RESUMO
Soft drink beverage waste (BW) was evaluated as a potential substrate for anaerobic co-digestion with sewage sludge to increase biogas production. Results from this study show that the increase in biogas production is proportional to the increase in organic loading rate (OLR) rate due to BW addition. The OLR increase of 86 and 171% corresponding to 10 and 20% BW by volume in the feed resulted in 89 and 191% increase in biogas production, respectively. Under a stable condition, anaerobic co-digestion with BW did not lead to any significant impact on digestate quality (in terms of COD removal and biosolids odour) and biogas composition. The results suggest that existing nutrients in sewage sludge can support an increase in OLR by about 2â¯kg COD/m3/d from a carbon rich substrate such as soft drink BW without inhibition or excessive impact on subsequent handling of the digestate.
Assuntos
Reatores Biológicos , Bebidas Gaseificadas , Esgotos , Anaerobiose , BiocombustíveisRESUMO
A pilot-scale study was conducted to investigate the fate of trace organic contaminants (TrOCs) during anaerobic digestion of primary sludge. Of the 44 TrOCs monitored, 24 were detected in all primary sludge samples. Phase distribution of TrOCs was correlated well with their hydrophobicity (>67% mass in the solid phase when LogDâ¯>â¯1.5). The pilot-scale anaerobic digester achieved a steady performance with a specific methane yield of 0.39-0.92â¯L/gVSremoved and methane composition of 63-65% despite considerable variation in the primary sludge. The fate of TrOCs in the aqueous and solid phases was governed by their physicochemical properties. Biotransformation was significant (>83%) for five TrOCs with logDâ¯<â¯1.5 and electron donating functional groups in molecular structure. The remaining TrOCs with logDâ¯<â¯1.5 were persistent and thus accumulated in the aqueous phase. Most TrOCs with logDâ¯>â¯1.5 were poorly removed under anaerobic conditions. Sorption onto the solid phase appears to impede the biodegradation of these TrOCs.