Enhancing kitchen waste minimization and energy generation at 20 °C: a psychrophilic anaerobic co-digestion study

Abstract

Background: In developing countries, anaerobic digestion still represents an emerging technology for solid waste management, despite the great energy potential of methane in biogas for heating purposes, especially in low-temperature regions. This research evaluated the effect of hydraulic retention time (40–120 days) on the anaerobic co-digestion of 35% w/w waste activated sludge and 65% w/w organic kitchen waste at a low temperature (20 °C). The anaerobic co-digestion was conducted in five 11-L semicontinuous anaerobic digesters. Additionally, the expected energy production from organic kitchen waste was calculated. Results: The specific methane yield (SMY) ranged from 0.20 to 0.27 LCH4 g-VSadd−1, comparable to the SMY reported for meso- and thermophilic anaerobic digestion. Moreover, the expected energy production was 1.06 MJ day−1 of equivalent liquefied petroleum gas, which could satisfy ≤6.6% of the daily water heating requirements of an average Mexican household. The hydraulic retention time in the range of 60–120 days did not seem to significantly affect the performance of the digesters. Conclusions: These digesters could easily be installed in low temperature regions for domestic use. The waste activated sludge substrate can be replaced with other nitrogen-rich substances for indoor use. The data shown in this research set the basis for further investigations and domestic applications. © 2023 Society of Chemical Industry (SCI).