PAES 413:2001 Biogas Plant Vocabulary

Vocabulary flashcards defining official standard terminology for biogas plant design and operations according to PAES 413:2001.

Biogas plant

Plant used to process animal wastes or manure to produce biogas and sludge consisting of an inlet/mixing tank, digester, gas chamber and outlet/sludge tank.

Integrated plant

Biogas plant where the digester and gas chamber form one unit.

Split-type plant

Biogas plant where the digester and gas chamber form separate units.

Multi-digester plant

Biogas plant with a series of digesters.

Floating type

Plant consisting of digester and a moving, floating gasholder that either float directly in the fermenting slurry or in a separate water jacket.

Fixed type

Closed digester with an immovable, rigid gas chamber and a displacement pit.

Balloon type

Plant consisting of a heat-sealed plastic or rubber bag (balloon), combining digester and gasholder.

Collecting tank

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

Inlet pipe

Serves as conveyor of the manure-water mixture or slurry from the mixing tank to the digester.

Digester

Any water and air tight container designed for the process of anaerobic microbiological degradation of organic matter into which the slurry is introduced for digestion and methanization.

Baffle board

Division in the digester that prevent the slurry from premature exit into the sludge/outlet tank.

Stirrer

Mechanical device inside the digester used to stir the slurry.

Gas chamber

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

Gasholder retainer

Cantilever beam that holds the gasholder/movable cover in position at the desired biogas pressure.

Outlet pipe

Serves as conveyor where the effluent or the slurry is forced out.

Backfill

Layer of compacted soil and gravel to support the digester wall.

Loading rate

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

Substrate

Organic material used to produce biogas.

Seeding

Adding or introducing anaerobic bacteria to the digester.

Slurry

Mixture of manure and water.

Freeboard

Difference in height between the digester wall and the filling line.

Filling line

Level of slurry when the digesters is at full load.

Retention time

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

Toxic materials

Materials that inhibit the normal growth of pathogens in the digester such as mineral ions, heavy metals and detergents.

Methanization

Various processes that take place among the methanogens, non-methanogens and substrates fed into the digester as inputs.

Methanogens

Anaerobic bacteria that act upon organic materials and in the process, produce biogas.

Mesophilic temperature range

Temperature range of $20\,^\circ\text{C} - 40\,^\circ\text{C}$ where mesophilic bacteria operates.

Gas production rate

Amount of biogas produced per day per cubic meter of slurry.

Biogas

Mixture of gas (composed of $50\%$ to $70\%$ methane and $30\%$ to $40\%$ carbon dioxide) produced by methanogenic bacteria.

Scum

Layer of floating material (mainly fibrous) on the slurry.

Sludge

Settled portion or precipitate of the slurry; a mud-like, semi-solid mass.

Effluent

Residue that comes out at the outlet after the substrate is digested/processed inside the digester.

Hydrolysis

Stage 1 of the digestion process where waste materials of plant and animal origins are solubilized into simpler ones with the help of extracellular enzyme released by the bacteria.

Acidification

Stage 2 of the digestion process where monomers such as glucose are fermented under anaerobic condition into various acids with the help of enzymes produced by acid-forming bacteria.