Mineral requirements for methane fermentation

Mineral deficiency appears to pose a more critical problem in the anaerobic treatment process than in the aerobic treatment process. Furthermore, the methane fermentation step of anaerobic treatment appears to be the stage most sensitive to mineral deficiency. Commonly the mineral deficiency is a trace metal, and, since the fermentation step is the terminal stage in the treatment process, a build‐up of these reactants (mainly acetate, propionate, butyrate and hydrogen) can adversely affect the overall process. A review of the literature follows concerning the mineral requirements of methane fermentation in order to facilitate a proper understanding of the anaerobic process, especially in its application to treatment of industrial waste waters that are prone to be deficient in certain minerals. Types of limiting nutrients are considered with specific attention given to nitrogen, sulfur, phosphorus and the trace metals, and the physiological role and intracellular concentration of minerals is discussed. An awareness of the mineral requirements of methane fermentation should provide a more rational basis to trouble‐shoot operational problems and therefore encourage the exploitation of the many advantages of this process for the treatment of industrial wastewaters.