1-Butyl-3-methylimidazolium Chloride Affects Anaerobic Digestion through Altering Organics Transformation, Cell Viability, and Microbial Community

Abstract

1-Butyl-3-methylimidazolium chloride (BmimCl), an imidazolium-based ionic liquid, is considered the representative emerging persistent aquatic pollutant, and its environmental toxicity has attracted a growing concern. However, most of the investigations focused on monocultures or a single organism, with little information available on the complex syntrophic consortium that dominates the complex and successional biochemical processes, such as anaerobic digestion. In this study, the effect of BmimCl at environmentally relevant levels on glucose anaerobic digestion was therefore investigated in several laboratory-scale mesophilic anaerobic digesters to provide such support. Experimental results showed that BmimCl at 1–20 mg/L inhibited the methane production rate by 3.50–31.03%, and 20 mg/L BmimCl inhibited butyrate, hydrogen, and acetate biotransformation by 14.29%, 36.36%, and 11.57%, respectively. Toxicological mechanism studies revealed that extracellular polymeric substances (EPSs) adsorbed and accumulated BmimCl through carboxyl, amino, and hydroxyl groups, which destroyed the EPSs’ conformational structure, thereby leading to the inactivation of microbial cells. MiSeq sequencing data indicated that the abundance of Clostridium_sensu_stricto_1, Bacteroides, and Methanothrix decreased by 6.01%, 7.02%, and 18.45%, respectively, in response to 20 mg/L BmimCl. Molecular ecological network analysis showed that compared with the control, the lower network complexity, fewer keystone taxa, and fewer associations among microbial taxa were found in the BmimCl-present digester, indicating the reduced stability of the microbial community.

Cetyltrimethylammonium Bromide Enhances Anaerobic Fermentative Production of Short-Chain Fatty Acids from Waste Activated Sludge

“…The maximum SCFA yield reached 290.3 ± 5.8 mg COD/g VSS in the 0.06 g/g TSS CTAB fermenter on day 8, while 0.09 and 0.12 g/g TSS CTAB fermentative groups obtained the highest SCFA yields of 262.4 ± 4.2 and 184.2 ± 5.4 mg COD/g VSS, respectively, on day 10. The reduction in the accumulated yield of SCFAs in fermenters with high doses of CTAB might be attributed to the inhibition of the activities of acid-producing bacteria by the high concentrations of chemicals . The SCFA yield decreased gradually after 10 days of fermentation, which might be caused by the rapid consumption of SCFAs by methanogens .…”

“…The reduction in the accumulated yield of SCFAs in fermenters with high doses of CTAB might be attributed to the inhibition of the activities of acid-producing bacteria by the high concentrations of chemicals. 30 The SCFA yield decreased gradually after 10 days of fermentation, which might be caused by the rapid consumption of SCFAs by methanogens. 31 It was noteworthy that the SCFA yield of 0.06 g/g TSS CTAB fermenter (290.3 ± 5.8 mg COD/g VSS) was not significantly improved compared to the 0.03 g/g TSS CTAB reactor (273.5 ± 3.6 mg COD/g VSS).…”

Insights into the Occurrence, Fate, Impacts, and Control of Food Additives in Food Waste Anaerobic Digestion: A Review

“…The adaptation of microorganisms in high-salinity environments (20 g/L NaCl) was explored by investigating the variations of bacterial and archaeal communities . It was found that at the phylum level, a high salinity significantly reduced the relative abundance of the phylum Euryarchaeota, which decreased from 48.77% to 18.26% after operation for 480 h. In contrast, the relative abundance of Firmicutes, Synergistetes, Thermotogae, and Actinobacteria increased, which were associated with accumulated VFAs in anaerobic digesters. , The promotion of these microorganisms might be due to the reduced relative abundance of methanogens and other functional microorganisms rather than an absolute increase in the number of bacteria associated with the production of VFAs. Additionally, these results also may be the microbial response to a salt shock.…”

Uncovering the Mechanisms of How Capsaicin Affects Short-Chain Fatty Acid Production during Food Waste Valorization

“…However, the influence of capsaicin on complex microbial systems (i.e., anaerobic fermentation system) has rarely been published. Anaerobic fermentation involves mainly substrates, microbes, and intricate biochemical reactions, namely, hydrolysis, acidification, and methanogenesis, each of which has the potential to become the rate-limiting step in the production of SCFAs . In this regard, it is imperative to discern the specific effects of capsaicin on each individual step in order to enhance our comprehension of the underlying mechanisms associated with the production of SCFAs.…”

“…Anaerobic fermentation involves mainly substrates, microbes, and intricate biochemical reactions, namely, hydrolysis, acidification, and methanogenesis, each of which has the potential to become the ratelimiting step in the production of SCFAs. 19 In this regard, it is imperative to discern the specific effects of capsaicin on each individual step in order to enhance our comprehension of the underlying mechanisms associated with the production of SCFAs. The systematic elucidation of microbial functional trait variations at the genetic level can provide insight into the influence of capsaicin on biological processes.…”