Slurry distribution
If the slurry distribution is done directly by gravity, the slurry furrows need to be checked and
slurry diverted accordingly. Slurry may be applied from the furrows directly to the plant with
the help of dippers or shovels.
Weekly / monthly operation
• Controlling of the water separator
• Renewing the agents of the gas purification system (if existing)
• Mixing the swimmig and sinking layers of in the expansion chamber of fixed dome
plants
• The water sealing of the lid in the man hole of a fixed dome plant should be checked
and filled up
• Gentle cleaning of the drum of a floating drum plant
• Checking and filling up the water jacket of water jacket plants
• Flexible pipes above ground should be checked for porosity
• Slurry storage tanks should be checked and emptied, if required and slurry flows
diverted accordingly
Annual operation
• Swimming layers should be removed from the digester
• The whole plant and digester should be exposed to a pressure test once a year to
detect lesser leakages
Security
When operating a biogas plant special attention has to be paid to the following dangers:
• Breathing in biogas in a high concentration and over longer periods of time can cause
poisoning and death from suffocation. The hydrogen sulfide contents of biogas is
highly poisonous. Unpurified biogas has the typical smell of rotten eggs. Purified
biogas is odorless and neutral. Therefore, all areas with biogas operating appliances
should be well ventilated. Gas pipes and fittings should be checked regularly for their
gas-tightness and be protected from damage. Gas appliances should always be
under supervision during operation. Everybody dealing with biogas, in particular
children, should be instructed well and made aware of the potential dangers of
biogas.
• After emptying biogas plants for repair, they have to be sufficiently ventilated before
being entered. Here the danger of fire and explosion is very big (gas/air mixture!).
The so-called chicken test (a chicken in a basket enters the plant before the person)
guarantees sufficient ventilation.
• Biogas in form of a gas-air mixture with a share of 5 to 12 % biogas and a source of
ignition of 600°C or more can easily explode. Danger of fire is given if the gas-air
mixture contains more than 12 % of biogas. Smoking and open fire must therefore be
prohibited in and around the biogas plant.
• The initial filling of a biogas plant poses a particular danger, when biogas mixes with
large empty air-spaces. A farmer may want to check with an open flame how full the
plant is already and cause an explosion.
• The digester of a biogas plant and the slurry storage facilities should be built in such
a way that neither persons nor animals are in danger of falling into them.
• Moved and movable parts should have a protective casing to avoid catching persons
or animals.
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