Filtering biomass

Spruce and fir trees have a larger filtering biomass than pine and deciduous trees. For example, in coniferous stands the dry deposition fluxes of sulfur are about 2.5-fold... 

Lime-Sulfuric. Recovery of citric acid by calcium salt precipitation is shown in Figure 3. Although the chemistry is straightforward, the engineering principles, separation techniques, and unit operations employed result in a complex commercial process. The fermentation broth, which has been separated from the insoluble biomass, is treated with a calcium hydroxide (lime) slurry to precipitate calcium citrate. After sufficient reaction time, the calcium citrate slurry is filtered and the filter cake washed free of soluble impurities. The clean calcium citrate cake is reslurried and acidified with sulfuric acid, converting the calcium citrate to soluble citric acid and insoluble calcium sulfate. Both the calcium citrate and calcium sulfate reactions are generally performed in agitated reaction vessels made of 316 stainless steel and filtered on commercially available filtration equipment. 

The nonvisual or subtle effects of air pollutants involve reduced plant growth and alteration of physiological and biochemical processes, as well as changes in the reproductive cycle. Reduction in crop yield can occur without the presence of visible symptoms. This type of injury is often related to low-level, long-term chronic exposure to air pollution. Studies have shown that field plantings exposed to filtered and unfiltered ambient air have produced different yields when no visible symptoms were present (5). Reduction in total biomass can lead to economic loss for forage crops or hay. 

Trickling filter An attached culture,wastewater treatment system. A large tank generally filled with rock or rings (see Bio-Tower). Wastewater is sprayed over the top of the media, providing the opportunity for the formation of slimes or biomass to remove wastes from the wastewater, through revolving arms which have spray nozzles. Water is pumped from the bottom of a trickle filter to a secondary clarifier. 

Initially fermentation broth has to be characterised on the viscosity of the fluid. If the presence of the biomass or cells causes trouble, they have to be removed. Tire product is stored inside the cells, the cells must be ruptured and the product must be freed. Intracellular protein can easily be precipitated, settled or filtered. In fact the product in diluted broth may not be economical enough for efficient recovery. Enrichment of the product from the bioreactor effluents for increasing product concentration may reduce the cost of product recovery. There are several economical methods for pure product recovery, such as crystallisation of the product from the concentrated broth or liquid phase. Even small amounts of cellular proteins can be lyophilised or dried from crude solution of biological products such as hormone or enzymes.2,3... 

Plate filters are suitable for filtration of batch fermentation broth accumulated biomass must be cleaned periodically. A rotary dram vacuum filter is used for a continuous system. 

A typical penicillin broth contains 20-35 mg/1 of antibiotic. Filtration is used to remove mycelial biomass from fermentation broth. The filtration may be subjected to filter aided polymers. Neutralisation of penicillin at pH 2-3 is required. Amyl acetate or butyl acetate is used as an organic solvent to remove most of the product from the fermentation broth. Finally, penicillin is removed as sodium penicillin and precipitated by a butanol-water mixture. 

Laboratory Microfiltration membranes have countless laboratory uses, such as recovering biomass, measuring particulates in water, clarifying and sterilizing protein solutions, and so on. There are countless examples for both general chemistry and biology, especially for analytical proc ures. Most of these apphcations are run in dead-end flow, with the membrane replacing a more conventional medium such as filter paper. 

Somewhat related is a process proposed and demonstrated on labscale by the University of Siegen (Germany). The process is called the (Herhof)-Integrierte Pyrolyse und Verbren-nung (IPV) process and is decribed in detail by Hamel et al.60 In this process, biomass is converted with high-temperature steam to pyrolysis gas in a fixed-bed reactor. The generated carbon from this reactor is led to a stationary FB combustor from which the hot ash is returned to the first-mentioned reactor. The ash works catalytically to reduce the tar content of the gas produced. The gas is further cleaned and conditioned using a scrubber and electrostatic filter from which the catch is returned to the FB combustor. 

Reactive brilliant red X-3B Activated sludge Activated sludge generated a heterogeneous biofilm of several bacterial species. Biomass was increased after ozonation. Combination of ozone oxidation and upflow biological aerated filter technique to treat azo dyes [8]... 

Tars have a tendency to cling to the filter surface and can undergo subsequent carbonization reactions that lead to fouling and plugging. Even in the absence of further decomposition, tars are difficult to remove from these materials. Examples of barrier filters suitable for biomass systems include rigid, porous-candle, or cross-flow filters constructed of metal or ceramic bag filters constructed of woven material, and packed-bed filters. 

These filters are well proven for removing particulates in a variety of systems but have not previously been used in biomass gasification systems. For gasification systems these filters require hot product gas to be cooled prior to filtration. For that reason, they are most appropriate for applications where retaining the sensible heat of the product gas is not critical. In addition, the presence of tars in the product gas can cause potential problems since tar condensation on the filter cake or the filter itself can lead to plugging. Care must be taken to ensure either that tars are removed from the stream prior to the bag filter or that the temperature remains high enough to prevent tar condensation. 

Electrostatic filters have been used in many coal-fired power stations, and they have been used in some biomass combustion facilities. Their use in medium- or large-scale gasification systems is limited. Electrostatic filters are best suited for large-scale operation due to their physical size and cost, and the primary impediment to their use in current gasification systems is an economic one. 

Nutritive sweeteners, 24 224 Nutritive sweeteners, 12 32, 38 Nutsche filter, 11 350-351, 352 Nutshells, as biomass, 3 684 Nutter ring, 3 770... 

Phenolic novolacs, 18 760-761 Phenolic resin adhesives, 18 783-784 Phenolic resin can coatings, 18 38 Phenolic resin composites, 18 792-794 Phenolic resin drying-oil varnishes, 18 783 Phenolic resin fibers, 18 797-798 mechanical properties of, 18 798 Phenolic resin foam, 18 795-796 Phenolic resin manufacturers, U.S., 18 774 Phenolic resin polymerization, 18 760-765 alkaline catalysts in, 18 762-765 neutral catalysts in, 18 761-762 strong-acid catalysts in, 18 760-761 Phenolic resin prepregs, 18 793 Phenolic resin production unit, 18 766 Phenolic resins, 10 409 18 754-755, 756-802 22 10 26 763 in abrasive materials, 18 786-787 in air and oil filters, 18 790 additional reactants in, 18 759 analytical methods for, 18 774-779 applications of, 18 781-798 batch processes for, 18 766 from biomass and biochemical processes, 18 769-770... 

Some fine char is inevitably carried in the liquid and can only be removed by liquid filtration using, for example, cartridge or rotary filters. Almost all of the ash in the biomass is retained in the char, so successful char removal gives successful ash removal. Char separation, however, is difficult and may not be nec-... 

Finally, it is noteworthy that not all marine organisms are classifiable as POM. Viruses, small bacteria, and archaea can pass through 0.2-p,m filter pores and, thus, are technically part of the DOM. Although these organisms are small (0.2 to 20 x 10 gC/cell for viruses and bacteria, respectively), their high numbers (10 to lO and 10 to 10 cells/L, respectively) cause their collective biomass in seawater to be similar to that of phytoplankton and zooplankton (<2mm) (Table 23.2). The biomass of the archaea and the macrozooplankton (>2 mm) are currently unknown. Nonetheless, these two groups play very important biogeochemical roles as described later. 

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