Pilot trial study of a compact macro-filtration membrane bioreactor process for saline wastewater treatment

Conventional membrane bioreactor (MBR) systems have increasingly been studied in recent decades. However, their applications have been limited due to their drawbacks such as low flux, membrane fouling, and high operating cost. In this study, a compact macro-filtration MBR (MfMBR) process was developed by using a large pore size membrane to mitigate the membrane fouling problem. A pilot trial of MfMBR process was set up and operated to treat 10 m(3)/day of saline wastewater within 4 h. The system was operated under an average permeate flux of 13.1 m(3)/(m(2)·day) for 74 days. The average total suspended solids, total chemical oxygen demand, biological oxygen demand, total Kjeldahl nitrogen, and total nitrogen removal efficiencies achieved were 94.3, 83.1, 98.0, 93.1, and 63.3%, respectively, during steady-state operation. The confocal laser scanning microscopy image indicated that the backwash could effectively remove the bio-cake and dead bacteria. Thus, the results showed that the MfMBR process, which is essentially a primary wastewater treatment process, had the potential to yield the same high quality effluent standards as the secondary treatment process; thereby suggesting that it could be used as an option when the economic budget and/or land space is limited.

The superior cycle and rate performance of a novel sulfur cathode by immobilizing sulfur into porous N-doped carbon microspheres

A novel S-immobilized N-doped carbon microspheres (NCMs) composite was synthesized and assembled as a cathode for Li–S batteries with significantly improved cycle stability and rate performance (e.g.0.030% per cycle for 500 cycles at 2.0 C).

Strained olefin enables triflic anhydride mediated direct dehydrative glycosylation

Tf₂O mediated dehydrative glycosylation was enabled by strained olefins, including beta-(−)-pinene, and inhibited by other typical bases.

Recent advances in Mn-based oxides as anode materials for lithium ion batteries

The Mn-based oxides including MnO, Mn₃O₄, Mn₂O₃, MnO₂, CoMn₂O₄, ZnMn₂O₄and their carbonaceous composite/oxide supports with different morphologies and compositions as anode materials are reviewed.

Threonine metabolism and embryonic stem cell self-renewal

PURPOSE OF REVIEW

Embryonic stem cells (ESCs) undergo unlimited self-renewal while maintaining a pluripotency, which is defined as the ability to develop into cells of all three embryonic germ layers. ESC self-renewal is characterized by special proliferative and epigenetic properties and a unique metabolic profile. One of the key features of this specialized nutritional metabolism is a stringent requirement for the amino acid threonine. Until recently, little was known about amino acid metabolism in stem cells beyond their general role in protein synthesis. Recent findings demonstrating a central role for threonine metabolism in multiple aspects of stem cell biology will be presented in this review.

RECENT FINDINGS

Amino acid catabolism supplies essential building blocks for biosynthetic pathways and for chemical modification of chromatin. In a series of recent studies employing combinative approaches of metabolomics, nutrition and genetics, the amino acid threonine was identified as an essential nutrient for mouse ESC (mESC). An unexpected finding from these studies was that in addition to its well known importance as protein precursor, threonine dehydrogenase-mediated threonine catabolism provides essential metabolic building blocks for use in multiple biosynthetic pathways and epigenetic modifications required for self-renewal and maintenance of pluripotency.

SUMMARY

Recent studies on threonine catabolism in mESCs suggest that amino acids can play both powerful biosynthetic and signaling roles in stem cells. These results described in mESCs should stimulate a new research area on the effect of amino acid metabolism in stem cell self-renewal and differentiation.

Construction of high-density genetic linkage maps for orange-spotted grouper Epinephelus coioides using multiplexed shotgun genotyping

Background

Orange-spotted grouper, Epinephelus coioides, is one of the most valuable fish species in China. Commercial production of orange-spotted grouper could be increased by developing higher growth rates and improving commercially important traits. Information on genetic markers associated with quantitative trait loci (QTL) can be used in breeding programs to identify and select individuals carrying desired traits. A high-density genetic linkage map is the basis for QTL study, and multiplexed shotgun genotyping (MSG) facilitates the development of single nucleotide polymorphisms (SNPs) and genotyping. In this study, the first high-density genetic linkage maps for groupers were generated on the basis of the MSG method.

Results

The sex-averaged map contained a total of 4,608 SNPs, which spanned 1581.7 cM, with a mean distance between SNPs of 0.34 cM. The 4,608 SNPs were located in 2,849 unique locations on the linkage map, with an average inter-location space at 0.56 cM. There were 2,516 SNPs on the female map, and the number of unique locus was 1,902. However, the male map contained more numbers of SNP (2,939) and unique locations (2,005). The total length of the female and male maps was 1,370.9 and 1,335.5 cM, respectively.

Conclusions

The high-resolution genetic linkage maps will be very useful for QTL analyses and marker-assisted selection (MAS) for economically important traits in molecular breeding of the orange-spotted grouper.

Fluorescent protein-based detection of φC31 integrase activity in mammalian cells

The enzyme φC31 integrase from Streptomyces phage has been documented as functional in mammalian cells and, therefore, has the potential to be a powerful gene manipulation tool. However, the activity of this enzyme is cell-type dependent. The more active mutant forms of φC31 integrase are required. Therefore, a rapid and effective method should be developed to detect the intracellular activity of φC31 integrase. We devised in this study an integrase-inversion cassette that contains the enhanced green fluorescent protein (EGFP) gene and the reverse complementary DsRed gene, which are flanked by attB and reverse complementary attP. This cassette can be inverted by φC31 integrase, thereby altering the fluorescent protein expression. Thus, φC31 integrase activity can be qualitatively or quantitatively evaluated based on the detected fluorescence. Furthermore, this cassette-based method was applied to several cell types, demonstrating that it is an efficient and reliable tool for measuring φC31 integrase activity in mammalian cells.

Single nucleotide polymorphisms in the leptin-a gene and associations with growth traits in the orange-spotted grouper (Epinephelus coioides)

Leptin is a multifunctional protein involved in processes such as body weight regulation, energy expenditure, fat metabolism, food intake, and appetite regulation. Duplicate leptin genes, leptin-a and leptin-b, were previously detected in the orange-spotted grouper. In this study, we cloned the full-length open reading frame (ORF) of the leptin-a gene in the orange-spotted grouper, searched for polymorphisms, and performed association analyses between these polymorphisms and seven growth traits. Six polymorphisms, consisting of 2 SNPs in intron 1 (c.182T > G, c.183G > T) and 4 SNPs in exon 2 (c.339C > G, c.345C > T, c.447G > A, c.531C > T), were identified and genotyped in 200 individuals. The c.182T > G and c.183G > T polymorphisms showed complete linkage and were analyzed together. Association analyses revealed that the c.182 + 183TG > GT polymorphism was significantly associated with body weight (BWT) and body width (BWH), with the AB (TG/GT) genotype showing positive effects on growth traits. Additionally, the SNP c.447G > A was significantly associated with BWT, BWH, overall length (OL), trunk width (TW), and head length (HL), with the GA genotype displaying positive effects on growth traits. The c.531C > T SNP showed a close association between the TT genotype and decreased growth. Our results demonstrate that several polymorphisms in the leptin-a gene are associated with growth traits and can be used for marker-assisted selection (MAS) in orange-spotted grouper populations.

Effect of sewage sludge amendment on heavy metal uptake and yield of ryegrass seedling in a mudflat soil

Mudflat soil amendment by sewage sludge is a potential way to dispose of solid wastes and increase fertility of mudflat soils for crop growth. The present study aimed to assess the impact of sewage sludge amendment (SSA) on heavy metal accumulation and growth of ryegrass ( L.) in a seedling stage. We investigated the metal availability, plant uptake, and plant yield in response to SSA at rates of 0, 30, 75, 150, and 300 t ha. The SSA increased the metal availability in a mudflat soil and subsequently metal accumulation in ryegrass. The SSA increased the bioavailable fraction of the metals by 4550, 58.8, 898, 189, 35.8, and 84.8% for Zn, Mn, Cu, Ni, Cr, and Cd, respectively, at an SSA rate of 300 t ha as compared to unamended soil. Consequently, the metal concentrations in ryegrass increased by 1130, 12.9, 355, 108, 2230, and 497% in roots and by 431, -4.3, 92.6, 58.3, 890, and 211% in aboveground parts, for Zn, Mn, Cu, Ni, Cr, and Cd, respectively, at the 300 t ha rate as compared to unamended soil. The enhanced metal accumulation, however, did not induce growth inhibition of ryegrass. Fresh weight of aboveground parts and roots of ryegrass at 300 t ha SSA rate increased by 555 and 128%, respectively, as compared to those grown in unamended soil. The study suggests that SSA can promote yield of ryegrass seedlings grown in mudflat soils. None of metal concentrations at all SSA rates was above the Chinese permissible limits. Despite the data at only the seedling stage, our results indicate that SSA in mudflat soils might be a potential way for mudflat soil fertility improvement and sewage sludge disposal. Further study at plants' maturity stage is warranted to fully assess the suitability of sewage sludge amendment on mudflat soils.

Synergetic interactions improve cobalt leaching from lithium cobalt oxide in microbial fuel cells

Cobalt leaching from lithium cobalt oxide is a promising reduction process for recovery of cobalt and recycle of spent lithium ion batteries, but suffers from consumption of large amount of reductants and energy, and generation of excess secondary polluted sludge. Thus, effective and environmental friendly processes are needed to improve the existing process limitations. Here we reported microbial fuel cells (MFCs) to effectively reduce Co(III) in lithium cobalt oxide with concomitant energy generation. There was a synergetic interaction in MFCs, leading to a more rapid Co(III) leaching at a rate 3.4 times the sum of rates by conventional chemical processes and no-acid controls. External resistor, solid/liquid ratio, solution conductivity, pH and temperature affected system performance. This study provides a new process for recovery of cobalt and recycle of spent lithium ion batteries with concomitant energy generation from MFCs.

Industrial flue gas desulfurization waste may offer an opportunity to facilitate SANI® application for significant sludge minimization in freshwater wastewater treatment

This paper reports an exploratory study on the use of a sulfite-rich industrial effluent to enable the integration of a sulfite-sulfide-sulfate cycle to the conventional carbon and nitrogen cycles in wastewater treatment to achieve sludge minimization through the non-sludge-producing Sulfate reduction, Autotrophic denitrification and Nitrification Integrated (SANI) process. A laboratory-scale sulfite reduction reactor was set up for treating sulfite-rich synthetic wastewater simulating the wastewater from industrial flue gas desulfurization (FGD) units. The results indicated that the sulfite reduction reactor can be started up within 11 d, which was much faster than that using sulfate. Thiosulfate was found to be the major sulfite reduction intermediate, accounting for about 30% of the total reduced sulfur in the reactor effluent, which may enable additional footprint reduction of the autotrophic denitrification reactor in the SANI process. This study indicated that it was possible to make use of the FGD effluent for applying the FGD-SANI process in treating freshwater-based sewage.

Granulation of anaerobic sludge in the sulfate-reducing up-flow sludge bed (SRUSB) of SANI(®) process

This study reports on anaerobic sludge granulation in a laboratory-scale sulfate-reducing up-flow sludge bed (SRUSB) in a novel sulfate reduction, autotrophic denitrification and nitrification integrated (SANI(®)) process for treatment of saline sewage. Granulation occurred in 30 d and reached full development in 90 d. The sulfate-reducing granules grew up to around 1 mm after 90 d with 21 mL/g SVI5 (sludge volume index measured after 5 min) and the biomass concentration reached 29 g/L after 4 months' operation. The reactor removed 89% chemical oxygen demand (COD) and reduced 75% sulfate within 1 h of hydraulic retention time, under a COD loading rate of up to 6.4 kg COD/(m(3) · d).

Combined effects of enrichment procedure and non-fermentable or fermentable co-substrate on performance and bacterial community for pentachlorophenol degradation in microbial fuel cells

Combined effects of enrichment procedure and non-fermentable acetate or fermentable glucose on system performance and bacterial community for pentachlorophenol (PCP) degradation in microbial fuel cells (MFCs) were determined in this study. Co-substrate and PCP were added into MFCs either simultaneously or sequentially. Simultaneous addition with glucose (simultaneous-glucose) achieved the shortest acclimation time and the most endurance to heavy PCP shock loads. Species of Alphaproteobacteria (simultaneous-acetate, 33.9%; sequential-acetate, 31.3%), Gammaproteobacteria (simultaneous-glucose, 44.1%) and Firmicutes (sequential-glucose, 31.8%) dominated the complex systems. The genus Sedimentibacter was found to exist in all the cases whereas Spirochaetes were merely developed in simultaneous-acetate and simultaneous-glucose. While Epsilonproteobacteria were only absent from sequential-acetate, simultaneous-glucose benefited to the evolution of Lentisphaerae. These results demonstrate simultaneous-glucose is a strategy for efficient system performance and the microbiological evidence can contribute to improving understanding of and optimizing PCP degradation in MFCs.

Two-Dimensional Mathematical Modeling of Heat and Mass Transfer in Fluidized-Bed Drying of Porous Material

A two-dimensional mathematical model of simultaneous heat and mass transfer for porous media drying was derived based on the Whitaker’s theory in the present study. The cylindrical coordinate system, which is more practical than the spherical one, was adopted. The model was solved numerically under the circumstance of fluidized-bed drying. The control-volume method with the fully implicit scheme was applied for discretization of governing equations. Physical properties of apple were selected in the simulation. Under typical operating conditions, heat and mass transfer mechanisms were analyzed based on the profiles of temperature and saturation inside the particles. Effects of the temperature, humidity and inlet velocity of hot gas were examined under different operating conditions. Simulation results show that the drying process can be significantly affected by coupled heat and mass transfer between gas and solid phases. The drying time increases with the increase in temperature and velocity of inlet hot gas, and decreases with the increase in humidity and bed area factor.

Reductive dechlorination and mineralization of pentachlorophenol in biocathode microbial fuel cells

Simultaneous anaerobic and aerobic degradation pathways in two-chamber, tubular microbial fuel cells (MFCs) facilitated pentachlorophenol (PCP) mineralization by a mediator-less biocathode. PCP was degraded at a rate of 0.263 ± 0.05 mg/L-h (51.5 mg/g VSS-h) along with power generation of 2.5 ± 0.03 W/m(3). Operating the biocathode MFC at 50°C improved the PCP degradation rate to 0.523 ± 0.08 mg/L-h (103 mg/g VSS-h) and power production to 5.2 ± 0.03 W/m(3). A pH of 6.0 increased the PCP degradation rate to 0.365 ± 0.02 mg/L-h (71.5mg/g VSS-h), but reduced power. While mediators were not needed, adding anthraquinone-2,6-disulfonate increased power and PCP degradation rates. Dominant bacteria most similar to the anaerobic Desulfobacterium aniline, Actinomycetes and Streptacidiphilus, and aerobic Rhodococcus erythropolis, Amycolatopsis and Gordonia were found on the biocathode. These results demonstrate efficient degradation of PCP in biocathode MFCs and the effects of temperature, pH and mediators.

Role of hydroxyl radicals and mechanism of Escherichia coli inactivation on Ag/AgBr/TiO2 nanotube array electrode under visible light irradiation

A ternary Ag/AgBr/TiO(2) nanotube array electrode with enhanced visible-light activity was synthesized by a two-step approach including electrochemical process of anodization and an in situ photoassisted deposition strategy. The dramatically enhanced photoelectrocatalytic activity of the composite electrode was evaluated via the inactivation of Escherichia coli under visible light irradiation (λ>420 nm), whose performance of complete sterilization was much superior to other reference photocatalysts. PL, ESR, and radicals trapping studies revealed hydroxyl radicals were involved as the main active oxygen species in the photoelectrocatalytic reaction. The process of the damage of the cell wall and the cell membrane was directly observed by ESEM, TEM, and FTIR, as well as further confirmed by determination of potassium ion leakage from the killed bacteria. The present results pointed to oxidative attack from the exterior to the interior of the Escherichia coli by OH(•), O(2)(•-), holes and Br(0), causing the cell to die as the primary mechanism of photoelectrocatalytic inactivation.