Ing. Joachim Werther on the occasion of his 80th birthdayFor developing technologies for innocent disposal of/energy recovery from high-ash oil sludge char (OSC), it was continuously combusted in a 10 kg h -1 fluidized-bed combustor. Addition of brown coal (BC) improved its combustion, but excessive BC was prone to cause slagging. Fine coke particles in OSC and volatiles in BC led to staged temperatures along the fluidized bed through air-staging co-combustion, enabling excellent combustion performance as well as efficient NO x reduction, especially when coupled with selective non-catalytic reduction. Thus, there is a potential to cleanly recover energy from OSC by its co-combustion with BC.