Pretreatment of Raw Materials

As far as possible, one should use the same pretreatment methods than that used for conventional extraction. Raw materials are supplied and stored under dried conditions to avoid degradation, not to lose valuable extractor volumes, and to limit the water concentration in extracts. Spices and herbs should have moisture contents between 8% and 12%, coffee beans between 35% and 45%, tea between 20% and 30%, fruits between 13% and 20%, and cereals about 12%. 

A certain content is required in order to avoid shrinking of the matrix and, consequently, hindrance in diffusion. For example, a reduced moisture content of 5% instead of 12% decrease the yield by the extraction of calendula from about 7.5% down to 5.5%. 

For total extraction, the raw materials are ground down to particle sizes of 0.3 mm-0.8 mm. Smaller particles would have a better mass transfer, but reduce the fluidized bed velocity - larger diameters and higher costs, or result in channeling. 

Some materials like chamomile with active components on the surface do not need to be milled. Grinding for most spices is executed by means of a hammer mill leaves, roots, or barks preferably with cutting mills and for some seeds and cereals, roller mills are used to destroy the structure. 

The bulk density is decisive for the plant capacity and economy and, therefore, raw materials with a low bulk density should if possible be pelletized, for hops one get an increase from about 150kg/m to 500kg/m and even more. 

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Pretreatment of Raw Materials. The following reasons may necessitate pretreatment steps ... 

It is a commonly held view that cellulase is an inducible enzyme, and that cellulose is the best inducer. In solid-state fermentation for cellulase production, cellulosic materials act as either the carbon source or the inducer. Some of the raw materials for solid-state fermentation and their composition are listed in Table 1. From Table 1 it is very clear that the raw materials for cellulase production using solid-state fermentation are abundant and cheap. Proper pretreatment of raw materials is generally required. The nitrogen source for solid-state fermentation includes inorganic compounds, such as urea and (NH4)2SO4, or natural products, such as bran. 

Utilities are required for operation of the main process reactors and related units for pretreatment of raw materials and processing of the products, for safe and efiftcient operation of plant and treatment of effluents. Main utilities are electrical power, treated water, steam, dry air, heating fuels (mediums), nitrogen flushing for the chemical plant. 

Auxiliary equipments for pretreatment of raw materials shall be in place to prevent deactivation of catalyst and fouling of heat transfer surfaces. Formats have been given elsewhere in this book for drawing attention to key equipments and consequences of their breakdown. 

Pretreatment of raw materials prior to feeding to the process units, e.g. crushing grinding (generation of dust), filtration (generation of filter cake) ... 

The major components of cellnlose feedstock include cellulose, hemicellulose, and lignin. The first step is the pretreatment of raw materials, removing the inhibitors of saccharification and fermentation. Second, cellulose is hydrolyzed into simple sugars by the action of acid or enzyme. Third, ethanol is formed by fermentation... 

There have been many attempts to produce LA from cheap raw materials such as starchy and cellulosic materials, whey, and molasses. Among these, starchy and ligno-cellulosic materials are currently receiving a great deal of attention, because they are cheap, abundant, and renewable (Wee et al., 2006). One bottleneck for LA production from starchy and lignocellulosic materials is the cost of pretreatment of raw materials. 

In this chapter, relevant background information will be provided regarding the principles of PEF and ultrasound technology, and its impact on biological tissues. The application of PEF as a pretreatment of raw materials prior to osmotic dehydration, air- and freeze-drying, with the resultant effects on drying characteristics and product quality, will be discussed. In the case of ultrasound, concepts for... 

Depending on the final product requirement, processing conditions, pressure, temperature, mass flow, and pretreatment of raw materials are influenced and fractionated separation or further downstream treatment as concentration, removal of moisture, or purification may be required. 

Unlike common industrial parks where factories are selected simply on the basis of their willingness to share the real estate, environmentally balanced industrial complexes (EBIC) are a selective collection of compatible industrial plants located together in a complex so as to minimize environmental impacts and industrial production costs [24,33]. These objectives are accomplished by utilizing the waste materials of one plant as the raw materials for another with a minimum of transportation, storage, and raw materials preparation costs. It is obvious that when an industry neither needs to treat its wastes, nor is required to import, store, and pretreat its raw materials, its overall production costs must be reduced significantly. Additionally, any material reuse costs in an EBIC will be difficult to identify and more easily absorbed into reasonable production costs. 

The final costs are highly dependent upon site-specific conditions. Contributing factors to the final cost include the waste characteristics, including its physical form and chemical makeup the amount of pretreatment required transportation of raw materials to the site and treated materials from the site and other random factors such as health and safety requirements and regulatory factors (D150141, p. 7.100). 

Peeling, one of the most delicate pretreatments, is achieved industrially by abrasion, high-pressure steam, treatment with sodium hydroxide solution, or mechanically. Abrasion is effected by rough, moving surfaces which remove the outer surface of the product, but it has the drawback of considerable loss of raw material. Steam peeling consists of heating the product to... 

The approach "select favorable raw material has a major impact on the selection of pretreatment processes. For example, the poplar responds splendidly to many pretreatments that fail with Douglas fir or pine-based materials (I). Specific tissues and cells of a given biomass raw material will respond quite differently. For example, the rind fiber of sugarcane bagasse behaves quite differently from the pith fiber (11)- In woody species, the selection of tissues low in bark and extractives is an important factor in the ease or resistance to cellulose hydrolysis. Before embarking on development of processes for hydrolysis of a biomass resource, it is highly desirable to exercise discretion with respect to the choice of raw materials at both the species and tissue levels. This idea is all the more important in an initial choice of species and pretreatment process. 

After the Kastenbeschicker several other machines carry out the subsequent pretreatment.The type of raw material and factory procedures determine which machines are used. Some of these machines are clay rasp or Kollerwalze, differential rollers, Kollergang and pregrinder. Let us have a closer look at the Kollergang. 

Presented are the examinations of the multifimctional mineral-earbon and zeolite-carbon sorbents prepared from kaolinite with an admixture of carbonaceous materials industrial waste deposits, municipal sewage sludge and cellulose. The mixture of raw materials was thermally and hydrothermally pretreated in order to facilitate their specific structure. The parameters of capillary structure (micro and mesopores) were determined. For examinations of porous structure the mereury porosimetry method was used. In order to evaluate the solid phase transformation during the each step of sorbent preparation the SEM observation with quantitative X-ray mieroanalysis were made. 

The adsorbents have been prepared fi-om the halloysite (H) - mineral fi-om kaolinite group with an admixture of carbonaceous materials refinery waste deposits (RSI), sediment communal sewage (CSew) and cellulose (Ce), and the fiaction of these mixtures were within 30 - 70 wt.%. The mbcture of raw material was thermally (carbonaceous materials carbonization, 973 K) and hydrothermally (crystallization of the amorphous metahalloysite in alkaline solution to zeolitic structure of NaA type, 373 K) pretreated in order to cilitate their specific structure [1,2]. 

Because every industrial chemical process is designed to economically produce a desired product from a variety of raw materials. The economical extraction and use of exploitable raw materials are the essential prerequisites for a chemical industry. These raw materials usually have to be pretreated. They may undergo a number of steps involving physical treatment, chemical reactions, separation, and purification before their conversion into a desired product. Figure 1.1 shows a typical structure of such a process. 

Confirmation that the pretreatment (drying, calcination, filtration, etc.) of raw materials has been done properly before feeding to process plant and that the process is in control at every stage by checking samples of critical streams. 

For direct saponification routes to soap, once a fat blend has been selected then particularly for toilet soap formulations, some method of raw material pretreatment is often applied. Commonly used methods involve bleaching, either with diatomaceous earth or activated carbon and, less commonly, deodorization... 

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