Biomass maintenance

If Ss is not sufficiently available to support the biomass maintenance energy requirement. 

Costs vary among units based on the specific configuration required at the site. Operating costs are also dependent upon the unit s configuration. Costs have been tracked for a 15,000-gal, 10-horsepower unit. Over the expected life of the unit costs are between. 60 and 1.00 per thousand gallons treated. This price includes oversight, power, biomass maintenance, and capital amortization (D14819Q, p. 2). 

Vonshak, A, Boussiba, S, Abeliovich, A, and Richmond, A. (1983) Production of Spirulina biomass maintenance of monoalgal culture outdoors. Biotech-nol Bioeng, 25 (2), 341-349. 

The eonsumption is used for biomass growth, penicillin production and biomass maintenance and can be described by a known function ... 

We have seen that both the maintenance energy requirement and the P/O quotient of the process micro-organism influences the rate of product formation. In the following sections we will consider how these two factors can be determined, together with the maximum biomass yield. 

Determination of maintenance energy requirement and maximum biomass yield... 

Maintenance energy requirements can be defined in terms of rate of substrate consumption per unit of biomass for maintenance this is known as the maintenance coefficient (m). 

The role of water in the life of plants is well known. In terms of its major effects this role consists in transporting the mineral nutrition, maintenance of intracellular pressure responsible for the vertical growth of plants and, finally, participation in photosynthesis which provide the biomass growth, or plainly speaking, the crop production. 

This section gives models for the rates of birth, growth, and death of cell populations. We seek models for (1) the rate at which biomass is created, (2) the rates at which substrates are consumed, (3) the rates at which products are generated, (4) the maintenance requirements for a static population, and (5) the death rate of cells. The emphasis is on unstructured models. 

Turning to the substrate balance, yeast cells contain about 50% carbon. The cell mass is measured as total dry weight, not just carbon. This gives Yx/s = 2 when S is measured as the carbon equivalent of glucose. A reasonable value for Yxis is 1 so that half the carbon goes into biomass and half meets the associated energy requirements. The maintenance coefficient in carbon-equivalent units is 0.008 h . Using these parameter estimates, the three simultaneous ODEs for 5" > 0, become... 

Continuous Stirred Tanks with Biomass Recycle. When the desired product is excreted, closing the system with respect to biomass offers a substantial reduction in the cost of nutrients. The idea is to force the cells into a sustained stationary or maintenance period where there is relatively little substrate used to grow biomass and where production of the desired product is maximized. One approach is to withhold some key nutrient so that cell growth is restricted, but to supply a carbon source and other components needed for the desired product. It is sometimes possible to maintain this state for weeks or months and to achieve high-volumetric productivities. There will be spontaneous cell loss (i.e., kd > 0), and true steady-state operation requires continuous purging and makeup. The purge can be achieved by incomplete separation and recycle... 

Combining ammonium immobilization rates with estimates of C inputs and C maintenance requirement (proportional to the active microbial biomass), whose difference gave C available for microbial growth from the same experimental system (111,128), it allowed the building up of a conceptual model for C and N... 

For effective biological treatment of dye wastewater, immobilization of bacteria under aerobic anaerobic high-rate reactors should be given special attention. The main cause of effective treatment of these xenobiotics under immobilized condition in high rate reactors is the rapid facile reduction of these compounds to products of lower toxicity [68, 69]. Moreover, the immobilization of anaerobic bacteria and maintenance of a high concentration of biomass in the high rate reactors are factors that improve the tolerance of the anaerobic system to toxic substances [70, 71]. 

The catabolic processes provide the energy needed for production of new cell biomass as well as for the maintenance of the fundamental functions in the existing biomass. 

The maintenance energy requirement rate, /mam[, of the suspended biomass is as follows ... 

Before adding the readily biodegradable substrate, the maintenance energy requirement of the active biomass should ideally correspond to the amount of readily biodegradable substrate produced by hydrolysis of the slowly biodegradable COD fraction, i.e., an equilibrium corresponding to an almost constant OUR must be seen. 

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