Heterotrophic demand

Continuous culture systems of aerobic treatment are likely to be more cost effective since in steady state conditions the respiration rate and hence oxygen requirement, remain constant. This report describes the effects of mean treatment time, treatment temperature and dissolved oxygen level in aerobic continuous culture systems on the removal of odorants from piggery slurry and on the heterotrophic oxygen demand during treatment. 

The oxygen demand of the heterotrophic microbes can be measured as the loss of COD. In the absence of oxygen limitation this was also described by equations (6, 7 8) developed from Monod kinetics (15). 

When nitrification occurs 4.57 gram oxygen are used per gram of ammonia nitrogen oxidised. Thus the total oxygen demand is then the sum of the autotrophic and heterotrophic respiration rates. 

Characterization of a satisfactory DO profile. A typical steady-state simulation of DO profiles in a plug flow reactor will illustrate the ideas. Ammonia-nitrogen from the influent flow is consumed by both nitrifying and heterotrophic organisms, fig 11. In a completed reaction the NH4-N approaches zero before the outlet. The Nitrosomonas oxygen demand is shown in fig 12. 

When we subtract the costs of all other metabolic processes by the chemoautotrophs and photoautotrophs, the organic carbon that remains is available for the growth and metabolic costs of heterotrophs. This remaining carbon is called net primary production (NPP) (Lindeman, 1942). From biogeochemical and ecological perspectives, NPP provides an upper bound for all other metabolic demands in an ecosystem. If NPP is greater than all respiratory consumption of the ecosystem, the ecosystem is said to be net autotrophic. Conversely, if NPP is less than all respiratory consumption, the system must either import organic matter from outside its bounds, or it will slowly mn down—it is net heterotrophic. 

Dinitrogen fixation is an energetically expensive reaction and is inhibited by micromolar levels of NH4, which requires comparatively little energy to assimilate. The energetic demands of the process is one reason why many diazotrophs are either photosynthetic themselves or occur in symbiotic relationships with plants. However, diazotrophy is certainly not restricted to these groups it occurs widely among heterotrophic and chemoautotrophic microorganisms, and both aerobes and anaerobes (Lovell et ai, 2001). 

Wavelength, m, or Empirical coefficient Empirical coefficients Empirical coefficients Advanced oxidation process Base excision repair Biochemical Oxygen Demand 5-d Biochemical Oxygen Demand Computational fluid dynamics Chemical oxygen demand Disinfection byproducts Deoxyribonucleic acid Heterotrophic plate count Low-pressure Low-pressure high-output Low-pressure low-output... 

Biochemical Oxygen Demand (BOD) estimation is based on a biodegradation. It is defined as the potential for removal of oxygen from water by aerobic heterotrophic bacteria which utilize organic matter for their metabolism and reproduction (Dupuit, 2006). Thus, it can be also considered as a biological parameter. This test requires a period of incubation (several days) at a controlled temperature in a sealed bottle in... 

In order to characterize water quality, the following parameters were measured from the water samples in accordance with Hungarian Standards total organic carbon (TOC), chemical oxygen demand, concentrations of ammonium, nitrite and nitrate ion, iron, manganese, pH, conductivity, m-alkality, turbidity, and heterotroph colony count. 

FIGURE 6.26 Relationship between soil oxygen demand (SOD) and heterotrophic microbial respiration by different wetland soils. Each data point represents soil from a different locations in the United States (D Angelo and Reddy, 1999). 

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