Biogas

Question 1

Layer of floating material (mainly fibrous) on the slurry

Answer 1

Scum

Question 2

Mixture of manure and water

Answer 2

Slurry

Question 3

Difference in height between the digester wall and filling line

Answer 3

Freeboard

Question 4

Organic material used to produce biogas

Answer 4

Substrate

Question 5

Settled portion or precipitate of the slurry, mad like and semi solid mass

Answer 5

Sludge

Question 6

Chamber where manure and water are collected, stored and separated from heavy and non-biodegradable materials before feeding them into the digester

Answer 6

Collecting tank

Question 7

Cantilever beam that holds the gas holder or movable covered position at the desired biogas pressure

Answer 7

Gasholder retainer

Question 8

Level of slurry when the digesters is at full load

Answer 8

Filling line

Question 9

Mesophilic temperature range

Answer 9

20° to 40°C

Question 10

Amount of slurry fed per unit volume of digester capacity per day

Answer 10

Loading rate

Question 11

Anaerobic bacteria that act upon organic materials and in the process and produced biogas

Answer 11

Methanogens

Question 12

Amount of biogas produced per day per cubic meter of slurry

Answer 12

Gas production rate

Question 13

Space inside or outside the digester for the collection and storage of biogas

Answer 13

Gas chamber

Question 14

Average period that a given quantity of slurry is retained in the digester for digestion

Answer 14

Retention time

Question 15

Layer of compacted soil and gravel to support the digester wall

Answer 15

Backfill

Question 16

Estimated daily quantity of available manure

Answer 16

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

Question 17

The minimum diameter of the inlet pipe shall be _____ .

Answer 17

0.2 m

Question 18

Retention time for animal manure for mesophilic temperature range

Answer 18

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

Question 19

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.

Answer 19

Fixed type

Question 20

For fixed type and balloon type, about ______% of the total digester volume is occupied
by the gas generated.

Answer 20

20%

Question 21

For floating and balloon type, the minimum of volume of the outlet tank shall be
equal to the _______________.

Answer 21

daily slurry input of the digester

Question 22

For fixed type, the volume of the outlet tank shall be _______ of digester volume occupied
by the slurry.

Answer 22

1/3

Question 23

Concrete channels shall be provided from the source of substrate to the collecting
tank with a minimum slope of _____.

Answer 23

2%

Question 24

Concrete channels shall be provided from the source of substrate to the collecting
tank with a minimum slope of _____.

Answer 24

2%

Question 25

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.

Answer 25

8.5% - 17.5%- inclined 0.2 m- elevation

Question 26

_______________ should be used as inlet pipe and it should be inclined _______ with digester wall.

Answer 26

Concrete pipe (prefabricated RC pipe) 58%

Question 27

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.

Answer 27

10 mm 0.15 m-spacing

Question 28

For anaerobic fermentation, mesophilic temperature range should be ________, with temperature fluctuations of( +- 1°C/h).

Answer 28

20°C – 40°C

Question 29

Digestion Process

Answer 29

* 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.

Question 30

Biogas pH value

Answer 30

7 - 8.5

Question 31

For anaerobic digestion of organic materials, a carbon/nitrogen ratio should be within the range of _______.

Answer 31

1:20 – 1:30 The C/N ration should not be more than 1:35.

Question 32

Gas production potential of various types of manure in m3/kg

Answer 32

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

Question 33

What is the mesophilic temperature range where the bacteria operates?

Answer 33

20 to 40°C

Question 34

In PAES 414-2:2002 Waste Management Structures, the percent moisture content that should be maintained to nourish the composting bacteria.

Answer 34

50-60%