Evaporation is a method used to concentrate non-steam-volatile wastewater components. The evaporation plant contains a vapor condenser by which vapor and steam-volatile compounds are separated from the concentrate. While the concentrate is then recycled into the evaporator, the exhaust steam can be used for indirect heating of other evaporator stages (Fig. 19).
The degree of concentration of the wastewater components depends on different factors, for example :
• reuse of the concentrate (e.g., reuse in production, use as fodder, recovery of recyclable material);
• type of disposal of the concentrate (e.g., incineration, landfill)
• properties of the concentrate (e.g., viscosity, propensity to form incrustation, chemical stability).
Advantages of this method include:
• the residue (dried oil wastes) can be reused as fodder and fertilizer;
• exhaust steam can be reused as energy;
• considered state of the art in the food industry .
• the exhaust steam from evaporation is organically polluted and needs treatment;
• rather high operation and maintenance costs;
• requires high energy;
• requires trained personnel.
Details about drying processes, including case studies for the treatment of olive oil mill wastes, are discussed in Section 17.6.2.
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