Hydrogen sulfide is a serious pollutant and causes a number of sulfide-related problems in sediment/aqueous systems. This thesis work discusses the integrated use of granular ferric hydroxide (GFH) and common oxidants for hydrogen sulfide control in aqueous and sediment systems. Hydrogen sulfide in the aqueous solutions and sediments was removed by GFH together with the formation of elemental sulfur (S₀), iron sulfide (FeS_(s)) and surface-associated Fe(II). The strong oxidants, including hydrogen peroxide, chlorine and persulfate, were periodically dosed to regenerate the exhausted GFH. The recovery in the hydrogen sulfide removal capacity of the exhausted GFH was mainly due to the oxidation of Fe(II) compounds (FeS_(s)) and surface-associated Fe(II)) accumulated on the GFH surface and t...[ Read more ]

Hydrogen sulfide is a serious pollutant and causes a number of sulfide-related problems in sediment/aqueous systems. This thesis work discusses the integrated use of granular ferric hydroxide (GFH) and common oxidants for hydrogen sulfide control in aqueous and sediment systems. Hydrogen sulfide in the aqueous solutions and sediments was removed by GFH together with the formation of elemental sulfur (S₀), iron sulfide (FeS_(s)) and surface-associated Fe(II). The strong oxidants, including hydrogen peroxide, chlorine and persulfate, were periodically dosed to regenerate the exhausted GFH. The recovery in the hydrogen sulfide removal capacity of the exhausted GFH was mainly due to the oxidation of Fe(II) compounds (FeS_(s)) and surface-associated Fe(II)) accumulated on the GFH surface and the formation of amorphous ferric (hydr)oxides of small particle size and large surface area. Simultaneously, the solid sulfide (FeS_(s)) on the surface of the exhausted GFH was oxidized to S₀, thiosulfate (S₂O₃^2-) and/or sulfate (SO₄^2-). The oxidation of the exhausted GFH was enhanced with decreasing solution pH and were inhibited by bicarbonate and NOM. The oxidation of the exhausted GFH involved homogeneous oxidation of the released Fe²⁺ and heterogeneous oxidation of the surface-bound Fe(II) by the oxidants and the radicals produced from the Fenton-like reactions during the regeneration. Compared to chlorine and hydrogen peroxide, the reaction of persulfate with the exhausted GFH generated much more radicals, including sulfate radicals (SO₄^-•) and hydroxyl radicals (OH•), from the interactions of persulfate with the surface Fe(II) products (FeS_(s) and surface-associated Fe(II)) and also with the released Fe²⁺ ions. The radical-induced pathway enhanced the the regeneration of the exhausted GFH by persulfate. The integrated technology discussed in this thesis provides a long-lasting and cost-effective approach to control the hydrogen sulfide in the aqueous and sediment systems.