Baghouse efficiency on a multiple-hearth incinerator burning sewage sludge

A pilot-scale fabric filter (baghouse) was evaluated for its removal performance for 23 metals and for sulfur as well as for total particles when fitted to a multiple-hearth incinerator burning sewage sludge. The small-scale baghouse was installed to take a slipstream of about 3% of the total incinerator emissions. Particle size fractions were collected from the gas streams entering and leaving the baghouse. Each particle-size fraction was analyzed for the 24 elemental species and baghouse performance was evaluated for overall removal efficiency, size-fraction removal efficiency, and for selective removal of specific metals. Total concentrations of each element in the controlled emission stream was determined as well as the proportionate concentrations of species in the solid and volatile states. Concentrations of each metal in the emission stream was compared with the concentration in a sludge residue. To obtain comparisons of baghouse performance with a more typical emission control device, the performance of the incinerator's full-scale wet scrubber was also evaluated.