Dissolved oxygen disturbs nitrate transformation by modifying microbial community, co-occurrence networks, and functional genes during aerobic-anoxic transition.

No consensus has been achieved among researchers on the effect of dissolved oxygen (DO) on nitrate (NO-N) transformation and the microbial community, especially during aerobic-anoxic transition. To supplement this knowledge, NO-N transformation, microbial communities, co-occurrence networks, and functional genes were investigated during aerobic-anoxic transition via microcosm simulation. NO-N transformation rate in the early stage (DO ≥2 mg/L) was always significantly higher than that in the later stage (DO <2 mg/L) during aerobic-anoxic transition, and NO-N accumulation was more significant during the anoxic stage, consistent with the result obtained under constant DO conditions.

Nitrogen species control the interaction between NO-N reduction and aniline degradation and microbial community structure in the oxic-anoxic transition zone.

Contrary to the fact that NO-N can serve as electron acceptor to promote organics degradation, it was also found NO-N reduction does not necessarily promote organics degradation. We speculate nitrogen (N) species may control the interaction between NO-N reduction and organics degradation via shifting related microbial community structure. To prove the hypothesis, oxic-anoxic transition zone (OATZ) microcosms simulated by lake water and sediment were conducted with the addition of N species (NO-N, NO-N, and NH-N) and aniline as typical organics.

Changes in the fluorescence intensity, degradability, and aromaticity of organic carbon in ammonium and phenanthrene-polluted aquatic ecosystems.

Mixed cultures were established by a sediment to investigate the changes in organic carbon (C) in a combined ammonium and phenanthrene biotransformation process in aquatic ecosystems. The microorganisms in the sediment demonstrated significant ammonium-N and phenanthrene biotransformation capacity with removal efficiencies of 99.96% and 99.

NH-N/NO-N ratio controlling nitrogen transformation accompanied with NO-N accumulation in the oxic-anoxic transition zone.

Although nitrogen (N) transformations have been widely studied under oxic or anoxic condition, few studies have been carried out to analyze the transformation accompanied with NO-N accumulation. Particularly, the control of mixed N species in N-transformation remains unclear in an oxic-anoxic transition zone (OATZ), a unique and ubiquitous redox environment. To bridge the gap, in this study, OATZ microcosms were simulated by surface water and sediments of a shallow lake.

Characteristics and metabolic pathway of the bacteria for heterotrophic nitrification and aerobic denitrification in aquatic ecosystems.

The present study investigated the nitrogen removal characteristics and metabolic pathway of bacteria in aquatic ecosystem, with a focus on heterotrophic nitrification and aerobic denitrification. The bacteria demonstrated significant heterotrophic nitrification and aerobic denitrification capacity. The highest ammonium-N, nitrate-N, and nitrite-N removal efficiencies were 95.

The correlation analyses of bacterial community composition and spatial factors between freshwater and sediment in Poyang Lake wetland by using artificial neural network (ANN) modeling.

As one of the most important components of the lake ecosystem, microorganisms from the freshwater and sediment play an important role in many ecological processes. However, the difference and correlation of bacterial community between these two niches were not clear. This study investigated the diversity of microbial community of freshwater and sediment samples from fifteen locations in Poyang Lake wetland.

A lab-scale study on heterotrophic nitrification-aerobic denitrification for nitrogen control in aquatic ecosystem.

Nitrogen (N) loss is generally caused by denitrification under anaerobic conditions and the N loss in the heterotrophic nitrificationaerobic denitrification (HNAD) system is of recent research interest. However, previous studies are generally focused on pure cultures-based system and the information on HNAD in the complex aquatic ecosystem is limited. In this study, HN-AD system was established in the mixed cultures of the sediments and the performances of HN-AD were evaluated under different conditions.

Effects of Ni(2+) on aluminum hydroxide scale formation and transformation on a simulated drinking water distribution system.

Observations of aluminum containing sediments/scales formed within the distribution pipes have been reported for several decades. In this study, the effect of Ni(2+) on the formation and transformation processes of aluminum hydroxide sediment in a simulated drinking water distribution system were investigated using X-ray diffraction spectrum (XRD), Fourier transform infrared spectrum (FT-IR), scanning electron microscope (SEM), and thermodynamic calculation methods. It was determined that the existence of Ni(2+) had notable effects on the formation of bayerite.