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Arsenic (As) is a toxic contaminant in surface waters and groundwater. Oxidation of arsenite (As(III)) to less toxic arsenate (As(V)) by hydrogen peroxide (H 2 O 2) is desirable for enhancing the immobilisation of Arsenic (As). However, this As(III) oxidation process is constrained by the strong pH dependence and the generated As(V) must also be removed for complete As remediation. This study developed and evaluated a novel heterogeneous catalytic system using manganese-doped Lanthanum oxycarbonate (MnL) to catalyse the oxidation of As(III) by H 2 O 2 and simultaneously adsorb the generated As(V). The presence of MnL enhanced the removal rate of As(III) by 35 times compared with systems utilising H 2 O 2 alone. Additionally, this superior performance was observed over a wide pH range (5–9), which demonstrated this approach could bypass the well-known pH restriction on oxidation by H 2 O 2. Mechanistic studies revealed that the long-lived superoxide radicals (·O 2 −/·OOH), present on the particle surfaces and derived from the dissociation of the Lewis acid-base adduct (La–OOH*), were the dominant active species for As(III) oxidation. Mn atoms with low valence states played a crucial role in As(III) oxidation through the provision of extra active sites to facilitate radical production. The La and Mn sites in MnL could rapidly immobilize the generated As(V) by forming precipitates, resulting in a final As removal efficiency of 99% even after three cycles of reutilisation. Overall, this study demonstrates the viability of the proposed novel multi-functional catalyst for efficient As remediation from aqueous environments. [Display omitted] • Manganese-doped Lanthanum oxycarbonate (MnL) catalysed H 2 O 2 oxidation to remove As. • The approach effectively oxidised As(III) and adsorbed As(V) over a wide pH range. • As(III) was mainly oxidised by ROSs generated from La(III) Lewis acid-base adduct. • The addition of Mn contributed both to catalytic ROSs generation and As adsorption. • MnL exhibited stable performance with coexisting ions and also after 3 times reuse. [ABSTRACT FROM AUTHOR]

Abstract: The biological stabilization process of cattle and poultry manure was studied using thermogravimetric analysis and 13C nuclear magnetic resonance. The stabilization processes carried out were composting, anaerobic digestion and a mixed process (partly aerobic, partly anaerobic). It was observed from the analyzed samples that the biological stabilization processes reduce the volatile content of the bio-wastes and increase the degree of aromaticity. The stabilization of cattle manure by means of aerobic processes was able to further oxidize and enriched in aromatic compounds the bio-waste when compared with the digestion process. On the other hand, the stabilization of poultry manure resulted in a greater aromatization under the digestion process. Stabilized samples with a high degree of aromaticity presented a lower volatile content accompanied by a reduction in the intensity of the differential thermogravimetry peak registered under an inert atmosphere, indicative of the thermal decomposition of the organic matter. The thermal decomposition of all the analyzed materials (fresh and stabilized samples) commenced at around 200°C but for the digested poultry manure, which decomposition initiated close to 250°C. All stabilized samples yielded a lower degree of volatilization to that one observed in fresh samples. [Copyright &y& Elsevier]

Analytical hydropyrolysis performed under high hydrogen gas pressure (>10 MPa) has been demonstrated to possess the unique ability to release high yields of biomarker hydrocarbons covalently bound within the non-hydrocarbon macromolecular fraction of crude oils and source rocks. This study describes the development of the experimental procedure for trapping the product oils (hydropyrolysates) on silica to facilitate more convenient recovery than conventional collection and to allow analysis by thermal desorption-GC–MS without any prior work-up. Conventionally, the trap has consisted of a stainless steel coil, cooled with dry ice from which the products are recovered in organic solvents. Replacing this with a system in which the hydropyrolysates are adsorbed on a small mass of silica greatly reduces the turn-around time between tests, and aids the recovery and separation of the products. This method has been developed using an oil shale and an oil asphaltene fraction, with the silica trap producing very similar biomarker profiles to that from the conventional trap. The quantitative recovery of hydrocarbons from a light crude oil desorbed from silica under hydropyrolysis conditions demonstrates no significant loss of the high molecular weight n-alkanes (>n-C10) for both trapping methods. The use of liquid nitrogen as the trap coolant results in significantly improved recovery of the lower molecular mass constituents. The silica trapping method allows for the hydropyrolysates to be characterised by thermal desorption-GC–MS, which has been investigated both on- and off-line. The oils undergo relatively little cracking during desorption, with similar n-alkane and biomarker profiles being obtained as with normal work-up and GC–MS analysis. Thus, in terms of fingerprinting geomacromolecules, “hypy-thermal desorption-GC–MS” appears to have the potential to be developed as an attractive alternative to traditional py-GC–MS. [Copyright &y& Elsevier]

Microwave pyrolysis has become an attractive form of processing technology to generate bio-oil, bio-char and syngas from different biomass feedstocks. In this study, microwave pyrolysis was performed on the UK native seaweed Laminaria digitata and its extract residue from a bio-refinery process. Pyrolysis of these two feedstocks was successfully achieved without the requirement of microwave susceptors, as pelletizing the biomass was sufficient to allow microwave pyrolysis to occur. It was found that average energy requirements as low as 1.84–2.83 kJ g−1 were required to pyrolyse 55–70% of both feedstocks and bio-oil yields of 5–8% and 10–14% for native and extraction residue L. digitata were produced, respectively. Maximum microwave pyrolysis processing times were in the order of 200 s. The bio-oil generated from both feedstocks contained no phenolic based compounds, but a greater number of nitrogen-containing compounds and compounds derived from macroalgal polysaccharides. Yields of certain compounds differed in bio-oils generated from the two L. digitata feedstocks, however it was observed that specific energy did not have a direct influence on bio-oil compound yield. Furthermore, the identification of a particular nitrogen-containing compound L-Proline, 1-methyl-5-oxo-, methylester is thought to be a unique product of microwave pyrolysis when carbon-based additives are avoided. Image 1 • Microwave pyrolysis of Laminaria digitata and its extraction residue were investigated. • Microwave pyrolysis was achieved without use of microwave susceptors. • Energy requirements of 1.84–2.83 kJ g−1 pyrolysed 55–70% of both feedstocks. • Maximum pyrolysis processing time of 200 s required. • Bio-oils contained no phenolic compounds but an abundance of nitrogen based compounds. [ABSTRACT FROM AUTHOR]

Graphene-based membranes have great potential for seawater desalination and water treatment, although it is still a great challenge to find an effective solution for the dilemma between water flux through the membrane and removal rate of salt ions. In this study, a novel strategy of coating polyelectrolytes on holey graphene oxide was designed in order to modify the surface charge on a graphene oxide membrane, aiming to simultaneously improve water flux and desalination performance. The resultant highly-charged graphene oxide membrane presents excellent opportunity to connect sheets together by the formation of chemical bonds, subsequently effectively enhancing the stability, surface potential and hydrophilicity of the membrane in water, improving the water flux and desalination performance. The nano-pores of holey graphene oxide, formed by H 2 O 2 etching, can improve the structure of two-dimensional nano-channels between slices and shorten the transport distance of water molecules, thus leading to a higher water flux. Moreover, coating the holey graphene oxide membrane with charged polyelectrolytes enhances excellent ion rejection by the combination of interlayer size screening and electrostatic repulsion. The cationic polyelectrolyte-coated composite membrane can achieve a water flux of 268.49 L m−2·h−1·MPa−1 and the desalination rate of 87.86% for 0.5 g L−1 NaCl, achieving an increase of 3.44 times and 37.65%, respectively, as compared with untreated graphene oxide film. The facile and scalable surface modification of this graphene oxide-based membrane produces a promising application prospect in desalination of wastewater with a high salinity. [Display omitted] • A novel strategy of coating polyelectrolytes on HGO was designed for desalination. • Water flux and desalination performance were simultaneously improved. • H 2 O 2 etching treatment shortened the transport distance of water molecules. • Coating HGO films with charged polyelectrolytes enhanced excellent ion rejection. [ABSTRACT FROM AUTHOR]

Reutilization of the waste by-products from industrial and agricultural activities is crucially important towards attainment of environmental sustainability and the 'circular economy'. In this study, we have developed and evaluated a sustainably-sourced adsorbent from coal fly ash, which was modified by a small amount of lanthanum (La-FA), for the recapture of phosphorous (P) from both synthetic and real natural waters. The prepared La-FA adsorbent possessed typical characteristic diffraction peaks similar to zeolite type Na–P1, and the BET surface area of La-FA was measured to be 10.9 times higher than that of the original FA. Investigation of P adsorption capability indicated that the maximum adsorption (10.8 mg P g−1) was 6.14 times higher than that (1.8 mg P g−1) of the original fly ash material. The ζ potentials measurement and P K-edge X-ray Absorption Near Edge Structure (XANES) spectra demonstrated that P was bonded on La-FA surfaces via an adsorption mechanism. After applying the proposed adsorbent to real lake water with La/P molar ratios in the range from 0.5:1 to 3:1, the La-FA adsorbent showed the highest phosphate removal ability with a La/P molar ratio 1:1, and the P adsorption was similar to that performance with the synthetic solution. Moreover, the La-FA absorbent produced a negligible effect on the concentrations of total dissolved nitrogen (TDN), NH 4 +-N and NO 3 −-N in water. This study thus provides a potential material for effective P recapture and details of its operation. [Display omitted] • Lanthanum modified fly ash (La-FA) was proven to act as a sustainable-sourced P absorbent. • La-FA showed 6 times higher P adsorption ability compared with the original material. • P removal performance from natural water was similar to that of synthetic solution. • Surface P adsorption was deemed the main mechanism via XANES spectral analyses. [ABSTRACT FROM AUTHOR]

l O 2 nanobubble technology is developed to tackle the As pollution in hypoxic waters. l O 2 nanobubbles induced biotic and geochemical reactions to mitigate the As risk. l Dark-produced hydroxyl radicals are dominant contributors to As abiotic oxidation. l O 2 -related functional microbial changes contribute to the As biotic transformation. l Fe-(hydr)oxide becomes the major sequestrator of As(V) in oxic sediments. The arsenic (As)-bearing eutrophic waters may suffer from the dual conditions of harmful algal blooms and release of As, driven by algal-induced hypoxia/anoxia. Here, we investigate the use of interfacial oxygen (O 2) nanobubble technology to combat the hypoxia and control As exposure in simulated mesocosm experiments. It was observed that remediation of algal-induced hypoxia at the sediment-water interfaces (SWI) by application of O 2 nanobubbles reduced the level of dissolved As from 23.2 μg L−1 to <10 μg L−1 and stimulated the conversion of As(III) to the less toxic As(V) (65–75%) and methylated As (10–15%) species. More than half of the oxidation and all the methylation of As(III) resulted from the manipulation by O 2 nanobubbles of microbes responsible for As(III) oxidation and methylation. Hydroxyl radicals were generated during the oxidation of reductive substances at the SWI in darkness, and should be dominant contributors to As(III) abiotic oxidation. X-ray absorption near-edge structure (XANES) spectroscopic analysis demonstrated that surface sediments changed from being sources to acting as sinks of As, due to the formation of Fe-(hydr)oxide. Overall, this study suggests that interfacial O 2 nanobubble technology could be a potential method for remediation of sediment As pollution through the manipulation of O 2 -related microbial and geochemical reactions. [Display omitted] [ABSTRACT FROM AUTHOR]

• Harmful cyanobacteria M. aeruginosa could effectively remediate antibiotic • Tetracycline removal by M. aeruginosa was significantly faster than C. pyrenoidosa • Biometabolism dominated tetracycline removal, led to distinct degradation products • Biomass growth and cell vitality showed limited inhibition by tetracycline exposure • Microcystin release was controlled to levels below the recreation water values The occurrence of pharmaceuticals and personal care products (PPCPs) in wastewater poses huge environmental threats, even at trace concentrations, and novel approaches are urged due to the inefficiencies of conventional wastewater treatment plants, especially when processing contaminants at high concentrations. Meanwhile, another widespread problem in the aquatic domain is the occurrence of harmful algal blooms (HABs) which cause serious damage to the ecosystem, but have rarely been investigated for possible valorization. This study investigated the possibilities, mechanisms, and effects of toxin release of using a harmful cyanobacterial species, Microcystis aeruginosa (M. aeruginosa), in order to remove the widely used drug, tetracycline, at high concentration. The results were compared with the performance obtained by the use of the hitherto generally-selected chlorophyte alga Chlorella pyrenoidosa (C. pyrenoidosa) for tetracycline concentrations of 10-100 mg L−1. M. aeruginosa exhibited a much more effective and rapid tetracycline removal (over 98.0% removal in 2 days) than did C. pyrenoidosa (36.7%-93.9% in 2 days). A comprehensive kinetic investigation into probable removal pathways indicated that, theoretically, bio-remediation dominated the process by M. aeruginosa (71.6%), while only accounting for 20.5% by C. pyrenoidosa. Both microalgae promoted the hydrolysis of tetracycline under conditions of increased pH and inhibited abiotic photolytic reactions by the shading effect to the water column, when compared with control experiments. Although identical degradation by-products were identified from treatments by both microalgal species, distinct by-products were also confirmed, unique to each treatment. Moreover, the growth of M. aeruginosa biomass exhibited strong tolerance to tetracycline exposure and released significantly lower levels of microcystin-LR, compared with the control systems. This study supports the possibility of reusing HABs species for the effective remediation of antibiotics at high concentrations. We have further suggested possible mechanisms for remediation and demonstrated control of toxin release. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Due to the finite stocks of phosphate rock and low phosphorus (P) use efficiency (PUE) of traditional mineral P fertilizers, more sustainable alternatives are desirable. One possibility is to culture microalgae in wastewater to recover the P and then convert the microalgae biomass into slow-release fertilizers through hydrothermal carbonization (HTC). Therefore, this study aimed to recycle P from wastewater to agricultural field using microalgae and HTC technology. Chlorella vulgaris (CV) and Microcystis sp. (MS) were cultured in poultry farm wastewater with an initial concentration of 41.3 mg P kg−1. MS removed 88.4% P from the wastewater, which was superior to CV. CV- and MS-derived hydrochars were produced at 200 or 260 °C, in solutions using deionized water or 1 wt % citric acid. The MS-derived hydrochar using 1 wt % citric acid solution at 260 °C (MSHCA260) recovered the highest amount of P (91.5%) after HTC. The charring promoted the transformation of soluble and exchangeable P into moderately available P (Fe/Al-bound P), and using citric acid solution as feedwater increased the P recovery rate and formation of Fe/Al-bound P. With the abundant moderately available P pool, hydrochar amendment released P more slowly and enhanced the soil P availability more persistently than chemical fertilizer did, which helped to improve PUE. In a wheat-cultivation pot experiment, MSHCA260 treatment improved wheat PUE by 34.4% and yield by 21.6% more than chemical fertilizer did. These results provide a novel sustainable strategy for recycling P from wastewater to crop-soil systems, substituting the mineral P fertilizer, and improving plant PUE. Image 1 • Chlorella vulgaris and Microcystis sp. (MS) removed 78.7% and 88.4% phosphorous (P). • 91.5% P was recovered from MS to MS-derived hydrochar produced at 260 °C (MSHCA260). • Microalgal hydrochars slowly released P and improved soil P availability. • MSHCA260 increased P use efficiency and wheat yield compared to chemical fertilizer. • Microalgae and hydrochar technology recycled P from wastewater to crop food. [ABSTRACT FROM AUTHOR]

Biogenic phosphorus (P), such as organic P and inorganic pyrophosphates, could substantially contribute towards eutrophication in aquatic systems by internal loading of P from sediment through P species transformation. Previous eutrophication management studies mainly focus on the removal of orthophosphate (Ortho-P), however, an effective approach for biogenic P control from water sources, prior to incorporation in sediment, is still lacking. In this study, a lanthanum/aluminum-hydroxide (LAH) composite was demonstrated to provide both superior removal of Ortho-P and biogenic P, employing myo-inositol hexakisphosphate (IHP) and pyrophosphate (Pyro-P) as model compounds. The maximum IHP and Pyro-P adsorption capacities by LAH attained 36.4 and 21.8 mg P g−1, respectively. In order to understand the mechanisms of adsorption, zeta potential, 31P solid-state nuclear magnetic resonance (NMR) spectroscopy and P K-edge X-ray absorption near edge structure (XANES) techniques were used to characterize the LAH after adsorption. The results supported the hypothesis that the interaction between LAH and P species was through surface adsorption, by the formation of inner-sphere complexes. Linear combination fitting results of XANES data indicated that IHP and Pyro-P preferentially bonded with La-hydroxide in LAH. This study elucidates the adsorption properties and binding mechanisms of IHP and Pyro-P on lanthanum-bearing compounds at the molecular level, indicating that LAH is a promising material for the control of eutrophication. Unlabelled Image • LAH adsorbent showed a high affinity to both orthophosphate and biogenic P species. • NMR and XANES were used to study the mechanism of P adsorption at the molecular level. • Surface adsorption, not precipitation, was the dominant mechanism for P adsorption. • P species were preferably bonded to lanthanum (La)- rather than aluminum-hydroxide. • La-based P adsorbent is a promising material for effective removal of P from water. [ABSTRACT FROM AUTHOR]