The Problems of Fats Oils and Grease
Fats and Oils currently represent one of the most difficult problems that maintenance managers in hotels, restaurants and industrial kitchens have to face. Not only because of its own facilities but also because fats and oils, not properly treated, cause serious inconvenience downstream to the general population
Fats and Oils currently represent one of the most difficult problems that maintenance managers in hotels, restaurants and industrial kitchens have to face. Not only because of its own facilities but also because fats and oils, not properly treated, cause serious inconvenience downstream to the general population
Waste Water Treatment Plants
In principle, the primary treatment in plants consists of removing fats by flotation, either by gravity or by air injection (DAF). Fats generally return to the environment as landfill.
In the secondary treatment, the fats and oils that pass the primary treatment, due to their oily nature, generate an adherent layer on the cell membrane of the bacteria, obstructing and inhibiting contact with organic matter and hindering the feeding process of the bacteria, which is, ultimately, the one that is directly related to the decrease in COD and BOD. That is, in the purification by the activated sludge system, the fats and oils hinder the correct aeration, reducing the transfer coefficient by 55-70% when the fats rise from 0 to 70 mg / L, and participate in the production of the phenomenon of "bulking" so common in plants with deficiencies in the removal of fats and oils.
To remedy this, it is necessary to eliminate the remanent grease and increase aeration either mechanically or chemically, increasing the dissolved oxygen in the water.
Lift Stations
Lift stations are used in cases where it is necessary to raise the height of the effluent so that it can reach the Treatment Plant by gravity.
Due to their configuration, the pumping stations are especially suitable for accumulating fats and oils. They need constant maintenance by Vactor trucks. These trucks are very expensive and require a lot of maintenance.
In certain situations the pumps in lift stations become clogged and draw more current, which in certain cases causes them to break down and need to be replaced.
In most cases the pumps are driven by floats, when the grease hardens, it can block these floats and cause the pumps to malfunction.
Besides, the gullies are generally located in urbanized areas and when the fats contain organic remains, they generate conditions of putrefaction, H2S and bad odors, which are a constant source of complaints from the residents.
Pipes (Fatbergs: Nightmare of Cities)
Fatbergs are blocks of fat that form on drain pipes and can be the size of a bus. The term was coined by the "Thames Waters" company, the UK's largest provider of drinking water and sewage services. Fatbergs are formed by the accumulation of fat and organic matter and harden for various reasons (See: "Learn more").
ALL CITIES IN THE WORLD WITH A DRAINAGE SYSTEM SUFFER FROM THIS PROBLEM
The City of London has a budget of around 13m Pounds only for cleaning pipes. For the removal they use machines with high pressure heads and blade systems to remove the fatbergs and the roots of the trees, although this means moving the problem from place to place.
Currently, fat from fatbergs is used in a high-tech plant that generates biodiesel, although the scale is not sufficient to remove a significant percentage of FOG.
Grease interceptors
Grease Interceptors are containers, with the same gravity separation system as grease traps, but larger and generally located on the outside of buildings. They must be emptied periodically according to the regulations of the municipalities.
Despite cleaning, a large amount of grease escapes from these interceptors for various reasons and ends up in the drains.
Generally, they are emptied by trucks with suction pumps. There are variables (the time the fat remains in the sump, the lack of hydration, the use of certain detergents, the salts dissolved in the water) that cause the fat on the surface to coalesce to the consistency of rock. This makes it sometimes almost impossible that they can be removed with a suction truck and have to be mechanically broken.
Grease traps
Grease Traps are the first line of defense in stopping grease on its way to drains, they are typically installed inside restaurant kitchens and are gravity driven, as grease floats on water, the trap lets the water out from underneath and holds the fat on the surface.
Traps are generally mechanically cleaned, meaning the grease is removed from the trap and disposed of in a suitable place.
They need to be cleaned very frequently, because if the grease accumulates above the capacity of the trap, the grease passes into the pipe causing a plugging that causes the trap to overflow. However, even though they are cleaned on a daily basis, grease always finds its way into the pipes.