Unraveling the synergistic promotion mechanism of Fe coupling phragmites australis biomass for nitrogen removal in coastal wetland: From low to moderate salinities.

The simulated coastal constructed wetlands supplemented with Fe and phragmites australis (P.A) biomass (CW-M) were constructed to improve nitrogen removal under different salinities (0-15‰). Results showed that the denitrification performance of CW-M were improved significantly, with the higher NO-N removal of 72-94% and lower NO emission flux, when compared with mono-P.

Unveiling the microplastic perturbation on surface flow constructed wetlands with macrophytes of different life forms: Responses of nitrogen removal and sensory quality.

Microplastics (MPs) discharging into constructed wetlands pose risks to these ecosystems. Nevertheless, the perturbation of MPs to different types of macrophytes, which play important roles in purifying pollutants of wetlands, has not been fully elucidated. In this study, polystyrene MPs (PS-MPs) perturbation on nitrogen removal and sensory quality of surface flow constructed wetlands planted with emergent and submerged macrophytes were investigated.

Reveling the micromolecular biological mechanism of acetate, thiosulfate and Fe in ecological floating beds for treating low C/N wastewater: Insight into nitrogen removals and greenhouse gases reductions.

Selecting an appropriate electron donor to enhance nitrogen removal for treating low C/N wastewater in ecological floating beds (EFBs) is controversy. In this study, a systematic and comprehensive evaluation of sodium acetate (EFB-C), sodium thiosulfate (EFB-S) and iron scraps (EFB-Fe) was performed in a 2-year experiment on long-term viability including nitrogen removal and greenhouse gas emissions associated with key molecular biological mechanisms. The results showed that EFB-C (43-85 %) and EFB-S (40-88 %) exhibited superior total nitrogen (TN) removal.

Boosting the denitrification efficiency of iron-based constructed wetlands in-situ via plant biomass-derived biochar: Intensified iron redox cycle and microbial responses.

Considering the unsatisfied denitrification performance of carbon-limited wastewater in iron-based constructed wetlands (ICWs) caused by low electron transfer efficiency of iron substrates, utilization of plant-based conductive materials in-situ for improving the long-term reactivity of iron substrates was proposed to boost the Fe (III)/Fe (II) redox cycle thus enhance the nitrogen elimination. Here, we investigated the effects of withered Iris Pseudacorus biomass and its derived biochar on nitrogen removal for 165 days in ICWs. Results revealed that accumulate TN removal capacity in biochar-added ICW (BC-ICW) increased by 14.

Simultaneously enhanced autotrophic-heterotrophic denitrification in iron-based ecological floating bed by plant biomass: Metagenomics insights into microbial communities, functional genes and nitrogen metabolic pathways.

In this study, the ecological floating bed supporting with zero-valent iron (ZVI) and plant biomass (EFB-IB) was constructed to improve nitrogen removal from low-polluted water. The effects of ZVI coupling with plant biomass on microbial community structure, metabolic pathways and functional genes were analyzed by metagenomic sequencing, and the mechanism for nitrogen removal was revealed. Results showed that compared with mono-ZVI system (EFB-C), the denitrification efficiencies of EFB-IB were effectively enhanced, with the higher average NO-N removal efficiencies of 22.

Effects of ferrous addition to Vallisneria natans: An attempt to apply ferrous to submerged macrophyte restoration.

Restoration of submerged macrophytes is an efficient way for endogenous nutrient control and aquatic ecological restoration, but slow growth and limited reproduction of submerged macrophytes still exist. In this research, the effect of ferrous on the seed germination and growth of Vallisneria natans (V. natans) were studied through aquatic simulation experiments and its influence on the rhizosphere microbial community was also explored.

Surface Structure Analysis and Formaldehyde Removal Mechanism of Lotus Shell Biochar: An Experimental and Theoretical Perspective.

The adsorption of gaseous HCHO by raw lotus shell biochar carbonized at 500, 700, and 900 °C from the perspective of its internal crystal structure and surface functional groups was investigated by an integrated approach of experiments and density functional theory calculations. The results showed that lotus shell biochar carbonized at 700 °C had the best adsorption effect at a HCHO concentration of 10.50 ± 0.

Efficient nitrogen removal pathways and corresponding microbial evidence in tidal flow constructed wetlands for saline water treatment.

The artificial tidal wetlands ecosystem was believed to be a useful device in treating saline water, and it played a significant part in global nitrogen cycles. However, limited information is available on nitrogen-cycling pathways and related contributions to nitrogen loss in tidal flow constructed wetlands (TF-CWs) for saline water treatment. This study operated seven experimental tidal flow constructed wetlands to remove nitrogen from saline water at salinities of 0-30‰.

Microbial response to nitrogen removal driven by combined iron and biomass in subsurface flow constructed wetlands with plants of different ages.

This study investigated the nitrogen removal enhanced by combined iron scraps and plant biomass, and its microbial response in the wetland with different plant ages and temperatures. The results showed that older plants benefitted the efficiency and stability of nitrogen removal, which could reach 1.97 ± 0.

Efficient nitrogen removal through coupling biochar with zero-valent iron by different packing modes in bioretention system.

Three kinds of bioretention were designed to explore the effects of zero-valent iron (ZVI) and biochar on the nitrogen removal performance and to seek a more reasonable packing method in this study. The results showed that the effluent removal rates of nitrate, ammonium and total nitrogen were 53.30 ± 12.

New insight and enhancement mechanisms for Feammox process by electron shuttles in wastewater treatment - A systematic review.

Ammonium oxidation coupled to Fe(III) reduction (Feammox) is a newly discovered iron-nitrogen cycle process of microbial catalyzed NH oxidation coupled with iron reduction. Fe(III) often exists in the form of insoluble iron minerals resulting in reduced microbial availability and low efficiency of Feammox. Electron shuttles(ESs) can be reversibly oxidized and reduced which has the potential to improve Feammox efficiency.

Mixotrophic denitrification improvement in ecological floating bed: Interaction between iron scraps and plant biomass.

In this study, an iron scrap (IS)-based ecological floating bed was constructed to couple with plant biomass (FeB-EFB) for treating low-polluted water, and the nitrogen removal performance and mechanism were explored. The results showed that the nitrogen could be effectively removed in FeB-EFB, and the nitrate removal efficiency was 29.14 ± 8.

Microbial response mechanism of plants and zero valent iron in ecological floating bed: Synchronous nitrogen, phosphorus removal and greenhouse gas emission reduction.

Iron-based ecological floating beds (EFBs) are often used to treat the secondary effluent from wastewater treatment plant to enhance the denitrification process. However, the impact and necessity of plants on iron-based EFBs have not been systematically studied. In this research, two iron-based EFBs with and without plants (EFB-P and EFB) were performed to investigate the response of plants on nutrient removal, GHG emissions, microbial communities and functional genes.

Molecular analysis of microbial nitrogen transformation and removal potential in the plant rhizosphere of artificial tidal wetlands across salinity gradients.

This study explored the microbial nitrogen transformation and removal potential in the plant rhizosphere of seven artificial tidal wetlands under different salinity gradients (0-30‰). Molecular biological and stable isotopic analyses revealed the existence of simultaneous anammox (anaerobic ammonium oxidation), nitrification, DNRA (dissimilatory nitrate reduction to ammonium) and denitrification processes, contributing to nitrogen loss in rhizosphere soil. The microbial abundances were 2.

Enhanced nitrogen removal via iron‑carbon micro-electrolysis in surface flow constructed wetlands: Selecting activated carbon or biochar?

The iron-assisted autotrophic denitrification was plagued by passivation when introduced in surface flow constructed wetlands (SFCWs). Iron‑carbon micro-electrolysis (Fe/C-M/E) could facilitate the transfer of electrons during the utilization of iron. In this study, iron scraps coupling with activated carbon and biochar were applied to explore the effects of carbon materials on autotrophic denitrification.

Response mechanism of different electron donors for treating secondary effluent in ecological floating bed.

Electron donors have been widely used to improve denitrification performance. However, it is controversial which electron donor could be chosen. In this study, three electron donors were used to improve nitrogen removal from ecological floating beds (EFBs).

Remediation of selenium-contaminated soil through combined use of earthworm Eisenia fetida and organic materials.

Selenium (Se)-polluted soils pose serious threats to terrestrial ecosystems through food chains. This study evaluated the use of earthworm Eisenia fetida and organic materials for Se remediation. The greater mortality (6.

Nitrogen removal through collaborative microbial pathways in tidal flow constructed wetlands.

Constructed wetlands are efficient in removing nitrogen from water; however, little is known about nitrogen-cycling pathways for nitrogen loss from tidal flow constructed wetlands. This study conducted molecular and stable isotopic analyses to investigate potential dissimilatory nitrate reduction to ammonium (DNRA), denitrification, nitrification, anaerobic ammonium oxidation (anammox), and their contributions to nitrogen removal by two tidal wetland mesocosms, PA (planted with Phragmites australis) and NP (unplanted), designated to treat Yangtze River Estuary water. Our results show the mesocosms removed ~22.

Biological iron nitrogen cycle in ecological floating bed: Nitrogen removal improvement and nitrous oxide emission reduction.

Ecological floating beds (EFBs) have become a superior method for treating secondary effluent from wastewater treatment plant. However, insufficient electron donor limited its denitrification efficiency. Iron scraps from lathe cutting waste consist of more than 95% iron could be used as electron donors to enhance denitrification.

Depth-specific distribution and significance of nitrite-dependent anaerobic methane oxidation process in tidal flow constructed wetlands used for treating river water.

Tidal flow constructed wetlands (TF CWs) have been considered an effective approach to treat contaminated river water, as well as a significant role in global matter cycles, especially for carbon and nitrogen. Notably, it has been thought that methane oxidation was completely catalyzed by the aerobic process, ignoring the anaerobic methane oxidation, such as the nitrite-dependent anaerobic methane oxidation (n-damo) process. In our current work, therefore, we used molecular and stable isotopes to investigate the biodiversity, quantity and potential rate of n-damo bacteria in the TF CWs located in the Xisha Wetland Park in the Yangtze River estuary, China.

Thiosulfate-driven autotrophic and mixotrophic denitrification processes for secondary effluent treatment: Reducing sulfate production and nitrous oxide emission.

Three ecological floating beds (EFBs) with different additional electron donors including sodium thiosulfate, mixed electron donors of sodium thiosulfate and sodium acetate and without additional electron donors were established to compare the differences of nitrogen removal efficiency, nitrous oxide emission, microbial community and functional gene between autotrophic and mixotrophic denitrification. Results showed denitrification efficiency was nearly 100% in both autotrophic and mixotrophic process when electron donors were sufficient while that ranged from 4 to 43% without additional electron donors. Sodium acetate addition could effectively decrease sulfate concentration in effluent and nitrogen oxide flux.

Nitrogen loss by anaerobic ammonium oxidation in a mangrove wetland of the Zhangjiang Estuary, China.

Anaerobic ammonium oxidation (anammox), a microbial process in which NH is oxidized to N gas, is considered a significant nitrogen cycle process, but its significance in mangrove wetland sediments, particularly its depth- and genus-specific distribution and activity have remained uncertain. Here we report the vertical distribution, abundance, activity and role of anammox bacteria in mangrove sediments of Zhangjiang Estuary, China. We used stable isotope-tracer techniques, 16S rRNA and anammox bacterial functional gene (Hydrazine synthase B: hzsB) clone libraries and quantitative polymerase chain reaction (qPCR) assays, along with an assessment of nutrient profiles of sediment core samples.

Simultaneous improving nitrogen removal and decreasing greenhouse gas emission with biofilm carriers addition in ecological floating bed.

Ecological floating bed (EFB) is a green technology for treatment of micro-polluted wastewater. However, its nitrogen removal efficiency is still unsatisfactory. In this study, two EFBs with additional carbon source were established to explore biofilm carriers addition on nitrogen removal and greenhouse gas (GHG) emissions at different C/N ratios and temperatures.