The incorporation of defects, such as vacancies, into functional materials could substantially tailor their intrinsic properties. Progress in vacancy chemistry has enabled advances in many ...technological applications, but creating new type of vacancies in existing material system remains a big challenge. We show here that ionized nitrogen plasma can break bonds of iron-carbon-nitrogen-nickel units in nickel-iron Prussian blue analogues, forming unconventional carbon-nitrogen vacancies. We study oxygen evolution reaction on the carbon-nitrogen vacancy-mediated Prussian blue analogues, which exhibit a low overpotential of 283 millivolts at 10 milliamperes per square centimeter in alkali, far exceeding that of original Prussian blue analogues and previously reported oxygen evolution catalysts with vacancies. We ascribe this enhancement to the in-situ generated nickel-iron oxy(hydroxide) active layer during oxygen evolution reaction, where the Fe leaching was significantly suppressed by the unconventional carbon-nitrogen vacancies. This work opens up opportunities for producing vacancy defects in nanomaterials for broad applications.
Anaerobic digestion, an economic and energy-efficient biological process, is extensively applied in the treatment of a variety of wastewater streams and organic wastes. However, the ineffective ...mineralization of degradation-resistant organic wastes is considered a limiting factor for this promising technology, and has prevented it from being widely adopted for the anaerobic treatment of chemical-industrial organic wastewater. In this work, the advantages and benefits of anaerobic digestion and those conventional physical/chemical/biological methods are compared. This review also suggests the current challenges and barriers to the application of anaerobic digestion to the treatment of chemical-industrial organic wastewater by considering some typical degradation-resistant organic wastes as examples. Design improvements are required to enhance the degradation from refractory organics to fermentable organics. The applications of the up-flow anaerobic sludge blanket, anaerobic membrane bioreactor and their derivatives are highly recommended in the anaerobic treatment of chemical-industrial organic wastewater. While some state-of-the-art physical/chemical technologies have been widely reported and are currently applied in anaerobic treatment of chemical-industrial organic wastewater, high energy consumption and low efficiency of these processes is an obstacle to their smooth operation and presents clear difficulties. Therefore, this work provides some perspectives for future applications and practical advice for improving and enhancing the hydrolysis step of those degradation-resistant organic wastes. Synergistic processes, such as the co-culturing method, co-digestion and nitrate-reducing anaerobic digestion are suggested as a means to achieve the effective anaerobic treatment of chemical-industrial organic wastewater and sustainable regeneration of cleaner production.
•Simultaneous N removal and P removal was achieved in a one-stage PNA-HAP reactor.•The novel aggregate comprised of biomass and HAP was formed.•Microbes retention was greatly improved through this ...novel process.•The aggregate structure could be effectively manipulated through SRT control.•The discharged sludge was suitable for P recovery.
For digestion effluent treatment, while the anammox-based process has been successfully applied for nitrogen removal, in most cases, phosphorus (P) represents another major concern. In this study, a novel process, integrating the partial nitritation/anammox and hydroxyapatite crystallization (PNA-HAP) in a single airlift reactor, was developed for the simultaneous nitrogen removal and P recovery from synthetic digestion effluent. With a stable influent P concentration of 20.0 mg/L, an HRT of 6 h, and alternating increases of influent calcium and ammonium, the final achieved nitrogen removal rate was 1.2 kg/m3/d and the P removal efficiency was 83.0%. The settleability of sludge was desirably enhanced with the calcium addition and a high biomass concentration was achieved in reactor. Quantitative and qualitative analyses confirmed that HAP was the main inorganic content in sludge, which could be harvested for P recovery. According to the Scanning Electron Microscope observation and the Energy Dispersive X-ray spectrometry analysis, the microbes were mainly distributed on the outer layer of the sludge aggregate, while the HAP mainly in the interior. The relevant theoretical calculation also revealed that the sludge discharge manipulation has direct effect on the sludge composition and aggregate structure. In sum, the results are evidence of the feasibility of simultaneous nitrogen removal and P recovery through one-stage PNA-HAP process for digestion effluent.
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Sewage sludge management is now becoming a serious issue all over the world. Anaerobic digestion is a simple and well-studied process capable of biologically converting the chemical energy of sewage ...sludge into methane-rich biogas, as a carbon-neutral alternative to fossil fuels whilst destroying pathogens and removing odors. Hydrolysis is the rate-limiting step because of the sewage sludge complex floc structure (such as extracellular polymeric substances) and hard cell wall. To accelerate the rate-limiting hydrolysis and improve the efficiency of anaerobic digestion, various pretreatment technologies have been developed. This paper presents an up-to-date review of recent research achievements in the pretreatment technologies used for improving biogas production including mechanical (ultrasonic, microwave, electrokinetic and high-pressure homogenization), thermal, chemical (acidic, alkali, ozonation, Fenton and Fe(II)-activated persulfate oxidation), and biological options (temperature-phased anaerobic digestion and microbial electrolysis cell). The effectiveness and relative worth of each of the studied technologies are summarized and compared in terms of the resulting sludge properties, the digester performance, the environmental benefits and the current state of real-world application. The challenge and technical issues encountered during sludge cotreatment are discussed, and the future research needs in promoting full-scale implementations of those approaches are proposed.
A novel fluorescent probe was developed by integrating chlorinated coumarin and benzothiazolylacetonitrile and exploited for simultaneous detection of cysteine (Cys), homocysteine (Hcy), and ...glutathione (GSH). Featuring four binding sites and different reaction mechanisms for different biothiols, this probe exhibited rapid fluorescence turn‐on for distinguishing Cys, Hcy, and GSH with 108‐, 128‐, 30‐fold fluorescence increases at 457, 559, 529 nm, respectively, across different excitation wavelengths. Furthermore, the probe was successfully applied to the fluorescence imaging of endogenous Cys and GSH and exogenous Cys, Hcy, and GSH in living cells.
All together now: A novel fluorescent probe was developed for simultaneous sensing of cysteine (Cys), homocysteine (Hcy), and glutathione (GSH). Featuring four binding sites and different reaction mechanisms for different biothiols, this probe exhibited rapid fluorescence turn‐on for distinguishing Cys, Hcy, and GSH. The probe was successfully applied to the fluorescence imaging of endogenous Cys and GSH and exogenous Cys, Hcy, and GSH in living cells.
•Advanced co-digestion of food waste and sewage sludge was performed by an AnMBR.•The optimal FW/SeS ratio for co-digestion performance was75%:25% among other ratios.•The synergistic effect of sewage ...sludge and food waste co-digestion was revealed.•Membrane rejected 90.2%, 82.2% and 72.3% of S-COD, S-carbohydrate and S-protein.•To explain the fouling mechanism, external forces on sludge flocs were firstly analyzed.
Disposal of the increasingly huge amounts of sewage sludge (SeS) has become an impending problem worldwide. To solve this problem, a high-solid anaerobic membrane bioreactor (AnMBR) was used for the anaerobic co-digestion (AcoD) of SeS and food waste (FW). This study investigated the effects of SeS ratio on the methanogenic performance of the AcoD with a gradual increase value from 0 to 25%, 50%, 75% and 100% (total solids based). The results showed that the highest methanogenic performance was achieved at mono FW digestion. As for the co-digestion, the optimal FW/SeS ratio for methanogenic performance was 75%:25% among all the mixing ratios. The COD based biogas yield and methane yield were 0.498 L-biogas/g-CODfed and 0.295 L-CH4/g-CODfed at this optimal mixing ratio, which were 67.7% and 67.6% higher than those of the mono SeS digestion, respectively. The upgraded values were attributed to the improved hydrolysis ratio (by 8.14%) and the balanced carbon-to-nitrogen (C/N) ratio by co-digestion with FW, which synergistically stimulated methanogenesis ratio by 81.0%. The continuous membrane filtration property was investigated and four typical trans-membrane pressure (TMP) variation curves at different fouling degrees were determined. The membrane could sustainably operate at a flux of 6 L/m2/h (LMH) at the mixed liquor total solids (MLTS) concentration of 25 - 30 g/L. The combination of continuous membrane filtration property, particle size distribution of the mixed liquor and the external forces analysis was firstly applied to unravel the membrane fouling mechanism of a high-solid AnMBR. The result of this study will contribute to the establishment of an efficient FW and SeS treatment strategy.
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•H2 and CH4 production were both enhanced with magnetite nanoparticles (MNPs).•H2 production (HP) pathway shifted to acetate pathway, leading to high NADH/NAD+.•Hydrogenase and ...electron transport system activities increased with MNPs during HP.•MNPs promoted the secretion of redox active humic substances during CH4 production.•Syntrophomonas and Methanosarcina were selectively enriched in the presence of MNPs.
The efficiency of microbial electron transfer is fundamental for determining the performance of fermentative hydrogen/methane production. To facilitate microbial electron transfer, conductive magnetite nanoparticles (MNPs) were added into a cascading dark fermentation and anaerobic digestion system that was inoculated with Enterobacter aerogenes ZJU1 and methanogenic activated sludge (MAS), respectively. During the hydrogen-producing stage, the ratio of NADH/NAD+ and the activities of hydrogenase and electron transport system (ETS) of E. aerogenes ZJU1 were all increased by dosing 200 mg/L MNPs, which was conducive to hydrogen production through the NADH-dependent pathway. In the presence of 200 mg/L MNPs, hydrogen production increased by 21.1%, while subsequent methane production improved by 22.9%. Electrochemical analysis demonstrated the improvement in extracellular electron transfer capacity of MAS after adding MNPs, which can be ascribed to the contribution of MNPs and electrochemically active extracellular polymeric substances (EPS) induced by MNPs, such as humic acid-like and fulvic acid-like substances. Bacteria Syntrophomonas and Archaea Methanosarcina were the dominating enriched syntrophic partners, and the expression of functional genes involved in CO2 reduction to methane pathway was found to increase. Therefore, a more efficient fermentative hydrogen and methane co-production system was established by improving microbial electron transfer with the addition of MNPs.
Semiconducting ferroelectricity is realized in hybrid perovskite‐type compounds (cyclohexylammonium)2PbBr4−4xI4x (x = 0–1). By adjusting the composition x, the bandgap is successfully tuned from ...previously reported 3.65 eV to as low as 2.74 eV, and the excellent ferroelectricity was kept intact. This finding may contribute to improving the photoelectronic and/or photovoltaic performance of hybrid perovskite‐type compounds.
Phosphorus recovery from municipal sewage sludge is a promising way to alleviate the shortage of phosphorus resources. However, the recovery efficiency and cost depend greatly on phosphorus species ...and fractions in different sewage sludges, i.e., waste activated sludge and chemically enhanced primary sludge. In this review, the phosphorous (sub-)species and fractions in waste activated sludge and chemically enhanced primary sludge are systematically overviewed and compared. The factors affecting phosphorus fractions, including wastewater treatment process, as well as sludge treatment methods and conditions are summarized and discussed; it is found that phosphorus removal method and sludge treatment process are the dominant factors. The characterization methods of phosphorus species and fractions in sewage sludge are reviewed; non-destructive extraction of poly-P and microscopic IP characterization need more attention. Anaerobic fermentation is the preferable solution to achieve advanced phosphorus release both from waste activated sludge and chemically enhanced primary sludge, because it can make phosphorus species and fractions more suitable for recovery. A post low strength acid extraction after anaerobic fermentation is recommended to facilitate phosphorous release and improve the total recovery rate.
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•P species & fractions in sewage sludges are compared and figured out quantitively.•P species & fractions mainly depend on P removal and sludge treatment process.•Quantitative characterization of Fe/Al–P is requisite for advanced P recovery.•Anaerobic fermentation + low strength acid is recommended for advanced P recovery.
Hydroxide exchange membrane fuel cells offer possibility of adopting platinum-group-metal-free catalysts to negotiate sluggish oxygen reduction reaction. Unfortunately, the ultrafast hydrogen ...oxidation reaction (HOR) on platinum decreases at least two orders of magnitude by switching the electrolytes from acid to base, causing high platinum-group-metal loadings. Here we show that a nickel-molybdenum nanoalloy with tetragonal MoNi
phase can catalyze the HOR efficiently in alkaline electrolytes. The catalyst exhibits a high apparent exchange current density of 3.41 milliamperes per square centimeter and operates very stable, which is 1.4 times higher than that of state-of-the-art Pt/C catalyst. With this catalyst, we further demonstrate the capability to tolerate carbon monoxide poisoning. Marked HOR activity was also observed on similarly designed WNi
catalyst. We attribute this remarkable HOR reactivity to an alloy effect that enables optimum adsorption of hydrogen on nickel and hydroxyl on molybdenum (tungsten), which synergistically promotes the Volmer reaction.
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