| 摘要 |
<p>PURPOSE: In upflow anaerobic sludge reactor, sulfate is reduced to sulfide by sulfate reducing bacteria (SRB). Heavy metals in wastewater react with this sulfide to form heavy metal precipitates. These heavy metal precipitates have different depth distribution according to the kind of heavy metal in reactor in proportion to its solubility constant. Therefore, it is possible to classify and thus separately recover heavy metals from heavy metal precipitates without interference. CONSTITUTION: When wastewater containing copper ion, cadmium ion and iron ion is introduced into an upflow anaerobic sludge reactor, sulfate is reduced to sulfide by sulfate reducing bacteria (SRB) and then heavy metals in wastewater react with this sulfide to form heavy metal precipitates. Among these heavy metal precipitates, CuS precipitate that has the lowest solubility constant is first observed in the layer(3a). Here, CdS precipitate can be observed in the layer(3a) if sulfur ion is present in the reactor enough to form CdS precipitate. Other heavy metals, under the lack of sulfur ion in the reactor, form precipitates in the layer(3b) or the layer(3c). Then, if a portion of effluent from the reactor is recirculated to the layer(3a), CuS precipitate is formed by substitution reaction between copper ion and CdS due to the lack of sulfur ion, accordingly Cd ion is precipitated in the layer(3b) or the layer(3c).</p> |
