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On-site sampling analysis and laboratory-scale experiments were conducted to study the pollution status and release potential of EDCs in Erhai Lake. We found that nitrogen and phosphorus pollution in Erhai Lake sediment were both at a high level, as well as EDCs pollution. The concentrations of BPA, E2α, E1, E2β, EE2, and E3 were 36.84 ng/g(DW), 13.04 ng/g(DW), 128.97 ng/g(DW), 52.57 ng/g(DW), 18.48 ng/g(DW) and 5.36 ng/g(DW), respectively. The concentrations of E2α, E1, E2β and EE2 in the bottom water were higher than the surface water due to the impact of sediment release. The results of the 20 days release test indicated that BPA release from the sediment had a greater correlation with the original concentration and the particle size of sediment, while the steroid EDCs had no obvious correlation with these two factors, probably due to the difference in hydrophobicity between them. Under hydraulic disturbance and aerobic conditions, the release process of EDCs was accompanied by a large amount of microbial degradation, and degradation amount > released amount. BPA was released quickly, 9.56% was released in 20 days, but only 3.37% of steroid EDCs released. In comparison, the release process of steroids was longer and posed a greater threat to aquatic ecology. [ABSTRACT FROM AUTHOR]

• The system performs best at 6 h hydraulic retention time. • It achieved 0.215 g/h salts removal at a wastewater treatment capacity of 10 L/d. • Microbial community structures are consistent with the spatial structure of cathode. • Catholyte circulation should be effective for the stratified microbial structures. In this study, two dual-anode assembled microbial desalination cells (DA-MDCs) composed of two anodes, one cathode and two membrane stacks were constructed, with a hollow fiber membrane (HFM) module coupling into the cathode to filtrate suspended solids and microbes. Enriched domestic wastewater treatment performance of the DA-MDC system under different hydraulic retention time (HRT) was investigated in detail. When HRT sequentially decreased from 10 h, 8 h, 6 h to 4 h, the conductivity in diluent effluent kept stable at first, but increased 519% at 4 h compared with 6 h. Nevertheless, the chemical oxygen demand, total nitrogen and total phosphorus in the effluent met the wastewater discharge standards in China at all HRTs. Additionally, transmembrane pressure of the HFM modules increased sharply when HRT changed from 6 h to 4 h. Therefore, HRT 6 h was selected as the optimal condition. Under such short HRT, the system realized wastewater treatment capacity of 10 L/d, surpassing all bio-cathode microbial desalination cell systems aiming to realize efficient treatment of domestic wastewater. Additionally, the salt removal rate of 0.215 g/h was more than two times compared with most similar systems. Finally, stratified microbial community structures in the cathodes of the system were found. This gave evidence on the efficient catholyte recirculation which might facilitate nitrogen removal from wastewater. [ABSTRACT FROM AUTHOR]

Groundwater denitrification is challenged by a lack of electron donors and usually requires additional energy input or chemical agents. MEC can convert organic pollution into clean electron donor (hydrogen) through a gas-liquid phase transition. In this study, the MEC was combined with permeable bio-reactive barrier (PRB) as a hybrid system to achieved simultaneous organic waste removal, hydrogen production and groundwater remadition via long-distance hydrogenotrophic denitrification by biogas. The semi-hydrophobic PTFE-coated granular activated carbons (GAC) and hydrophilic GAC were filled as two kinds of biocarriers in PRBs, in which the hydrophobic PTFE surface coating improved hydrogen utilization. The PTFE-coated GAC maked the denitrification performance of PRB insensitive to hydrogen partial pressure within the tested range of 0.01–0.04 MPa and achieved effluent nitrate concentration of <20 mg L−1 within 12 h (The Water Quality Standard for Drinking Water Sources in China). The gas production in MECs was actively pumped to PRBs and spontaneously achieve negative pressure on the MEC side and positive pressure on the PRB side. The actively pumping of biogas induced negative pressure in MEC and positive pressure in PRB. The negative pressure improved current density by 18.6 ± 0.7% in MECs and the MEC-PRB hybrid system achieved a nitrate removal of 85.0 ± 0.8% in actual groundwater with an effluent concentration of 15.0 ± 0.8 mg L−1 at 72 h. This work demonstrated the feasibility of matching MEC and PRB as a novel hybrid system for organic pollution degradation and effective nitrogen removal in electron-donor-lacking groundwater. [Display omitted] • MEC-PRB achieved simultaneous organic waste removal and groundwater denitrification. • MEC-PRB enabled long-distance electronic compensation for denitrification by biogas. • The 1/2-PTFE coated granular activated carbons (GAC) improve hydrogen utilization. • Actively pumping biogas from MEC to PRB improved H 2 production and current density. • The gas composition of MEC contained CH 4 and H 2 increased bacteria diversity in PRB. [ABSTRACT FROM AUTHOR]

The alarming decline in phosphate raw materials and increase in eutrophication has escalated interest in struvite research. This manuscript presents scientometric analysis on struvite for fertilizing applications to comprehend the evolution and transformation of the field, investigate the existing challenges, research gaps, and developments to gain insights on the emerging trends for further studies. A total of 1550 scientific documents, between the years 1999–2020, were collected from Scopus® and PubMed® using an appropriate trail of keywords and analyzed using CiteSpace 5.7. R2. Ten attributes such as annual publication output and types, co-authorship network, co-occurring author keywords, the network of authors' countries and institutions, author co-citation network, document co-citation network, journal co-citation network, and co-occurring subject categories were investigated. Based on the distinct network patterns generated by the software, progress of the field, paradigm shifts, knowledge gaps, and scientific frontiers were identified and mapped. The literature on struvite research was found to have bloomed in the early 2000s and accelerated significantly until now, with maximum contribution from China and United States. Journal of cleaner production ranks 5th with 3.35% share of the total contribution according to journal co-citation analysis. Cluster analysis of co-occurring author keywords revealed the research progression through the expanse, knowledge gaps, disciplinary and inter-disciplinary advancements, and future exploration trends. The research has evolved from evaluating the process influencing parameters and developing suitable reactor designs to installation of pilot-scale plants for commercialization. However, lack of experiments on real-time wastewater, plant growth studies and the underlying nutrient uptake mechanisms persist as major research gaps. Focussing on these aspects along with integrated advanced technologies such as microbial fuel cells, microbial electrolysis cells, electrochemical precipitation of struvite and wider application of struvite can pave way for enormous progress of this field. [Display omitted] • Scientometric analysis of struvite research over the last 20 years were performed. • Ten scientometric attributes on struvite research arena were explored. • Research gaps, trends and future scope in struvite research were highlighted. • The commercial scenario of struvite for fertilizer applications were emphasized. [ABSTRACT FROM AUTHOR]

[Display omitted] • Etching terminal wastewater is efficiently treated in MECs of different scales. • MECs performance scales almost with the reactor volume. • Electrode potentials in scaled-up MECs (40 L) are resilient to wastewater strength. • Switch from low to high strengths wastewater alters microbial community composition. The treatment of actual low and high strengths etching terminal wastewater (ETW) from plating and electronic industry meeting national discharge standards is demonstrated in laboratory scale (1 L) and in scaled-up (40 L) microbial electrolysis cells (MECs). Both cylindrical single-chamber MECs achieved complete removal of heavy metals and efficient treatment of organics using either low strength ETW at an hydraulic retention time (HRT) of 5 d, or high strength wastewater at HRTs of 7 d (1 L) or 9 d (40 L). The removal rate of organics and heavy metals increased by 36-fold and scaled almost with the reactor volume ratio of 40. Electrode potentials in the scaled-up MECs (40 L) were resilient to the wastewater strength. Bacterial communities on both anodes and cathodes of the 1 L and the 40 L reactors experienced a selective shock and a significant community change after switching from low to high strengths wastewater, although reactor performance was effectively maintained. This study demonstrates complete removal of multiple heavy metals with simultaneous efficient wastewater treatment in MECs of different scales meeting China national discharge standards and provides a plausible approach for simultaneous removal of value-added products (e.g., heavy metals) and efficient treatment of practical etching terminal wastewater. [ABSTRACT FROM AUTHOR]

• Chemical signatures of a black chert nodule from Doushantuo Formation are examined. • Raman and infrared (IR) spectral analyses are reported. • Data indicate that the examined acritarchs have a eukaryotic cyst origin. • Organic matter likely derives from microbial cells and extracellular compounds. • Results confirm the presence of a diverse Doushantuo microbiota community. Raman and Fourier-transform infrared (FTIR) microspectroscopic analyses were performed to examine the chemical signatures and their spatial distribution of organic-walled microfossils together with organic matter (OM) in a black chert nodule from the Ediacaran (635–551 Ma) Doushantuo Formation in China. Raman spectral parameters (I-1350/1600 values) reveal that the acritarchs, bundled filaments, and OM have different degrees of structural order, and that there is no significant difference in I-1350/1600 values among the different portions of individual acritarchs (i.e., inner structure, inner membrane, and outer wall). The IR mapping reveals portion-specific chemical signatures within the individual acritarch specimens. The inner membrane of Tianzhushania contains aliphatic C-H bonds. The acritarchs, including Tianzhushania , show chemically four types of inner structures: (1) aromatic C-H-rich type, (2) aliphatic C-H-rich type, (3) aromatic/aliphatic C-H-poor type, or (4) heterogeneous. All of the examined acritarchs have aromatic C-H rich outer wall, irrespective of the presence/absence of processes. These features support a eukaryotic cyst origin, although it is difficult to determine whether the acritarchs correspond to the cysts of Protista or Metazoa. The bundled filaments also consist of an aromatic C-H bond, but its origin is uncertain. The OM shows a high degree of variation in Raman spectral I-1350/1600 values, as does the IR spectral intensity ratio of asymmetric aliphatic CH 3 /CH 2 , alongside a heterogeneous spatial distribution of aromatic and aliphatic C-H bands. This suggests the contribution of various precursors derived from dead microbial cell debris and extracellular organic compounds. Overall, these results confirm the presence of diverse microorganisms in the Doushantuo microbiota. Furthermore, the spatial distribution of organic functional groups in individual microfossils could provide clues about the taxonomy of microfossils of unknown origin. [ABSTRACT FROM AUTHOR]

In order to discover the biochemistry mechanism of sediments in eutrophic grass-type lakes, this study selected four grass-type lakes in north China to explore the relation between enzyme activities of sediments and lake eutrophication condition. By applying the assessment method of organic nitrogen (ON) and total phosphorus (TP), the nutrition of lake sediments were assessed. As the results show, Hengshui (HS) Lake and Baiyangdian (BY) Lake, suffering severe pollution, have much higher urease activity in comparison with Nansi (NS) Lake and Dongping (DP) Lake. In addition, there is significant positive correlation between the urease activity and the contents of total nitrogen (TN) and organic matter (OM) of sediments ( r = 0.805, p < 0.01; r = 0.840, p < 0.01). It's the same case between alkaline phosphatase (APA) activity and TP content ( r = 0.876, p < 0.01). The activities of both cellulase and protease in HS Lake and BY Lake are weaker than those of NS Lake and DP Lake. The changes in the activities of polyphenol oxidase and peroxidase tend to be similar and their distributions are closely related to the degree of pollution and disruption caused by human activities. The enzymatic activity of lake sediments can serve as an indicator that reflects how serious lake eutrophication is. [ABSTRACT FROM AUTHOR]

Soil salinity greatly influences soil organic carbon (SOC) stocks. However, how soil salinity affect SOC formation by changing microbial utilization of newly input organic C and subsequent microbial residues retention remains unclear. In this study, high salinity (HS, EC 1:5 20.04 dS m−1) and low salinity (LS, EC 1:5 0.90 dS m−1) soils were collected in a newly reclaimed coastal area in eastern China. Soil salt content decreased rapidly in the LS site due to irrigation and drainage management. The effect of soil salinity on microbial transformation of straw was investigated by adding 13C-labelled ryegrass straw into the HS and LS soils in a 180-day incubation experiment. Results showed that straw-derived dissolved organic C was higher in the HS soil. The higher availability of labile substrate in the HS soil offset the negative effect of high salinity on Gram-negative bacteria and fungi, but did not on Gram-positive bacteria. Microbial biomass C (MBC) and microbial C use efficiency (CUE) of straw were higher in the HS soil at 3 days due to the higher assimilation of straw C by Gram-negative bacteria and fungi. Straw-derived MBC and microbial CUE decreased over time and were similar between both soils at 60 and 180 days. Thus, high salinity did not decreased quantity and efficiency of microbial utilization of straw C. However, newly formed amino sugars were lower in the HS soil at 60 and 180 days suggesting that high salinity was not beneficial to the retention of microbial residues after microbial cells died. In conclusion, high salinity reduced microbial-derived SOC formation primarily by affecting stabilization and recycling of microbial necromass rather than by decreasing microbial utilization of newly input organic carbon in the studied coastal soil. • High salinity increased straw C availability. • High salinity did not decrease straw C mineralization and microbial assimilation. • Straw addition offset the effect of salinity on Gram-negative bacteria and fungi. • High salinity did not decrease microbial carbon use efficiency of straw. • High salinity reduced the retention of microbial residues. [ABSTRACT FROM AUTHOR]

Presently more energy is sourced from the natural gas grid than the electricity grid in the EU and the US. Furthermore hard-to-abate sectors such as heavy-duty transport are not readily served by electricity. Decarbonised energy systems will require renewable fuels (such as biomethane) to reduce the reliance on fossil-based diesel and natural gas. Anaerobic digestion (AD) is a technology which with other bio-based technologies can effect improved energy conversion and reduction in greenhouse gas (GHG) emissions across sectors beyond energy. Here, an AD-centred cascading circular system with carbon capture and utilisation was proposed by incorporating power to gas (P2G), microbial electrolysis cell (MEC), and digestate valorisation for biochar production. The system as modelled converted CO 2 to biomethane and digestate to biochar for CO 2 sequestration. This was exemplified through cattle slurry with an annual production of 3.03 billion tons in three studied regions (the EU, China and the US), which was shown to produce a maximum of 2.29 EJ (equivalent to 1.64% of natural gas demand in 2018) of total energy in the form of advanced biofuels (biomethane, bio-oil and syngas) via the AD-MEC system, which was preferable to a conventional AD or an AD-P2G system. The treatment of cattle slurry with AD-MEC led to a combined 397.4 MtCO 2 e of GHG emission savings in the three regions. This could contribute to avoiding 2.0% of GHG emissions (total 20.1 GtCO 2 e) in the three regions. The sustainability of such a system was shown to be dependent on access to low-carbon and low-cost electricity systems. [Display omitted] • Anaerobic digestion-centred carbon capture and utilisation technologies are assessed. • Anaerobic digestion with microbial electrolysis can almost double biomethane yield. • The system is exemplified by cattle slurry as feedstock in the EU, China and the US. • The system may supply 1.64% of global natural gas demand in 2018. • The system may reduce 2.0% of annual GHG emissions in three studied regions. [ABSTRACT FROM AUTHOR]