Biogas Flashcards
Layer of floating material (mainly fibrous) on the slurry
Scum
Mixture of manure and water
Slurry
Difference in height between the digester wall and filling line
Freeboard
Organic material used to produce biogas
Substrate
Settled portion or precipitate of the slurry, mad like and semi solid mass
Sludge
Chamber where manure and water are collected, stored and separated from heavy and non-biodegradable materials before feeding them into the digester
Collecting tank
Cantilever beam that holds the gas holder or movable covered position at the desired biogas pressure
Gasholder retainer
Level of slurry when the digesters is at full load
Filling line
Mesophilic temperature range
20° to 40°C
Amount of slurry fed per unit volume of digester capacity per day
Loading rate
Anaerobic bacteria that act upon organic materials and in the process and produced biogas
Methanogens
Amount of biogas produced per day per cubic meter of slurry
Gas production rate
Space inside or outside the digester for the collection and storage of biogas
Gas chamber
Average period that a given quantity of slurry is retained in the digester for digestion
Retention time
Layer of compacted soil and gravel to support the digester wall
Backfill
Estimated daily quantity of available manure
Animals. Manure Available
(kg/day/animal)
Pigs 18-36 kg. 2.55
Cow-Feedlot animal. 14
Chicken:
Layer, 6 months or older 0.075
Broiler, day-old to 8 weeks 0.025
The minimum diameter of the inlet pipe shall be _____ .
0.2 m
Retention time for animal manure for mesophilic temperature range
Substrate Retention time Day Liquid pig manure 15 – 25
Liquid cow/carabao manure. 20 – 30
Liquid chicken manure 20 – 40
Animal manure mixed with plant
material. 50 – 80
The digester and gas chamber is integrated into one tank. The total height of
the plant depends on the sum of the digester and gas chamber volume. Eighty percent of the
total digester volume is occupied by the slurry.
Fixed type
For fixed type and balloon type, about ______% of the total digester volume is occupied
by the gas generated.
20%
For floating and balloon type, the minimum of volume of the outlet tank shall be
equal to the _______________.
daily slurry input of the digester
For fixed type, the volume of the outlet tank shall be _______ of digester volume occupied
by the slurry.
1/3
Concrete channels shall be provided from the source of substrate to the collecting
tank with a minimum slope of _____.
2%
Concrete channels shall be provided from the source of substrate to the collecting
tank with a minimum slope of _____.
2%
The floor of the mixing tank should be inclined from _________ toward the inlet
pipe and it should be elevated at least ______m from the filling line.
8.5% - 17.5%- inclined
0.2 m- elevation
_______________ should be used as inlet pipe and it should be inclined _______
with digester wall.
Concrete pipe (prefabricated RC pipe)
58%
For reinforced digester, reinforcement shall be a minimum of _______ diameter RSB
spaced at _____ (both the curved and the horizontal bars) and the curved bars shall be
anchored at the top beam.
10 mm
0.15 m-spacing
For anaerobic fermentation, mesophilic temperature range should be ________, with
temperature fluctuations of( +- 1°C/h).
20°C – 40°C
Digestion Process
- Stage 1 – Hydrolysis
- solubilized into simpler ones with the help of
extracellular enzyme released by the bacteria. - Stage 2 – Acidification
- the acid-forming bacteria break down molecules of six atoms of carbon into molecules of less atoms of carbon which are in more reduced state.
- Stage 3 – Methanization
- The principal acids produce in stage 2 are processed by methanogenic bacteria to produce
methane.
Biogas pH value
7 - 8.5
For anaerobic digestion of organic materials, a carbon/nitrogen ratio should be within
the range of _______.
1:20 – 1:30
The C/N ration should not be more than 1:35.
Gas production potential of various types of manure in m3/kg
Manure Retention Period
days
25 30 35 50
Pig 0.058 0.063 0.068 0.077
Cow 0.030 0.034 0.037 0.043
Buffalo 0.030 0.034 0.037 0.043
Horse 0.045 0.051 0.056 0.065
Chicken 0.060 0.065 0.069 0.078
What is the mesophilic temperature range
where the bacteria operates?
20 to 40°C
In PAES 414-2:2002 Waste Management Structures, the percent moisture content that should be maintained to nourish the composting bacteria.
50-60%
