Small-scale Production Solutions

Restoring the solution concentration by adding dry solute or mixing with concentrated solution can save energy costs as it avoids heat of evaporation and the need for expensive plants. The method can be suggested successfully for small-scale production, at a low-technological level process, where the initial solution mass is small. Indeed, the main hurdle of this technique is the increase of the solution mass, even if a constant loss in volume of syrup (9-14%) is due to adherence to the food pieces (Bolin et al., 1983). 

Electrolysis of Water. Electrolysis of acidified water at Pt electrodes is commonly used to demonstrate the composition of water, and is a small-scale production method for generating hydrogen and oxygen. Very pure hydrogen of more than 99.99% can be formed from the electrolysis of warm aqueous solutions of barium hydroxide between nickel electrodes, via the following reaction ... 

Zinc metal seems to have been produced in India in the 7 century ad and in China in the 11 century [33.3]. Indian metallurgists wrote careful recipes, describing how calamine, an impure zinc oxide, should be mixed with organic matter such as sugar solution, mustard seeds and fruits of different sorts. When the mixture was heated in a covered crucible, a metal, similar to tin, was obtained. This small-scale production was mainly for medical use. In China, the manufacturing technique was developed into an important industry. It is described in the book Tien-kong-kai-ou, published in the first part of the 17 century and referred to by W. Hommel in ref [33.1] (see Figure 33.1). 

Reflux Distillation Unit. The apparatus shown in Fig. 38 is a specially designed distillation-unit that can be used for boiling liquids under reflux, followed by distillation. The unit consists of a vertical water-condenser A, the top of which is fused to the side-arm condenser B. The flask C is attached by a cork to A. This apparatus is particularly suitable for the hydrolysis of esters (p. 99) and anilides (p. 109), on a small scale. For example an ester is heated under reflux with sodium hydroxide solution while water is passed through the vertical condenser water is then run out of the vertical condenser and passed through the inclined condenser. The rate of heating is increased and any volatile product will then distil over. 

Biopolymer Extraction. Research interests involving new techniques for separation of biochemicals from fermentation broth and cell culture media have increased as biotechnology has grown. Most separation methods are limited to small-scale appHcations but recendy solvent extraction has been studied as a potential technique for continuous and large-scale production and the use of two-phase aqueous systems has received increasing attention (259). A range of enzymes have favorable partition properties in a system based on a PGE—dextran—salt solution (97) ... 

The first two categories, clarifying and crossflow filters, have been very well developed and optimized for use in biotechnology and standard wastewater treatment applications. Equipment is easily available for these applications, whether as small 0.2 micron sterilizing filter used to terminally sterilize 100 ml of product solution, or a small 500 ml crossflow filter used to concentrate a small amount of antibody solution. Many vendors of this equipment to wastewater treatment applications have their origins in the CPI (Chemical Process Industries), and have incorporated many of the scale-up and optimization properties developed in much larger units used in large scale chemical production. As a result, these two filtration unit operations are one of the most optimized and efficient used in wastewater treatment. 

Dimensional analysis techniques are especially useful for manufacturers that make families of products that vary in size and performance specifications. Often it is not economic to make full-scale prototypes of a final product (e.g., dams, bridges, communication antennas, etc.). Thus, the solution to many of these design problems is to create small scale physical models that can be tested in similar operational environments. The dimensional analysis terms combined with results of physical modeling form the basis for interpreting data and development of full-scale prototype devices or systems. Use of dimensional analysis in fluid mechanics is given in the following example. 

Even if the fatty acid esters have been sulfonated under optimal conditions the ester sulfonates are dark-colored [12,33] so the sulfonated product has to be bleached. The second pretreatment is the neutralization of the acid product to obtain the salt of the a-sulfo fatty acid ester. Different techniques have been published in the literature. Kapur et al. suggested bleaching with 3-4 wt % NaOCl (15 wt % solution) after neutralization with a 30% aqueous solution of sodium hydroxide. This technique is for small-scale sulfonation [46]. 

The solution of these problems is based on a simple idea the developed laboratory-scale process is used for manufacturing of a chemical product by parallelization of many small units. Although promising great advantages over scale-up, this procedure, denoted numbering-up , is not trivial by far. It cannot be carried out in a simple way due to the tremendous technological effort necessary a chemical plant with hundreds or even thousands of small-scaled vessels, stirrers, heaters, pumps. 

If the product is handmade on a small scale the flour used is less critical than if the product is made on a large scale on an automated plant. Mixing cold and baking the product before the gluten separates may be a useful small scale solution but on a large scale where the batter has to be pumped to the ovens to be baked it will not work. 

---