###### Abstract
On the other hand, there are arguments that the use of FWDs can be beneficial, because it reduces the amount of food waste generated by 42%, thereby reducing the costs of its disposal [10]. Ground food waste discharged with sewage to the municipal wastewater treatment plant increases the concentration of organic matter in the sludge, which increases biogas production [11]. Research by [PERSON] [3] showed that household food waste ground in an FWD had COD (Chemical Oxygen Demand) values ranging from 10,600 to 28,600 mg/L and BOD values in the range from 4760 to 13,700 mg/L. It also needs to be emphasized that 40% of COD and 30% of nitrogen present in wastewater were in the soluble form [12]. In addition, the use of FWDs results in the generation of larger volumes of sludge and sewage, as well as higher energy consumption and a greater demand for water. The BOD load in influents entering the wastewater treatment plant may increase by 17-62%, and that of total suspended solids by 1.9-7.1%. A total of 11.7 L of water is needed to prepare and drain 1 kg of food waste [9]. Research by [PERSON] and [PERSON] [11] showed that the use of FWDs in a developing economy characterized by a high share of food waste can be an alternative solution to reducing emissions in emissions trading. Experimental results demonstrated a reduction in emissions of approximately 42%, with savings of up to 28%, taking into account environmental external factors, including sludge management. In the case of waste generated in catering facilities, it is possible to develop and implement a system that will enable exploiting its energy potential and, at the same time, minimize problems and costs associated with the operation of the sewerage system and wastewater treatment plants. This should be the case because European regulations urge the pursuit of such solutions. As a result of implementing EU legislation, feeding livestock with food waste is strictly prohibited [13]. Food waste from restaurants must be stored in properly maintained containers and then forwarded to the entrepreneur acting on the basis of the Waste Act [14]. However, such activities are labor intensive. Food waste from restaurants, bars, cafeterias, etc. is commonly ground and discharged to the sewerage system, despite the fact that it is prohibited in the EU (including Poland). This treatment of food waste is against provisions of the Act on collective water supply and collective sewage disposal [15]. Wastewater generated in restaurants has high concentrations of total suspended solids, BOD, COD, and contents of fat and oil [16]. The volumes and composition of wastewater generated in restaurants depend on the restaurant type (i.e., Italian, Chinese, Indian, etc. ), kitchen size, the time of served meals, the category of meals, and restaurant size. Qualitative studies of food waste generated in catering facilities conducted in Korea and the USA (Table 1) showed that the percentage share of organic substances in this type of waste was 95 and 85.3%, respectively. Ground food waste generates substantial costs, especially due to high electric energy consumption in WWTPs [3; 19]. The scale of the problem is evidenced by the results of research on waste from academic cantens that was ground in mills, whose COD ranged from 500,000 to 2,000,000 g O\({}_{2}\)/m\({}^{3}\)[20]. The severity of the problem is also indicated by the quantities of hardly biodegradable pollutants, such as fats and oils, which are present in large quantities in catering wastewater. Their concentration was even up to 6500 mg/L (Table 2). On the other hand, this proves the high energy potential of this wastewater [21]. It can be expected that food waste will significantly change the proportions of organic and biogenic compounds in wastewater inflowing to the treatment plant. Table 3 presents