Quorum sensing responses of r-/K-strategists Nitrospira in continuous flow and sequencing batch nitrifying biofilm reactors.

A better understanding of r-/K-strategists nitrifiers will help to balance the design and operation of bioprocesses for efficient pollution removal from wastewater. The objectives of study were to investigate the nitrite oxidation biokinetics, biofilm property, microbial community and quorum sensing (QS) of nitrifying biofilm in a continuously flow reactor (CFR) and a sequencing batch reactor (SBR). Results showed that nitrite-oxidizing bacteria were estimated to have a nitrite half saturation constant of 76.

Effects of ferroferric oxide on propionate methanogenesis in sequencing batch reactors: Microbial community structure and metagenomic analysis.

This study investigated the effects of ferroferric oxide (FeO) on propionate methanogenesis in anaerobic sequencing batch reactor (ASBR). Compared to ASBR (without FeO addition), the addition of 10 g/L FeO (ASBR) decreased the maximum methane production rate by 69.6 % when propionate was used as the sole substrate.

Analyzing the effect of organic carbon on partial nitrification-anammox process based on metagenomics and quorum sensing.

The effects of adding organic carbon on the performance of different partial nitrification-anammox (PNA) process (the activated sludge process and biofilm process) were studied, especially nitrogen removal, functional microbial activity, and microbial community structure. The potential influences of quorum sensing (QS) on the nitrogen metabolism were also analyzed. The results showed that the addition of organic carbon in biofilm systems could reduce total nitrogen (TN) removal percentages, while in activated systems it could increase TN removal percentages.

Coupled effects of ferroferric oxide supplement and ethanol co-metabolism on the methanogenic oxidation of propionate.

Direct interspecies electron transfer (DIET) is a new electron-transfer strategy for enhanced propionate degradation. Ethanol can enrich the DIET species of Geobacter and conductive ferroferric oxide (FeO) can promote DIET. Therefore, coupled effects of ethanol and FeO on propionate degradation were investigated.

Microbial interactions regulated by the dosage of ferroferric oxide in the co-metabolism of organic carbon and sulfate.

Effects of ferroferric oxide (FeO) and organic carbon on co-metabolism of sulfate and organic carbon were investigated. With FeO, the degradation of acetate and sulfate was inhibited when fed with acetate, while the degradation of acetate and propionate produced from ethanol was promoted when fed with ethanol. The dominant sulfate reducing bacteria (SRB) of acetate-fed reactors were Desulfobacteraceae (complete oxidizing SRB, CO-SRB) and Desulfurmonas (incomplete oxidizing SRB, IO-SRB).

Effects of carbon source on methanogenic activities and pathways incorporating metagenomic analysis of microbial community.

In this study, the effects of four types of organic compounds (tryptone, acetate/propionate, glucose and ethanol) on methanogenesis, electron transfer processes and microbial community structure were examined. When tryptone and acetate/propionate were used, the dominant methanogenic pathway was aceticlastic methanogenesis and Methanosarcina was the most abundant methanogen. When glucose or ethanol were provided as the external carbon source, the aceticlastic and hydrogenotrophic pathways were utilised simultaneously, and Methanosarcina and Methanobacterium were enriched.

Dynamics of intracellular polymers in enhanced biological phosphorus removal processes under different organic carbon concentrations.

Enhanced biological phosphorus removal (EBPR) may deteriorate or fail during low organic carbon loading periods. Polyphosphate accumulating organisms (PAOs) in EBPR were acclimated under both high and low organic carbon conditions, and then dynamics of polymers in typical cycles, anaerobic conditions with excess organic carbons, and endogenous respiration conditions were examined. After long-term acclimation, it was found that organic loading rates did not affect the yield of PAOs and the applied low organic carbon concentrations were advantageous for the enrichment of PAOs.