The use of microorganisms with broad range substrate utilisation for the ferricyanide-mediated rapid determination of biochemical oxygen demand

The feasibility of replacing oxygen with a synthetic electron acceptor in microbial catabolism was investigated as a rapid method for the determination of biochemical oxygen demand (BOD). Microorganisms known for their broad range organic substrate utilisation were investigated. It was shown that Trichosporon cutaneum, Pseudomonas putida and Bacillus licheniformis could utilize the ferricyanide ion as an alternative electron acceptor, in place of oxygen, for the catabolic oxidation of a range of simple organic compounds. The biochemical reactions were monitored by measuring the amount of microbially produced ferrocyanide using amperometry at a Pt disk microelectrode. Catabolic degradation efficiencies approaching those of the conventional 5-day assay were achieved in 1 h. BOD₅ equivalent values for a range of simple organic solutions were determined for each of the microorganisms. The effect of increased incubation time and the choice of appropriate calibration standards for rapid BOD assays were also considered.     

Solid state reactions between nickel(II) sulphide and oxides of manganese and iron

Thermogravimetry and differential thermal analysis have shown that, when nickel(II) sulphide and manganese or iron oxides are heated together, several reactions occur depending on the molar ratio of the reactants. Detailed examinations of these reactions have shown that there are a number of intermediate stages, including the formation of sulphates.

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Zusammenfassung Thermogravimetrie und Differentialthermoanalyse zeigen, daß bei gemeinsamer Erhitzen von Nickel(II)-Sulfid und Manganoder Eisenoxiden, in Abhängigkeit von dem Molarverhältnis der Reaktionspartner verschiedene Reaktionen stattfinden. Das eingehende Studium dieser Reaktionen zeigte das Auftreten einer Anzahl Zwischenstufen, darunter auch die Bildung von Sulfaten.

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Résumé On montre par thermogravimétrie et analyse thermique différentielle que plusieurs réactions peuvent se produire suivant les rapports molaires des constituants lorsque l'on chauffe du sulfure de nickel(II) avec des oxydes de manganèse ou de fer. L'étude détaillée de ces réactions a mis en évidence un certain nombre d'étapes intermédiaires, avec formation de sulfates.

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