Isotope analysis of nitrogen removal pathways and NO production potential in the SDAD-anammox system under different N/S ratios.

This study explored the impact of varying nitrate to sulfide (N/S) ratios on nitrogen removal efficiency (NRE) in the sulfide-driven autotrophic denitrification and anammox (SDAD-anammox) system. Optimal nitrogen removal was observed at N/S ratios between 1.5 and 2.

Integrated process of Tetrasphaera-dominated in-situ waste activated sludge fermentation, biological phosphorus removal and endogenous denitrification in single reactor for treatment of wastewater with limited carbon sources.

An integrated process of sludge in-situ fermentation, biological phosphorus removal and endogenous denitrification (ISFPR-ED) was developed to treat low ratio of chemical oxygen demand to nitrogen (COD/N) wastewater and waste activated sludge (WAS) in a single reactor. Nutrient removal and WAS reduction were achieved due to Tetrasphaera-dominated sludge fermentation provided organic carbon in extending the anaerobic duration. The WAS reduction efficiency, effluent orthophosphate (PO-P) and total inorganic nitrogen reached 28.

Impact of organic carbon on sulfide-driven autotrophic denitrification: Insights from isotope fractionation and functional genes.

Additional organics are generally supplemented in the sulfide-driven autotrophic denitrification system to accelerate the denitrification rate and reduce sulfate production. In this study, different concentrations of sodium acetate (NaAc) were added to the sulfide-driven autotrophic denitrification reactor, and the S accumulation increased from 7.8% to 100% over a 120-day operation period.

Combined Phototrophic Simultaneous Nitrification-Endogenous Denitrification with Phosphorus Removal (P-SNDPR) System Treating Low Carbon to Nitrogen Ratio Wastewater for Potential Carbon Neutrality.

Conventional biological nutrient removal processes rely on external aeration and produce significant carbon dioxide (CO) emissions. This study constructed a phototrophic simultaneous nitrification-denitrification phosphorus removal (P-SNDPR) system to treat low carbon to nitrogen (C/N) ratios wastewater and investigated the impact of sludge retention time (SRT) on nutrient removal performance, nitrogen conversion pathway, and microbial structure. Results showed that the P-SNDPR system at SRT of 15 days had the highest nutrient removal capacity, achieving over 85% and 98% removal of nitrogen and phosphorus, respectively, meanwhile maintaining minimal CO emissions.

An integrated system combining Tetrasphaera-dominated enhanced biological phosphorus removal with sulfur autotrophic denitrification to enhance biological nutrients removal.

This study developed a two-stage process, including Tetrasphaera-dominated enhanced biological phosphorus-removal (EBPR(T)) sequencing batch reactor (SBR), followed by sulfur autotrophic denitrification (SADN) SBR, to achieve advanced nutrients removal from low VFAs wastewater. The removal efficiencies of nitrogen and phosphorus (PO-P) reached 99 % with effluent PO-P and total inorganic nitrogen (TIN) below 0.5 mg/L and 1 mg/L in EBPR(T) and SADN SBR, respectively.

Optimizing sludge retention time for sustainable photo-enhanced biological phosphorus removal systems: Insights into nutrient fate, microbial community, and bacterial phototolerance.

Photo-enhanced Biological Phosphorus Removal (PEBPR) systems, promising wastewater treatment technology, offer efficient phosphorus removal without external oxygen. However, comprehending the impact of sludge retention time (SRT) on the system is crucial for successful implementation. This study investigated the SRT effect on nutrient fate, microbial community, and bacterial phototolerance in PEBPR systems.

The successful application of light to the system of simultaneous nitrification/endogenous denitrification and phosphorus removal: Promotion of partial nitrification and glycogen accumulation metabolism.

Partial nitrification (PN) and high glycogen accumulating metabolism (GAM) activity are the basis for efficient nitrogen (N) and phosphorus (P) removal in simultaneous nitrification endogenous denitrification and phosphorus removal (SNDPR) systems. However, achieving these processes in practical operations is challenging. This study proposes that light irradiation is a novel strategy to enhance the nutrient removal performance of the SNDPR system with low carbon to nitrogen ratios (C/N of 3.

Simultaneous nitrogen and sulfur removal through synergy of sulfammox, anammox and sulfur-driven autotrophic denitrification in a modified bioreactor enhanced by activated carbon.

Anaerobic ammonium (NH - N) oxidation coupled with sulfate (SO) reduction (sulfammox) is a new pathway for the autotrophic removal of nitrogen and sulfur from wastewater. Sulfammox was achieved in a modified up-flow anaerobic bioreactor filled with granular activated carbon. After 70 days of operation, the NH - N removal efficiency almost reached 70%, with activated carbon adsorption and biological reaction accounting for 26% and 74%, respectively.

Sulfide inhibition on polyphosphate accumulating organisms and glycogen accumulating organisms: Cumulative inhibitory effect and recoverability.

Sulfate in wastewater can be reduced to sulfide and its impact on the stability of enhanced biological phosphorus removal (EBPR) is still unclear. In this study, the metabolic changes and subsequent recovery of polyphosphate accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs) were investigated at different sulfide concentrations. The results showed that the metabolic activity of PAOs and GAOs was mainly related to HS concentration.

An effective titanium salt dosing strategy for phosphorus removal from wastewater: Synergistic enhancement of chemical and biological treatment.

Titanium salt coagulant, as a new type of water treatment agent, has been widely studied, but most researches do not consider its effect on the biological treatment. In this study, different doses of TiCl were added to the biological phosphorus removal (BPR) system to investigate the impact of TiCl on BPR. The results showed that the addition of TiCl not only significantly reduced the phosphorus concentration in effluent (below 0.

Phosphorus removal performance, intracellular metabolites and clade-level community structure of Tetrasphaera-dominated polyphosphate accumulating organisms at different temperatures.

Tetrasphaera are polyphosphate accumulating organisms (PAOs) that play an important role in enhanced biological phosphorus removal (EBPR) from wastewater. The effect of a wide range of temperature changes (1-30 °C) on phosphorus removal, metabolism and clade-level community structure of Tetrasphaera-dominated PAOs was investigated. At 10 °C, the bioactivities of Tetrasphaera-dominated communities were obviously inhibited and the EBPR efficiency was only 73 %.

Identification of partial denitrification granulation enhanced by low C/N ratio in the aspect of metabolomics and quorum sensing.

Partial denitrification granular sludge (PDGS) and denitrification granular sludge (DGS) play an important role in nitrogen removal from wastewater. However, the inherent cause of aggregation capacity related to the ratio of COD to nitrogen (COD/N) is still unclear. In this study, metabolomics analysis was combined with microbiological analyses, granular performance and extracellular polymeric substances (EPS) structure to explore the granulation mechanism at different influent COD/N ratios.

Achieving enhanced biological phosphorus removal utilizing waste activated sludge as sole carbon source and simultaneous sludge reduction in sequencing batch reactor.

Achieving enhanced biological phosphorus removal dominated by Tetrasphaera utilizing waste activated sludge (WAS) as carbon source could solve the problems of insufficient carbon source and excessive discharge of WAS in biological phosphorus removal. Up to now, the sludge reduction ability of Tetrasphaera remained largely unknown. Furthermore, the difference between traditional sludge fermentation and sludge fermentation dominated by Tetrasphaera was still unclear.

Bioinspired Anti-Plateau-Rayleigh-Instability on Dual Parallel Fibers.

The Plateau-Rayleigh instability (PRI) is a well-known phenomenon where a liquid column always breaks up into droplets to achieve the minimization of surface energy. It normally leads to the non-uniformity of a liquid film, which, however, is unfavorable for the fluid coating process. So far, strategies to overcome this instability rely on either the surfactants, UV/high-temp curing treatments, or specific chemical reactions, which suffer from both limited liquid composition and complicated experimental conditions.

Insights into the effects of acetate on the community structure of Candidatus Accumulibacter in biological phosphorus removal system using DNA stable-isotope probing (DNA-SIP).

Sodium acetate has been most commonly used as the external carbon source to achieve successful performance of full-scale enhanced biological phosphorus removal (EBPR) processes, but its microbial mechanism for the improvement of phosphorus removal performance was still unclear. DNA based stable-isotope probing (DNA-SIP) is able to discriminate the metabolic activity of different microbes for specific substrates, thus it was applied to explore the different effects of sodium acetate on the community structure of Candidatus Accumulibacter (hereafter called Accumulibacter) and Candidatus Competibacter (hereafter called Competibacter) in a modified University of Cape Town (MUCT) process treating the real domestic sewage. Results showed that acetate addition significantly improved the abundance of Accumulibacter and Competibacter in MUCT.

Investigation of the polyphosphate-accumulating organism population in the full-scale simultaneous chemical phosphorus removal system.

The simultaneous chemical phosphorus removal (SCPR) process has been widely applied in wastewater treatment plants (WWTPs) due to the high phosphorus removal efficiency through the synergy of biological and chemical phosphorus removal (BPR and CPR). However, phosphorus removal reagents could affect the bacterial community structure in the SCPR system and further affect the BPR process. The BPR phenotypes and community structures in the SCPR system, especially the population of polyphosphate-accumulating organisms (PAOs), are not completely clear.

Transcriptional responses of Candidatus Accumulibacter clades to environmental dynamics in enhanced biological phosphorus removal.

The dynamic response mechanism of Candidatus Accumulibacter clades to environmental factors in enhanced biological phosphorus removal (EBPR) was unclear. This study investigated the relationship between the transcriptional responses of Candidatus Accumulibacter clades and environmental dynamics. Results suggested that Candidatus Accumulibacter clade IIA only responded in initial 20 and 30 min of P-release and P-uptake stage, respectively, and was also the first clade to stop responding among the six Candidatus Accumulibacter clades.

Microbial community at transcription level in the synergy of GAOs and Candidatus Accumulibacter for saving carbon source in wastewater treatment.

The microbial community in endogenous denitrification and denitrifying phosphorus removal treatment at transcription level was unknown. This study first confirmed the expression of actually active bacteria in endogenous denitrification and denitrifying phosphorus removal system to treat low C/N municipal wastewater. No external carbon source was added to influent wastewater.

Effects of polyaluminium chloride addition on community structures of polyphosphate and glycogen accumulating organisms in biological phosphorus removal (BPR) systems.

Polyaluminium chloride (PAC) was added into the biological phosphorus removal (BPR) systems to investigate the populations of polyphosphate and glycogen accumulating organisms (PAOs and GAOs). Typical BPR performed under Al:P of 1:1, while BPR almost disappeared at Al:P of 4:1. Even with high PAC addition, PAOs still existed in systems.

Bioinspired Controllable Liquid Manipulation by Fibrous Array Driven by Elasticity.

Fibers exhibit excellent performance in liquid manipulation that is normally aroused by either the structural or the chemical gradient. Here, we developed radially arranged fiber arrays with different fibrous elasticities that exhibited distinctly different performances in liquid manipulation in terms of the fibrous elastocapillary coalescence, the high-efficiency water encapsulation, and the inability to manipulate liquid. It is proposed that the fiber elasticity acts as a driving force when interacting with liquid, equivalent with the structural and chemical gradient.

Bioinspired Dynamic Wetting on Multiple Fibers.

Natural fibers have versatile strategies for interacting with water media and better adapting to the local environment, and these strategies offer inspiration for the development of artificial functional fibers with diverse applications. Wetting on fibers is a dynamic liquid-moving process on/in fibrous systems with various patterns, and the process is normally driven by the structural gradient, chemical gradient, elasticity of a single fiber, or the synergistic effect of these factors in multiple fibers in an integrated system in which the spatial geometry of the fibers is involved. Compared with the directional liquid movement on a single fiber, wetting on multiple fibers in both the micro- and macroscales is particularly fascinating, with various performances, including directional liquid transport, controllable liquid transfer, efficient liquid encapsulation, and capillary-induced fibrous coalescence.

Highly Boosted Oxygen Reduction Reaction Activity by Tuning the Underwater Wetting State of the Superhydrophobic Electrode.

By rationally designing superhydrophobic electrodes with different underwater wetting states, it is revealed that only the underwater Wenzel-Cassie coexistent state shows the clearly enhanced ability in catalyzing the oxygen reduction reaction, a typical underwater gas-consuming reaction at electrode. It is proposed that the maximizing and stabilizing the liquid/gas/solid triphase interface, endowed by the underwater Wenzel-Cassie coexistent state, plays a rather crucial role.

Facile One-Step Strategy for Highly Boosted Microbial Extracellular Electron Transfer of the Genus Shewanella.

High performance of bacterial extracellular electron transfer (EET) is essentially important for its practical applications in versatile bioelectric fields. We developed a facile one-step approach to dramatically boost the bacterial EET activity 75-fold by exogenous addition of ethylenediamine tetraacetic acid disodium salt (EDTA-2Na, 1 mM) into the electrochemical cells, where the anodic process of microbial EET was monitored. We propose that EDTA-2Na enables both the alternation of the local environment around the c-type cytochromes located on the outer membrane channels (OMCs), which therefore changes the redox behavior of OMCs in mediating the EET process, and the formation of densely packed biofilm that can further facilitate the EET process.

Instability of Liquids in Flexible Fiber Brushes under Applied Pressure.

We theoretically predict the stability of liquid in a model brush made of flexible fibers for cases in which liquid is supplied from an ink reservoir. The volume of the liquid in the brush increases with increasing applied pressure by the reservoir, and the liquid shows instability at a critical pressure. When the fibers are shorter than a critical length, the end of the brush opens continuously with increasing applied pressure.