Anaerobic co-digestion of waste activated sludge and greasy sludge from flotation process: Batch versus CSTR experiments to investigate optimal design

Abstract

In this study, the maximum ratio of greasy sludge to incorporate with waste activated sludge was investigated in batch and CSTR experiments. In batch experiments, inhibition occurred with a greasy sludge ratio of more than 20-30% of the feed COD. In CSTR experiments, the optimal greasy sludge ratio was 60% of the feed COD and inhibition occurred above a ratio of 80%. Hence, batch experiments can predict the CSTR yield when the degradation phenomenon are additive but cannot be used to determine the maximum ratio to be used in a CSTR configuration. Additionally, when the ratio of greasy sludge increased from 0% to 60% of the feed COD, CSTR methane production increased by more than 60%. When the greasy sludge ratio increased from 60% to 90% of the feed COD, the reactor yield decreased by 75%.

Effects of lipid inhibition on biogas production of anaerobic digestion from oily effluents and sludges: An overview

“…Dewatered FOG when co digested with sewage sludge was reported to increase 2.95 times of methane production at 48% VS added as demonstrated by [16]. Apart from that, [19][20][21] evaluated the possibility of FOG as co-substrates were successful in enhancing the methane production. Methane production was also feasible for plug flow digester treating swine manure and used cooking grease.…”

“…The content of lipid can vary greatly depending on types of the sources of wastes. Listed characteristics as shown in Table 3 proved that the higher content of volatile solid is constituted by lipid content [21]. Moreover, a lipid constituent is contributes to high COD content in pet food processing wastewater [28].…”

“…The positive yield in biogas and methane production by high lipid wastewater is extensively reported from previous researchers [3,5,[15][16][17][18][19][20][21]. Apart from being disposed, the interest towards of lipid exploitation and its potential of becoming a source of renewable energy have shown an increase, especially in terms of waste recovery.…”

The Influence of Inoculum to Substrate Ratio on the Biochemical Methane Potential of Fat, Oil, and Grease in Batch Anaerobic Assays

“…Girault et al (2012) indicated that significant differences occur due to the presence of high lipid/fat fraction in the FOG. Therefore, high lipid wastes are often avoidable to be used as a main substrate for anaerobic digestion because it will cause inhibition to the methane production process.…”

Bovine bile as a bio-surfactant pre-treatment option for anaerobic digestion of high-fat cattle slaughterhouse waste

“…As evidenced by Girault et al [26] and Martin-Gonzalez et al [27], once an anaerobic consortium had overcome initial LCFA inhibition, the rate of biogas production increases to a similar rate as the controls. While the ATA was digesting cellulose, the recovery of the rate kinetics reproduced in the ATA indicated that bile produced reversible inhibition, while a dose of 6 g bile/L induced the first signs of decline in reaction kinetics.…”