Kinetic Studies of the Microbiological Conversion of Sulphate to Hydrogen Sulphide and their Relevance to Sulphide Generation within Sewers

Abstract

The relevance of the studies carried out, to the important practical problem of predicting sulphide generation rates within sewers, is discussed in the introduction section of the paper. The predictive equations presently in use are compared, and the desirability of replacing these empirical equations by a more scientific approach based on an analysis of mass transport and biochemical reaction is stressed. A theoretical analysis of mass transport and metabolism of sulphate during laminar flow in a model sewer is then described. This theoretical section is followed by the description of the laboratory experimental studies. These studies consisted of flowing simulated sewage through tubes containing biofilms of mixed cultures of sulphate reducing bacteria. The results obtained in the laboratory studies showed that the diffusional resistance in the liquid phase was negligible and that the biological conversion of sulphate to sulphide followed zero order kinetics when mass transfer was not rate limiting. The observed sulphate removal rates gave good agreement with Australian field data for sulphide generation in sewers. The value of the zero order rate constant (measured at 41 °C) was 30 mg cm−3 h−1.