Methods and ventilation system for controlling a biological treatment process

A method in a ventilation system comprising ventilation ducts, a control system, at least one sensor, camera, and/or microphone and/or acoustic wave sensor and a plurality of spray nozzles, said method comprising the steps of:

• a) spraying, by the plurality of spray nozzles, a liquid mist onto different portions of the inner surface of the ventilation system, wherein the plurality of spray nozzles are spraying liquid mist toward mutually different inner portions of the ventilation ducts of the ventilation system, and wherein said liquid mist is containing a culture of microorganisms adapted for biologically treating fat, oil and grease present on the different portions of the inner surface of the ventilation ducts, thereby providing for partial biodegradation of the fat, oil and grease present on the at least one portion of the inner surface;
• b) obtaining, by the at least one sensor, camera, and/or microphone and/or acoustic wave sensor, sensor data, audio data and/or image data;
• c) determining, by the control system, estimated amounts of fat, oil and grease accumulated on different inner surfaces of the ventilation system, wherein said determining is based on said obtained sensor data, audio data and/or image data;
• d) controlling, by the control system, the plurality of spray nozzles so that different amounts of liquid mist are sprayed onto the different portions of the inner surfaces based on the estimated, by the control system, different amounts of accumulated fat, oil and grease present on the different inner surfaces of the ventilation ducts;
• and
• e) changing, by the control system, the amounts of liquid mist sprayed onto different inner surfaces of the ventilation system based on the determined amounts of accumulated fat, oil and grease.