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Design and construction of a membrane that can achieve selective separation of uranium from spent fuel or seawater is a big challenge in the field of separation science. In this work, 1,3,5-benzenetricarboxylic acid (BTC) and three different nitrates (Zn/Ni/Cu) were used to prepare metal-organic frameworks (BTC-MOFs) with different pore sizes, and then, BTC-MOFs were intercalated into the interlayers of graphene oxide (GO) for preparing the composite membranes which presented selective separation of uranium with strong acid resistance. Composite membranes prepared by Zn/Ni/Cu-BTC-MOFs and GO can achieve the separation between ions of different valence states, and their permeability and selectivity depend on the membrane thickness, the acidity of driving solution, and the pore sizes of MOFs. Importantly, Cu-BTC-MOF-intercalated GO membranes can not only achieve the selective separation of Th4+ and UO22+ with a selectivity of ≈6 but also induce the ultra-high selectively separation of UO22+ and Ce3+ because the rejection rate of Ce3+ is about 100%. Moreover, the Zn-BTC-MOF-intercalated GO membrane shows an excellent selectivity of Th4+ and UO22+ with a selectivity of ≈25, and it may also achieve selective separation of uranium from seawater.

The aquaculture of yellowtail kingfish (Seriola lalandi) has expanded around the globe, including China. Genetic resource of Chinese S. lalandi urgently needs to be assessed for improving production. Here, we collected wild S. lalandi samples from the Bohai Sea, China and evaluated its genetic diversity based on 17,690 nuclear loci. A population from the Southern Ocean, Australia was used for comparison. The analyses showed that the Chinese and Australian S. lalandi formed two completely distinct clusters and there was no genetic introgression from the Australian S. lalandi into the Chinese S. lalandi population. The genetic diversity is slightly lower, but comparable in Chinese versus Australian yellowtail kingfish (Chinese population, expected heterozygosity: 0.19, observed heterozygosity: 0.19, nucleotide diversity: 0.19 ± 0.09; Australian population, expected heterozygosity: 0.23, observed heterozygosity: 0.22, nucleotide diversity: 0.22 ± 0.11). Overall, our results indicated that Chinese S. lalandi could be a potential subject for genetic breeding programs. We also investigated morphological characters and developed molecular markers for population identification. Comparison of meristic characters between the Chinese population and the Australian population revealed that main shape difference were in the number of dorsal spines, dorsal fin rays and the number of upper gill rakers. Geometric morphology based on eight landmarks also revealed significant difference between the two populations including the distance between the tip of snout to origin of pelvic fin and the distance between the tip of snout to origin of pectoral fin. These morphological characters can be used for easy identification of the Chinese S. lalandi.

Adequate treatment of skin wounds is vital to health. Nitrocellulose bandage as a traditional wound dressing is widely used for wound healing, but its limited air permeability and poor sterilization need to be improved for enhancing the actual efficacy. Here, nanoporous graphene (NPG) is used to mix into nitrocellulose for preparing a composite membrane, which exhibits a moderate transmission rate of water vapor, excellent toughness performance, and good biocompatibility. Moreover, the membrane shows an excellent broad-spectrum antibacterial property (98%

Rare earth elements (REEs) are used widely in devices of many fields, but it is still a troublesome task to achieve their selective separation and purification. Metal–organic frameworks (MOFs) as a...

Chiral materials are usually the key to the separation of chiral membranes. In this work, we propose a new strategy that chiral porous graphene membrane can be fabricated from nonchiral porous graphene by mechanical stirring to induce vortex structure. Porous graphene with controlled, nanosized pores was synthesized by a newly designed, one-pot process directly from graphite as opposed to graphene oxide. Then porous graphene was immobilized on ultrafiltration membrane through filtering while stirring to form porous graphene membrane, which was applied for enantioselective separation toward DL-amino acids: for example, the separation factor of l-/d-phenylalanine reached 4.76. Interestingly, we first observed that the front and back sides of the porous graphene membrane exhibited opposite optical activities.

Graphene with a porous structure can provide low-resistant pathways and short ion diffusion channels for energy storage, and thus is expected to be an excellent electrode material. Here, a simple partial combustion route was used to synthesize porous graphene with controllable pore size as a high-performance electrode material for supercapacitors. The results indicated that the obtained porous graphene exhibits the highest specific capacitance in this study is 284 F/g at the current density of 0.2 A/g in 6 M KOH. Moreover, porous graphene showed good cycle durability over 83% at the current density of 1.0 A/g after 5000 cycles, and with columbic efficiency over 95%.

Elucidation of the linkages between the bacterial community composition and chromophoric dissolved organic matter (CDOM) in lake ecosystems is critical for the understanding of the inland water carbon cycling. Despite substantial research into the relationship between the bacteria community and the bulk DOM pool, knowledge of the specific relationship between the optical dynamics of DOM and the bacterioplankton community in lake ecosystems is still poor. We investigated the linkages between the optical dynamics of DOM and bacteria composition in shallow eutrophic Lake Taihu, China. Redundancy Analysis (RDA) indicated that besides water temperature and phytoplankton biomass, also CDOM was an important factor determining the composition of the bacterial community. Generalized Additive Models (GAM) showed that terrestrial humic-like C1 and tyrosine-like C4 were the key factors explaining the abundance of the main bacterial clades. C1 was closely correlated with Verrucomicrobia, Actinobacteria, Alphaproteobacteria, Betaproteobacteria and Planctomycetes, and C4 was closely related to the latter two and to Bacteroidetes. At family level, the dominant families – Pelagibacteraceae (Alphaproteobacteria) and Gemmataceae (Planctomycetes) – were related to both allochthonous and autochthonous CDOM fluorophores but responded differently to the various CDOM components. Tryptophan-like C2 was significantly and positively correlated with Gemmataceae and Ellin6075 (Acidobacteria). Additionally, we found that the biomasses of Cyanophyta, terrestrial humic-like C1, tryptophan-like C4 and C5 were significantly related to the richness of heterotrophic bacterioplankton. Our results provide new insight into the relationship between bacteria and DOM optical dynamics although the mechanisms leading to these relationships need further experimental investigations.

Biofloc technology involves manipulation of the C/N ratio to convert toxic nitrogenous wastes into useful microbial protein and helps improve the water quality in a closed system. Poly-β-hydroxybutyric (PHB) has been demonstrated to have positive effects on aquatic animals in an aquaculture system. A 40-day lab scale trial was carried out to investigate the potential of PHB as an additional carbohydrate for a shrimp Litopenaeus vannamei bioflocs nursery in brackish water. Three methods of carbohydrate supplementation were investigated. The first method was the addition of glucose daily at a percentage of 75% of the feed (GLU-group). The second method was the addition of PHB plus glucose; when the total ammonia nitrogen (TAN) level above 2 mg L−1 was observed, glucose was added, 6 g C to 1 g TAN (PHB + GLU-group). The third method was the addition of PHB only (PHB-group). During the 40-d trial, most of the ratios of dissolved organic carbon to total ammonium nitrogen (DOC/TAN) were maintained at 20 in the three groups. The average concentration of TAN in the PHB + GLU-group (0.23 ± 0.19 mg L−1) was significantly lower than those of the GLU-group (0.28 ± 0.26 mg L−1) and the PHB-group (0.30 ± 0.33 mg L−1) (P .05). The survival rate and final weight in the PHB + GLU group were significantly higher than those of the other groups (P

In situ suspended growth aquaculture systems for oligotrophic species suffer from excess total suspended solids, low dissolved oxygen, and other associated problems. To address these disadvantages, this study designed and tested a closed recirculating aquaculture system containing 3 pilot-scale suspended growth bioreactors (SGBRs) for the water treatment of pollutants. These SGBRs were designed to control extra carbon addition at carbon/nitrogen ratios of 12, 8, and 4, respectively. It was determined that the culture tanks removed total ammonia nitrogen (TAN) and nitrite (NO2−-N) by nitrification, and the SGBRs removed nitrate (NO3−-N) by denitrification and also soluble reactive phosphate (SRP). Concentrations of NO3−-N and SRP in the effluent decreased, as the controlled carbon/nitrogen ratio of the SGBR increased. When carbon was controlled at a carbon/nitrogen ratio of 12, the influent concentrations of NO3−-N (35.41 ± 1.22 mg·L−1) and SRP (4.60 ± 0.67 mg·L−1) were reduced to 7.70 ± 3.58 mg·L−1 and 0.30 ± 0.16 mg·L−1, respectively. Thus, this proposed system had the ability to control simultaneously TAN, NO2−-N, NO3−-N and SRP. The survival rate of Anguilla marmorata was 98.00 ± 1.41%, with a final stocking density of 56.46 ± 0.51 kg·m−3. We suggest that various adjustments in the carbon/nitrogen ratios of SGBRs can be practically controlled according to the concentrations of pollutants in the culture tanks.

Heteroatom-doped nanopores graphene has great potential as emerging energy storage materials, but the complex synthetic routes and disordered structure limit the improvement of supercapacitance performance. Herein, we develop a one-step synthesis strategy to obtain nitrogen/sulfur doped nanopores graphene (NS-NG). Graphene oxides absorbed with dyes are burned in a confined interlayer to obtain porous hydrotalcite for preparing NS-NG. Interestingly, the NS-NG retains the morphology of multilayer graphene oxides coated with fiber rods before combustion, so it exhibits the annual ring -shaped structure, larger surface area, and highly porosity. Importantly, the NS-NG not only shows a high specific capacitance of 325 F g-1, and also has a high energy density of 25 Wh kg-1 at a high power density of 1906 W kg-1 with an excellent capacity retention of 86% after 10,000 cycles applied in the two-electrode symmetric supercapacitor at a current density of 2 A g-1 in 0.5 M Na2SO4 aqueous solution.

Rare earth elements (REEs) are used widely in devices of many fields, but it is still a troublesome task to achieve their selective separation and purification. Metal-organic frameworks (MOFs) as an emerging porous crystalline material have been used for selective separation of REEs using the size-selective crystallization properties. However, so far, almost all MOFs cannot be used directly for selective separation of REEs in strong acid

GIFT Oreochromis niloticus was cultured in a bio-floc technology (BFT) system to identify the floral structure of the biofloc water and in the intestine of the fish. High-throughput sequencing technology was used to detect the microbes in the culture water, in the intestines and gills of farmed fish. The effective sequence coverage rate of each sample exceeded 99% and the sequencing results were true and reliable. The results show that according to Chao1 and Simpson indices, the microbial richness and diversity of flocs increase with the increase of culture time. Flocs initially favoured the thick-walled bacterium ( Firmicutes ) as the dominant fungi with abundance of 86%, whiles the rest were all less than 10% in abundance. At the end of the experiment the abundance of Chlorofiexi was 43% , Proteobacteria 26%, and Bacteroidetes 12%. During the early stages, Bacillus was the most dominant group of about 86% abundance. However, this declined towards the end of the breeding period and the abundance was recorded to reduce to about 3%. The highest abundance was associated with the bacterial described as unclassified species called N orank-f-caldilineaceae representing 40% and the abundance of Flavobacterium found to be 2%. The dominant bacteria in the intestinal tract of fish were Proteobacteria (35%), Bacillus (16%) and Cetobacterium (13%). The main heterotrophic assimilation functions in the BFT system were bacillus and chlorocampylobacter . However, flavobacterium was found in the BFT system indicating the presence of on-going denitrification

Summary Rare earth separation is still a major challenge in membrane science. Nitrogen-doped nanoporous graphene (NDNG) is a promising material for membrane separation, but it has not yet been tested for rare earth separation, and it is limited by multi-complex synthesis. Herein, we developed a one-step, facile, and scalable approach to synthesize NDNG with tunable pore size and controlled nitrogen content using confinement combustion. Nanoporous hydrotalcite from Zn(NO3)2 is formed between layers of graphene oxide (GO) absorbed with phenylalanine via confinement growth, thus preparing the sandwich hydrotalcite/phenylalanine/GO composites. Subsequently, area-confinement combustion of hydrotalcite nanopores is used to etch graphene nanopores, and the hydrotalcite interlayer as a closed flat nanoreactor induces two-dimensional space confinement doping of planar nitrogen into graphene. The membrane prepared by NDNG achieves separation of Sc3+ from the other rare earth ions with excellent selectivity (∼3.7) through selective electrostatic interactions of pyrrolic-N, and separation selectivity of ∼1.7 for Tm3+/Sm3+., Graphical Abstract, Highlights • A multiple confinement strategy is constructed to achieve the synthesis of NDNG • Planar nitrogen-doped NDNG with tunable pore size is obtained by one-step synthesis • NDNG membrane presents excellent selectivity for rare earth in strong acidic media, Separation Science; Chemical Synthesis; Porous Material

The production of bioflocs with the solid waste from recirculating aquaculture systems (RAS) and feeding Artemia results in additional nutrient retention and lowers waste discharged from RAS. The solid waste from the drum-filters of two RAS, which stocked European eel (Anguilla anguilla) and Nile tilapia (Oreochromis niloticus), was used as substrate to produce bioflocs in suspended growth reactors, referred to as E-flocs and T-flocs, respectively. Mono-diets consisting of 100% E-flocs and 100% T-flocs were added to culture Artemia, referred as E-Artemia and T-Artemia, respectively, in a laboratory scale test. The efficiency of this feeding regime was investigated. A significant difference was observed in terms of crude protein content (35.59 ± 0.2%) for E-flocs, (29.29 ± 0.95)% for T-flocs, (70.01 ± 0.92)% for E-Artemia and (65.63 ± 0.89)% for T-Artemia. 134 out of the total operational taxonomic units (OTUs) were present in E-flocs and T-flocs from the analysis of high-throughput sequencing data. Most of the shared OTUs belonged to cyanobacteria. C18:1n7 of T-flocs was higher than that of E-flocs (P < 0.05). C18:2n6 of E-flocs was significantly higher than that of T-flocs (P < 0.05). No significant difference was observed in the other fatty acid compositions (P > 0.05). The survival rate of E-Artemia was (22 ± 0.02) %, significantly higher than that of T-Artemia (16% ± 0.02%) (P < 0.05). No significant difference was observed between the average body weight of E-Artemia (2.38 ± 0.40 mg) and E-Artemia (2.91 ± 0.21) (P > 0.05). The EPA of Artemia fed with E-flocs was (3.00 ± 0.46)%, significantly higher than that of T-Artemia (1.57 ± 0.19%) (P < 0.05). This study offers a method for reusing the aquaculture waste, which will be helpful to achieve a zero-pollution discharge for aquaculture systems. Keywords: Bioflocs, Fish waste, Artemia, Recirculating aquaculture system, Suspended growth reactors

A denitrification reactor packed with polycaprolactone (PCL) as a carbon source and biofilm carrier was developed to remove nitrate nitrogen ( $$ {\mathrm{NO}}_3^{-}-\mathrm{N} $$ ) from the water of a recirculating aquaculture system for 115 days. The hydraulic retention time was set to 6 h, and the water flow rate was 0.95 L h−1. The removal rates of $$ {\mathrm{NO}}_3^{-}-\mathrm{N} $$ ranged from 34.67 to 155.7 g $$ {\mathrm{NO}}_3^{-}-\mathrm{N} $$ m−3 day−1 when the effluent $$ {\mathrm{NO}}_3^{-}-\mathrm{N} $$ concentrations ranged between 1.62 and 72.25 mg L−1. No obvious changes in the Fourier transform infrared spectra of the PCL before and after use were observed. Bacterial community structure in the biofilm of the PCL granules was analyzed using Illumina MiSeq sequencing technology. Proteobacteria and Bacteroidetes were predominant in the biofilm, with relative abundances of 63.9 and 27.4%, respectively. Three genera, Acidovorax, Azospira, and Diaphorobacter, were capable of both denitrification and PCL degradation. This study indicates that PCL-packed reactors may be used and optimized for removing nitrate from aquaculture effluents.

Aquaponic systems consisting of recirculating aquaculture systems and hydroponic beds. Raft-floating aquaponics integrated with a moving-bed biofilm reactor (MBBR) was established. Humic acid (HA) was added to the aquaponic systems to promote nutrient recovery. An elementary analyzer was used to determine the nitrogen content of fish, plants, and sediments to calculate the NUE. High-throughput sequencing and quantitative polymerase chain reaction (qPCR) were conducted to reveal the influence of HA on microbial communities and nitrification genes. During an 80 day experimental period, the effects of water quality parameters, nitrogen utilization efficiency (NUE), and microbial communities in variable concentrations of HA-based aquaponic systems were compared. Among the HA-based systems, the one with an optimal concentration of 15 ppm indicated the best performance. In HA-based aquaponic systems with 15 ppm concentration, the maximum concentrations of total ammonia nitrogen and NO2−–N were 6.02 mg/L and 12.693 mg/L, which were significantly lower than those in aquaponic systems with 0 ppm and 30 ppm. However, the accumulation of nitrate in the HA-based aquaponic systems with 15 ppm was greater than that in the others. The NUE of the 15 ppm HA-based aquaponic system was 58.34%, which was significantly higher than that of the 0 ppm (50.83%) and the 30 ppm (47.25%) systems. Consequently, the threshold concentration of HA was established as 15 ppm. The microbial communities of different HA-based systems revealed the presence of denitrifying and nitrifying microbial populations for nitrogen recovery in moving bed biofilm reactors (MBBRs); higher levels of these microbial populations thrived in the 15 ppm HA system than in the other systems. However, there was no significant difference in microbial communities from root samples. The highest copies of amoA and nxrB were found at 15 ppm for both MBBRs and roots, indicating that the addition of HA to the aquaponic systems yielded more products and improved water quality and NUE by changing the composition of microbial communities based on the threshold for HA input concentration. This study provided that HA show enormous potential for an interesting research and the development of green technologies for biological wastewater treatment and bioremediation.

Heteroatom-doped nanoporous graphene has great potential as emerging energy storage materials, but the complex synthetic routes and disordered structure limit the improvement of supercapacitance performance. Herein, we develop a one-step synthesis strategy to obtain nitrogen/sulfur doped nanoporous graphene (NS-NG). Graphene oxides absorbed with dyes are burned in a confined interlayer of porous hydrotalcite for preparing NS-NG. Interestingly, the NS-NG retains the morphology of multilayer graphene oxides coated with fiber rods before combustion, so it exhibits the annual ring -shaped structure, larger surface area, and highly porosity. Importantly, the NS-NG not only shows a high specific capacitance of 325 F g−1, and also has a high energy density of 25 Wh kg−1 at a high power density of 1906 W kg−1with an excellent capacity retention of 86% after 10,000 cycles applied in the two-electrode symmetric supercapacitor at a current density of 2 A g−1 in 0.5 M Na2SO4 aqueous solution.

Manipulating the C:N ratio is a practical way to reduce the accumulation of ammonium nitrogen (NH 4 + -N) in an aquaculture system. In this study, we investigated the use of poly-β-hydroxybutyric (PHB) and polycaprolactone (PCL) as carbon sources to support a limited discharge tilapia aquaculture system conveniently. The water was not changed for 120 days. No significant differences in the final biomass were observed between the PHB group (37.93 ± 8.87 kg m − 3 ) and the PCL group (34.29 ± 9.29 kg m − 3 ) or between the PHB group and the group with glucose as an external carbohydrate (44.14 ± 10.51 kg m − 3 ). NH 4 + -N and nitrite nitrogen (NO 2 − -N) were − 1 and 0.8 mg L − 1 at steady state, respectively. The assimilation of NH 4 + -N and nitrate nitrogen (NO 3 − -N), nitrification and denitrification were observed in the batch tests of the bioflocs taken from the fish tank. No significant differences were detected in the bioflocs' crude protein content (31–39%) between the PCL group and the PHB group or between the PHB group and the glucose group. Microbial analysis, assessed by high-throughput sequencing, revealed that the bacterial community was similar between the three groups. Although not every parameter was better than glucose, PHB or PCL was still considered preferable to glucose because of greater convenience. Collectively, our results showed that both PHB and PCL are favorable and convenient external carbohydrates for biofloc-based tilapia aquaculture systems.

The performance of microbial flocs as food for Artemia, which were produced using waste from a recirculating aquaculture system stocking European eel (Anguilla anguilla), was investigated in an 18-day feeding trial. Four dietary treatments were used: Chlorella only (diet 1), flocs only (diet 2), and both Chlorella and flocs offered as mixed diets in different proportions (diets 3 and 4). The survival rate of Artemia fed diets 1 and 4 were significantly higher than those fed diets 2 and 3. The survival rate of Artemia fed diet 4 was the highest among the four diets. Individual length (10.02 ± 2.44 mm) and biomass production of diet 3 (3.2 ± 0.40 g L–1) were the highest among the four diets. The crude protein contents for Artemia fed diets 2, 3 and 4 were 591.22 ± 30.15, 580.34 ± 22.42 and 533.27 ± 34.19 g kg–1, respectively, which were significantly higher than that of diet 1 (461.25 ± 10.33 g kg–1). The concentrations of free amino acids and the fatty acid compositions in the four diets were equal, except for the C24:0 content. The highly unsaturated fatty acid concentration of Artemia fed diet 2 was higher than those of the other three diets. It showed that microbial flocs produced from fish waste can be used for Artemia.

To achieve high water-treatment efficiencies and simplify the setup of recirculating aquaculture systems (RAS), this study examined the use of suspended growth reactors (R1 and R2) based on biofloc technology (BFT) as water-treatment biofilters. Moreover, the conversion of the heterotrophic R1 biofilter to a nitrifying role was investigated. During RAS operation using heterotrophic BFT biofilters, R1 and R2 simultaneously controlled total ammonium nitrogen, nitrite (NO2−-N), nitrate (NO3−-N), soluble reactive phosphate (SRP), and alkalinity, with relevant functional microbes including denitrifying bacteria (DNB), phosphorus accumulating organisms (PAOs), denitrifying PAOs (DNPAOs), glycogen accumulating organisms, ammonia oxidizing bacteria, and nitrite oxidizing bacteria. To achieve low concentrations of nitrogen, phosphorus, and save carbon sources, we were able to quickly convert R1 into a nitrifying BFT biofilter by stopping carbohydrate addition. Although there were dominant relative abundances of DNB, PAOs, and DNPAOs in the converted R1, the lack of carbon sources resulted in continuous rise of NO3−-N in the effluent, stable NO2−-N removal efficiency, and absence of SRP removal after 40 h. However, R2 retained the previous NO3−-N and SRP removal efficiencies with carbohydrate addition. This indicated that this novel RAS using BFT biofilters achieved simultaneous nitrogen and phosphate removal, and that the convertible water-treatment efficiencies of BFT biofilters could be controlled by carbohydrate addition. This approach could simplify the RAS setup and meet real-time water quality demands.

With additional organic carbon, fish waste can be used as a substrate to produce bioflocs, a protein source for aquaculture animals. In choosing a carbon source, one should consider convenience, cost and biodegradability. This study investigates the efficiency of poly-β-hydroxybutyric acid (PHB), a biologically degradable polymer, as a carbon source to produce bioflocs in suspended growth bioreactors (SGRs), PHB-SGRs, compared with glucose (GLU-SGRs). The C:N ratio in PHB-SGRs could be maintained around 15:1. The volatile suspended solids (VSS) yield was 2.94 ± 0.72 gVSS/g fish waste for PHB-SGRS and 4.90 ± 0.23 gVSS/g fish waste for GLU-SGRs. The recycling rate of nitrogen in aquaculture solid waste was 56 ± 2% and 87 ± 7% for the PHB-SGRs and Glu-SGRs. No significant differences were found in the bioflocs produced and in the crude protein content of the produced bioflocs between PHB-SGRs and GLU-SGRs. PHB-SGRs and GLU-SGRs could remove dissolved inorganic nitrogen from aquaculture wastewater, with average values of 11.82 ± 8.95 and 16.27 ± 3.95 mg/g TSS/d. Because the calculation of the added amount of carbon and the multiple additions of carbon was avoided, PHB is considered to be a good choice as an organic carbon source for this process, even though not all parameters used for assessment were better than those of GLU-SGRs.