Dosage-Dependent Toxicity of Universal Solvent Dimethyl Sulfoxide to the Partial Nitrification Wastewater Treatment Process

Abstract

Laboratory-scale bioreactors were used to study the effect of dimethyl sulfoxide (DMSO) on the start-up, pollutant removal efficiency, and microbial community of nitrification (basic wastewater treatment process). The partial nitrification start-up time with 1 and 2% DMSO addition was 14 and 20 days, and reactor with 3.5% DMSO addition did not start up successfully until 42 days. When the DMSO concentration was above 2%, it had a significant inhibitory effect on the nitrification process. Although the abundance of Nitrosomonas increased from 9.7% (the control) to 11.9% (3% DMSO), the specific oxygen uptake rate of ammonia-oxidizing bacteria decreased from 0.64 to 0.08 mg O2/(gMLSS·min). The principal component analysis results indicated that when the DMSO concentration exceeded 2%, the microbial community was significantly different from that at a low concentration. The key classes of Blastocatellia and Clostridia under low concentration DMSO changed to Actinobacteria and Acidobacteria under high DMSO content environment. LC–MS analysis revealed that DMSO was degraded in the reactor, and a large amount of methanesulfenic acid was generated. Apparently, the widely used biological solvent DMSO was toxic to microorganisms at high concentration, and the concentration should be less than 2% when using DMSO as a solvent.

Fullerene (C60) Supplementation Stimulated Anammox Granules at Low Doses and Inhibition Occurred at High Doses: Phenomenon and Mechanism

“…Therefore, this study aims to utilize C60 as a supplement to stimulate anammox granules and enhance nitrogen removal performance in a long-term operation. The main targets of this work include (1) determining the effect of C60 on the nitrogen removal performance of an anammox reactor by tracking and monitoring the nitrogen fraction content; (2) analyzing the influence of C60 on the morphology of anammox granules; (3) revealing the alteration in microbial community dynamics and functional genes as a result of C60 supplementation; (4) exploring the interaction between C60 and hydrazine synthase, the main anammox-related enzyme, by molecular docking analysis; and (5) investigating the mechanism behind anammox enhancement due to C60 supplementation. This research study would provide comprehensive information on how C60 affects the microbial activity of anammox granules and an explanation of the mechanisms involved.…”

“…Microbial transformation has been recognized as a central participant in the nitrogen cycle in different ecosystems. Bacteria are capable of diverse nitrogen biotransformation, including fixation, remineralization, nitrification, denitrification, and anaerobic ammonium oxidation (anammox), owing to their metabolic versatility. , Under anaerobic conditions, anammox bacteria could convert ammonium and nitrite into dinitrogen, playing a significant role in the global nitrogen cycle. , Anammox is a generally recognized cost-effective wastewater treatment technology; thus, anammox-based technologies have been the research focus for many years and have been applied in high-ammonia-containing industrial wastewater treatment . However, the low growth rate of anammox bacteria remains an issue, making them susceptible to operational and environmental variables .…”