Long-Term Pre-Treatment of Municipal Sewage Sludge with Solidified Carbon Dioxide (SCO2)—Effect on Anaerobic Digestion Efficiency

Studies on harnessing solidified carbon dioxide (SCO2) for municipal sewage sludge (MSS) pre-treatment have been conducted exclusively in batch reactors. This makes it difficult to accurately assess how long-term SCO2 treatment affects anaerobic digestion (AD) conditions and performance. The aim of our study was evaluate the effect MSS with AD conditions, bacterial community, biogas composition yields. presented experiments are first studies efficiency continuous So far, impact organic load rate (OLR) methane fermentation has not assessed, which is also a novelty research. process continuous-stirred, continuous-flow an active volume 20 dm3. run at 38 ± 1 °C. experiment divided into two stages. Raw (non-pretreated) used stage 1, whereas 2 pre-treated SCO2. SCO2/MSS ratio 1:3. Each sub-divided four variants, different levels OLR ranging from 2.0 5.0 gCOD/dm3·day. Pre-treatment found improve performance 3.0–4.0 gVS/dm3·day. 3.0 gVS/dm3·day variant offered best production performance—both daily (29 1.3 dm3/day) per VS added (0.49 0.02 dm3/gVS)—as well as highest CH4 content (70.1 1.0%). In this variant, energy output 187.07 1.5 Wh/day obtained. change pH, FOS/TAC, or community composition. Instead, these variables were mainly affected by OLR. Our shows that 0.3 (by volume) significantly improves terms feedstock mineralization. no negative operation reactor.