Anaerobic co-digestion of biodiesel waste glycerin with municipal wastewater sludge: Microbial community structure dynamics and reactor performance

Optimization of Methane Production Based on Mixture Content of Sewage Sludge, Food Waste, and Glycerol

“…According to a review of literature, in a binary combination with sewage sludge, process optimization is limited to a concentration of glycerol up to 1% [19][20][21][22][23][24][25] or 2-3% [7,8]. In most of these studies, authors observed similar results with regard to raw glycerol limit concentration of 1% (v/v), as it led to an organic overloading and a marked decrease in biogas production after a few days of operation.…”

“…Nghiem et al [21], evaluated the co-digestion of 0.63 up to 3.00% (v/v) of raw glycerol and sludge mixture, and they reported that the lowest raw glycerol content presented the best result in terms of biogas production, achieving 1.3 m³ CH 4 /L applied raw glycerol. Razaviarani et al [22,23] added up to 1.8% (v/v) of raw glycerol to sludge and deduced that co-digestion optimization was related to the specific production of 880 mL CH 4 /g VTS applied , a value obtained by the addition of just 1.0% raw glycerol. Later, the same authors reported inhibitory effects to anaerobic co-digestion by the addition of 1.8% (v/v) and that 1.1% (v/v) addition was able to increase VTS destruction and biogas production [25].…”

A Review on Anaerobic Co-Digestion with a Focus on the Microbial Populations and the Effect of Multi-Stage Digester Configuration

“…A 4.6 and 1.3-times increase in the sequence abundances of the genera Methanomicrobium and Methanosaeta was obtained by the addition of 1.35% (v/v) biodiesel waste glycerin to the feed. These findings indicated that a greater number of hydrogenotrophic methanogens existed in the co-digestion reactor in comparison to the control reactor [86].…”

“…The growth of many more hydrogenotrophic populations than acetoclastic methanogens in the co-digestion reactor in phase 2 was observed. As reported elsewhere [86,103], this is assumed to be due to degradation of propionic acid, the major product of glycerol degradation, which is accelerated in the presence of H 2 -utilizing methanogens. Additionally, the production of methane from propionate degradation is thermodynamically feasible only when the H 2 partial pressure is maintained between 0.1 and 10.1 Pa by H 2 -utilizing methanogens.…”

“…The analysis of 16S rRNA proved stage 3 to be the most productive stage, as indicated by the increase in populations of both archaea and bacteria, and also the approximately 50% removal and conversion of VSS to biogas. Razaviarani et al [86] studied the correlation between the reactor performance and the microbial community dynamics during the AnCoD of different loadings of biodiesel waste glycerin with municipal wastewater sludge in a two-phase digester. The genus Methanomicrobium (hydrogenotrophic methanogens) and the genus Methanosaeta (acetoclastic methanogens) were found to be the dominant methanogenic populations.…”