Online monitoring of volatile organic compound production and emission during sewage sludge composting

► The production and emission of VOCs were evaluated using online monitoring method. ► Total VOCs production was 2.3 times as high as its emission. ► Maximum production and emission masses occurred in the mesophilic phase. ► Relation of production rates and time can be expressed as a quadratic equation. ► Relation of emission rates and time can be expressed as a linear equation.