microorganisms in a standard mathematical model (1-4). A practical problem is, however, that the values of these parameters can vary by more than two orders of magnitude for different electron donors or acceptors used by different microorganisms, as indicated in Figure 1. It should be realized that conventionally stoichiometric parameters are expressed with C-mol of biomass, C-mol of electron donor for organic, and mol of donor for inorganic donors (C-mol X/(C)-mol D). It is therefore of interest to provide a general method to estimate values of these parameters for any chemotrophic growth system. Such methods have been provided by, for example, Battley (5), Roels (1), and Westerhoff (6). Recently (2,9) these methods have been critically evaluated with respect to general applicability and internal consistency. It was concluded (2,7,8) that none of these methods was satisfying. However a new method was proposed that is generally applicable and lacks the mentioned problems (2,8). Further, it should be recognized that in growth processes not only biomass production (rx in C-mol biomass per m3 reactor/h) and electron donor (substrate) consumption rD in C-mol substrate (for carbon compounds), or mol substrate (for noncarbon compounds) per m3 reactor/h are important. Also, the other conversions, such as O2 consumption, N source consumption, heat production, and CO2 production are highly relevant for the process design to calculate, for example, the required O2 and heat transfer. Clearly, the full stoichiometry of the growth process should also be calculated and methods to achieve this are of major interest.

Brew Your Own Beer

Brew Your Own Beer

Discover How To Become Your Own Brew Master, With Brew Your Own Beer. It takes more than a recipe to make a great beer. Just using the right ingredients doesn't mean your beer will taste like it was meant to. Most of the time it’s the way a beer is made and served that makes it either an exceptional beer or one that gets dumped into the nearest flower pot.

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