The Influence of Pandemic Lockdowns on Municipal Wastewater Quality as a Consequence of Not Discharging Food Waste from Restaurants

Abstract

The use of food waste disposers in gastronomical facilities influences municipal wastewater composition. Ground food waste poses problems in the operation of the sewerage network and generates high electric energy consumption in wastewater treatment plants (WWTPs). This study aimed to determine, for five towns with a PE (Population Equivalent) ranging from 4000 to 220,000, the volumes of catering waste discharged to the WWTPs. The towns differed in the number of inhabitants, beds in hotels, and catering places. The calculations were undertaken based on data received from the operators of the WWTPs. The pollutant concentrations in 2019 were compared with data from the “pandemic” year—2020. The loads of catering waste entering the sewerage system in 2019 ranged from 32.7 to 1062 tons. In the town with the largest tourist base, the BOD (Biochemical Oxygen Demand) value in 2020 accounted for 62.3% of the 2019 value. In the largest town, the annual energy consumption for food waste treatment could be up to 2,539,770 kWh. If the waste was fermented, up to 1,376,650 m3 of methane could be obtained. There is a strong need to implement a collection system for food waste from catering facilities, and the fermentation of this waste to produce methane, which can be used for energy purposes.