Dewatering for food waste.

Publisher Summary The food industry produces a variety of wastes that require handling in an environmentally friendly and sustainable way. Depending on the type of waste, numerous waste handling alternatives are available from fermentation, separation, biofuel conversion, composting, extraction, and more. Choosing the right waste handling process can help to meet environmental regulations and provide a useful by-product for further processing, recovery or animal consumption. A lower moisture content of the waste material reduces the cost of transport due to reduced volume and weight. This chapter discusses the concentration of solids from food waste using dewatering techniques. The reduction of moisture content offers flexibility in terms of handling, shelf-life, and subsequent use of the waste. A liquid/solid separation process involves multiple steps: pre-treatment, thickening, separation, and post-treatment. Common dewatering processes use mechanical means of separation, such as screens, screw presses, belt presses, vacuum filters, and centrifuges, which can all be combined with additional forces to remove the water, such as an electric field, ultrasonics, vibrations, chemical treatments, etc. In any dewatering application, there is a definite advantage of combining multiple dewatering fields to promote the synergy of separation forces. The selection of an adequate dewatering process depends on numerous factors, such as the type and quantity of the waste product, the end-use of the dewatered/dried solids and environmental and economic considerations. With a dewatering process, the underlying advantage is that the water is removed in the liquid state. The lack of a phase change renders the process less energy-intensive and in some instances may improve the end-product quality. Dewatering lowers the moisture content to a level not low enough for shelf stability and thus the dewatered material requires a finish drying treatment or further processing.

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