Improve biogas production from low-organic-content sludge through high-solids anaerobic co-digestion with food waste. (November 2016)

• Record Type: Journal Article
• Authors: Liu, Chuanyang; Li, Huan; Zhang, Yuyao; Liu, Can
• Is Part Of: Bioresource technology. Volume 219(2016)
• Page Start: 252
• Page End: 260
• Publication Date: 2016-11
• Subjects: Anaerobic digestion -- Biogas -- Food waste -- Sewage sludge; Biomass -- Periodicals; Biomass energy -- Periodicals; Bioremediation -- Periodicals; Agricultural wastes -- Periodicals; Factory and trade waste -- Periodicals; Organic wastes -- Periodicals; Bioénergie -- Périodiques; Déchets agricoles -- Périodiques; Déchets industriels -- Périodiques; Déchets organiques -- Périodiques; Déchets (Combustible) -- Périodiques; 662.88
• DOI: 10.1016/j.biortech.2016.07.130
• Languages: English
• ISSNs: 0960-8524

Abstract

Highlights: More biogas produced by adding food waste to low-organic-content sludge. No synergetic effect of co-substrate for biogas production at low solid concentration. Excessive acidification is the key risk inhibiting low-solids co-digestion. The blend ratio 1:1 of food waste and sludge is optimal for high-solids co-digestion. Cumulated free ammonia is the key risk threatening high-solids co-digestion. Abstract: Anaerobic co-digestion of sewage sludge and food waste was tested at two different total solid (TS) concentrations. In the low-solids group with TS 4.8%, the biogas production increased linearly as the ratio of food waste in substrate increased from 0 to 100%, but no synergetic effect was found between the two substrates. Moreover, the additive food waste resulted in the accumulation of volatile fatty acids and decelerated biogas production. Thus, the blend ratio of food waste should be lower than 50%. While in the high-solids group with TS 14%, the weak alkaline environment with pH 7.5–8.5 avoided excessive acidification but high concentration of free ammonia was a potential risk. However, good synergetic effect was found between the two substrates because the added food waste improved mass transfer in sludge cake. Thus, 50% was recommended as the optimum ratio of food waste in substrate because of the best synergetic effect.