Biomass Morphology

A widely used parameter in the quantitative analysis of the oxygen transfer rate in wastewater treatment bioreactors is the dimensionless factor, a, defined by the following equation  

The impact of biomass concentration on energy costs is substantial, and clearly an optimnm biomass concentration exists that maximizes volnmetric reaction rate while minimizing the aeration costs. Most fnll-scale MBR plants aim to operate at a biomass concentration between 10 and 15 g L [50]. The average a valne at typical MBR for municipal wastewater with an MLSS concentration of 12 kg m MLSS for municipal MBRs is abont 0.6 [20]. 

Biomass morphology also impacts on sludge treatability. Ng and Hermanowitz [51] showed that MBR sludge was more difficult to dewater than that from CAS operated under the same conditions. Values of the sludge resistance to filtration (SRF) in the MBR were, in fact, an order of magnitnde higher than in the CAS (typically 1 x 10 m kg .  

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Cylindrical pellets arc made from the USDA samples expressly to remove consideration of native biomass morphology. We have shown biomass morphology alters pyrolysis slate (Chan et al 1988). If necessary, the sample is ground further in a Wile mill and reformed in a cylindrical die to the native density, approximately 1.0 g/cm, Three holes are made radially in the pellet with a small drill and thermocouples are inserted at distances of 2, 4 and 6 mm from the heated lace of the pellet. The pellet is then fitted tightly in a glass sleeve joined to the reactor via an O-ring seal. Real time intraparticle temperatures are displayed on the computer monitor and digitized at a rate of 1 Hz. The moisture content of the pellet is constant al a 5.0 wt %, equilibrium moisture except for some data in Chan et al (1988). 

When determining the potential influence of cover crops on the physicochemical state of Cecil A no-till soils or tilled soils, there are a variety of factors that are of interest. Among them are above- and below-ground cover crop biomass, morphology of cover crops (as related to shading and root distribution), soil temperature, soil moisture, soil compaction, soil pH, chemical composition of cover crops before and after glyphosate desiccation (e.g., C/N ratio and phenolic acid content), soil C/N ratio, soil nitrate-N, and soil phenolic acid content. 

Temperature also affects production rates but, through its influence on the thermal expansion of water, it also induces changes in the depth of vertical mixing and resistance to wind-stirring processes. Reactions to temperature of other components of the food chain are also important in the regulation of phytoplankton biomass by consumers. Different phytoplankton species, with important morphological differences, are differentiated selectively by the interplay of these factors. " ... 

The rate of product formation, rfi, depends upon the state of the cell population, environmental condition, temperature, pH, media composition and morphology with cell age distribution of the microorganism.2 3 A similar balance can be formulated for microbial biomass and cell concentration. The exponential phase of the microbial growth in a batch culture is defined by ... 

Position 5 in Fig. lb describes the brief explosive development of biomass in an ephemeral species capable of exploiting a productive but temporary habitat. Here again morphological plasticity would be expected to predominate. In the vegetative phase, plasticity in root and shoot morphology will be an integral part of the mechanism of resource capture. 

In order to gain some information about the fundamentals of the hydrothermal carbonization process, the hydrothermal carbonization of different carbohydrates and carbohydrate products was examined [12, 13]. For instance, hydrothermal carbons synthesized from diverse biomass (glucose, xylose, maltose, sucrose, amylopectin, starch) and biomass derivatives (HMF and furfural) were treated under hydrothermal conditions at 180 °C and were analyzed with respect to their chemical and morphological structures by SEM,13 C solid-state NMR and elemental analysis. This was combined with GC-MS experiments on residual liquor solutions to analyze side products... 

Dong, M. and de Kroon, H., Plasticity in morphology and biomass allocation in Cynodon dactylon, a grass species forming stolons and rhizomes, Oikos, 70, 99-106, 1994. 

The measure of mass is important with respect to calculating mass balance. However, the elemental composition of biomass is normally ill defined. Another reason for determining biomass is the need for a reference when calculating specific rates (q ) q = r /x. An ideal measure for the biocatalysts in a bioreaction system of interest would be their activity, physiological state, morphology or other classification rather than just their mass. Unfortunately, these are even more difficult to quantify objectively and this is obviously why the biomass concentration is still of the greatest interest. 

Properties such as cell volume, morphology or cell size are nowadays determined using flow cytometers or image analysis, e.g. [35,95,181,440], or by in situ microscopy, e.g. [422]. Biomass quantification by image analysis is treated extensively by Pons and Vivier in this volume. 

The discussion of the approaches to analyse microbial biomass for physiological status information starts with the better known methods and proceeds to more novel developments. Morphology has been used for a long time to... 

Dielectric spectroscopy or culture capacitance measurement is used as an on-line, non-invasive method for biomass estimation (see the chapter by Sonnleitner in this issue - the section on electrical properties) and responds mainly to living cells [43,44]. Observed difficulties in using the signal as a pure biomass concentration sensor, i.e. deviations from the simple correlation with cell density, were attributed to dependencies on the physiological state [43], and could be used to discriminate different populations in yeast cultures [45]. Connections with morphological features could be found for budding yeast... 

The reaction appears to be well suited for selective conversion of biomass carbohydrates into their corresponding oxidized derivatives. This system serves to oxidize several polymeric carbohydrates including starches and pullulan.445 49 More recent work has described the TEMPO-catalyzed introduction of carboxyl groups in native cellulose and its different morphological forms,45(M52 cellulose derivatives,453 and the surface of cellulose nanocrystals.454 The related biopolymer, chitin, also is oxidized under these conditions.455... 

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