Microbial aerobic denitrification dominates nitrogen losses from reservoir ecosystem in the spring of Zhoucun reservoir.

In-situ remediation of sediment by calcium nitrate combined with composite microorganisms under low-DO regulation

Effects of nitrate dosing on the migration of reduced sulfur in black odorous river sediment and the influencing factors

Reservoir water stratification and mixing affects microbial community structure and functional community composition in a stratified drinking reservoir.

Nitrogen (N) loss is generally caused by denitrification under anaerobic conditions and the N loss in the heterotrophic nitrification_aerobic denitrification (HN_AD) system is of recent research interest. However, previous studies are generally focused on pure cultures-based system and the information on HN_AD 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. Further, the N loss mechanism in HN_AD system was explored. The study found that the N was lost in the sediment cultures with ammonium-N (NH4+_N) (or) and nitrate-N (NO3−_N) as N source under aerobic conditions. The highest N loss rate was achieved under the TOC/TN mass ratio of 10 with citrate as the carbon source. Under this condition, the N loss percentages of NH4+_N (201.91 mg/L) and NO3−_N (130.00 mg/L) reached 99.61% and 100.00%, respectively, which were higher than those in the pure HN_AD strains reported in the literature. High NH4+_N removal efficiencies were also achieved at low C/N mass ratio and high NH4+_N concentration (493.12 mg L−1). The N loss pathway in the system was investigated by adding Na2WO4 as the nitrate reductase inhibitor. The study found that the N was not lost via partial nitrification/denitrification pathway, i.e., NH4+ → NH2OH → NO2− → N2O (N2), instead via full nitrification/denitrification pathway, i.e., NH4+ → NH2OH → NO2− → NO3− → NO2− → N2O (N2), since nitrate was a key intermediate. The variation in NH4+_N, NO3−_N, and NO2−_N concentrations in the HN_AD processes further confirmed the N transformation pathway. Therefore, HN_AD may occur and cause N loss in natural aquatic ecosystems. The results of this study demonstrate that N was lost through HN-AD and that the well-cultured HN-AD sediments could be useful biological tool to remediate eutrophic water bodies.

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

Mechanism of aerobic denitrifiers and calcium nitrate on urban river sediment remediation.

True morels (Morchella, Pezizales) cultivated in soil are subject to complex influences from soil microbial communities. To explore the characteristics of soil microbial communities on morel cultivation, and evaluate whether these microbes are related to morel production, we collected 23 soil samples from four counties in Sichuan and Yunnan Provinces, China. Based on ITS and 16S rDNA amplicon sequencing, the alpha diversity analysis indicated that the biodiversity of morel cultivation soil showed a downward trend compared with the bare soil. The results also showed that there were no significant differences in soil microbial communities between OC (bare soil) and OO (after one-year suspension of sowing). This means that, after about one year of stopping sowing, the component and structure of soil that once cultivated morel would be restored. In co-occurrence networks, some noteworthy bacterial microbes involved in nitrogen fixation and nitrification have been identified in soils with high morel yields, such as Arthrobacter, Bradyhizobium, Devosia, Pseudarthrobacter, Pseudolabrys, and Nitrospira. In contrast, in soils with low or no morel yield, some pathogenic fungi accounted for a high proportion, including Gibberella, Microidium, Penicillium, Sarocladium, Streptomyces, and Trichoderma. This study provided valuable information for the isolation and culturing of some beneficial microbes for morel cultivation in further study and, potentially, to harness the power of the microbiome to improve morel production and health.

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Morel Production Associated with Soil Nitrogen-Fixing and Nitrifying Microorganisms

Large amounts of low-temperature and medium-temperature waste heat are produced and often go unused in the petrochemical industry. Low-temperature power generation technology is considered an important solution for waste heat recovery. This paper presents a feasibility analysis for a low-temperature power generation system (LTPGS) based on the organic Rankine cycle (ORC). The paper begins with an introduction to the ORC and makes contrastive analyses of six candidate working fluids, leading to the selection of TY-1 as the best fluid. Secondly, experimental research was used to obtain the relationships between the system parameters. Thirdly, based on long-term experimental data and experiences in engineering applications, the LTPGS was designed taking into account the chemical process. The process of purified wastewater has been taken as a case to subject to feasibility analysis about economic and environmental benefits. The results show that the LTPGS power-generating efficiency is 8.4% in winter ...

Mengyi Lv

Papers

Mechanism of aerobic denitrifiers and calcium nitrate on urban river sediment remediation.

Morel Production Associated with Soil Nitrogen-Fixing and Nitrifying Microorganisms

Experimental Research and Feasibility Analysis of Low-Temperature Power Generation Systems Used in Petrochemical Industry