Difference between revisions of "Anaerobic Digestion"

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(Created page with "{{Template:CiteAuthors}} == Introduction == Anaerobic digestion is the conversion of organic matter to biogas which is flammable if the methane content of the biogas is high...")
 
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== Introduction ==
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=Principles of Operation=
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Anaerobic digestion is the conversion of organic matter to biogas which is flammable if the methane content of the biogas is high enough.  Digestion
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<!-- Only briefly state anything that the StemNode Diagrams can cover within subsystems.  This section is often omitted for specific systems (manuals on a specific make, model, or serial number) -->
  
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== Principles of Operation ==
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Anaerobic digestion is the conversion of organic matter to biogas which is flammable if the methane content of the biogas is high enough.  Digestion. Bacteria and Archea that perform the individual stages of anaerobic digestion are naturally present in the feces and organic matter that enter the digester or can be introduced from an already functioning digester.  The conditions within the digester can select for which organisms will perform best.
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Bacteria and Archea that perform the individual stages of anaerobic digestion are naturally present in the feces and organic matter that enter the digester or can be introduced from an already functioning digester.  The conditions within the digester can select for which organisms will perform best.
 
  
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=== Alkalinity ===
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==Operating Requirements and Conditions==
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(Needs work)
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<!-- Only briefly state anything that the StemNode Diagrams can cover as inputs. Use metric base units (Kg, L, m, A, cd, mol) where practical, with the exception of temperature which should be in Celsius instead of Kelvin. Chemical and biochemical processes should be in molar ratios.-->
  
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== Versions on Market ==
 
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[[File:Home_Biogas.jpg|right]]
 
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[https://homebiogas.com/ Home Biogas 2.0]is a market ready version marketed for use in digested food waste to produce biogas.
 
  
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== Regulations ==
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{| class="wikitable sortable"
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(Needs work)
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|-
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! Condition
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! Optimum(s)
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! Range
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! Unit
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! Notes
  
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== Operating Requirements ==
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|-
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| Temperature*
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| 15, 30-38, 50-57
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| 15-57
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| °C
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| See [[#Modes of Operation|Modes of Operation]]
  
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=== Site Requirements ===
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|-
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| pH
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| 7
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| ??
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| -
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|}
  
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=== Temperature ===
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==Ratios of Inputs to Outputs==
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Three different temperature ranges are ideal for anaerobic digestion, (but successful operation can be achieved outside these ranges); phsycrophilic (insert temp), 30-38°C (85-100°F) for Mesophilic Digestion, 50 to 57°C (122-135°F) for thermophilic digestion.   Of these psyochrophilic and mesophilic digestion is more commonly used at the building scale level.
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<!--Use metric base units (Kg, L, m, A, cd, mol) where practical, with the exception of temperature which should be in Celsius instead of Kelvin. Chemical and biochemical processes should be in molar ratios. Alternate units can be placed in parentheses -->
  
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== Troubleshooting Common Failures ==
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==Mathematic Models==
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<!-- Alternatively "Mathematical Models". Link to code sets, MatLab models ect. hosted on external websites.  Use [http://www.example.com link title], and replace "link title" with the desired text to appear -->
  
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=== Lack of Methane Production ===
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==Modes of Operation==
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Methanogens are typically the most sensitive organisms in the process but are the most crucial because they perform the final step of converting acids to methane.  Methanogen can be sensitive to high amounts of acid or high amounts ammonia. A low pH indicates high amounts of acid which can occur by putting too much organic matter in the digester.  This is especially the case with carbohydrates (e.g. from food waste) which break down quickly to acids causing acid build up.  A high pH could The quickest indicator of conditions that are hostile to methanogens is pH, which should be near 7.
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Three different temperature ranges are ideal for anaerobic digestion, (but successful operation can be achieved outside these ranges); 15°C for phsycrophilic , 30-38°C (85-100°F) for Mesophilic Digestion, and 50 to 57°C (122-135°F) for thermophilic digestion. Of these psyochrophilic and mesophilic digestion is more commonly used at the building scale level, while thermophilic is typically only operated at large scale facilities. The rates of organic matter and biogas production increase with increasing temperature
  
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=== Non-flammable Gas ===
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=Maintenance and Repair=
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Non-flammable gas could be due to too much moisture in the gas or not enough methane in the gas.  In order to ignite, biogas must be at least X% methane.  This is common for some time during digester startup.  It may indicate too much oxygen is being introduced which drives a higher portion of CO2 in the final gas.
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==Maintenance Schedule==
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<!--This section is for expected maintenance. Repairs of unexpected problems should go under the "Typical Failures and Known Solutions" section. Cost data should be omitted since it will change over time-->
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{| class="wikitable sortable"
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|-
 +
! Frequency
 +
! Action
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! Who Performs?
 +
! Time to Complete
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|-
 +
| state the frequency
 +
| state the action
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| User, Professional, Manufacturer, Anyone
 +
| Number and unit of time
 +
|}
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==Failures and Known Solutions==
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<!--Historical significance of a failure is better suited for Wikipedia or other sites.  You are encouraged to link out to these sites from this section -->
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 +
{| class="wikitable sortable"
 +
|-
 +
! Problem
 +
! Symptom (s)
 +
! Fundamental Cause
 +
! Solution
 +
 
 +
|-
 +
| low gas production
 +
| low pH
 +
| Neutral volatile fatty acids or lactic acid penetrate the cell walls of methanogens and inactivate the organisms
 +
| Reduce inputs, especially carbohydrates, until symptoms relieve, or dilute with water, or add buffers like CaCO3
 +
|-
 +
| low gas production
 +
| high ammonia
 +
| Ammonia can penetrate the cell walls of methanogens and inactivate the organisms
 +
| Reduce inputs until symptoms relieve, dilute with water, or add buffers like CaCO3
 +
|-
 +
| non-flammable gas
 +
| high moisture in gas
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| Moisture is evaporated during burning and can reduce the temperature below the level that a flame can be sustained.
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| Add a cooling trap where moisture can condense in the gas line
 +
|-
 +
| non-flammable gas
 +
| high CO2 in gas
 +
| Biogas must be above ?% methane for combustion. Inadvertent introduction of oxygen can increase CO2 production.
 +
| Add a cooling trap where moisture can condense in the gas line
 +
|}
 +
 
 +
Methanogens are typically the most sensitive organisms in the process but are the most crucial because they perform the final step of converting acids to methane.  Methanogens can be sensitive to high amounts of acid or high amounts ammonia.  A low pH indicates high amounts of acid which can occur by putting too much organic matter in the digester.  This is especially the case with carbohydrates (e.g. from food waste) which break down quickly to acids causing acid build up.  A high pH could The quickest indicator of conditions that are hostile to methanogens is pH, which should be near 7.
 +
 
 +
Non-flammable gas could be due to too much moisture in the gas or not enough methane in the gas. This is common during digester startup.   
 +
 
 +
==Warranty==
 +
<!--This only applies to specific systems (manuals on a specific make, model, or serial number).  Delete section for generalized systems -->
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=Instances of the System=
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<!--This only applies to generalized systems (those that do not have a make, model, or serial number).  Delete section for specific systems -->
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 +
{| class="wikitable sortable"
 +
|-
 +
! Make
 +
! Model
 +
! Start of Production
 +
! End of Production
 +
! Number Produced
 +
 
 +
|-
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| Home Biogas
 +
| 2.0
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| October 2018
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| In Production
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| ?
 +
|}
 +
 
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=System Modifications=
 +
<!--Discuss Variations on the System.  Typically these are not Manufacturer Sanctioned and therefor they apply only to specific systems (manuals on a specific make or model) -->
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=Visual models=
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<!-- This section is often only useful for specific systems (manuals on a specific make and model). Link to CAD drawings, PDFs ect on external websites that host the files.  Use [http://www.example.com link title], and replace "link title" with the desired text to appear -->
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=Intellectual Property=
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<!-- List any relevant patents, copyrights, or trade secrets on the system -->
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=Regulations=
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<!-- Subsections should be organized in alphabetical order by country, then state, where the regulations apply -->

Revision as of 08:25, 7 November 2018

Authors:

Principles of Operation

Anaerobic digestion is the conversion of organic matter to biogas which is flammable if the methane content of the biogas is high enough. Digestion. Bacteria and Archea that perform the individual stages of anaerobic digestion are naturally present in the feces and organic matter that enter the digester or can be introduced from an already functioning digester. The conditions within the digester can select for which organisms will perform best.

Operating Requirements and Conditions

Condition Optimum(s) Range Unit Notes
Temperature* 15, 30-38, 50-57 15-57 °C See Modes of Operation
pH 7 ?? -

Ratios of Inputs to Outputs

Mathematic Models

Modes of Operation

Three different temperature ranges are ideal for anaerobic digestion, (but successful operation can be achieved outside these ranges); 15°C for phsycrophilic , 30-38°C (85-100°F) for Mesophilic Digestion, and 50 to 57°C (122-135°F) for thermophilic digestion. Of these psyochrophilic and mesophilic digestion is more commonly used at the building scale level, while thermophilic is typically only operated at large scale facilities. The rates of organic matter and biogas production increase with increasing temperature

Maintenance and Repair

Maintenance Schedule

Frequency Action Who Performs? Time to Complete
state the frequency state the action User, Professional, Manufacturer, Anyone Number and unit of time

Failures and Known Solutions

Problem Symptom (s) Fundamental Cause Solution
low gas production low pH Neutral volatile fatty acids or lactic acid penetrate the cell walls of methanogens and inactivate the organisms Reduce inputs, especially carbohydrates, until symptoms relieve, or dilute with water, or add buffers like CaCO3
low gas production high ammonia Ammonia can penetrate the cell walls of methanogens and inactivate the organisms Reduce inputs until symptoms relieve, dilute with water, or add buffers like CaCO3
non-flammable gas high moisture in gas Moisture is evaporated during burning and can reduce the temperature below the level that a flame can be sustained. Add a cooling trap where moisture can condense in the gas line
non-flammable gas high CO2 in gas Biogas must be above ?% methane for combustion. Inadvertent introduction of oxygen can increase CO2 production. Add a cooling trap where moisture can condense in the gas line

Methanogens are typically the most sensitive organisms in the process but are the most crucial because they perform the final step of converting acids to methane. Methanogens can be sensitive to high amounts of acid or high amounts ammonia. A low pH indicates high amounts of acid which can occur by putting too much organic matter in the digester. This is especially the case with carbohydrates (e.g. from food waste) which break down quickly to acids causing acid build up. A high pH could The quickest indicator of conditions that are hostile to methanogens is pH, which should be near 7.

Non-flammable gas could be due to too much moisture in the gas or not enough methane in the gas. This is common during digester startup.

Warranty

Instances of the System

Make Model Start of Production End of Production Number Produced
Home Biogas 2.0 October 2018 In Production ?

System Modifications

Visual models

Intellectual Property

Regulations

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