Denitrification Using Thiosulfate and Sulfide

Autotropic denitrification using enriched cultures of Thiobacillus denitrificans was investigated. Thiosulfate and sulfide were used as electron donors in laboratory scale denitrification systems. The stoichiometric ratio of the amount of sulfur electron source (sulfide or thiosulfate) needed to reduce a given amount of nitrate was determined. This ratio (called the consumptive ratio, CR) is concluded to be approximately 1.35 on an electron equivalent basis. The systems were tested under dynamic loading conditions to assess overall operational stability. In all experiments denitrification proceeded efficiently. It is concluded that autotropic denitrification using sulfide or thiosulfate has potential as a wastewater treatment process.