Reduction of sludge volume is often the first important step in
the disposal of sludge and in recycling it as a renewable resource.
Sludge drying is an effective way to reduce sludge volume by evaporating
moisture either at ambient or heated temperatures. During
the sludge thermal drying process, different malodorous gases will
be released, including volatile compounds (VCs),NH3 andHCNhave
been studied [7,16]. H2S, a colorless gas with rotten-egg odor and
harmful to human health, is one of the gaseous species. H2S can
cause respiratory and eye irritation in low concentrations and will
result in coma, or even death if a large quantity is inhaled [14]. Consequently,
the mitigation of H2S release is an important step in the
sludge drying process.
H2S in sludge can be produced by two ways [9], one directly
transforms from the sulphide in sludge; other results from