Digester performances Sample Clauses

Digester performances. During the first 7 days of the experiment, the OLR of FOGs were kept at 0.25 g VS L-1, d-1 and then raised to 0.5 g VS L-1 d-1 to acclimate the digesters to the new substrate. The control digester maintained specific methane production of 307 (+2.4%, -4.8%) NmL g VS-1, d-1 throughtout phase 1 (Figure 16). However, at day 19-27 and 34-37, the gas production fluctuated a lot. In the experimental digester, the specific methane production was increasing from around 307 NmL g VS-1, d-1 between day 11-14, to around 380 between day 24-27and D. Afterwards, the methane yield started to decrease. Like the control digester, the experimental digesters gas production started to fluctuate at day 24- 27and 34-37, thus indicating digestion inefficiency in the digesters. During phase 1, the experimental digester maintained a specific methane yield of 363 (+3.3, -2.1) NmL g VS-1. In the second phase, the BiSl TS increased with about 47% and the PrSl TS dropped by 50%, hence creating a large shift in the TS ratio between the PrSl and the BiSl. This also resulted in an overall lower OLR which made the FOGs contribution greater, hence the specific methane yield increased in the digesters. Between day 40-50 in phase 2, the cavitated digester stabilized quicker compared to the control digester (Fel! Hittar inte referenskälla.), consequently reaching a specific methane production of 412 (+3.3, -2.1) NmL g VS-1. In contrast, the methane yield gradually increased in the control between day 40-51 until it stabilized between day 51-63, resulting in a specific methane yield of 358 (+1.9%, - 0.7%) (Figure 16). In the third phase, the BiSl and PrSl TS increased with 24% and 83% respectively, thus the overall OLR was substantially increased. This caused a decrease in the specific methane yield in the digesters, but as the digester acclimated to the conditions and the old liquid phase were substituted, the specific methane yield increased. The specific methane yield went from 266 to 288 (+ 2.6%, -2.7%) NmL g VS-1 in the control and 308 to 347 (+ 4.9%, -3.2%) NmL g VS-1 in the cavitated digester (Figure 16). In the fourth phase, the TS conditions were similar to the previous phase. However, the FOGs’ addition in the HC pre-treatment was adjusted to accommodate for the detected TS reduction in the process optimisation and in the previous phases. This resulted in a close to equal OLR between the control and the cavitated digester, but it also put some strain on the experimental digester whic...