Direct gaseous (CO2, CH4, N2O) emissions during the rearing of BSF larvae.

BSF emissions occur during the production process as both larvae and microorganisms actively respire and release gases. Understanding BSF emissions is essential for optimizing environmental performance and improving waste treatment efficiency.

Microorganisms contribute significantly to CO₂ release during rearing. They can account for around 30% of total CO₂ emissions. Several factors influence CO₂ output per kilogram of dried larvae, including diet type, larval density, starter larval age, and how frequently operators measure gas emissions (for example, daily versus weekly sampling).

Methane (CH₄) emissions mainly result from anaerobic microbial activity. Increasing aeration—either through forced airflow or natural larval movement—can effectively reduce CH₄ emissions. Larvae reared on pig manure tend to produce much higher CH₄ emissions compared to other substrates. This happens because pig manure contains high moisture levels (around 76%), which promote anaerobic fermentation.

Nitrous oxide (N₂O) emissions form when nitrogen-rich compounds such as ammonia interact with oxygen and moisture under microbial activity. Managing substrate conditions plays a key role in controlling these emissions.