PNS/BAFS 364:2023 Flashcards
biological conversion of biodegradable materials by microorganisms in the absence of oxygen creating 2 main products: biogas and digestate
anaerobic digestion process
amount of organic matters in a substance that can be degraded by anaerobic microorganisms. it also indicates the biogas output per unit quantity of substrate
biochemical methane potential (BMP)
gas produced by anaerobic digestion of organic matter.
biogas
biogas typically consists of ______ methane, _______ carbon dioxide, along with small amounts of water vapor and other gases
40 - 75% methane
14 - 45% carbon dioxide
system used to process agricultural, fishery, and agro-industrial waste to produce biogas and sludge consisting of, but not limited to, a mixing tank/inlet, digester, gas chamber, and outlet/sludge tank/hydraulic pressure tank.
biogas system
non-fossiled, biodegradable organic materials originating from naturally occurring or cultured plants, animals and microorganisms, including agricultural products, by-products and residues that can be used in biconversion process
biomass resources
biomass
consists of solid and liquid waste, slurry including by-products and residues resulting from the production and processing of crop, livestock, poultry, and fishery
agricultural and fishery wastes
consists of solid and liquid waste generated from local activity or series of activities to maintain or raise the quality or change the form or characteristics of agricultural, fisheries, and forestry products
agro-industrial wastes
ratio of carbon and nitrogen content in substrate
carbon and nitrogen ratio (C?N)
amount of oxygen consumed by oxidizing substrate under heating conditions with chemical oxidants, usually expressed in terms of oxygen consumption in mg/L or g?L
chemical oxygen demand (COD)
anaerobic digestion installation including reactors, tanks, and related equipment
digester
residue that comes out at the outlet after the substrate is digested/processed inside the digester
effluent
safety component meant to combust biogas during exceptional situations when the biogas is not utilized
flare
distance as measured from the slurry filling line to the inside top of the inlet tank
freeboard
space inside or outside the digester for the collection and storage of biogas; also known as gasholder or biogas storage
gas chmaber
average period that a given quantity of slurry is retained in the digester expressed either in hours or days
hydraulic retention time
retention time
serves as passage or duct of the slurry from the inlet tank to the digester
inlet pipe
chamber where substrate and water are collected, stored and separated from heavy and non-biodegradable materials before feeding them into the digester; also known as mixing tank or equalization tank
inlet tank
temperature range of 20 to 40 deg C
mesophilic temperature
serves as passage or duct where the effluent or the slurry is forced out
outlet pipe
amount of volatile organic dry matter entering the digester over time, measured in kg/m3 digester volume/day
organic loading rate
chamber where digestate is stored
outlet tank
layer of floating material that may accumulate on the surface of the digester tank
scum
adding or introducing anaerobic microorganism to the digester to enhance bio-digestion
seeding
settled portion of precipitate of the slurry; a mud-like, semi-solid mass
sludge
average period time the slurry is in the tank prior to digestion, expressed in days
storage period
part of the biomass which is biodegradable and converted by anaerobic MO and/or enzymes as catalyst into biogas
substrate
feedstock
amount of residues remaining after evaporation and hydration of substrate at a certain temperature, expressed in percent (%); it is also referred to as dry matter, expressed in g/L
total solid (TS)
of the total solids and ash content (remaining solid after burning total solids for 1 hour at 550 plus/minus 50 deg C), expressed in %; it is also referred to as organic dry matter, expressed in g/L
volatile solid (VS)robic
digestion which uses organic material with consistency of 10-20% dry matter or less
wet anaerobic digestion
volume for biogas digester in m3 for household and its estimated energy content per year (GWh/yr)
less than 140 m3
less than 0.1 GWh/yr
volume for biogas digester in m3 for non-household small-scale and its estimated energy content per year (GWh/yr)
140 - 7000 m3
0.1 - 5 GWh/yr
volume for biogas digester in m3 for non-household medium-scale and its estimated energy content per year (GWh/yr)
7000 to 140 000 m3
5 to 100 GWh/yr
volume for biogas digester in m3 for non-household large-scale and its estimated energy content per year (GWh/yr)
greater than 140 000 m3
greater than 100 GWh/yr
a type of biogas system uses biomass resources from 1 household for its own use and consists of a digester and an application for cooking, heating, or lighting only
household biogas system
according to utilization, this type of biogas system uses agricultural fishery and agro-industrial wastes from a farm for its own use and an application for heating, lighting, or electrical power production only
farm-scale biogas system
according to utilization, this type of biogas system uses agricultural fishery and agro-industrial wastes to produce biogas available for sale
commercial-scale biogas system
according to energy content, this biogas system with a production capacity of bigas having an energy content of 0.1 GWh/yr
small
according to energy content, this biogas system with a production capacity of bigas having an energy content of 5 - 100 GWh/yr
medium
according to energy content, this biogas system with a production capacity of bigas having an energy content of more than 100 GWh/yr
large
according to the number of digesters, this biogas system composed of only one digester
single-digester biogas system
according to the number of digesters, this biogas system composed of 2 or more digesters arranged in either series or parallel or a combination of both
multi-digester biogas system
multi-stage digester biogas system
according to feeding method, this biogas system that is fed with substrate continuously to produce biogas
continuous-fed
according to feeding method, this biogas system that are filled and discharged completely after a fixed retention time
batch-fed (mixed or unmixed)
the location for non-household biogas system should require ______ distance from vulnerable areas and water sources in compliance with local and national ordinances
25 m
the size of the inlet tank should hold the equivalent volume for a minimum of ___ day/s and maximum of ____ day/s
min of 1 day
max of 10 days
the biogas shall have an _____ to allow the slurry to enter the digester, where it will be broken down by microorganisms to produce biogas
inlet pipe
classification of biogas digester according to gas chamber design, composed of a moving gas chamber that either floats directly in the fermenting slurry or in a separate water jacket
floating type
classification of biogas digester according to gas chamber design, composed of a gas chamber fixed to the digester.
fixed type
classification of biogas digester according to position, digester placed above ground level
ground digester
classification of biogas digester according to position, digester placed below ground level to avoid disruption
underground digester
regulating devices
pressure valves/ gas meter, open manometer
for this type, the biogas chamber shall be equipped with an appropriately designed stopper for safety purposes
floating type
the biogas system shall have an ________ to facilitate the removal of digested material or digestate from the digester
outlet pipe
the biogas system shall have an ______ to receive and temporarily store the effluent coming out from the digester
outlet tank
for floating, the minimum volume of the outlet tank shall be ____ to the daily slurry input of the digester
equal
for fixed type, the volume of the tank shall be ______ of the difgester volume occupied by the slurry
1/3
for batch-fed type, the outlet tank shall function as a _____ with a minimum volume equal to the digester before disposal
storage tank
the biogas system shall have an ________ to collect, store, and treat the effluent coming from the tank
effluent management unit
the biogas system shall have a _____ to process and manage the residual sludge generated during the anaerobic digestion process.
sludge management unit
an auxiliary component that shall act as a pressure regulator and outlet of the biogas digester
hydraulic pressure tank
material requirement for biogas system with a minimum requirement of <350 cc/m2/d/bar of methane
gas permeability
material requirement for biogas system for tensile strength
12 MPa (12 N/mm2)
a type of plastic that is recommended for gas holder/ gas storage lining in conformance with ASTM 3350
high density polyethylene (HDPE)
for non-household biogas system, before construction, a _____ shall be conducted in the area where the biogas system shall be built. the result of the investigation shall then be incorporated into the design of the biogas system
geotechnical investigation
geotechnical investigation shall include
location of water table
soil bearing capacity
etc
geotechnical investigation for household biogas system shall include
ocular inspection
manual digging of about 1.5 m to check the level of the water table
excavation for the digester should be vertical as possible. A _____ minimum gap on both sides shall be allowed for backfill
0.15 m
foundation of the digester should be made of _____ or ___, and tamped before pouring of concrete
cobbles or crushed stones
for loose soil, the mixture of the backfill should be ___ gravel or broken stones and ___ soil. Water content in the backfill soil should be about ____.
30% gravel
70% soil
20-25%
for the design of any pressurized component of the biogas system, a minimum factor of safety of ___ shall be used
2.0 m
discharge of vent pipes shall not be located near ignition sources or ventilation openings, altitudes where the risk of inhalation is possible. A minimum required safety distance of ___ shall be applied
5m
the initial raw materials should contain slurry with a high bacterial population. about ___ of the total slurry volume should be added when the digester is about ___ full
5-10% of the total slurry
25% full
according to ISO 2425:2021, it is determined that 1 Nm3 of biogas composed of 100% methane yields an energy content of
9.97 kWh
digester retention time for liquid pig manure
15 - 25 days
digester retention time for cow/carabao manure
20-30 days
digester retention time for chicken manure
20-40 days
digester retention time for animal manure mixed with plant material
50-80 days