Anaerobic Co-digestion of the Liquid Fraction of Food Waste with Waste Activated Sludge

Abstract

The present study investigated the feasibility of the anaerobic co-digestion (AcoD) of condensate, resulting from drying food waste, with Waste Activated Sludge in a pilot scale continuous stirred tank reactor. Different parameters were assessed in order to enhance the AcoD performance; the condensate potency (condensate A: 13 gCOD/L and condensate B: 4 gCOD/L), the volumetric ratio of condensate to WAS (0–67% v/v) and the hydraulic retention time (HRT) (20, 15 and 12 days). The results showed that increasing the condensate content in the feed from 0 to 67% v/v, enhances the organic load removal (up to 41% increased total COD removal) and the bioenergy production (up to 35% increased biomethane production). Moreover, in the case of condensate A, the reduction of HRT from 20 to 15 days enhanced the bioenergy production (up to 19% increased biomethane production) while the reduction of HRT from 20 to 12 days in the case of condensate B did not significantly affect the reactor’s performance. Overall it is concluded that condensate can be safely introduced in existing facilities for anaerobic digestion, while maintaining a more stable operation and improved effluent quality and bioenergy production in comparison with conventional anaerobic sludge digestion. Graphical Abstract

European Green Deal: Justification of the Relationships between the Functional Indicators of Bioenergy Production Systems Using Organic Residential Waste Based on the Analysis of the State of Theory and Practice

“…In order to substantiate effective scenarios for the creation of bioenergy production systems using the organic waste of residential areas, it is necessary to perform modeling, which is based on the disclosure of relationships between various functional indicators of individual processes [3,[54][55][56][57]. At the same time, there is a need to substantiate the interrelationships between the functional indicators of bioenergy production from the organic waste of residential areas, taking into account the type and quality of organic waste, which determine the volume of bioenergy generation and the efficiency of its production.…”

“…It is known [48,49] that the collection of waste at the place of its direct processing provides the highest amount of biogas output. At the same time, the highest yield of biogas is observed in pre-sorted organic waste, while mechanical sorting leads to an increase in the duration of waste storage and, accordingly, a decrease in available energy [55][56][57][58]. Pre-sorted organic waste in households ensures an increase in the efficiency of bioprocesses and, accordingly, an increase in the volume of biogas production [10][11][12][13][14][15][16][17][18][19].…”