Food waste shock for reducing methane emissions from sewer pipelines

초록

Sewer pipelines, while essential for urban sanitation, are significant sources of methane (CH4) emissions, especially when food waste (FW) is introduced via kitchen disposers. This study explores a novel mitigation method "FW shock" inspired by shock loading known to disrupt anaerobic digestion. Five lab-scale gravity sewer pipelines (P1-P5) were operated, initially with only domestic wastewater (DWW), followed by FW addition: continuously in P1 and intermittently in P2-P5 after accumulating FW for 2 to 7 days. Continuous FW addition in P1 led to a sustained CH4 increase (from 44.6 to 98.0 mL CH4/Lsewage), while FW shocks induced peak emissions on the shock day, followed by rapid declines. The greatest reduction (61.8 %) was observed in P4 (5-day shock). pH dropped to similar to 6.4 in P4, compared to >7.8 in P1, contributing to methanogenic inhibition. Microbial and enzymatic analyses confirmed suppression of acetoclastic methanogens under low pH conditions induced by FW shock.

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