Processing and drying of protein raw materials like fish and meat and bone from animals create strong, unpleasant
smells that have to be removed or reduced.
Plants near cities need 100% smell removal while plants in the country side need some degree of smell removal.
Smell removal (odor control or deodorizing) systems are becoming increasingly important in the fishmeal and
meat and bone animal rendering industries, and often has to follow strict regulations issued by governments.

The smell removal systems are composed of two parts:

– Cooling and condensing of vapors from cookers and dryers to be rest-gas and air of temperature less than 40 deg C. using
shell and tube (or plate) condensers with cooling water from cooling towers, or air-cooled condensers.

– Remove final smell from cooled down rest-gas and air coming from condensers, point suction like presses, coolers,
bins and tanks and negative pressure buildings, using chemical or thermal (heat) systems such as:

Scrubbing (washing with sea or river water where available and permitted)
Chemical additive like sodium-hypochlorite added to water scrubber with recirculation
Ozone, added and mixed with the rest gas outlet in chimney or stack
Burning in boiler or thermal oxidizer
Bio-filter where the rest gas runs through a tank filled with bio media like bark or coconut husk and retention time 30 to 60 seconds

Most used system is shell and tube condenser with cooling tower and a bio filter.

Thermal Oxidiser is the ultimate smell removal system as it burns 100% of all vapors and gases but has high energy consumption for the burners,
And is used especially in very hot countries like the Middle East where temperatures can reach 40-50 deg C.

Combinations of the systems mentioned above can be used.
It is important to combine calculations and experience to get the system to work correctly.