Removal of hydrogen sulphide from wastewater and waste gases by biological conversion to elemental sulphur Colloidal and interfacial aspects of biologically produced sulphur particles

摘要

The biological oxidation of hydrogen sulphide by aerobic Thiobacillus-like bacteria has been described. The hydrogen sulphide is oxidised into sulphur particles which are in the submicron range. The colloidal properties of these sulphur particles are compared with those of a standard LaMer sulphur sol. The biologically produced sulphur particles are composed of a core of elemental sulphur covered by a layer of natural charged polymers, presumably proteins. The polymer layer renders the particles hydrophilic. Colloidal stability can be attributed mainly to steric repulsion. Although the electrokinetic charge is always negative with varying pH, the point of zero charge is found at pH 5.8. This indicates that the polymeric molecules are oriented with their negative charges to the bulk solution. An expanded-bed reactor was developed in order to stimulate the aggregation of the sulphur particles into large, well-settleable sulphur flocs with a diameter of about 3 mm.