeks to be an example of eco-living. He has a 7 pigs, one rooster, a small garden and his home is made of [[super adobe]] and recycled materials. When we began our work on the location, the site for the biodigester showed many obstacles. There were two large mounds of pig manure, a rainwater cistern, and a variety of scrap wood.  
[[File:Measuring Trench.jpg|thumb|right|500px|]]
 
  
 +
<gallery>
 +
File:Site uncleared.JPG|Site for the biodigester
 +
File:Biodigester site final flat.jpg|Site (roughly 7m x 3m) cleared and ready to begin digging.
 +
File:Pigs sawdust.jpg|The pigpen used to be given a layer of sawdust to facilitate cleaning but this practice had to be given up since the biodigester is unable to break down the lignin in the sawdust. (ref.)
 +
File:Juan's Pigs.JPG|Juan has three grown pigs, two females and one male. It's recommended that there be at least 6 pigs for there to be enough waste to put into the biodigester. Fortunately, he also has a future generation, four piglets. Once they're grown it will mean more Biol<ref name="Biol">Biol, a nitrogen rich liquid fertilizer, is the end product of the input effluent into the Biobolsa system. IRRI "Presentación_FIRA_lite.pfd"</ref> and biogas produced more quickly.
 +
</gallery>
  
== Literature Review  ==
+
== Waste Chute ==
  
Biodigestion describes the biological process by which organic matter is digested by anaerobic bacteria over the course of time. In the natural world, biodigestion occurs in a variety of anaerobic, that is to say, oxygen-free, environments, such as within marshes, rice paddies, and upon the ocean floor. A biodigestion system, or biodigestor, is a system which uses the metabolism of anaerobic bacteria in order to digest animal manure, producing biogas, a clean, renewable fuel source, as well as effluent, an organic fertizilizer which in the case of our Biobolsa system we call Biol.
+
The waste chute, or Registro, is the structure in which the pig excrement drains from the Pigpen. Conveniently, Juan's pigpen had a small aperture in the side of the back wall which the piglets had priorly used to escape into the garden. We built our waste chute based on that aperture, using the opening as a space through which the excrement could be swept into the waste chute. The waste chute itself was constructed of compacted bricks and concrete. The most important feature of the waste chute is the 4" PVC pipe at the chute's far end. Through this pipe, the excrement travels by gravity into the Biobolsa.  
  
 +
<gallery>
 +
File:Sifting.jpg|Sand is sifted for concrete mixture.
 +
File:Rubble Compaction.jpg|Compacting bricks for base of waste chute.
 +
File:Chute1.jpg|Chicken wire is laid on top of crushed bricks for base.
 +
File:Chute2.jpg|Concrete and recycled brick is used to build the sides.
 +
File:Cutting PVC.jpg|PVC pipe is cut to connect to Biobolsa.
 +
File:Chute4.jpg|Pipe is inserted and held with concrete. 
 +
File:Chute7.jpg|Bricks are covered and sealed in concrete.
 +
File:Chute8.JPG|Waste chute is connected to the Biobolsa.
 +
</gallery>
  
=== Animal Waste ===
+
== Digging the Biodigester Trench ==
  
Animal waste is a broad term which considers all digestive products of an animal: feces, urine, respiration and fermenation gases. This project will focus on solid waste products, that is to say, animal feces, or manure. Manure is composed of undigested dietary residues, endogenous secretions and a variety of naturally occuring anaerobic bacterias; these bacteria are critical players in animal digestion, and some are sloughed off during excretion. Once excreted, manure undergoes a series of microbial conversions conveyed by these same anaerobic bacteria. <ref>
+
The dimensions of the trench were determined by the dimensions of the Biobolsa. Based on the size 3 Biobolsa, we needed a trench with the following dimensions: ( 140 cm width * 460 cm length * 80 cm deep).  
Mackie et al "Biological Identification and Biological Origin of Key Odor Components in Livestock Waste" J Anim Sci 1998. 76:1331-1342. http://www.animal-science.org/cgi/reprint/76/5/1331
 
</ref>
 
  
=== Decomposition  ===
+
<gallery>
Left to decompose in an open environment, a body of animal manure is digested by anaerobic bacteria leached from the digestive tract of the animal during excretion. This form of digestion is called fermentation, in which anaerobic bacteria render large macromolecules of undigested dietary residues into vaporized end products, methane and carbon dioxide. <ref>
+
File:Digging thehole.jpg| Breaking ground!
Mackie et al "Biological Identification and Biological Origin of Key Odor Components in Livestock Waste" J Anim Sci 1998. 76:1331-1342. http://www.animal-science.org/cgi/reprint/76/5/1331 </ref>
+
File:Measuring Trench.jpg| Here we marked the dimensions of the trench. Note the water collecting in the trench, a problem which we mitigated by building a rubble trench drainage system.  
Approximiately 90% of the energy of the manure is converted to these fermentation gases, assuming appropriate temperature and anaerobic conditions. The fact remains that open air decomposition of animal manure does not assure these characteristic conditions, with the result that -- "When manure undergoing degradation has a surface exposed to the atmosphere, volatile products and intermediates are emitted into the environment." <ref> Bhattacharya A. N. and Taylor J. C. "Recycling Animal Waste as a Feedstuff: A Review" J Anim Sci 1975. 41:1438-1457. http://jas.fass.org/cgi/reprint/41/5/1438.pdf </ref>
+
File:Digging Trench.jpg| Alex of IRRI directs some hardworking student volunteers.  
 +
File:Tamp.jpg| A tamp is used to level out the sides of the hole.
 +
</gallery>  
  
=== Hazards ===
+
== Rubble Trench Drain ==
  
Mismanagement of animal waste is problematic with consideration to both the health of the planet as well as the health of its inhabitants, humans and other animals alike.<ref>
+
We built our rubble trench drainage system in response to a large torrential rain which left our trench water logged. First, we dug a canal downhill from the biodigester site that terminated in a hole. We placed a PVC tube in the canal to accommodate drainage. Then we filled both the canal and the hole with large rocks. Lastly, we covered the system with dirt so that the ground would remain a viable workspace.  
"38% of pigfarms dispose of their wastewaters without any treatment directly into the nation's waterbodies, which in turn has a severe impact on the environment"  Sustainable Management of Effluent from Small Pigery Farms in Mexico
 
</ref>  The odors themselves can be harmful to human health, causing irritation of the eye, nose, throat, headache, nausea, vomiting.  <ref> Mackie et al "Biological Identification and Biological Origin of Key Odor Components in Livestock Waste" J Anim Sci 1998. 76:1331-1342. http://www.animal-science.org/cgi/reprint/76/5/1331 </ref>  Furthermore, the decomposition of animal manure in an open environment potentates the spread of a suite of zoonotic pathogens which are extremely transmittable to humans. Raw, or partially digested, manure retains hazardous pathogens which can be spread to humans through premature composting, agricultural run off and contamination of the water table. <ref> Guan, Tat Yee and Holley, Richard A. "Pathogen Survival in Swine Manure Environments and Transmission of Human Enteric Illness" Dept. of Food Science, Faculty of Food and Agricultural Science, University of Manitoba, Winnepeg, Manitoba R3T 2NT Canada. http://jeq.scijournals.org/cgi/reprint/32/2/383.pdf </ref>
 
The unmanaged  (uncontained) decomposition of animal manure releases a host of environmentally destructive gases into the atmosphere, byproducts of fermentation. Furthermore, surface run off of manure contributes to the degradation of local ecology. <ref>
 
Mackie et al "Biological Identification and Biological Origin of Key Odor Components in Livestock Waste" J Anim Sci 1998. 76:1331-1342. http://www.animal-science.org/cgi/reprint/76/5/1331 </ref> :
 
  
VOLATILE GAS GENERATION
+
<gallery>
*Methane: CH<sub>4</sub> accumulates in the atmosphere, which has a greenhouse gas potential 20% more destructive than CO<sub>2</sub> (Schulte, 1997)
+
File:RubbleTrench1.jpg| Here we see the terminal point of the drain, packed with large rocks.  
*Carbon Dioxide: CO<sub>2</sub> is also released ; "Geological records show that, on current trajectories of CO2-e increase, we are likely to see sea level rise by around 25 meters, with temperatures 2-3°C higher and permanent El Nino conditions."<ref>
+
File:RubbleTrench2.jpg| PVC directs water to the end point.
Glikson, Andrew, PhD. “THE THREAT TO LIFE POSED BY ATMOSPHERIC CO2-e OVER 450 ppm” Submission to the Senate Inquiry into the exposure drafts of the legislation to implement the Carbon Pollution Reduction Scheme  Australian National University Canberra, Australia </ref>
+
File:Rubble Trench3.jpg| Here students begin to recover  the drainage system with dirt
*Ammonia: NH<sub>3</sub> is volatized, which causes acid rain (Lowe, 1995; Likens et al., 1996).
+
File:RubbleTrench4.jpg| In total, the system spanned 5 meters.  
*Nitrous Oxide: N<sub>2</sub>O is released, which contributes to ozone depletion.  (Schulte, 1997).
+
</gallery>
SURFACE RUN OFF
 
*contamination of the water table
 
*Ammonia toxicification of water
 
*Eutrophication of water: algal blooms
 
*Phosphorous toxification of topsoil
 
*Salination of topsoil
 
  
=== Potential as Fertilizer ===
+
== Prepping the Pigpen ==
  
The use of animal manure as organic fertilizer to improve crop yields is practice long applied by agriculturists around the world. <ref>
+
The cleaning of the pigpen is necessary to ensure that no food waste enters the system upon installation. First, we collected all large solids in a series of 5 gallon buckets; this included both excrement and food waste. Care was taken to separate the two, so that the excrement present could be measured in the calculation of HRT. Then, while someone outside the pigpen gently sprayed the floor with water, the pigpen was swept clean of all food waste. After installing the waste chute, we noticed that some of the piglets had been taking advantage of the opening to escape from the Pigpen into the biodigester itself. Our final step in prepping the pigpen was the construction of a small bar to close off the entrance to the waste chute from the pigpen.  
"Animal manure is a valuable fertilizer as well, conferring inputs to the soil over and above the simple chemical nutrients of N, P and K. As an input into the crop cultivation systems, manure continues to be the link between crop and animal production throughout the developing world."  Rodríguez et al. "Integrated farming systems for efficient use of local resources" University of Tropical Agriculture-UTA, Finca Ecológica, College of Agriculture and Forestry,Thu Duc, Ho Chi Minh, Vietnam </ref>
 
However, research has proven that manure that has undergone biodigestion is a more effective fertilizer than raw, or fresh, manure.
 
<ref>
 
"The biomass yield, and content of moisture and crude protein, of Chinese cabbage was highest when fertilized with biodigester effluent and lowest when fresh residual solids from manure were used." Thy, San and Buntha, Pheng "Evaluation of fertilizer of fresh solid manure, composted manure or biodigester effluent for growing Chinese cabbage (Brassica pekinensis)" Center for Livestock and Agriculture Development (UTA-Cambodia), POB 2423, Phnom Penh 3, Cambodia
 
</ref>
 
  
=== Anaerobic Digestion  ===
+
<gallery>
 +
File:Sweeping corral.JPG| The pigpen is swept getting rid of any remaining sawdust.
 +
File:Pigpoop cleaning.JPG| Pig waste solids are then collected in buckets for measuring.
 +
File:Cleaningcorral intobucket.jpg| A final sweep is done to fully clean out pigpen and this was pushed through to the registro.
 +
File:Poop bucket.jpg| From the registro the dirty water drains into a bucket.
 +
</gallery>
  
[[Image:Methanogenesis.png|thumb|left]]
 
  
Anaerobic digestion is a series of processes in which microorganisms break down biodegradable material without oxygen. In order to promote this anaerobic process biobolsas and similiar systems are sealed to keep out as much air as possible. Anaerobic processes have the benefits of producing less biological sludge, minimal amount of energy required and methane is produced which can be used as an energy source. <ref> Ibanez, J. G., Hernandez-Esparza, M., Doria-Seranno, C., Singh, M. M. (2007).''Environmental Chemistry: Fundamentals'', 1st Ed., Springer, New York.</ref>
+
== Roof  ==
  
The digestion process begins with bacterial hydrolysis of the input materials in order to break down insoluble organic polymers such as carbohydrates and make them available for other bacteria. Acidogenic bacteria then convert the sugars and amino acids into carbon dioxide, hydrogen, ammonia, and organic acids. Acetogenic bacteria then convert these resulting organic acids into acetic acid, hydrogen, and carbon dioxide. Methanogens, finally are able to convert these products to methane and carbon dioxide.<ref>TerraForm (2009)."Anaerobic Digestion" &amp;amp;lt;http://terraformenergy.net/anaerobic.html&amp;amp;gt;. </ref> The methanogenic bacteria in stage three of the anaerobic digestion is responsible for the formation of methane. There are two common ways of forming methane, by splitting acetate (Equation 1) and by the reduction of carbon dioxide (Equation 2). The methanogens which splits the acetate is about half as common as the methanogens that reduced carbon dioxide which explains why the resulting biogas is normally around 65% methane and 35% carbon dioxide. Biogas is also made up of small amounts of other gases such as hydrogen sulfide and some water vapor. <ref> Eaton, A.B. (2009) "The Role of Small-Scale Biodigesters in the Engery, Health and Climate Change Baseline in Mexico" Masters Thesis, HSU Environmental Resource Engineering.</ref>
+
In order to maximize the durability of the Biobolsa, a roof is necessary to protect the system from the harshness of the elements. Additionally, as the anaerobic bacteria within the system require a mesophilic atmosphere to achieve optimal biodigestion, we used transparent corrugated plastic sheeting so that the roof system could serve as the basis for the development of a low tech greenhouse to house the Biobolsa.  
<center>Equation 1:
 
CO2 +8H‐&gt;CH4 +2H2O
 
  
Equation 2:  
+
<gallery>
CH3COOH ‐&gt; CH4 + CO2 <ref> Gerardi, M. H. (2003) “Microbiology of Anaerobic Digesters” 1st Ed., Hoboken, New Jersey. </ref> </center>
+
File:Dig postholes.jpg| Spacing for posts is measure and holes about one meter deep are dug.
 +
File:Roof level alex.jpg| The posts are placed in the holes and checked to be level.
 +
File:Cement postholes.JPG| The hole with the post in it is then filled with cement.
 +
</gallery>
  
=== Gas Scrubbing ===
+
The rest of the roof was constructed by Juan.
  
Typically, biogas is composed of 55 - 65% methane, 35-45% carbon dioxide, a small fraction of hydrogen sulfide gas, and other trace gases. Of these impurities, the presences of CO<sub>2</sub> and H<sub>2</sub>S are the most problematic. Both reduce combustion and efficiency of biogas, and each presents a unique obstacle not only to efficient and durable use of biogas technology. Although H<sub>2</sub>S constitutes less than 0.5% of the gas stream, it is extremely corrosive. Any equipment used within a biogas system to convert the gas to either direct heat applications (a boiler) or to more complex energy exchanges (a generator) will therefore degrade relatively quickly. <ref> Taylor, John Poe , Removal of Hydrogen Sulfide from Biogas, August 2003. http://www.cowpower.cornell.edu/project_docs/Thesis_jpt7.pdf  </ref> 
+
== Blanket &amp; Costal Barrier ==
To be continued
 
  
=== Economic Incentive  ===
+
A geotextile blanket was placed in the trench in order to protect the Biobolsa from earthen weathering, including small rocks and pointed objects. To ensure that animals do not enter into the system, we built a barrier of ''costals'', which are large 80 Liter sandbags that are often used in [[superadobe]] construction. As we eventually covered these costals in super adobe, the barrier served the dual function of insulating the system.
  
"Before a biogas plant is built or a biogas program is implemented, a techno-economic assessment should be made. For this, two sets of cost-benefit analyses have to be carried out: · The macro-economic analysis (economic analysis) which compares the costs of a biogas program and the benefits for the country or the society. · The micro-economic analysis (financial analysis) which judges the profitability of a biogas unit from the point of view of the user. In judging the economic viability of biogas programs and -units the objectives of each decision-maker are of importance. Biogas programs (macro-level) and biogas units (microlevel) can serve the following purposes: · the production of energy at low cost (mainly micro-level); · a crop increase in agriculture by the production of bio-fertilizer (micro-level); · the improvement of sanitation and hygiene (micro and macro level); · the conservation of tree and forest reserves and a reduction in soil erosion (mainly macro-level); · an improvement in the conditions of members of poorer levels of the population (mainly macro-level); · a saving in foreign exchange (macro-level); · provision of skills enhancement and employment for rural areas (macro-level)."
+
<gallery>
 +
File:Costal moving.jpg | costals are moved from across the yard to the site and at an estimated 100+ pounds was no small feat!
 +
File:Costales inplace.JPG | To achieve a workable surface for the super adobe project to follow, Juan batters the costals to level the dirt clumps.
 +
File:Costales blanket.JPG | Here we see the beginnings of the costal wall. Underneath, the geotextile blanket is held firm in place.  
 +
</gallery>
  
Habermehl Stefan, Kossmann Werner, Pönitz Uta, Biogas Digest:Volume III Biogas - Costs and Benefits and Biogas – Programme Implementation &lt;www.gtz.co.za/de/dokumente/en-biogas-volume3.pdf&gt; (July 11, 2010)
+
== Installation of Biobolsa  ==
  
 +
Installing the Biobolsa is a crucial process which requires care, precision and a strong understanding of the system's layout. For optimal functioning the Biobolsa must be perfectly centered in the trench with both the input and output pipes level. The biobolsa was placed directly on the geotextile blanket. We then filled the Biobolsa with water so as to displace the oxygen and initiate the anaerobic environment.
  
 +
<gallery>
 +
File:Glue PVC.jpg| IRRI President and Biobolsa designer Alex glues PVC to the intake pipe
 +
File:Gas reactor alex.jpg| Alex explains the functioning of the gas release system
 +
File:Biodigester empty demo.jpg| A view of the Biobolsa immediately before installation in the site
 +
File:Biodigester intrench.jpg| Here we have placed the Biobolsa in the trench, aligning its intake with the pigpen outlet
 +
File:Connecting biodigester.JPG| Juan and Alex work together to connect the Bolsa´s intake to the pigpen outlet
 +
File:Connecting gashose.JPG|Alex connects the gas release system
 +
File:Sulfur filter.JPG| Here we see the sulfur filter - our gas scrubber- of the gas release system
 +
</gallery>
  
(ROBERT: This reference is difficult to read. Maybe try paraphrasing the information....)
+
== Biol exit &amp; Overflow  ==
  
=== Social Incentive  ===
+
We decided to build an overflow system for the Biol to create a system which could function without constant maintenance. Beneath the Biol exit, we dug a hole to accommodate a 20 liter bucket. We extended a canal 5 meters from that hole downhill and dug a second hole for the second, overflow bucket.
  
"Biogas technology not only supports national economies and the environmental protection, but as its main outcome for the local population it provides for a wide range of improvements in overall living conditions. Sanitary and health conditions improve and the quality of nutrition is enhanced by an improved energy availability. Through the provision of lighting and the reduction of time-consuming fuel gathering cultural and educational activities are supported. Employment, professional qualification and overall food supply of the local population can be improved as well. But biogas technology can also contribute to an accentuation of existing differences in family income and property. Establishing community-level biogas systems is a way to ensure that the technology benefits a greater number of residents. If social policies of a developing country are clearly focusing on poverty alleviation, biogas technology may not be the first choice among other "village technologies". It’s place is shifting rather towards the rural agricultural middle class, communities (for waste water treatment) and industries." Habermehl Stefan, Kossmann Werner, Pönitz Uta, Biogas Digest:Volume III Biogas - Costs and Benefits and Biogas – Programme Implementation &lt;www.gtz.co.za/de/dokumente/en-biogas-volume3.pdf&gt; (July 11, 2010)
+
== Insulating the System  ==
  
"Considerable workload reduction in rural areas: This is particularly true for rural women engaged in day to day household work. Installing a biogas unit will relieve her of the tiring and tedious job of collecting and ferrying firewood. Since, biogas burns cleanly, the rural homes will not suffer from smoke and consequently rural denizens will suffer less from physical problems like bronchial complications. Cooking is also easier with a gas stove and takes less time."
+
To optimize internal temperatures within the Biobolsa, we built a greenhouse to house the Biobolsa. The roof itself is constructed of semi-transparent corrugated plastic sheets to trap heat from the sun. From the roof posts, we extended plastic sheets to create a greenhouse effect. By fastening the plastic sheeting to the costal barrier, the heat trapped by the plastic is conserved by the super adobe. To close the system, we built a super adobe wall of recycled bottles extending from the already existing cement wall of the pigpen.  
  
Economy watch (2010) &lt;http://www.economywatch.com/renewable-energy/advantages-of-biogas.html&gt; (July 11, 2010)
+
== Finishing Touches  ==
  
 +
As our system will function as a demonstration Biodigester, we wanted it to be as comprehensive as possible. To accomplish this, we finished our system by installing a series of informative signs to explain the various processes of our Biobolsa system. We created both Spanish and English language versions, and translated the key words of each sign into a regional language of San Cristobal to achieve maximum accessibility for visitors to the site. Here is a link to a word document of all the signs.
  
"Conversion of natural organic waste into fertilizer: The conversion is carried out in a machine called the polythene bio gas digester. Cow dung slurry is put into the machine. The product is organic fertilizer of high quality. The fertilizer obtained is rich in nitrogen. It has been analyzed, that, fertilizer made by the polythene bio gas digester contains nitrogen content 3 times more than the product made by conventional processes. It is completely natural and free from harmful synthetic chemicals."
+
== The Future of the System  ==
  
Economy watch (2010) &lt;http://www.economywatch.com/renewable-energy/advantages-of-biogas.html&gt; (July 11, 2010)
+
As his pigs are not yet producing the desired amount of waste, Juan has mentioned that he is considering pursuing another supply of animal waste from a friend who raises cattle. With the proposed deposit of 3 kg daily of cattle manure, Juan will be able to boast the activity of anaerobic bacteria within his Sistema Biobolsa and reduce his HRT significantly. Another exciting plan includes using the waters harvested by the recently installed [[HSU Chiapas Rainwater Catchment]] system to plant a fall garden, which will be fertilized by Biol from the Biodigester.
  
=== Environmental Incentive  ===
 
 
'''Carbon Offset &amp; Methane Reduction'''
 
 
"Each year some 590-880 million tons of methane are released worldwide into the atmosphere through microbial activity. About 90% of the emitted methane derives from biogenic sources, i.e. from the decomposition of biomass. The remainder is of fossil origin (e.g. petrochemical processes). In the northern hemisphere, the present tropospheric methane concentration amounts to about 1.65 ppm(parts per million)...Unlike fossil fuel combustion, biogas production from biomass is considered CO2 neutral and therefore does not emit additional Greenhouse Gases (GHG) into the atmosphere...However, if biogas is not recovered properly, it will contribute to a GHG effect 20 times worst than if methane is simply combusted. Therefore, there is a real incentive to transfer biogas combustion energy into heat and/or electricity."
 
 
Singh, Chandan (2006) &lt;http://projectsimilipal.blogspot.com/2006/07/benefits-of-using-biogas.html&gt; (July 11, 2010)
 
 
"Biogas not only releases far less carbon dioxide than fossil fuels, but it also produces smaller quantities of other pollutants such as heavy metals, sulfur dioxide, nitrogen and particulates...One of the gases produced by the decomposition of manure is methane gas, which is estimated to trap 20 to 30 times as much atmospheric heat as carbon dioxide, and reducing methane releases into the air is a crucial element of the fight to limit global warming. The relatively simple digestion process that produces biogas converts a foul-smelling manure pile from a methane-emitting climate villain to high-quality... fuel. And digestion doesn’t reduce the value of manure as an agricultural fertilizer. The important substance for plant growth is nitrogen, which remains in place after extraction of biogas...This leads to further environmental advantages. By reducing the weight and volume of fertilizer, biogas extraction cuts down on transportation pollution. And increasing the amount of fertilizer available from composted waste reduces the need for artificial fertilizers, which release the extremely powerful greenhouse gas nitrous oxide."
 
 
Advantage Environment (2009) &lt;http://advantage-environment.com/upplevelser/double-environmental-benefit-from-biogas/ &gt; (July 11, 2010)
 
 
The size of the biodigester determines offsets in regards to wood and carbon as well as the methane reductions. For example, "1 biogas plant is computed to save 32 liters of kerosene and 4 tons of firewood every year."
 
 
Economy Watch (2010) &lt;http://www.economywatch.com/renewable-energy/advantages-of-biogas.html&gt; (July 11, 2010)
 
 
Another type:"Each biogas plant saves about 2.5 tonnes/year of fuelwood, equivalent to about four tonnes/year of CO2. And incidence of respiratory diseases has reduced among users."
 
 
The Ashden Awards (2010) &lt;http://www.ashdenawards.org/winners/vknardep&gt; (July 11, 2010)
 
 
"Another major environmental target is the mitigation of deforestation and soil erosion through the substitution of firewood as an energy source." Habermehl Stefan, Kossmann Werner, Pönitz Uta, Biogas Digest:Volume III Biogas - Costs and Benefits and Biogas – Programme Implementation &lt;www.gtz.co.za/de/dokumente/en-biogas-volume3.pdf&gt; (July 11, 2010)
 
 
=== IRRI  ===
 
 
"IRRI Mexico is dedicated to promoting sustainable use of natural resources. We provide education, develop new technologies, and install systems that help low income families meet their basic energy, water, and sanitation needs in a sustainable way. Our projects aim to empower families, communities, and businesses to produce their own clean energy, obtain their own water, and manage their own resources and wastes in ways that benefit them and the environment simultaneously."<ref>Instituto Internacional de Recursos Renovables (2010). "Welcome." IRRI, &amp;amp;lt;http://www.irrimexico.com/english/&amp;amp;gt; (Jul. 12, 2010).</ref>
 
 
'''Mission'''
 
 
Our Mission is to promote programs and businesses that produce sustainable goods and services and help reduce reliance on fossil fuels. IRRI supports rural and low-income communities with the objective of improving the quality of life through generating, developing, and conserving local resources. IRRI’s vision is sustainable and equitable prosperity in a world without contamination."<ref>Instituto Internacional de Recursos Renovables (2010). "Mission." IRRI, &amp;amp;lt;http://www.irrimexico.com/english/&amp;amp;gt; (Jul. 12, 2010).</ref>
 
 
=== Dissemination of Different Models  ===
 
Worldwide, the dissemination of different models of biodigestion systems has seen three general trends of biodigestor design which are identified by their different countries of origin. (Preston 2002, Lansing 2007).
 
 
'''China'''
 
 
From A CHINESE BIOGAS HANDBOOK <ref>
 
Translated by Michael Cook,  edited by: Ariane van Buren "A Chinese Biogas Handbook"
 
Published by: Intermediate Technology Publications, Ltd. London WC2E 8HN United Kingdom 1979 </ref>
 
"Since the 1950s China has experimented with the production of biogas from agricultural wastes, a practice based upon an
 
age-old Chinese tradition of cornposting human, animal and piant wastes to produce an organic fertilizer of high quality.
 
The breakthrough came in 1975 when a process was developed to ferment the materials in an airtight and watertight container
 
in order to produce methane gas."
 
This "breakthrough" describes the innovation of the Chinese Fixed Dome biodigestor, which has been reproduced in over 7 million systems around the world although the majority of these systems operate in China. The system is constructed of cement, thereby requiring skilled labor and an extensive installation time. In the field, the design has shown structural weakness in the low production of gas and the frequent occasion of gas leaks.  <ref> Eaton, A.B. (2009) "The Role of Small-Scale Biodigesters in the Engery, Health and Climate Change Baseline in Mexico" Masters Thesis, HSU Environmental Resource Engineering.</ref>
 
 
 
 
'''India'''
 
The floating cover, to be continued
 
 
'''Taiwan'''
 
The plug flow digester bag! to be continued
 
 
'''Mexico'''
 
 
*Current:
 
**Of the approximately 250 industrial biodigester projects that the Clean Development Mechanism (a mechanism of the Kyoto Protocol) has funded 200 of those are in Brazil and Mexcio. Additionally, nearly 30% of all the 'waste gas recovery projects' are in Mexico making up about 110 projects of which the great majority are anaerobic digesters. <ref>Eaton, A.B. (2009) "The Role of Small-Scale Biodigesters in the Engery, Health and Climate Change Baseline in Mexico" Masters Thesis, HSU Environmental Resource Engineering.</ref>
 
*Future:
 
**Anaerobic digester systems may not be possible in some areas of Mexico due to water shortages. <ref> Secretaría de Medio Ambiente y Recursos Naturales (2008) "Animal Waste Management  Methane Emissions" Presentation prepared for Methane to Market. &amp;amp;lt;http://www.methanetomarkets.org/documents/ag_cap_mexico.pdf&amp;amp;gt; </ref>
 
  
=== Logistical Analysis of Site ===
+
== Testing ==
  
*Address + GPS
+
'''Hydraulic Retention Time'''('''HRT''') = total liquid volume of system (L)/ daily input of water and effluent mixture (L/day)
  
Client: Juan Hidalgo Calle Tapachula #55 San Cristóbal de las Casas, Chiapas Mexico 16° 44’ 27.46’’ N 92° 37’ 39.78’’ W Elev. 2154m Espacio: 7m x 2.7m
+
This equation illustrates the amount of time that material (effluent) will reside within a biodigestion system before exiting as Biol<ref name="Biol"/>, however due to sedimentation not all material will have the same HRT.  
  
=== Climate of San Cristobal  ===
+
In order to calculate the HRT, we measured the amount of waste produced by Juan´s pigs within a 24 hour period. Our HRT, based on three separate collections, is:
  
• Monthly temperature averages for San Cristóbal de las Casas
+
*Total volume of system = 3,000 liter (L)
 +
*Daily input of water and effluent mixture = 2 liters of effluent/day + 12 liters of water/day = 14 L/day
 +
*1 month = 30.5 days
  
"January Avg low: 17° Avg hi: 29° Avg precip: 0.03 cm February Avg low: 18° Avg hi: 30° Avg precip: 0.19 cm March Avg low: 19° Avg hi: 33° Avg precip: 0.02 cm April Avg low: 21° Avg hi: 35° Avg precip: 0.61 cm May Avg low: 22° Avg hi: 34° Avg precip: 3.45 cm June Avg low: 22° Avg hi: 32° Avg precip: 14.23 cm July Avg low: 21° Avg hi: 31° Avg precip: 9.64 cm August Avg low: 21° Avg hi: 31° Avg precip: 12.78 cm September Avg low: 21° Avg hi: 30° Avg precip: 12.15 cm October Avg low: 20° Avg hi: 30° Avg precip: 3.45 cm November Avg low: 19° Avg hi: 30° Avg precip: 0.77 cm December Avg low: 18° Avg hi: 29° Avg precip: 0.28 cm"
+
3,000 L / 14 L/day = 214.3 days, or 7 months
  
Foreca 2010 &lt;http://weather.msn.com/monthly_averages.aspx?&amp;wealocations=wc%3a7246&amp;q=San+Crist%C3%B3bal+de+las+Casas%2c+MEX&amp;setunit=C&gt; (July 11, 2010)
+
This value indicates that the system will require 7 months to complete biodigestion given a daily input of 2 liters of waste. As we have stated, the pigs in question are 3 mature pigs and 4 young piglets. As the four piglets grow, the daily input of waste is sure to follow. That said, the HRT can be expected to decrease with time.
  
• Daytime temperatures average from 19° C. (66° F.) in winter and 23° C. (73° F.) in summer. Overnight lows average from 5° C. (41° F.) in winter and 13° C. (55° F.) in summer. &lt; http://www.innvista.com/culture/travel/mexico/sclc.htm &gt; (July 11, 2010)
+
Optimally, a company of pigs will produce 3 kg of waste per day. Given these conditions, we can calculate the rate of amortization.  
  
=== Thermophilic Bacteria  ===
+
'''Àmortization''' = (Cost of system) / ((Energy Produced/Year) + (Fertilizer/Year) + (Emissions Reduced/Year) + (Health Benefits) + (Quality of Life))
  
Micro-organisms which live in temperatures of 40°C-80°C are "thermophiles" and those that live in 10°C-47°C "mesophiles."<ref> Rose, A. H., and Wilkinson, J. F. (1979) "Advances in Microbial Physiology" Vol. 19, 1st Ed., New York, New York. </ref> A study was performed to assess the effect of temperature variations on the performance of a mesophilic (35 degreesC) and a thermophilic (55 degreesC) upflow anaerobic filter treating a simulated papermill wastewater. It was found that the thermophilic produced much less diversity in bacteria than the mesophilic. The study showed that both systems had a decrease in productivity (produced less biogas) when temperatures were dropped to 35 degrees C.<ref>Ahn, JH and Forster, CF (2002) The effect of temperature variations on the performance of mesophilic and thermophilic anaerobic filters treating a simulated papermill wasterwater. Process Biochemistry, 37 . pp. 589-594. ISSN 0032-9592</ref>
+
This equation illustrates the amount of time the Biobolsa will take to pay back its initial investment (not including the cost of infrastructure) as a result of energy produced (displacing the cost of other fuel sources), emissions reduction (which can be translated financially due to carbon market equivalencies), fertilizer produced (displacing the cost of fertilizer) along with the non quantifiable benefits of improved health and quality of life.  
  
==Tentative Schedule==
+
For the System Biobolsa at Juan´s house, we calculate:
*Week 1:  
 
**Literature Review
 
**Criteria
 
**Meeting with [http://www.irrimexico.com/ IRRI] (7/8)
 
**Set up Site Visit with [[user:soysinlimites|Kiva]]
 
  
*Week 2:
+
$800 USD / (($300/year) + ($300/year) + ($40/year) + (Health Benefits) + (Quality of Life)) = 1.25 years*.
**Continue Investigation
 
**Site Evaluation (Wed 7/14)
 
**Arrange Site with [http://www.irrimexico.com/ IRRI] and report to Lonny
 
  
 +
* This value does not include the value of health benefits or quality of life, which are indirect economic factors and challenging to quantify. However, it does indicate that once the system has reached optimal biodigestion, the system will pay back its initial investment after 1.25 years of functioning at capacity.
  
*Week 3:
+
<br>
**Class Installation (Tue/Wed)
 
  
*Week 4:
+
==Video==
**Assist [http://www.irrimexico.com/ IRRI] with public course
+
<center>{{#widget:YouTube|id=8Y8cPdjobQw}}</center>
**Second Installation
 
**Tests and Infrastructure
 
  
*Week 5:
+
== References ==
**Complete page on biodigestion on [http://www.irrimexico.com/ IRRI]'s website
 
  
===References===
+
<small><references /> </small>
<references/>
 
  
[[Category:HSU Chiapas Program 2010]]
+
[[Category:HSU Chiapas Program]]
[[Category:Biofuels]]
+
[[Category:HSU Chiapas Program 2010]]  
 +
[[Category:Biogas]]
 +
[[Category:Projects]]
 +
[[Category:Videos]]
 +
[[Category:Appropriate technology videos]]
 +
[[Category:Energy videos]]

Latest revision as of 16:49, 30 April 2013

[ Invitation ] - [ Handbook ] - [ What to Pack ] - [ Chiapas Program 2010 ] - [ Parras Program 2005-2008 ]

Demonstration Biodigester in San Cristóbal de las Casas, Chiapas, Mexico
Team Biogas and Biodigester (photo: Lonny Grafman)

Objective[edit]

In the summer of 2010, a collaboration between students of Humboldt State University and the International Institute of Renewable Resources (IRRI) will seek the construction and dissemination of a biodigestion system, the Sistema Biobolsa, within the community of San Cristóbal de las Casas, Chiapas. The objective of this project is to promote the realization of further Biobolsa projects in the San Cristobal de las Casas area by constructing a successful Biodigester demonstration system in the eco-home of local builder and home designer Juan Hidalgo.

International Renewable Resources Institute-Mexico[edit]

"IRRI Mexico is dedicated to promoting sustainable use of natural resources. We provide education, develop new technologies, and install systems that help low income families meet their basic energy, water, and sanitation needs in a sustainable way. Our projects aim to empower families, communities, and businesses to produce their own clean energy, obtain their own water, and manage their own resources and wastes in ways that benefit them and the environment simultaneously."[1]

Appropedia Page: International Renewable Resources Institute-Mexico
Website: http://www.irrimexico.org
General Information: info@irrimexico.org
Executive Director Alex Eaton: alexAtsymbol.pngirrimexicoDot.pngorg
Coordinator Helene Gutiérrez: heleneAtsymbol.pngirrimexicoDot.pngorg
Telephone: + (52) 55 52 56 56 86
Instituto Internacional de Recursos Renovables
A.C.
37 Amatlán, 1st Floor
Col Condesa, Mexico D.F. 06140

IRRI's Mission

"To promote programs and businesses that produce sustainable goods and services and help reduce reliance on fossil fuels. IRRI supports rural and low-income communities with the objective of improving the quality of life through generating, developing, and conserving local resources. IRRI’s vision is sustainable and equitable prosperity in a world without contamination."[2]

Biodigestion[edit]

In Chiapas, Mexico, mismanagement of animal waste is problematic for the health of the planet as well as its inhabitants.[3] The odors themselves can be harmful to human health, causing irritation of the eye, nose, throat, headache, nausea, vomiting. [4] Raw, or partially digested, manure retains hazardous pathogens which can be spread to humans through premature composting, agricultural run off and contamination of the water table. [5]Furthermore, surface runoff of manure contributes to the degradation of local ecology. [4] Decomposition of animal manure releases gases, such as methane, into the atmosphere that can be environmentally destructive. These gasses are byproducts of fermentation. Methane is a greenhouse gas is approximately 21 times more potent than carbon dioxide. [6]

One way to mitigate these effects is to install a biodigester. Biodigestion describes the biological process by which organic matter is digested by anaerobic bacteria over the course of time. In the natural world, biodigestion occurs in a variety of anaerobic (oxygen-free) environments that include: marshes, the ocean floor, the human body, and manure. A biodigester is a system which uses the metabolism of anaerobic bacteria in order to digest animal manure producing biogas, a clean, renewable fuel source, as well as effluent, an organic fertilizer which in the case of our Biobolsa system we call Biol. [1]

The Biogas produced in a biodigester system is a key incentive. Approximately 25% of rural populations in Mexico currently use wood as a primary cooking fuel. [7] Wood as a fuel has several drawbacks: it is labor intensive to collect, it contributes to deforestation, and upon combustion poses significant respiratory risks to users.[8] The popular alternative to wood use is Liquid Petroleum (LP) gas and electricity, the both of which require elevated operational costs. [9] Biogas can be an alternative to shouldering such an economic burden by providing low cost energy and increasing energy security.[10]

Typically, biogas is composed of 55 - 65% methane, 35-45% carbon dioxide, a small fraction of hydrogen sulfide gas, and other trace gases. Of these impurities, the presence of H2S (hydrogen sulfide) is the most problematic. Although H2S constitutes less than 0.5% of the gas stream, it is extremely corrosive. Any metal equipment used within a biogas system to convert the gas to either direct heat applications (a boiler) or to more complex energy exchanges (a generator) will therefore degrade relatively quickly. [11] The larger the system, the larger the impact the presence of gaseous impurities will have on biogas production. As we are building a small, size 3 Biobolsa system [12], the intended application of the biogas is relatively small and therefore will not require an industrial approach to gas scrubbing. In order to reduce the H2S in the biogas, our system uses a packet of non-stainless steel wool in the gas regulator; with this type of filter, the the H2S will corrode the non-stainless steel wool before it has a chance to degrade metal equipment interior to the biogas´s end-use.

Animal manure has its high macro-nutrient content. It confers considerable amounts of nitrogen, potassium and phosphorous to germinating crops and can critically improve soil health. [13]. However, research has proven that manure that has undergone biodigestion is a more effective fertilizer than raw, or fresh, manure. [14] Furthermore, the application of raw manure to soil can potentially contaminate agricultural products with hazardous pathogens. These pathogens are heat-sensitive, generally destroyed by temperatures of 36 degrees celsius or greater.[15] The active anaerobic bacterias of a biodigestion system are mesophilic, meaning that they thrive in temperatures of 15-47 degrees C, [16] although many show the ability to produce diverse and productive colonies in temperatures as low as 10 degrees celsius. [17] Biodigestion occurs optimally at 15-40 celsius.[1] This means that the effluent produced is pathogen free.

Dissemination of Different biodigester Models[edit]

Worldwide, the dissemination of different models of biodigestion systems has seen three general trends of biodigester design which are identified by their different countries of origin. [1]

China[edit]

From A CHINESE BIOGAS HANDBOOK [18] "Since the 1950s China has experimented with the production of biogas from agricultural wastes, a practice based upon an age-old Chinese tradition of composting human, animal and plant wastes to produce an organic fertilizer of high quality. The breakthrough came in 1975 when a process was developed to ferment the materials in an airtight and watertight container in order to produce methane gas." This "breakthrough" describes the innovation of the Chinese Fixed Dome biodigester, which has been reproduced in over 7 million systems around the world although the majority of these systems operate in China. The system is constructed of cement, thereby requiring skilled labor and an extensive installation time. In the field, the design has shown structural weakness in the low production of gas and the frequent occasion of gas leaks. [1]

India[edit]

The floating cover, or Indian, biodigester was designed to address the problem of gas leaks in the Chinese Fixed Dome. In this model, the gas storage mechanism consists of a floating cover, typically constructed of fiberglass, which rises in response to the generation of gas, therefore having a larger gas storage capacity. Although over 3 million have been constructed around the world, this system too is difficult to effectively demonstrate as the system consists of moving parts of high industrial cost (fiberglass). [1]

Taiwan[edit]

The Taiwanese, or "tubular plastic", design is the most economical of the 3 models discussed. As a result of high installation costs and difficulty in replacing parts, a continuous flow digester contained within a plastic bag was developed in order to achieve 1) greater weatherability 2) more efficient gas production 3) cheaper and more uniform manufacture and 4) a shorter installation time. [1]

Our project is based on this tubular plastic model for a biodigester. Specifically, we will be building a Biobolsa system, engineered by Sistema Biobolsa [19]

Mexico[edit]

  • Current:
    • Of the approximately 250 industrial biodigester projects that the Clean Development MechanismW (a mechanism of the Kyoto ProtocolW) has funded 200 of those are in Brazil and Mexico. Additionally, nearly 30% of all the 'waste gas recovery projects' are in Mexico making up about 110 projects of which the great majority are anaerobic digesters. [1]
  • Future:
    • Anaerobic digester systems may not be possible in some areas of Mexico due to water shortages. [20] However, in conjunction with the recently installed HSU Chiapas Rainwater Catchment system at Juan´s house, we foresee the functioning of our system without a considerable additional cost for water.

Criteria[edit]

Criteria Description Weight
Potential for Community Involvement Must be a demonstration biodigester designed for educating the community. 10
Cost Needs to have enough spending to support project but not so much to bankrupt the community 9
Level of Appropriateness Project must be able to be incorporated in the setting and to the appeal of client 9
Durability Needs to withstand use with no more than of $5-10 yearly maintenance. 8
Adherence to the Mission of IRRI Meets IRRI's educational standards 8
Level of Energy Generation Amount of Methane Produced 7
Level of Fertilizer Generation Amount of Fertilizer Bi-product Produced 7

Budget[edit]

Materials Unit Price (Pesos) Quantity Cost
High Density Polypropylene Biobolsa (3000 liters) and Kit [21] $8000 1 $8000
4" PVC pipe $35/m 2 meters $70
4" PVC wye fitting $25 2 $50
3/8" flexible hose (gas) $7/meter 55 meters $385
Cement $115/bag 2 $230
Chicken Wire $22/meter 1 $22
nails $50 / kilo found on site $0
4" PVC pipe (for drainage system) $46/meter 5meters $232
Printing of Interpretive Signs $2 6 $12
Laminating of interpretive signs $16 12 $192
Glue (for PVC) $12.5 1 $12.5
Corrugated Plastic Roofing Sheets $360/sheet 9 $3240
Post for roof (wooden) $50/post 6 $300
Buckets $15/bucket 2 $30
Cross Beams $30/beam 3 $90
Beams $15/beam 7 $105
Plastic Sheeting $45/5 meters 2 $90
bricks found on site 12-18 $0
natural gas stove $210 1 $210
Total $13270.5

Materials[edit]

The Site[edit]

We built our biodigester, the Sistema Biobolsa, at the house of Juan Hidalgo, on Calle Tapachula #55 in San Cristobal de las Casas. In San Cristobal, daytime temperatures average from 19° C. (66° F.) in winter and 23° C. (73° F.) in summer. Overnight lows average from 5° C. (41° F.) in winter and 13° C. (55° F.) in summer. < http://www.innvista.com/culture/travel/mexico/sclc.htm > (July 11, 2010)

The coordinates of the house are : 16° 44’ 27.46’’ N 92° 37’ 39.78’’, at an elevation of 2154 m.

The house of Juan Hidalgo is a demo-house, in which the property itself seeks to be an example of eco-living. He has a 7 pigs, one rooster, a small garden and his home is made of super adobe and recycled materials. When we began our work on the location, the site for the biodigester showed many obstacles. There were two large mounds of pig manure, a rainwater cistern, and a variety of scrap wood.

Waste Chute[edit]

The waste chute, or Registro, is the structure in which the pig excrement drains from the Pigpen. Conveniently, Juan's pigpen had a small aperture in the side of the back wall which the piglets had priorly used to escape into the garden. We built our waste chute based on that aperture, using the opening as a space through which the excrement could be swept into the waste chute. The waste chute itself was constructed of compacted bricks and concrete. The most important feature of the waste chute is the 4" PVC pipe at the chute's far end. Through this pipe, the excrement travels by gravity into the Biobolsa.

Digging the Biodigester Trench[edit]

The dimensions of the trench were determined by the dimensions of the Biobolsa. Based on the size 3 Biobolsa, we needed a trench with the following dimensions: ( 140 cm width * 460 cm length * 80 cm deep).

Rubble Trench Drain[edit]

We built our rubble trench drainage system in response to a large torrential rain which left our trench water logged. First, we dug a canal downhill from the biodigester site that terminated in a hole. We placed a PVC tube in the canal to accommodate drainage. Then we filled both the canal and the hole with large rocks. Lastly, we covered the system with dirt so that the ground would remain a viable workspace.

Prepping the Pigpen[edit]

The cleaning of the pigpen is necessary to ensure that no food waste enters the system upon installation. First, we collected all large solids in a series of 5 gallon buckets; this included both excrement and food waste. Care was taken to separate the two, so that the excrement present could be measured in the calculation of HRT. Then, while someone outside the pigpen gently sprayed the floor with water, the pigpen was swept clean of all food waste. After installing the waste chute, we noticed that some of the piglets had been taking advantage of the opening to escape from the Pigpen into the biodigester itself. Our final step in prepping the pigpen was the construction of a small bar to close off the entrance to the waste chute from the pigpen.


Roof[edit]

In order to maximize the durability of the Biobolsa, a roof is necessary to protect the system from the harshness of the elements. Additionally, as the anaerobic bacteria within the system require a mesophilic atmosphere to achieve optimal biodigestion, we used transparent corrugated plastic sheeting so that the roof system could serve as the basis for the development of a low tech greenhouse to house the Biobolsa.

The rest of the roof was constructed by Juan.

Blanket & Costal Barrier[edit]

A geotextile blanket was placed in the trench in order to protect the Biobolsa from earthen weathering, including small rocks and pointed objects. To ensure that animals do not enter into the system, we built a barrier of costals, which are large 80 Liter sandbags that are often used in superadobe construction. As we eventually covered these costals in super adobe, the barrier served the dual function of insulating the system.

Installation of Biobolsa[edit]

Installing the Biobolsa is a crucial process which requires care, precision and a strong understanding of the system's layout. For optimal functioning the Biobolsa must be perfectly centered in the trench with both the input and output pipes level. The biobolsa was placed directly on the geotextile blanket. We then filled the Biobolsa with water so as to displace the oxygen and initiate the anaerobic environment.

Biol exit & Overflow[edit]

We decided to build an overflow system for the Biol to create a system which could function without constant maintenance. Beneath the Biol exit, we dug a hole to accommodate a 20 liter bucket. We extended a canal 5 meters from that hole downhill and dug a second hole for the second, overflow bucket.

Insulating the System[edit]

To optimize internal temperatures within the Biobolsa, we built a greenhouse to house the Biobolsa. The roof itself is constructed of semi-transparent corrugated plastic sheets to trap heat from the sun. From the roof posts, we extended plastic sheets to create a greenhouse effect. By fastening the plastic sheeting to the costal barrier, the heat trapped by the plastic is conserved by the super adobe. To close the system, we built a super adobe wall of recycled bottles extending from the already existing cement wall of the pigpen.

Finishing Touches[edit]

As our system will function as a demonstration Biodigester, we wanted it to be as comprehensive as possible. To accomplish this, we finished our system by installing a series of informative signs to explain the various processes of our Biobolsa system. We created both Spanish and English language versions, and translated the key words of each sign into a regional language of San Cristobal to achieve maximum accessibility for visitors to the site. Here is a link to a word document of all the signs.

The Future of the System[edit]

As his pigs are not yet producing the desired amount of waste, Juan has mentioned that he is considering pursuing another supply of animal waste from a friend who raises cattle. With the proposed deposit of 3 kg daily of cattle manure, Juan will be able to boast the activity of anaerobic bacteria within his Sistema Biobolsa and reduce his HRT significantly. Another exciting plan includes using the waters harvested by the recently installed HSU Chiapas Rainwater Catchment system to plant a fall garden, which will be fertilized by Biol from the Biodigester.


Testing[edit]

Hydraulic Retention Time(HRT) = total liquid volume of system (L)/ daily input of water and effluent mixture (L/day)

This equation illustrates the amount of time that material (effluent) will reside within a biodigestion system before exiting as Biol[22], however due to sedimentation not all material will have the same HRT.

In order to calculate the HRT, we measured the amount of waste produced by Juan´s pigs within a 24 hour period. Our HRT, based on three separate collections, is:

  • Total volume of system = 3,000 liter (L)
  • Daily input of water and effluent mixture = 2 liters of effluent/day + 12 liters of water/day = 14 L/day
  • 1 month = 30.5 days

3,000 L / 14 L/day = 214.3 days, or 7 months

This value indicates that the system will require 7 months to complete biodigestion given a daily input of 2 liters of waste. As we have stated, the pigs in question are 3 mature pigs and 4 young piglets. As the four piglets grow, the daily input of waste is sure to follow. That said, the HRT can be expected to decrease with time.

Optimally, a company of pigs will produce 3 kg of waste per day. Given these conditions, we can calculate the rate of amortization.

Àmortization = (Cost of system) / ((Energy Produced/Year) + (Fertilizer/Year) + (Emissions Reduced/Year) + (Health Benefits) + (Quality of Life))

This equation illustrates the amount of time the Biobolsa will take to pay back its initial investment (not including the cost of infrastructure) as a result of energy produced (displacing the cost of other fuel sources), emissions reduction (which can be translated financially due to carbon market equivalencies), fertilizer produced (displacing the cost of fertilizer) along with the non quantifiable benefits of improved health and quality of life.

For the System Biobolsa at Juan´s house, we calculate:

$800 USD / (($300/year) + ($300/year) + ($40/year) + (Health Benefits) + (Quality of Life)) = 1.25 years*.

  • This value does not include the value of health benefits or quality of life, which are indirect economic factors and challenging to quantify. However, it does indicate that once the system has reached optimal biodigestion, the system will pay back its initial investment after 1.25 years of functioning at capacity.


Video[edit]

References[edit]

  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Eaton, A.B. (2009) "The Role of Small-Scale Biodigesters in the Engery, Health and Climate Change Baseline in Mexico" Masters Thesis, HSU Environmental Resource Engineering.
  2. http://www.irrimexico.org
  3. "38% of pig farms dispose of their wastewaters without any treatment directly into the nation's water bodies, which in turn has a severe impact on the environment" Victoria-Almeida, et al. "Sustainable Management of Effluent from Small Pigery Farms in Mexico" Instituo de Ingenieria, Universidad Nacional Autonoma de Mexico, Cd Universitaria 04510 D.F., Mexico.
  4. 4.0 4.1 Mackie et al "Biological Identification and Biological Origin of Key Odor Components in Livestock Waste" J Anim Sci 1998. 76:1331-1342. http://www.animal-science.org/cgi/reprint/76/5/1331
  5. Guan, Tat Yee and Holley, Richard A. "Pathogen Survival in Swine Manure Environments and Transmission of Human Enteric Illness" Dept. of Food Science, Faculty of Food and Agricultural Science, University of Manitoba, Winnepeg, Manitoba R3T 2NT Canada. http://jeq.scijournals.org/cgi/reprint/32/2/383.pdf
  6. To convert a known mass of methane to the universal CO2 equivalent (tonnes CO2e) global warming potential, multiply the methane mass by 21 (UNFCCC, 2008). Eaton, A.B. (2009) "The Role of Small-Scale Biodigesters in the Energy, Health and Climate Change Baseline in Mexico" Masters Thesis, HSU Environmental Resource Engineering.
  7. "One in four households use fuel wood for either all or part of their energy for cooking" [Masera O. 2005. From Cookstoves to Cooking Systems: The Integrated Program on Sustainable Household Energy Use in Mexico. Energy for Sustainable Development 9, no. 1: 25-36.]
  8. "Visible improvement in rural hygiene: Biogas contributes positively to rural health conditions. Biogas plants lower the incidence of respiratory diseases. Diseases like asthma, lung problems, and eye infections have considerably decreased in the same area when compared to the pre-biogas plant times. Biogas plants also kill pathogens like cholera, dysentery, typhoid, and paratyphoid." Economy Watch (2010) (July 11, 2010)
  9. "One in four households use fuel wood for either all or part of their energy for cooking (Masera, 2005). The remaining energy needs throughout the country are met largely with Liquid Petroleum (LP) gas and electricity at a large economic burden for much of the low_income rural population."[Eaton, A.B. (2009) "The Role of Small-Scale Biodigesters in the Engery, Health and Climate Change Baseline in Mexico" Masters Thesis, HSU Environmental Resource Engineering.]
  10. "Before a biogas plant is built or a biogas program is implemented, a techno-economic assessment should be made. For this, two sets of cost-benefit analyses have to be carried out: · The macro-economic analysis (economic analysis) which compares the costs of a biogas program and the benefits for the country or the society. · The micro-economic analysis (financial analysis) which judges the profitability of a biogas unit from the point of view of the user. In judging the economic viability of biogas programs and units the objectives of each decision-maker are of importance. Biogas programs (macro-level) and biogas units (microlevel) can serve the following purposes: · the production of energy at low cost (mainly micro-level); · a crop increase in agriculture by the production of bio-fertilizer (micro-level); · the improvement of sanitation and hygiene (micro and macro level); · the conservation of tree and forest reserves and a reduction in soil erosion (mainly macro-level); · an improvement in the conditions of members of poorer levels of the population (mainly macro-level); · a saving in foreign exchange (macro-level); · provision of skills enhancement and employment for rural areas (macro-level)."[Habermehl Stefan, Kossmann Werner, Pönitz Uta, Biogas Digest:Volume III Biogas - Costs and Benefits and Biogas – Programme Implementation <www.gtz.co.za/de/dokumente/en-biogas-volume3.pdf>] (July 11, 2010)
  11. Taylor, John Poe , Removal of Hydrogen Sulfide from Biogas, August 2003. http://www.cowpower.cornell.edu/project_docs/Thesis_jpt7.pdf
  12. http://sistemabiobolsa.com/
  13. "Animal manure is a valuable fertilizer as well, conferring inputs to the soil over and above the simple chemical nutrients of N, P and K. As an input into the crop cultivation systems, manure continues to be the link between crop and animal production throughout the developing world." Rodríguez et al. "Integrated farming systems for efficient use of local resources" University of Tropical Agriculture-UTA, Finca Ecológica, College of Agriculture and Forestry,Thu Duc, Ho Chi Minh, Vietnam
  14. "The biomass yield, and content of moisture and crude protein, of Chinese cabbage was highest when fertilized with biodigester effluent and lowest when fresh residual solids from manure were used." Thy, San and Buntha, Pheng "Evaluation of fertilizer of fresh solid manure, composted manure or biodigester effluent for growing Chinese cabbage (Brassica pekinensis)" Center for Livestock and Agriculture Development (UTA-Cambodia), POB 2423, Phnom Penh 3, Cambodia
  15. Ingham, et al. "Escherichia coli Contamination of Vegetables Grown in Soils Fertilized with Noncomposted Bovine Manure: Garden-Scale Studies" Department of Food Science,1 Hancock Agricultural Research Station,2 Lancaster Agricultural Research Station, 3 West Madison Agricultural Research Station, University of Wisconsin—Madison, Madison, Wisconsin (Received 5 March 2004/ Accepted 1 July 2004)-
  16. "Micro-organisms which live in temperatures of 40°C-80°C are "thermophiles" and those that live in 10°C-47°C are "mesophiles." Rose, A. H., and Wilkinson, J. F. (1979) "Advances in Microbial Physiology" Vol. 19, 1st Ed., New York, New York.
  17. Ahn, JH and Forster, CF (2002) The effect of temperature variations on the performance of mesophilic and thermophilic anaerobic filters treating a simulated papermill wasterwater. Process Biochemistry, 37 . pp. 589-594. ISSN 0032-9592
  18. Translated by Michael Cook, edited by: Ariane van Buren "A Chinese Biogas Handbook" Published by: Intermediate Technology Publications, Ltd. London WC2E 8HN United Kingdom 1979
  19. http://sistemabiobolsa.com/
  20. Secretaría de Medio Ambiente y Recursos Naturales (2008) "Animal Waste Management Methane Emissions" Presentation prepared for Methane to Market. &amp;amp;lt;http://www.methanetomarkets.org/documents/ag_cap_mexico.pdf&amp;amp;gt;
  21. the IRRI Biobolsa system includes: the gas regulator system with sulfur filter, hose to connect to Biobolsa system and valve, a biogas reservoir bag and plastic net to suspend bag from roofing, a recycled PET plastic blanket to protect the Biobolsa, a repair kit for the Biobolsa and a use and maintenance manual for the whole system. <http://sistemabiobolsa.com/> Manual de Instalación.
  22. 22.0 22.1 Biol, a nitrogen rich liquid fertilizer, is the end product of the input effluent into the Biobolsa system. IRRI "Presentación_FIRA_lite.pfd"