Transcript Free mature pig

Greek-Albanian cross border cooperation in Biomass Exploitation
Biological Conversion Technologies
Overview of Anaerobic Digestion and Digesters
Effluent
biogas
Influent
Presentation Outlines
• Introduction
 Basic anaerobic digestion (AD) terminology
 Some facts about the methan and microbiological process
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Anaerobic digestion
Principle of biogas production
Why Biogas?
Anaerobic digestion process overview
Factors influencing the biogas production
Basic parts of Biogas plant (Digester)
Types of Biogas Plants
Application of biogas
Biogas yield
Biogas Digester System Concerns
Greek-Albanian cross border cooperation in Biomass Exploitation
Introduction
• Biological Conversion
– Conversion of the biomass to fuel by exposing biomass
to certain microorganisms is called biological
conversion.
– The secondary fuels are produced as a result of
metabolic activity of the microorganisms.
– Anaerobic digestions and fermentation are the two
most common biological conversion processes and
products of these processes are biogas and ethanol .
Greek-Albanian cross border cooperation in Biomass Exploitation
Introduction
Greek-Albanian cross border cooperation in Biomass Exploitation
Basic anaerobic digestion (AD) terminology
Term
Description
Anaerobic
Without oxygen
Aerobic
With oxygen, e.g. in activated sludge plants or
in aerobic ponds
Anaerobic digestion /
degradation / treatment
These terms are all used interchangeably, and
mean “breaking down of organic matter”
Digestate / digester residue /
digested organic matter
The effluent from a digester; the liquid
product of the anaerobic digestion process
Biogas
Gas produced by microorganisms in anaerobic
process (typically 66% methane content)
Biogas digester / anaerobic
digester
A covered vessel (or reactor) in which
anaerobic digestion occurs
Greek-Albanian cross border cooperation in Biomass Exploitation
Greek-Albanian cross border cooperation in Biomass Exploitation
Introduction
Basic anaerobic digestion (AD) terminology
Just as an aside: Another note on terminology
In Germany (and other countries, too) there is currently still
an unwritten convention:
 Plants/processes where the input is mainly agricultural
waste are called biogas plants
 Plants/processes where the input is mainly municipal
organic solid waste (“green waste”) are called fermenters
or anaerobic digestion plants
Greek-Albanian cross border cooperation in Biomass Exploitation
Greek-Albanian cross border cooperation in Biomass Exploitation
Introduction
Terms to know
 Volatile Solids (VS) - A measure of the weight of solids that is combustable
“volatilized” at a temperature of 600 °C. It is reported as a percent of the
total weight of the manure sample.
 Methane production is often based on the volatile solids portion of
the manure.
 Total Solids (TS) – The weight of the dry matter of a sample of manure
and reported as a percent of the total weight of the manure sample.
 The type of digester used is based primarily on total solids content of
the waste.
 Hydraulic Retention Time (HRT) – The amount of time the manure spends
in the digester. Reported as the ratio of digester volume to the amount of
manure added per day.
 HRT affects the amount of methane produced.
 Loading Rate - amount of volatile solids per unit of time per volume of
digester. A “standard” digester will have loading rates of between 8 to 16
kg VS/day/m3 digester (30 day HRT).
Greek-Albanian cross border cooperation in Biomass Exploitation
Greek-Albanian cross border cooperation in Biomass Exploitation
Some facts about Methane
• Methane is the major component of “natural gas”, about
97% by volume
• At room temperature and standard pressure, methane is a
colorless, odorless gas (the smell characteristic of natural
gas is an artificial safety measure caused by the addition of
an odorant)
• Methane has a boiling point of −162°C at a pressure of one
atmosphere
• As a gas it is flammable only over a narrow range of
concentrations (5–15%) in air (explosive at 5-15%)
• Methane has a calorific value of 10 kWh/Nm3 or 35,900
kJ/Nm3
• Hence, biogas with 65% methane has a calorific value 6.5
kWh/m3 (23,300 kJ/m3)
Greek-Albanian cross border cooperation in Biomass Exploitation
Greek-Albanian cross border cooperation in Biomass Exploitation
Some facts about the microbiological process
• Under anaerobic conditions, organic substances are not
aerated (oxidised), but are fermented (reduced)
(Reduction = assimilation of electrons)
• Energy-rich end products, like organic acids or alcohols are
electron acceptors.
• It is quite a “slow” process (low growth rate of
methanogens) compared to aerobic processes
relatively
long sludge retention times are required.
• Like all biological processes, it is temperature dependent
(higher conversion rates at higher temperatures)
digesters are typically heated / insulated or below ground.
• Anaerobic digestion is a multi-stage process involving two to
four steps, depending on where you want to draw lines in
the process (see next slide).
Greek-Albanian cross border cooperation in Biomass Exploitation
Greek-Albanian cross border cooperation in Biomass Exploitation
Anaerobic digestion
• Anaerobic microbiological decomposition is a process in
which micro-organisms derive energy and grow by
metabolising organic material in an oxygen-free environment
resulting in the production of methane (CH4).
• The anaerobic digestion or anaerobic fermentation process
involves the conversion of decaying wet biomass and animal
waste into biogas through decomposition process by the
action of anaerobic bacteria.
• The most useful biomass for production of biogas are animal
and human waste, plant residue and other organic waste
material with high moisture content.
• A simplified stoichiometry for anaerobic digestion of
biomass is:
C 6 H10 O 5  H 2 O  3CH 4  3CO 2
Greek-Albanian cross border cooperation in Biomass Exploitation
Greek-Albanian cross border cooperation in Biomass Exploitation
Anaerobic digestion Overview
Greek-Albanian cross border cooperation in Biomass Exploitation
Greek-Albanian cross border cooperation in Biomass Exploitation
Biogas cycle
Greek-Albanian cross border cooperation in Biomass Exploitation
Greek-Albanian cross border cooperation in Biomass Exploitation
Principle of biogas production
• Basic Process
– The stage anaerobic fermentation of biomass
Fermentative
bacteria
Organic waste
(Cellelose, Starch, Protein,
Lipid)
H2, CO2, Acedic Acid
Alcohol, organic acids, amino
acids , hydrogen sulphide and
other compounds
Acetogenic
bacteria
Methanogenic
bacteria
Hydrolysis
H2, CO2, Acedic Acid
CH4, CO2
Acidification
Methane
formation
Greek-Albanian cross border cooperation in Biomass Exploitation
Principle of biogas production
Greek-Albanian cross border cooperation in Biomass Exploitation
The four stage anaerobic fermentation of biomass
Greek-Albanian cross border cooperation in Biomass Exploitation
Greek-Albanian cross border cooperation in Biomass Exploitation
Principle of biogas production
14
Greek-Albanian cross border cooperation in Biomass Exploitation
Greek-Albanian cross border cooperation in Biomass Exploitation
Principle of biogas production
The stage anaerobic fermentation of biomass:
Hydrolysis: conversion of non-soluble biopolymers to soluble
organic compounds.
–
–
–
In hydrolysis aerobic micro-organisms convert complex
organic compounds with heavy molecular weight
(carbohydrates, proteins and fats) into simple forms - amino
acids, monosaccharides and fatty acids respectively, which
are soluble and can be consumed by the micro-organisms.
This process takes place by hydrolytic bacteria.
As an example, Polysaccharides are converted into
monosaccharides, lipids to fatty acids, proteins to amino
acids and peptides
C6H10O4 + 2H2O → C6H12O6 + 2H2
Greek-Albanian cross border cooperation in Biomass Exploitation
Greek-Albanian cross border cooperation in Biomass Exploitation
Principle of biogas production
The stage anaerobic fermentation of biomass:
Fermentation or Acidogenesis: conversion of soluble organic
compounds to volatile fatty acids (VFA) and CO2.
 In the second stage, acidogenic bacteria transform the products of the first
reaction into short chain volatile acids, ketones, alcohols, hydrogen and
carbon dioxide.
 The principal acidogenesis stage products are propionic acid, butyric acid,
acetic acid (CH3COOH), formic acid, lactic acid, ethanol (C2H5OH) and
methanol (CH3OH), among other
 The hydrogen, carbon dioxide and acetic acid will skip the third stage,
acetogenesis, and be utilized directly by the methanogenic bacteria in the
final stage
 three typical acidogenesis reactions where glucose is converted to
ethanol, propionate and acetic acid, respectively.
C6H12O6 ↔ 2CH3CH2OH + 2CO2
C6H12O6 + 2H2 ↔ 2CH3CH2COOH + 2H2O
C6H12O6 → 3CH3COOH
Greek-Albanian cross border cooperation in Biomass Exploitation
Greek-Albanian cross border cooperation in Biomass Exploitation
Principle of biogas production
The stage anaerobic fermentation of biomass:
• Acetodogenesis: conversion of volatile fatty acids to acetate
and H2
 The rest of the acidogenesis products, i.e. the propionic acid, butyric acid
and alcohols are transformed by acetogenic bacteria into hydrogen, carbon
dioxide and acetic acid.
 Hydrogen plays an important intermediary role in this process, as the
reaction will only occur if the hydrogen partial pressure is low enough to
thermodynamically allow the conversion of all the acids.
 Equation A represents the conversion of propionate to acetate, only
achievable at low hydrogen pressure. Glucose (Eq. B) and ethanol (Eq. C)
among others are also converted to acetate during the third stage of
anaerobic fermentation/
Equation A: CH3CH2COO- + 3H2O ↔ CH3COO- + H+ + HCO3- + 3H2
Equation B: C6H12O6 + 2H2O ↔ 2CH3COOH + 2CO2 + 4H2
Equation C: CH3CH2OH + 2H2O ↔ CH3COO- + 2H2 +H+
Greek-Albanian cross border cooperation in Biomass Exploitation
Greek-Albanian cross border cooperation in Biomass Exploitation
Principle of biogas production
Methanogenesis: conversion of acetate and CO2 plus H2 to
methane gas (CH4)
– In the final step, microorganisms convert the hydrogen and
acetic acid formed by the acid formers to methane gas and
carbon dioxide.
– The bacteria responsible for this conversion are called
methanogens and are strict anaerobes.
Greek-Albanian cross border cooperation in Biomass Exploitation
Greek-Albanian cross border cooperation in Biomass Exploitation
Principle of biogas production
Two Types of Anaerobic Digestion
• Mesophilic process
25-38°C for 14-30 days
• Thermophilic process
50-60°C for 12-14 days
• Produced from Anaerobic digestion in Anaerobic
Digesters (AD)
Greek-Albanian cross border cooperation in Biomass Exploitation
Greek-Albanian cross border cooperation in Biomass Exploitation
Biogas process overview
Schematic representation of the course of anaerobic methane generation from
complex organic substances
Greek-Albanian cross border cooperation in Biomass Exploitation
Greek-Albanian cross border cooperation in Biomass Exploitation
Bacteria of biogas processes
A. Methanosarcina (cocci)
Syntrophomonas wolfei
Methanosaeta
Clostridium formicoaceticum
Greek-Albanian cross border cooperation in Biomass Exploitation
Principle of biogas production
Greek-Albanian cross border cooperation in Biomass Exploitation
Volatile Fatty Acids
Volatile fatty acids (VFAs) are an intermediate product:
 They should not accumulate under appropriate operation
 VFAs (e.g. acetic acid) accumulate if step 4 is inhibited
 In that case, pH value will drop (e.g. to pH of 4.8) and
the digestion process will stop (no more gas
production)
 This is also called a “sour” digester, and is usually very
smelly (a well operating digester produces almost no
odours)
Greek-Albanian cross border cooperation in Biomass Exploitation
Greek-Albanian cross border cooperation in Biomass Exploitation
Biogas composition
The methane fraction produced in the biogas varies with the
input material; as a rule of thumb:

carbohydrates:
approx. 50 vol.-% methane

fats:
approx. 70 vol.-% methane

proteins:
approx. 84 vol.-% methane
Compound
Vol %
Methane
50-75
Carbon dioxide
25-45
Nitrogen
<7
Oxygen
<2
Hydrogen sulfide
<1
Ammonia
<1
Greek-Albanian cross border cooperation in Biomass Exploitation
Greek-Albanian cross border cooperation in Biomass Exploitation
Why Biogas?
3
FOODER
2
LIQUID
MANURE
BIOGAS
COMFORT
&
SAVING
ENVIORNMENTAL
PROTECTION
A Biogas Unit:
 3 Components
(1,2 & 3)
 Form Natural Cycle
 All 3 has Direct
Benefits to Farmer
& his Economy.
1
The cycle of Organic matter & the Benefits of an
Agricultural Bio gas Unit
Greek-Albanian cross border cooperation in Biomass Exploitation
Greek-Albanian cross border cooperation in Biomass Exploitation
Why Biogas?
WATER
3
FOODER
2
ENVIORNMENTAL
PROTECTION
DUNG + URINE
LIQUID
MANURE
BIOGAS
COMFORT
&
SAVING
Animal : Dung
Gas plant : Manure
1
The cycle of Organic matter & the Benefits of an
Agricultural Bio gas Unit
Plantation: Fodder
Greek-Albanian cross border cooperation in Biomass Exploitation
Greek-Albanian cross border cooperation in Biomass Exploitation
Why Biogas?
WATER
3
FOODER
2
ENVIORNMENTAL
PROTECTION
DUNG + URINE
LIQUID
MANURE
BIOGAS
COMFORT
&
SAVING
Biogas Significance:
Clever way of
Exploiting Nature,
without Destroying
1
Optimizes Farm
Economy
The cycle of Organic matter & the Benefits of an
Agricultural Bio gas Unit
It support Self Reliance
& Sustainable
Development
Greek-Albanian cross border cooperation in Biomass Exploitation
Greek-Albanian cross border cooperation in Biomass Exploitation
Anaerobic digestion process overview
 In the anaerobic digestion process, micro-organisms convert
complex organic matter to biogas, which consists of methane
(CH4) and carbon dioxide (CO2)
 Some organic matter remains even after the digestion step, and
this is called digestate or digester residue or digested organic
matter
 Anaerobic digestion is used to treat high-strength wastewater,
organic solid waste, sewage sludges, blackwater, faecal sludge,
agricultural waste, food industry waste (e.g. breweries, slaughter
houses, dairy), manure, ....
 Anaerobic digestion with biogas production also occurs in
landfills, septic tanks, cows’ rumen, natural or constructed
wetlands, dams where vegetation was flooded
all these sites produce methane gas!
Greek-Albanian cross border cooperation in Biomass Exploitation
Anaerobic digestion process overview
Greek-Albanian cross border cooperation in Biomass Exploitation
Benefits of Digestion










Production of energy (heat, light, electricity),
Odor Control
Transformation of organic waste into high quality fertilizer,
Conversion of organic N to inorganic N
Improvement of hygienic conditions via reduction of pathogens, worm
eggs and flies,
Increase of productivity, mainly for women, in firewood collection and
cooking,
Environmental advantages through protection of soil, water, air and
woody vegetation,
Micro-economical benefits through energy and fertilizer substitution,
Additional income sources and increasing yields of animal husbandry
and agriculture,
Macro-economical benefits through decentralized energy generation,
import substitution and environmental protection.
Greek-Albanian cross border cooperation in Biomass Exploitation
Anaerobic digestion process overview
Greek-Albanian cross border cooperation in Biomass Exploitation
Other Key Facts
• There is “no” reduction in manure volume
• There is no reduction in manure nutrients
Some organic nitrogen is converted to ammonia nitrogen
and could be volatilized in the manure storage
• There is no increase in manure nutrients
Greek-Albanian cross border cooperation in Biomass Exploitation
Greek-Albanian cross border cooperation in Biomass Exploitation
Conditions to produce Biogas
Digestible
Substrate, i.e.
Organic matter
+ Water
A vessel where
Substrate is not
in contact with
air (O2 absent)
A digestion
temperature
between
150C – 350C
A Retention
time longer
than 30 days
 If methane producing bacteria present in the Substrate
(present in Dung) Biogas production begins in 3 to 5 days.
Greek-Albanian cross border cooperation in Biomass Exploitation
Factors influencing the biogas production
Greek-Albanian cross border cooperation in Biomass Exploitation
– Substrate temperature

Optimal temperature range for biogas production: 20-28°C.

This can be achieved in a satisfactory level only where mean
annual temperatures are around 20°C or above or where the
average daily temperature is at least 18°C.
If the temperature is below 15°C, gas production will be so low
that the biogas plant is no longer economically feasible.

– Changes in temperature



The process is very sensitive to changes in temperature.
Most of the biogas plants are builds in underground in order to
overcome this issue.
The temperature fluctuations between day and night are no great
problem for plants built underground, since the temperature of
the earth below a depth of one meter is practically constant.
Greek-Albanian cross border cooperation in Biomass Exploitation
Factors influencing the biogas production
Greek-Albanian cross border cooperation in Biomass Exploitation
– Available nutrient




In order to grow, bacteria need organic substances as a
source of carbon and energy.
In addition to carbon, oxygen and hydrogen, the generation of
bio-mass requires an adequate supply of nitrogen, sulfur,
phosphorous, potassium, calcium, magnesium and a number
of trace elements such as iron, manganese, molybdenum,
zinc, cobalt, selenium, tungsten, nickel etc.
"Normal" substrates such as agricultural residues or municipal
sewage usually contain adequate amounts of the mentioned
elements.
Higher concentration of any individual substance usually has
an inhibitory effect, so that analyses are recommended on a
case-to-case basis to determine which amount of which
nutrients, if any, still needs to be added.
Greek-Albanian cross border cooperation in Biomass Exploitation
Factors influencing the biogas production
Greek-Albanian cross border cooperation in Biomass Exploitation
– Retention time




The effective retention time may vary widely for the individual
substrate constituents depending on the vessel geometry, the
means of mixing, etc.
Selection of a suitable retention time depends on process
temperature as well as on the type of substrate used.
For liquid manure undergoing fermentation, the following
approximate values apply:
- liquid cow manure: 20-30 days
- liquid pig manure: 15-25 days
- liquid chicken manure: 20-40 days
- animal manure mixed with plant material: 50-80 days
If the retention time is not maintained properly and it is too short,
the bacteria in the digester are "washed out" faster than they can
reproduce, and fermentation practically comes to a standstill. This
problem rarely occurs in WAB systems.
Greek-Albanian cross border cooperation in Biomass Exploitation
Factors influencing the biogas production
Greek-Albanian cross border cooperation in Biomass Exploitation
– pH Value
 The best condition for the methane-producing bacteria is neutral to
slightly alkaline conditions.
 Once the process of fermentation has stabilized under anaerobic
conditions, the pH will normally take on a value of between 7 and
8.5.
 If the pH value drops below 6.2, the medium will have a toxic effect
on the methanogenic bacteria.
– Nitrogen inhibition



Nitrogen in the substrate inhibits the process of fermentation.
Noticeable inhibition occurs at a nitrogen concentration of roughly
1700 mg ammonium-nitrogen (NH4-N) per liter substrate.
The main prerequisite is that the ammonia level does not exceed
200-300 mg NH3-N per liter substrate.
Greek-Albanian cross border cooperation in Biomass Exploitation
Factors influencing the biogas production
Greek-Albanian cross border cooperation in Biomass Exploitation
– C/N ratio


–
Microorganisms required both nitrogen and carbon for
assimilation into their cell structures.
Various experiments have shown that the metabolic activity of
methanogenic bacteria can be optimized at a C/N ratio of
approximately 8-20, whereby the optimum point varies
depending on the nature of the substrate.
Substrate solid content



Solid content of the substrate impaired the mobility of the
methanogens within the substrate.
Therefore the biogas yield decreases with the increase of solids
content.
No generally valid guidelines can be offered with regard to
specific biogas production for any particular solids percentage.
Greek-Albanian cross border cooperation in Biomass Exploitation
Digester
Greek-Albanian cross border cooperation in Biomass Exploitation
Anaerobic digestion unit
Greek-Albanian cross border cooperation in Biomass Exploitation
Digester
Greek-Albanian cross border cooperation in Biomass Exploitation
What is a Digester?
•
Digester is a vessel or container where
the biogas process takes place.
Bacteria breaks down manure or other
waste products to create biogas.
•
Products may be fed into the chamber
such as manure or the container could
be used to cover a place that is already
giving off biogas such as a swamp or a
landfill.
How Digester Works
 Temperature must be kept between 65 degrees and
150 degrees
 4 Types of bacteria breakdown the waste
 Hydrolytic breaks organic material to simple sugar
and amino acids
 Fermentative then converts to organic acids
 Acidogenic convert to carbon dioxide, acetate, and
hydrogen
 Methanogenic produces biogas
Greek-Albanian cross border cooperation in Biomass Exploitation
Greek-Albanian cross border cooperation in Biomass Exploitation
Basic parts of Biogas plant
1. INFLUENT COLLECTING TANK
(Mixing tank) :
- To homogenize various substrates & to
setup required consistency.
4. DISPLACEMENT PIT
(SLURRY STORAGE)
- The fully Digested slurry leaves
the Digester through the Outlet
pipe into it.
1
4
2
3
2. DIGESTER
3. GAS HOLDER & GAS PIPE
- The bacteria multiply & produce
Biogas into the Digester.
- Digester provides the required
conditions for this process
- The Biogas is stored until consumption
into the Gasholder
- The gas pipe carries the Gas to the
Desired place of Consumption.
*Depending on the plant type & requirements Variations & Additions in components are possible
Greek-Albanian cross border cooperation in Biomass Exploitation
BIOGAS
Gaseous fuel - Microbial decomposition - Organic matter - In absence of oxygen
Methane
(CH4) ,
 USES : Clean combustible fuel.
Carbon dioxide
(CO2) ,
Cooking , Space heating , Lightning, etc..
Hydrogen
(H2) ,
Hydrogen sulphide (H2S).
BIOGAS PLANT :
Valve
Dome
Slurry
Sludge
Digestor
BIOGAS PLANT :
Valve
Dome
CONSTRUCTION :
Two main parts - Digestor , Dome

DIGESTOR
Slurry
Well like structure containing
Animal waste in the form of slurry
Sludge
Digestor
Below the ground level

Dome
WORKIING :
 Slurry – slurry tank - DIGESTOR
Fixed type
Floating type
 TWO PIPES
Feeding animal waste ,
SLURRY (Cow dung and water)
Taking out the used slurry “SLUDGE”.
 VALVE
Like a tap
 Anaerobic microorganisms decomposes
the slurry in presence of water.
 In few days BIOGAS is evolved.
 80% methane, (CO2), (H2), (H2S).
[excellent fuel , burns without smoke.]
 Biogas – DOME.through valve can be used
 Residue left behind–“SLUDGE”-sludge tank
 SLUDGE – very good fertilizer
 Rich in N2, P,K. –excellent fertilizers.
BIOGAS PLANT :
Gas to kitchen
Sludge used as a
fertiliser
Stops air getting into the
digester- creates
anaerobic condition
Greek-Albanian cross border cooperation in Biomass Exploitation
Types of Biogas Plants
 There are various types of biogas plants available in the world
and they are classified mainly based on feeding method and
construction.
On the Basis of Feed method the 3 types are:
BATCH PLANTS
CONTINUOUS PLANTS
SEMI-BATCH PLANTS
- Filled & Emptied
completely after a
fixed retention time.
- Charged & Discharged regularly
- Operated when
straw & dung are
digested together
- Generally used as farmers Biogas
plant with automatic discharge at
overflow.
- Gas production is Constant &
Higher
Greek-Albanian cross border cooperation in Biomass Exploitation
Types of Biogas Plants
Greek-Albanian cross border cooperation in Biomass Exploitation
Classification of Biogas Plants
Biogas plants are mainly classified as:
1. Continuous and batch type(as per the process)
a) Single stage process
b) Double stage process
2. The dome and drum type
3. Different variation in the drum type
Greek-Albanian cross border cooperation in Biomass Exploitation
Greek-Albanian cross border cooperation in Biomass Exploitation
Types of Biogas Plants
 The main features of Continuous plant are as follows:
 It will produce gas continuously.
 It require small digestion chambers.
 It needs smaller period of digestion.
 It has less problem compared to batch type and it is easier in
operation.
 The main features of Batch type plant are:
 The gas production is intermittent, depending upon the clearing of
the digester.
 It needs several digesters or chambers for continuous gas production,
these are fed alternately.
 Batch plants are good for long fibrous materials.
 This plant needs addition of fermented slurry to start the digestion
process.
 This plant is expensive and has problems comparatively, the
continuous plant will have less problems and will be easy for
operation.
Greek-Albanian cross border cooperation in Biomass Exploitation
Greek-Albanian cross border cooperation in Biomass Exploitation
Types of Biogas Plants
On the Basis of the type of construction the 3 well performing &
Mature Designs suitable for Farming Households are:
A. FIXED-DOME PLANT :
1. Gas collection
2. Expansion Chamber
B. FLOATING-DRUM
PLANT :
C. PLASTIC COVERED /
BALLON PLANT:
3. Gas collects in a
floating steel gas holder
4. The gas collected under
an inflating plastic cover
5. A wooden roof to
protect plastic against
sunlight
Main Building Material
Plastered Brickwork.
A.
2
B.
3
C.
5
4
1
Greek-Albanian cross border cooperation in Biomass Exploitation
Greek-Albanian cross border cooperation in Biomass Exploitation
Types of Biogas Plants
On the Basis of the type of construction the 3 well performing &
Mature Designs suitable for Farming Households are:
A. FIXED-DOME PLANT :
B. FLOATING-DRUM
PLANT :
C. PLASTIC COVERED /
BALLON PLANT:
- Relatively low cost
- Long life (20yrs or more)
- Least Maintenance.
- Simple Mechanism
- No day/night temp
Fluctuations so better
Bacteriological processes
- Labor intensive – Employment
- Great care-design&
workmanship.
- Which rises according to the
volume of gas production
- Easy to understand & operate
- Provide Gas at constant
pressure
- Stored Gas-volume
recognizable
- Expensive , Maintenance
Intensive (painting, cleaning)
- Drum life is Short(abt 10years)
- Standardized prefabrication
- Suitable for high ground water
table - high digester temp warm climate
- Uncomplicated Cleaning,
Emptying & Maintenance
- Low gas pressure, short life,
damage, not repaired locally
A.
2
B.
3
C.
5
4
1
Greek-Albanian cross border cooperation in Biomass Exploitation
Types of Biogas Plants
Greek-Albanian cross border cooperation in Biomass Exploitation
Fixed-Dom Type
Greek-Albanian cross border cooperation in Biomass Exploitation
Types of Biogas Plants
Greek-Albanian cross border cooperation in Biomass Exploitation
Fixed-Dom Type
A fixed-dome plant comprises of a closed, dome-shaped digester
with an immovable, rigid gas-holder and a displacement pit.
Greek-Albanian cross border cooperation in Biomass Exploitation
Types of Biogas Plants
Greek-Albanian cross border cooperation in Biomass Exploitation
Fixed dome type digester
 The gas is stored in the upper part of the digester.
 When gas production commences, the slurry is displaced into the
displacement tank.
 Gas pressure increases with the volume of gas stored, i.e. with the
height difference between the two slurry levels.
 If there is little gas in the gasholder, the gas pressure is low.
 The digesters of fixed-dome plants are usually masonry structures,
structures of cement and ferro-cement exist.
 Main parameters for the choice of material are technical suitability
(stability, gas- and liquid tightness), cost-effectiveness, availability in
the region and transport costs and availability of local skills for
working with the particular building material.
Greek-Albanian cross border cooperation in Biomass Exploitation
Types of Biogas Plants
Greek-Albanian cross border cooperation in Biomass Exploitation
Floating Drum plants
 Major difference between fixed dome and floating drum type plant is, a
floating-drum plant consists of a floating gas-holder, or drum.
Greek-Albanian cross border cooperation in Biomass Exploitation
Types of Biogas Plants
Greek-Albanian cross border cooperation in Biomass Exploitation
Floating drum type digester
 This floats either directly in the fermenting slurry or in a separate
water jacket.
 The drum in which the biogas collects has an internal and/or external
guide frame that provides stability and keeps the drum upright. If
biogas is produced, the drum moves up, if gas is consumed, the
gasholder sinks back.
 Floating-drum plants are used mainly in continuous feed mode of
operation.
 They are used most frequently by small- to middle-sized farms
(digester size: 5-15m3) or in institutions and larger agro-industrial
estates (digester size: 20-100 m3)
Greek-Albanian cross border cooperation in Biomass Exploitation
Greek-Albanian cross border cooperation in Biomass Exploitation
Types of Biogas Plants
– Advantages of fixed dome type.
 Produce just as much gas as floating-drum plants, if they
are gas-tight.
 Low cost operation
 Simple design
 Long life of the plant (20 years or more)
– Disadvantages of fixed dome type.
 Utilization of the gas is less effective as the gas pressure
fluctuates substantially.
 Labor-intensive design
 Not easy to build.
 Difficult to achieve gas tightness.
Greek-Albanian cross border cooperation in Biomass Exploitation
Greek-Albanian cross border cooperation in Biomass Exploitation
Types of Biogas Plants
– Advantages of floating drum type.
 Simple operation
 Provide gas at a constant pressure
 Stored gas-volume is immediately recognizable by the
position of the drum.
– Disadvantages of floating drum type.
 The steel drum is relatively expensive and maintenanceintensive.
 Removing rust and painting has to be carried out regularly.
 The life-time of the drum is short (up to 15 years; in
tropical coastal regions about five years).
Greek-Albanian cross border cooperation in Biomass Exploitation
Anaerobic digestion
Greek-Albanian cross border cooperation in Biomass Exploitation
Applicable substrates
 Anaerobic treatment works with organic input materials,
such as:
 liquid organic material
 solid organic material (water content of ~ 50% or more),
i.e.
 slurries/sludges
 organic kitchen waste
 grops
 greywater together with excreta
 The end product (digested material) is not pathogen-free,
but often suitable for further applications
Greek-Albanian cross border cooperation in Biomass Exploitation
Greek-Albanian cross border cooperation in Biomass Exploitation
Application of biogas
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Biogas is used as cooking fuel.
Biogas is mental light gas burner for lighting purpose.
Biogas is used for water heating.
It is used as fuel in I.C. Engine.
It is used as fuel to run agricultural machineries.
It is used to run diesel engine generator set to produce
electricity.
Heat of biogas is utilized in the dryer for drying the
agricultural products.
Heat of biogas is used to heat ammonia of refrigerating plant.
It is used for running pumps for irrigation purpose.
Methane and carbon dioxide are used as raw chemical feed
stock to manufacture various chemicals.
Greek-Albanian cross border cooperation in Biomass Exploitation
Greek-Albanian cross border cooperation in Biomass Exploitation
Application of biogas
Greek-Albanian cross border cooperation in Biomass Exploitation
Greek-Albanian cross border cooperation in Biomass Exploitation
Biogas yield
 Biogas yield of a biomass material depends on the organic
fraction of dry matter in the material and the waste
management system associated with it.
 The dry matter (DM) of the waste is the matter left after
removal of its moisture content. It may be obtained as the
weight loss on heating to a temperature of 105 C.
 Whereas, Volatile Solids (VS) are defined as the organic
fraction of dry matter in waste.
 Around 50-60% of the initial energy content in the organic
material can be converted to biogas in a properly operated
digester.
Greek-Albanian cross border cooperation in Biomass Exploitation
Biogas yield
Greek-Albanian cross border cooperation in Biomass Exploitation
Biogas production after addition of substrate
Greek-Albanian cross border cooperation in Biomass Exploitation
Greek-Albanian cross border cooperation in Biomass Exploitation
Biogas yield
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The resultant gas mixture consists of about 50 - 70%, CH4 and
the rest is CO2 with small amounts of water vapours, H2S, NH3,
and some organics that give bad odour.
Methodology of Estimation:
• Amount of biogas that can be potentially produced from
recoverable wastes
= Amount of dry matter recoverable (kg DM/year)  Volatile
solids fraction in dry matter (kg VS/kg DM)  Biogas yield
(m3/kg VS)
• Energy potential of the biogas recoverable (MJ /year)
= Amount of biogas recoverable (m3/year)  Heating value of
biogas (MJ /m3)
Greek-Albanian cross border cooperation in Biomass Exploitation
Greek-Albanian cross border cooperation in Biomass Exploitation
Biogas yield
 The heating value of the biogas depends on its composition,
especially the amount of methane.
 HHV of methane is about 35.8 MJ/m3 and therefore biogas
with 60% methane, HHV could be taken as 20 MJ/m3.
Selected values for waste characteristics
Animal Type
Cattle
Fraction of Volatile Biogas Yield
Solid (VS/DM)
(m3/kg of VS)
0.8
0.20 – 0.3
0.8
0.35 – 0.60
Pigs
0.7 – 0.8
0.25 – 0.50
Straw
0.8 – 0.9
0.15 – 0.35
Grass
0.9
0.55
Fruit Waste
0.75
0.25 – 0.50
Garden Waste
0.9
0.20 – 0.50
Poultry
Greek-Albanian cross border cooperation in Biomass Exploitation
Greek-Albanian cross border cooperation in Biomass Exploitation
Biogas Digester System Concerns
• Releases Nitrogen and ammonia into the
atmosphere both of which hazardous
• Can release Hydrogen Sulfide a very toxic gas
• Methane released can create explosive
atmosphere
• Should raw materials get into water supply can
contaminate the water
• Transportation is of a concern because
methane is explosive although new technology
may allow it to be stored in powder form
Greek-Albanian cross border cooperation in Biomass Exploitation
Biogas Digester System Concerns
Greek-Albanian cross border cooperation in Biomass Exploitation
Site selection
Following factors must be considered while selecting the site for
a biogas plant:
1.Distance
2.Minimum gradient
3.Open space
4.Water table
5.Seasonal run off
6.Distance from wells
7.Space requirements
8.Availability of water
9.Sources of cow dung/materials for biogas generation
Greek-Albanian cross border cooperation in Biomass Exploitation
Greek-Albanian cross border cooperation in Biomass Exploitation
Biogas Digester System Concerns
Biogas isn’t just for rural areas....
Advantages
• 1x
•
=3kW hours of electricity
Save on fossil fuels
• Save time collecting fuels
• Improve hygienic conditions
• Reduce pollution
Save Money
Protect Forests
Produce high quality
fertiliser
Greek-Albanian cross border cooperation in Biomass Exploitation