Co‐digestion of food waste and sewage sludge using the combination of a thermal alkali pre‐treatment and a two‐stage anaerobic digestion system

Abstract

A thermal alkali pre-treatment anaerobic digestion elutriated phased treatment (T-ADEPT) was developed by combining the thermal-alkali pre-treatment (TAP) with the anaerobic digestion elutriated phased treatment (ADEPT) for the anaerobic codigestion of food waste (FW) and dewatered sewage sludge (SS). To improve the solubilization efficiency and methane yield, the optimal conditions for the TAP and ADEPT processes were identified. The soluble chemical oxygen demand (SCOD) solubilization, volatile suspended solids (VSS) reduction rate, volatile fatty acid (VFA) concentration, and methane yield all improved with our proposed process. The variations of the physical properties of the FW and SS mixtures confirm that the TAP process enhances the solubilization of organic matter. The methane yield of the T-ADEPT process was 0.368 L CH 4 /g VS added , which was approximately 1.4 and 1.2 times higher than the values for a conventional two-stage anaerobic digestion (AD) process and an AD process with pre-treatment, respectively. These results show that the application of TAP and ADEPT processes using granular sludge can be an effective approach for the anaerobic co-digestion of FW and SS. The proposed technique is more tolerant of the inhibitory effects of high concentrations of toxic compounds compared with a conventional two-stage AD system. Modifying a conventional anaerobic digester has the potential to deliver low hydraulic retention times (HRTs) and high organic loading rates (OLRs).

Co-digestion approach for enhancement of biogas production by mixture of untreated napier grass and industrial hydrolyzed food waste

“…Nevertheless, the methane production yield still surpassed those of the two feedstocks. Recent studies involving food waste co-digestion with a variety of wastes exhibited a lower methane production yield than this study ( Liu X. et al, 2022 ; Kosheleva et al, 2023 ; Lee et al, 2023 ; Yang et al, 2023 ). Alkaline pretreatment of food waste used for co-digestion with sewage sludge in two-stage anaerobic digestion ( Lee et al, 2023 ) resulted in lower methane yield production.…”

“…Recent studies involving food waste co-digestion with a variety of wastes exhibited a lower methane production yield than this study ( Liu X. et al, 2022 ; Kosheleva et al, 2023 ; Lee et al, 2023 ; Yang et al, 2023 ). Alkaline pretreatment of food waste used for co-digestion with sewage sludge in two-stage anaerobic digestion ( Lee et al, 2023 ) resulted in lower methane yield production. According to the comparison, the most suitable condition for methane production performance and effective energy recovery from these feedstocks is the combination of Napier grass and pretreated food waste with subcritical water hydrolysis in two-stage anaerobic digestion.…”

Enhancement of anaerobic digestion of dairy wastewater by addition of conductive materials with or without the combination of external voltage application

“…Numerous methods have been studied in the past to improve biogas production, including feedstock pretreatment, 2 process optimization, 3 co‐digestion 4 and bioaugmentation 5 . These efforts have led to an overall improvement in the anaerobic digestion process.…”

Comparative Environmental and Economic Analysis of Biomethane Production from Co-Digestion of Rice Straw and Spent Mushroom Compost: Application of Zero-Valent Iron Nanoparticles

“…The two-phase sludge AD procedure biogas output from acidogenic and methanogenic reactors with or without nitrite shows that nitrite has no substantial influence (Sheng et al, 2023). Lee et al (2022) investigated optimal thermal-alkali pre-treatment and anaerobic fermentation elutriated phased treatment settings to improve solubilization efficiency and methane output. The suggested approach enhanced soluble chemical oxygen demand (SCOD) solubilization, volatile suspended solids reduction, volatile fatty acid concentration, and methane yield.…”