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Denitrifying sulfide removal (DSR) process simultaneously removes nitrate, sulfide and organic matters in the same reactor. This study applied Azoarcus sp. NSC3 and Pseudomonas sp. CRS1 mix for DSR tests in autotrophic, heterotrophic and mixotrophic growths. Negligible NO-compounds were noted in heterotrophic or mixotrophic growths, while most cells were damaged and bound with NO-compounds in autotrophic growth. Nitroprusside (SNP) ions were applied as model compound to reveal the formation of nitrososulfide complex (RSNO) by nitroso (NO+) and excess sulfide (S2-), rather than the previously proposed mechanism by direct reaction between nitric oxide (NO) and S2-. We speculated that RSNO was then abiotically decomposed to NO and elemental sulfur in the presence of biological cells. A revised nitrogen cycle considering interactions with sulfur compounds was proposed. We also speculated that SNO and NO were inhibitory to the functional strains, whose efficient removals were essential to reach high-rate DSR performance. [ABSTRACT FROM AUTHOR]

High-strength cresol isomers were treated with phenol-acclimated granules in batch experiments. The aerobic granules effectively metabolized cresol isomers at concentrations up to 1,500 mg l. The modified Haldane kinetic model, used to assess the kinetic behavior during cresol degradation by granule cells, yielded a high maximum specific growth rate (1.13-1.45 h) and inhibition constant (617-952 mg l). The microbial community structure, which was stable under cresol stress, was principally composed of genera Bacillus, Acinetobacter, Corynebacterium, and Nocardioides. Enzyme assay results suggest simultaneous expression of ortho- and meta-cleavage pathways during cresol degradation. Under high cresol concentrations, however, cresol isomers were largely degraded via the meta-cleavage pathway, likely attributable to the activity of Bacillus. The aerobic granular sludge system is a promising biotechnology for degrading wastewater containing high-strength cresols. [ABSTRACT FROM AUTHOR]

The membrane fouling layer in the combined aerobic granular membrane bioreactor (AGMBR) process and the conventional MBR process was probed in this study using the multiple staining and confocal laser scanning microscope (CLSM) technique. The fouling layer built up outside and inside the membrane was principally composed of live cells embedded in a matrix of proteins and polysaccharides. The fouling layer presented outside the membrane is noted denser in structure than that inside the membrane. [ABSTRACT FROM AUTHOR]

The soluble microbial products (SMP) and extracellular polymeric substances (EPS) significantly affect fouling in membrane filtration. This work filtered SMP and fractionated EPS of activated sludge using a 0.45 mm filter membrane. The fluorescently labeled stains and confocol laser scanning microscopy (CLSM) images in situ visualized the distributions of proteins, α-polysaccharides, β-polysaccharides, lipids, total cells, and dead cells of different EPS fractions in the fouling layers. The role of individual SMP and fractionated EPS fractions on membrane fouling was discussed. [ABSTRACT FROM AUTHOR]

Fouling is an inevitable hurdle limiting flux and performance of membrane processes. This paper reviewed the literature studies on physical cleaning methods and chemical cleaning and commented on the indices for cleaning efficiencies therein used in literature works. [ABSTRACT FROM AUTHOR]

Aerobic sludge granules are compact, strong microbial aggregates that have excellent settling ability and capability to efficiently treat high-strength and toxic wastewaters. Aerobic granules disintegrate under high organic loading rates (OLR). This study cultivated aerobic granules using acetate as the sole carbon and energy source in three identical sequencing batch reactors operated under OLR of 9–21.3 kg chemical oxygen demand (COD) m−3 day−1. The cultivated granules removed 94–96% of fed COD at OLR up to 9–19.5 kg COD m−3 day−1, and disintegrated at OLR of 21.3 kg COD m−3 day−1. Most tested isolates did not grow in the medium at >3,000 mg COD l−1; additionally, these strains lost capability for auto-aggregation and protein or polysaccharide productivity. This critical COD regime correlates strongly with the OLR range in which granules started disintegrating. Reduced protein quantity secreted by isolates was associated with the noted poor granule integrity under high OLR. This work identified a potential cause of biological nature for aerobic granules breakdown. [ABSTRACT FROM AUTHOR]

The aerobic sludge granules cultivated at high organic loading rates could effectively convert 100–700 mg l−1 nitrite to nitrogen gas with 400 or 1,200 mg l−1 dosed acetate. The denitrifying microbial community structure of the so-cultivated granules was investigated by 16S rRNA gene sequences and localized using fluorescence in situ hybridization (FISH). The 16S rRNA gene phylotypes in the clone library and FISH probes used exhibited high diversity among the bacteria and denitrifying communities, with the members of Betaproteobacteria predominant that were closely related to families Comamonadaceae, Nitrosomonadaceae, Alcaligenaceae, and Rhodocyclaceae. The confocal laser scanning microscope and staining test revealed that active microbial community principally distributed at 200–250 μm beneath the outer surface, embedded in extracellular polymeric substances. [ABSTRACT FROM AUTHOR]

Nitrite accumulates during biological denitrification processes when carbon sources are insufficient. Acetate, methanol, and ethanol were investigated as supplementary carbon sources in the nitrite denitrification process using biogranules. Without supplementary external electron donors (control), the biogranules degraded 200 mg l−1 nitrite at a rate of 0.27 mg NO2–N g−1 VSS h−1. Notably, 1,500 mg l−1 acetate and 700 mg l−1 methanol or ethanol enhanced denitrification rates for 200 mg l−1 nitrite at 2.07, 1.20, and 1.60 mg NO2–N g−1 VSS h−1, respectively; these rates were significantly higher than that of the control. The sodium dodecyl sulfate polyacrylamide gel electrophoresis of the nitrite reductase (NiR) enzyme identified three prominent bands with molecular weights of 37–41 kDa. A linear correlation existed between incremental denitrification rates and incremental activity of the NiR enzyme. The NiR enzyme activity was enhanced by the supplementary carbon sources, thereby increasing the nitrite denitrification rate. The capacity of supplementary carbon source on enhancing NiR enzyme activity follows: methanol > acetate > ethanol on molar basis or acetate > ethanol > methanol on an added weight basis. [ABSTRACT FROM AUTHOR]

Efficient nitrification and denitrification of wastewater containing 1,700 mgl−1 of ammonium-nitrogen was achieved using aerobic granular sludge cultivated at medium-to-high organic loading rates. The cultivated granules were tested in a sequencing batch reactor (SBR) fed with 6.4 or 10.2 kg NH-N m−3 day−1, a loading significantly higher than that reported in literature. With alternating 2 h oxic and 2 h anoxic operation (OA) modes, removal rate was 45.5 mg NH-N g−1 volatile suspended solids−1 h−1 at 6.4 kg NH-N m−3 day−1 loading and 41.3 ± 2.0 at 10.2 kg NH-N m−3 day−1 loading. Following the 60 days SBR test, granules were intact. The fluorescence in situ hybridization and confocal laser scanning microscopy results indicate that the SBR-OA granules have a distribution with nitrifers outside and heterotrophs outside that can effectively expose functional strains to surrounding substrates at high concentrations with minimal mass transfer limit. This microbial alignment combined with the smooth granule surface achieved nitrification–denitrification of wastewaters containing high-strength ammonium using aerobic granules. Conversely, the SBR continuous aeration mode yielded a distribution with nitrifers outside and heterotrophs inside with an unsatisfactory denitrification rate and floating granules as gas likely accumulated deep in the granules. [ABSTRACT FROM AUTHOR]

Aerobic granules are cultivated by a single bacterial strain, Acinetobacter calcoaceticus, in a sequencing batch reactor (SBR). This strain presents as a good phenol reducer and an efficient auto coagulator in the presence of phenol, mediated by heat-sensitive adhesins proteins. Stable 2.3-mm granules were formed in the SBR following a 7-week cultivation. These granules exhibit excellent settling attributes and degrade phenol efficiently at concentrations of 250–2,000 mg l−1. The corresponding phenol degradation rate reached 993.6 mg phenol g−1 volatile suspended solids (VSS) day−1 at 250 mg l−1 phenol and 519.3 mg phenol g−1 VSS day−1 at 2,000 mg l−1 phenol concentration. Meanwhile, free A. calcoaceticus cells were fully inhibited at phenol >1,500 mg l−1. Denaturing gradient gel electrophoresis fingerprint profile demonstrated no genetic modification in the strain during aerobic granulation. The present single-strain granules showed long-term structural stability and performed high phenol degrading capacity and high phenol tolerance. The confocal laser scanning microscopic test revealed that live A. calcoaceticus cells principally distributed at 200–250 μm beneath the outer surface, with an extracellular polymeric substance layer covering them to defend phenol toxicity. Autoaggregation assay tests demonstrated the possibly significant role of secreted proteins on the formation of single-culture A. calcoaceticus granules. [ABSTRACT FROM AUTHOR]

Effect of air aeration intensities on granule formation and extracellular polymeric substances content in three identical sequential batch reactors were investigated. The excitation–emission–matrix spectra and multiple staining and confocal laser scanning microscope revealed proteins, polysaccharides, lipids, and humic substances in the sludge and granule samples. Seed sludge flocs were compacted at low aeration rate, with produced extracellular polymeric substances of 50.2–76.7 mg g−1 of proteins, 50.2–77.3 mg g−1 carbohydrates and 74 mg g−1 humic substances. High aeration rate accelerated formation of 1.0–1.5 mm granules with smooth outer surface. The corresponding quantities of extracellular polymeric substances were 309–537 mg g−1 of proteins, 61–109 mg g−1 carbohydrates, 49–92 mg g−1 humic substances, and 49–68 mg g−1 lipids. Intermediate aeration rate produced 3.0–3.5 mm granules with surface filaments. Reactor failure occurred with overgrowth of filaments, probably owing to the deficiency of nutrient in liquid phase. No correlation was noted between extracellular polymeric substances composition and the proliferation of filamentous microorganisms on granule surface. [ABSTRACT FROM AUTHOR]

Multiple fluorochrome experiments with as many fluorochromes as possible are desired for exploring the detailed structure of bioaggregates. Spectral peak interference and other practical limitations, however, restrict the maximum number of stains used simultaneously to three. This current study proposes a sixfold labelled scheme to stain the total cells, dead cells, proteins, lipids, and α- and β-polysaccharides in bioaggregates. Two aerobic granule systems, the phenol-fed and the acetate-fed granules, were utilized as the testing samples for demonstrating the use of the proposed scheme. [ABSTRACT FROM AUTHOR]

Operators at waterworks in which flat-bottom floc blanket clarifiers are used, are advised to increase coagulant dose when the turbidity of clarified water is high, to stabilize the blanket and yield quality drinking water. This work showed that, even when the raw water is sufficiently alkaline, the blanket responded anomalously to the increased dose of polyaluminum chloride (PACl), which was used herein as a coagulant. Restated, rather than being stabilized, the blanket was destabilized by the high dose of PACl. This “anomalous” behavior of the blanket is caused by a temporary drop in local pH at the injection port at the bottom of the blanket, which is caused by poor PACl dispersion, and the subsequent charge reversal of the constituent particles and the decline in the blanket stability. A step increase in PACl dose may result in complete blanket loss. [ABSTRACT FROM AUTHOR]

Membrane biofouling by microbial products adversely impacts the feasibility of adopting membrane bioreactors (MBRs) for treating wastewater. The fouling layer structure determines the pressure drop across the fouling layer. Three-dimensional distributions of nucleic acids, proteins, α-D-GLUCOPYRANOSE POLYSACCHARIDES, AND B-D-glucopyranose polysaccharides in the fouling layer formed on a mixed cellulose ester membrane were generated utilizing a quadruple staining protocol combined with confocal laser scanning microscopy (CLSM). For the first time, this study constructed a three-dimensional volumetric grids model representing the fouling layer structure on the basis of a series of CLSM images. Quantitative structural information about the fouling layer was extracted from the CLSM images. [ABSTRACT FROM AUTHOR]

Membrane biofouling via microbial products limits the feasibility of utilizing membrane bioreactor (MBR) for treating wastewater. Fouling layer would be built up when activated sludge was filtered with a mixed cellulose ester membrane. This study probed the three‐dimensional distributions of protein, α‐polysaccharide, and β‐polysaccharide in fouling layer using fluorescently labeled lectins and fluorescein isothiocyanate (FITC) as staining agents in combination with confocal laser scanning microscopy (CLSM). These extracellular polymeric substances (EPS) distributed heterogeneously in the fouling layer, with α‐polysaccharide being concentrated close to the membrane surface. The flow pattern yielded in the fouling layer determines the filtration resistance of biofouling. [ABSTRACT FROM AUTHOR]

Membrane biofouling via microbial products limits the feasibility of utilizing membrane bioreactor (MBR) for treating wastewater. Fouling layer would be built up when activated sludge was filtered with a mixed cellulose ester membrane. This study probed the three‐dimensional distributions of protein, α‐polysaccharide, and β‐polysaccharide in fouling layer using fluorescently labeled lectins and fluorescein isothiocyanate (FITC) as staining agents in combination with confocal laser scanning microscopy (CLSM). These extracellular polymeric substances (EPS) distributed heterogeneously in the fouling layer, with α‐polysaccharide being concentrated close to the membrane surface. The flow pattern yielded in the fouling layer determines the filtration resistance of biofouling. [ABSTRACT FROM AUTHOR]

Waste disposal problems are often the result of rapid industrial and economic developments in land-scarce municipalities. Waste utilization could be a viable choice to alleviate the problems by transforming wastes into useful products while conserving natural resources. Previous studies by the writers indicated that in the process of thermal conversion of industrial sludge and dredged marine clay mixes into concrete aggregates, pyro-expansion and bloating were often exhibited by the aggregates. The expansion and bloating mechanisms, however, have not been looked into in greater detail. This research examines the petrology of sintered industrial sludge–marine clay aggregates in order to better understand the mechanisms leading to pyro-expansion and bloating of the aggregates. The study would enable development of an efficient and cost-effective bloating methodology for lightweight aggregate production. Main factors investigated were sludge–clay mix proportions, firing temperatures, and salt additives. The investigation revealed that firing at temperatures of 1,200 and 1,300°C produced aggregates of lower specific gravity in the range of 0.5–1.6. The highest aggregate porosity can be achieved at 1,200°C with a clay content of 50%. Scanning electron microscope images indicated that the intrinsic lightweight characteristic of the aggregates could be attributed to large pores within a dense surrounding matrix. The effect of lightweight structures may be ascribed to the release of volatile substances at each respective peak endothermic transitions during firing. The release of substances in vapor form required a large amount of energy, which resulted in the peak endothermic transitions that correspond to the formation of the porous lightweight structures. The results suggested that it is possible to promote pores formation in the production of aggregates possessing lightweight characteristics through careful control of temperature and the selection of sludge–clay proportion. [ABSTRACT FROM AUTHOR]

The interaction of gold nanoparticles (AuNP) with human immune-deficiency virus aspartic protease (HIVPR) is modelled using a regime of molecular dynamics simulations. The simulations of the ‘docking’, first as a rigid-body complex, and eventually through flexible-fit analysis, creates 36 different complexes from four initial orientations of the nanoparticle strategically positioned around the surface of the enzyme. The structural deviations of the enzymes from the initial x-ray crystal structure during each docking simulation are assessed by comparative analysis of secondary structural elements, root mean square deviations, B-factors, interactive bonding energies, dihedral angles, radius of gyration (Rg), circular dichroism (CD), volume occupied by Cα, electrostatic potentials, solvation energies and hydrophobicities. Normalisation of the data narrows the selection from the initial 36 to one ‘final’ probable structure. It is concluded that, after computer simulations on each of the 36 initial complexes incorporating the 12 different biophysical techniques, the top five complexes are the same no matter which technique is explored. The significance of the present work is an expansion of an earlier study on the molecular dynamic simulation for the interaction of HIVPR with silver nanoparticles. This work is supported by experimental evidence since the initial ‘orientation’ of the AgNP with the enzyme is the same as the ‘final’ AuNP-HIVPR complex generated in the present study. The findings will provide insight into the forces of the binding of the HIVPR to AuNP. It is anticipated that the protocol developed in this study will act as a standard process for the interaction of any nanoparticle with any biomedical target. [ABSTRACT FROM AUTHOR]

The article offers information on a study which suggests approaches for regaining a balance between satisfying human demands and maintaining ecosystems. It mentions that role of wastewater infrastructure is evolving toward resource recovery for addressing challenges like adverse impact of human activities over nature. It states that rise in urbanization and economic activity has compelled urban areas to increase their wastewater services.

This study adopted rapid alkaline treatment at pH 12 to hydrolyze 66% of total chemical oxygen demands. Then the hydrolyzed liquor was fermented in a continuous-flow stirred reactor to produce volatile fatty acids (VFAs) at 8-h hydraulic retention time and at 35 °C. The maximum VFA productivity reached 365 mg VFAs g ∇1 volatile suspended solids in a 45-d operation, with most produced VFAs being acetate and propionate, principally produced by protein degradation. The Bacteroidia , ε-proteobacteria and the Clostridia were identified to be the classes correlating with the fermentation processes. The fermented liquor was applied to denitrifying phosphorus removal process as alternative carbon source after excess phosphorus and nitrogen being recycled via struvite precipitation. Fermented liquors from alkaline hydrolysis–acid fermentation on waste activated sludge are a potential renewable resource for applications that need organic carbons. [ABSTRACT FROM AUTHOR]

Nutrients discharge correlates to eutrophication of receiving waters. Phosphorus (P) and nitrogen (N), if recovered from wastewaters, can be applied to land as essential nutrients for plant growth. This study used natural zeolite in batch and continuous tests to simultaneously remove P and N from orthophosphate and ammonium-nitrogen laden wastewaters at pH 3-11. In P only tests, pH > 9 is favorable to P removal. When ammonium was also present, P removal was significantly enhanced. Ammonium was first adsorbed onto the zeolite via ion exchange to release Ca2+ ions from the zeolite lattice. This ion exchange reaction was independent of the presence of P. Then the released Ca2+ ions precipitated the dissolved phosphate, which was greatly dependent on the concentration of ammonium. Zeolite column could effectively remove P and N from fermentation liquor with minimal adsorption of volatile fatty acids. Implications to practice of zeolite treatment were discussed. [ABSTRACT FROM AUTHOR]

Long-term storage and successful reactivation after storage are essential for practical applications of aerobic granules on wastewater treatment. This study cultivated aerobic granules (SI) in sequencing batch reactors and then stored the granules at 4 °C in five liquid media (DI water (SW), acetone (SA), acetone/isoamyl acetate mix (SAA), saline water (SS), and formaldehyde (SF)) for over 1 year. The first four granules were then successfully reactivated in 24 h cultivation. The specific oxygen uptake rates (SOUR) of the granules followed SI > SS > SA > SAA > SW > SF; and the corresponding granular strengths (10 min ultrasound) followed SI > SA = SS > SAA > SW >> SF. During storage the granular cells secreted excess quantities of cyclic-diguanylate (c-di-GMP) and pentaphosphate (ppGpp) as responses to the stringent challenges. We proposed that to force cells in granules (Alphaproteobacteria, Flavobacteria, Betaproteobacteria, Gammaproteobacteria, Actinobacteria, Sphingobacteria, and Clostridia) entering viable but non-culturable (VBNC) status is the key of success for extended period storage of granules. [ABSTRACT FROM AUTHOR]

Electrokinetic (EK) migration of β-cyclodextrin (β-CD), which is inclusive of total petroleum hydrocarbon (TPH), is an economically beneficial and environmentally friendly remediation process for oil-contaminated soils. Remediation studies of oil-contaminated soils generally prepared samples using particular TPHs. This study investigates the removal of TPHs from, and electromigration of microbial cells in field samples via EK remediation. Both TPH content and soil respiration declined after the EK remediation process. The strains in the original soil sample included Bacillus sp. , Sporosarcina sp. , Beta proteobacterium, Streptomyces sp., Pontibacter sp. , Azorhizobium sp., Taxeobacter sp., and Williamsia sp. Electromigration of microbial cells reduced the biodiversity of the microbial community in soil following EK remediation. At 200 V m for 10 days, 36% TPH was removed, with a small population of microbial cells flushed out, demonstrating that EK remediation is effective for the present oil-contaminated soils collected in field. [ABSTRACT FROM AUTHOR]

This study isolated strains in suspended liquor, the surface fouling layer, and biofilm inside hollow-fiber membranes of a membrane bioreactor (MBR); analyzed their distributions, sizes, surface charges, and growth behaviors; and determined the quantities of extracellular polymeric substances (EPS) secreted by these strains under different organic loadings. Three strains, which may penetrate the microfiltration membranes, were close relatives of the Ralstonia mannitolilytica strain SDV (GenBank Accession No. GU451066), Arthrobacter sp. BJQ-2 (GenBank Accession No. GU451067), and Actinobacterium DS3 (GenBank Accession No. GU451068). Among these three strains, only Arthrobacter sp. developed an internal biofilm. The relatively short length of Arthrobacter sp. minimizes resistance to cells moving through the membrane matrix, thereby enhancing its ability to build a biofilm in the interior surface of membranes. [ABSTRACT FROM AUTHOR]

Membrane fouling results in flux decline or transmembrane pressure drop increase during membrane bioreactor (MBR) operation. Physical and chemical cleanings are essential to keep an MBR operating at an appropriate membrane flux. Considerable residual membrane permeability loss that cannot be removed by conventional cleaning requires membrane replacement. This study demonstrates that an internal biofilm can develop inside a hollow-fiber membrane and can probably account for up to 58.9 and 81.3% of total membrane resistance for aerobic granular MBR operated in sequencing batch reactor (SBR) mode or continuous-fed mode, respectively. The Arthrobacter sp. (accession no. AM900505 in GenBank) corresponded to internal biofilm development by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis and the agar-plating technique. This study also identifies a single strain, Arthrobacter sp., generates the internal biofilm. The Arthrobacter sp. is a rod-shaped bacterium with a size close to that of membrane pores, and can secrete excess bound proteins, hence can penetrate and attach itself inside the membrane and grow. Internal biofilm growth could contribute significantly to membrane resistance during long-term MBR operation. [ABSTRACT FROM AUTHOR]

This purpose of this investigation is to develop a new method for obtaining pore-size distribution (PSD) and other pore parameters from inner structure images. This method can be summarized into four key procedures to realize its functionality. A MATLAB program was composed to make the method applicable for image analysis. Image tests on wastewater biofouling layer samples showed the validity and feasibility of the method for analyzing intrinsic porous structures The structural information obtained by this method can facilitate the understanding of transport phenomena, e.g., water flow and species diffusion inside porous structures. [ABSTRACT FROM AUTHOR]

Rapid industrialization and urbanization in a highly limited land area leads to serious waste disposal problems. Scarcity of land causes the disposal of waste in landfills to be extremely uneconomical. An attractive alternative to waste disposal is conversion of waste into new resources. Past studies have indicated that the conversion of wastes into construction materials is a potential option for management of high volume wastes. However, due to the high processing costs of the wastes, the conversion may not be economically viable. This study examines the detailed thermochemistry of sludge-clay mixes in providing an in-depth understanding of the reactions involved during the process of fusion. Thermal gravimetric analysis detected increased weight loss of the materials around the temperatures of 520 and 900°C, indicating volatilization of organic matter and inorganic salts, at the two respective temperature levels. Differential scanning calorimetry results revealed endothermic reactions, possibly due to dehydroxylation of clay, between temperatures of 480 and 600°C, and calcite decomposition between the temperatures of 680 and 900°C. Intensified endothermic peaks were observed in the mixes of the two materials. Thermal gravimetric analysis–infrared absorption spectrometry revealed increased intensities of the absorption bands at 1,600 cm-1 at 630°C and 2,900 cm-1 at 710°C, as a result of the breakdown of organic matter and alkanes, respectively. Energy demand analysis determined the energy required for raising the temperature of each mix to reach each specific temperature. The intrinsic energy required to raise the firing temperature of the aggregates from 400 to 900°C was determined to be within the range of 20,347 and 38,254 kJ/kg, with 100% sludge exhibiting the lowest energy requirement and 20% sludge exhibiting the highest energy requirement. [ABSTRACT FROM AUTHOR]

Environmental stimuli-responsive nucleobase-functionalized supramolecular polymers, a combination of oligomeric polypropylene glycol segments as a thermosensitive element and hydrogen-bonded uracil as a photosensitive moiety, were successfully developed and undergo spontaneous self-assembly to form uniform nanosized micelles via self-complementary double hydrogen bonding interactions between the uracil moieties in an aqueous environment. These micelles exhibit unique properties such as dual thermo- and photoresponsiveness, controllable lower critical concentration solution temperature (LCST), photoreactivity, and morphological transformation, making them highly attractive for various applications. More importantly, phase transitions and morphological studies confirmed the LCST behavior, size, and shape of the micelles can be easily tuned by adjusting the concentration and duration of ultraviolet irradiation of samples in aqueous solution, indicating introduction of uracil molecules into a water-soluble polymer matrix may represent a promising approach toward development of multiple stimuli-responsive polymeric micelles whose self-assembly behavior can be manipulated. In view of the ease of fabrication, high biocompatibility, multifunctionality, and tailorable micellar properties, this newly developed supramolecular micelle may be a promising candidate nanocarrier for controlled drug delivery and bioimaging systems. [ABSTRACT FROM AUTHOR]

A new method for exfoliation of hexagonal boron nitride (h-BN) into few-layered nanosheets has been developed by employing noncovalent assembly of networks upon association with a supramolecular polymer. In this work, we developed a simple, reliable, effective approach for preparation of exfoliated h-BN nanosheets from bulk h-BN via liquid-phase exfoliation using a low-molecular weight adenine-functionalized polypropylene glycol (A-PPG) supramolecular polymer. A-PPG self-assembled into either long-range ordered lamellar or micelle-like structures on the surface of h-BN because of the strong specific interactions between A-PPG and h-BN. The level of h-BN nanosheet exfoliation could be controlled by adjusting the amount of A-PPG incorporated. This newly developed composite exhibited excellent phase transition behavior and thermal stability, and few-layer thickness with good dispersion of h-BN nanosheets, indicating self-assembled A-PPG functions as an efficient dispersant and stabilizer to manipulate the physical and morphological properties of exfoliated h-BN. This method of producing multifunctional exfoliated h-BN provides a unique paradigm for developing the next generation of thermoconductive devices and solution-processed semiconductors. [ABSTRACT FROM AUTHOR]

Global expectations for wastewater service infrastructure have evolved over time, and the standard treatment methods used by wastewater treatment plants (WWTPs) are facing issues related to problem shifting due to the current emphasis on sustainability. A transition inWWTPs toward reuse of wastewater-derived resources is recognized as a promising solution for overcoming these obstacles. However, it remains uncertain whether this approach can reduce the environmental footprint of WWTPs. To test this hypothesis, we conducted a net environmental benefit calculation for several scenarios for more than 50 individual countries over a 20-y time frame. For developed countries, the resource recovery approach resulted in ∼154% net increase in the environmental performance of WWTPs compared with the traditional substance elimination approach, whereas this value decreased to ∼60% for developing countries. Subsequently, we conducted a probabilistic analysis integrating these estimates with national values and determined that, if this transition was attempted for WWTPs in developed countries, it would have a ∼65% probability of attaining net environmental benefits. However, this estimate decreased greatly to ∼10% for developing countries, implying a substantial risk of failure. These results suggest that implementation of this transition for WWTPs should be studied carefully in different temporal and spatial contexts. Developing countries should customize their approach to realizing more sustainable WWTPs, rather than attempting to simply replicate the successful models of developed countries. Results derived from the model forecasting highlight the role of bioenergy generation and reduced use of chemicals in improving the sustainability of WWTPs in developing countries. [ABSTRACT FROM AUTHOR]

A nucleobase-assembled supramolecular nanofiber is capable of forming network-like polymeric clusters through complementary hydrogen-bonding interactions. It behaves as an effective chromophore that greatly enhances the light emission efficiency of fluorescent fibers, reaching up to three times higher efficiency than the control samples. [ABSTRACT FROM AUTHOR]

Limited-oxygen mediated synergistic relationships between sulfate-reducing bacteria (SRB), nitrate-reducing bacteria (NRB) and sulfide-oxidizing bacteria (SOB, including nitrate-reducing, sulfide-oxidizing bacteria NR-SOB) were predicted to simultaneously remove contaminants of nitrate, sulfate and high COD, and eliminate sulfide generation. A lab-scale experiment was conducted to examine the impact of limited oxygen on these oxy-anions degradation, sulfide oxidation and associated microbial functional responses. In all scenarios tested, the reduction of both nitrate and sulfate was almost complete. When limited-oxygen was fed into bioreactors, S0 formation was significantly improved up to ~70%. GeoChip 4.0, a functional gene microarray, was used to determine the microbial gene diversity and functional potential for nitrate and sulfate reduction, and sulfide oxidation. The diversity of the microbial community in bioreactors was increased with the feeding of limited oxygen. Whereas the intensities of the functional genes involved in sulfate reduction did not show a significant difference, the abundance of the detected denitrification genes decreased in limited oxygen samples. More importantly, sulfide-oxidizing bacteria may alter their populations/genes in response to limited oxygen potentially to function more effectively in sulfide oxidation, especially to elemental sulfur. The genes fccA/fccB from nitrate-reducing, sulfide-oxidizing bacteria (NR-SOB), such as Paracoccus denitrificans, Thiobacillus denitrificans, Beggiatoa sp., Thiomicrospira sp., and Thioalkalivibrio sp., were more abundant under limited-oxygen condition. [ABSTRACT FROM AUTHOR]

Chlorinated nitroaromatic antibiotic chloramphenicol (CAP) is a priority pollutant in wastewaters. A fed-batch bioelectrochemical system (BES) with biocathode with applied voltage of 0.5 V (served as extracellular electron donor) and glucose as intracellular electron donor was applied to reduce CAP to amine product (AMCl2). The biocathode BES converted 87.1 ± 4.2% of 32 mg/L CAP in 4 h, and the removal efficiency reached 96.0 ± 0.9% within 24 h. Conversely, the removal efficiency of CAP in BES with an abiotic cathode was only 73.0 ± 3.2% after 24 h. When the biocathode was disconnected (no electrochemical reaction but in the presence of microbial activities), the CAP removal rate was dropped to 62.0% of that with biocathode BES. Acetylation of one hydroxyl of CAP was noted exclusive in the biocatalyzed process, while toxic intermediates, hydroxylamino (HOAM), and nitroso (NO), from CAP reduction were observed only in the abiotic cathode BES. Electrochemical hydrodechlorination and dehalogenase were responsible for dechlorination of AMCl2 to AMCl in abiotic and microbial cathode BES, respectively. The cyclic voltammetry (CV) highlighted higher peak currents and lower overpotentials for CAP reduction at the biocathode compared with abiotic cathode. With the biocathode BES, antibacterial activity of CAP was completely removed and nitro group reduction combined with dechlorination reaction enhanced detoxication efficiency of CAP. The CAP cathodic transformation pathway was proposed based on intermediates analysis. Bacterial community analysis indicated that the dominate bacteria on the biocathode were belonging to α, β, and γ-Proteobacteria. The biocathode BES could serve as a potential treatment process for CAP-containing wastewater. [ABSTRACT FROM AUTHOR]

Current estimation schemes as decision support tools for the selection of wastewater treatment alternatives focus primarily on the treatment efficiency, effluent quality, and environmental consequences for receiving water bodies. However, these schemes generally do not quantify the potential to convert pollutants in wastewater to recoverable resources. This study proposes a refined evaluation scheme for choices of wastewater treatment processes that quantifies not only adverse environmental effects but also bioenergy and nutrient recovery indices. An original means of data processing was established and clear estimate indicators were consequently obtained to allow a smooth overall estimation. An array of wastewater treatment alternatives that meet three effluent limits were used as case studies to demonstrate how the present scheme works, simultaneously, to identify optimum choices. It is concluded in the overall estimation that the lower sustainability of wastewater treatment contributed by increasingly stringent discharge demands was offset and mitigated by the resource-recovery scenarios involved, and the scenario of recovering nutrients via excess-sludge composting was of more benefit. Thus, before tightening wastewater discharge requirements, one should bear in mind the situation of multiple sustainability by setting a goal to achieve not only the greatest reduction in environmental burden but also the maximum resource-recovery benefits. [ABSTRACT FROM AUTHOR]

Aerobic granulation (AG) and membrane bioreactor (MBR) are two promising, novel environmental biotechnological processes that draw interest of researchers working in the area of biological wastewater treatment. Membrane fouling in the combined aerobic granular membrane bioreactor (AGMBR) process and the conventional MBR process was investigated in this work. The irreversible fouling on hollow-fibre membranes in both reactors were observed with the multiple staining and confocal laser scanning microscope technique. Following physical and chemical washing, the external fouling layers were mostly removed. However, the biofilms built up in the interior surface of membrane remained and contributed to the irreversible fouling resistance. AGMBR retained most cells with granules, thereby reducing their penetration through membrane and thus the chance to form internal fouling layer. The internal biofilm layer was principally composed of live cells embedded in a matrix of proteins and polysaccharides, with that on AGMBR denser and thicker than that on MBR. Prevention of development of internal biofilm is essential to reduce irreversible fouling of AGMBR and MBR membranes. [ABSTRACT FROM AUTHOR]

Denitrifying sulfide removal (DSR) processes simultaneously convert sulfide, nitrate, and chemical oxygen demand from industrial wastewater into elemental sulfur, dinitrogen gas, and carbon dioxide, respectively. The failure of a DSR process is signaled by high concentrations of sulfide in reactor effluent. Conventionally, DSR reactor failure is blamed for overcompetition for heterotroph to autotroph communities. This study indicates that the elementary sulfur produced by oxidizing sulfide that is a recoverable resource from sulfide-laden wastewaters can be reduced back to sulfide by sulfur-reducing Methanobacterium sp. The Methanobacterium sp. was stimulated with excess organic carbon (acetate) when nitrite was completely consumed by heterotrophic denitrifiers. Adjusting hydraulic retention time of a DSR reactor when nitrite is completely consumed provides an additional control variable for maximizing DSR performance. [ABSTRACT FROM AUTHOR]

The characteristics of aerobic granules for wastewater treatment are greatly related to their complex internal structure. However, due to the limitation of characterizing methods, information about the granule internal morphology and structure is very sparse, and mechanism of mass transfer process is yet unclear. In this work, the internal structure of aerobic granules was explored using nitrogen adsorption method and confocal laser scanning microscopy technique. It was found that aerobic granules had multiporous structure with cross-linked gel matrix structure. With a consideration of the hydrodynamic regime and the porous structure of granules, a two-dimensional percolation model was established to describe the mass transfer in granules. With the approaches, interesting and useful results regarding the pore distribution and mass transfer in aerobic granules have been obtained. The results demonstrate that the intragranule convection could enhance mass transfer, hence ensure an efficient and stable operation of aerobic-granule-based reactors. Such approaches might also be applicable to characterizing the multiporous structure and mass transfer of other microbial aggregates for wastewater treatment. [ABSTRACT FROM AUTHOR]

The internal structure of aerobic granules has a significant impact on the hydrodynamic performance and mass transfer process, and severely affects the efficiency and stability of granules-based reactors for wastewater treatment In this study, for the first time the granule complex structure was correlated with the hydrodynamic performance and substrates reactions process. First, a series of multiple fluorescence stained confocal laser scanning microscopy images of aerobic granules were obtained. Then, the form and structure of the entire granule was reconstructed. A three-dimensional computational fluid dynamics study was carried out for the hydrodynamic analysis. Two different models were developed on the basis of different fluorescence stained confocal laser scanning microscopy fluorescence stained confocal laser scanning microscopy images to elucidate the roles of the granule structure in the hydrodynamic and mass transfer processes of aerobic granules. The fluid flow behavior, such as the velocity profiles, the pathlines and hence the hydrodynamic drag force, exerted on the granule in a Newtonian fluid, was studied by varying the Reynolds number. Furthermore, the spatial distribution of dissolved nutrients (e.g., oxygen) was acquired by solving the convection-diffusion equations on the basis of the reconstructed granule structure. This study demonstrates that the reconstructed granule model could offer a better understanding to the mass transfer process of aerobic granules than simply considering the granule structure to be homogeneous. [ABSTRACT FROM AUTHOR]

Denitrifying sulfide removal (DSR) process simultaneously converts sulfide, nitrate, and chemical oxygen demand from industrial wastewaters to elemental sulfur, nitrogen gas, and carbon dioxide, respectively. This investigation utilizes a dilution-to-extinction approach at 10−2 to 10−6 dilutions to elucidate the correlation between the composition of the microbial community and the DSR performance. In the original suspension and in 10−2 dilution, the strains Stenotrophomonas sp. , Thauera sp., and Azoarcus sp. are the heterotrophic denitrifiers and the strains Paracoccus sp. and Pseudomonas sp. are the sulfide-oxidizing denitrifers. The 10−4 dilution is identified as the functional consortium for the present DSR system, which comprises two functional strains, Stenotrophomonas sp. strain Paracoccus sp. At 10−6 dilution, all DSR performance was lost. The functions of the constituent cells in the DSR granules were discussed based on data obtained using the dilution-to-extinction approach. [ABSTRACT FROM AUTHOR]

Aerobic granules were adopted to degrade high-strength phenol wastewater in batch experiments. The acclimated granules effectively degraded phenol at a concentration of up to 5,000 mg l−1 without severe inhibitory effects. The biodegradation of phenol by activated sludge was inhibited at phenol concentrations >3,000 mg l−1. The granules were composed of cells embedded in a compact extracellular matrix. After acid or alkaline pretreatment, the granules continued to degrade phenol at an acceptable rate. The polymerase chain reaction-denaturing gradient gel electrophoresis technique was employed to monitor the microbial communities of the activated sludge and the aerobic granules following their being used to treat high concentrations of phenol in batch tests. [ABSTRACT FROM AUTHOR]

Denitrifying sulfide removal (DSR) process incorporates interactions between autotrophic and heterotrophic denitrifiers and reveals difficulty to achieve high removal rate of nitrogen and sulfur in practice. We compared the DSR performance of an expanded granular sludge bed (EGSB) reactor and an upflow anaerobic sludge blanket (UASB) reactor, both fed with wastewaters comprising sulfide, nitrate and acetate. The EGSB reactor can sustain at higher loading rates than UASB reactor, probably owing to the less elemental sulfur production rate for the latter in operation. [ABSTRACT FROM AUTHOR]

High-rate biological conversion of sulfide and nitrate in synthetic wastewater to, respectively, elemental sulfur (S0) and nitrogen-containing gas (such as N2) was achieved in an expanded granular sludge bed (EGSB) reactor. A novel strategy was adopted to first cultivate mature granules using anaerobic sludge as seed sludge in sulfate-laden medium. The cultivated granules were then incubated in sulfide-laden medium to acclimate autotrophic denitrifiers. The incubated granules converted sulfide, nitrate, and acetate simultaneously in the same EGSB reactor to S0, N-containing gases and CO2 at loading rates of 3.0 kg S m−3 d−1, 1.45 kg N m−3 d−1, and 2.77 kg Ac m−1 d−1, respectively, and was not inhibited by sulfide concentrations up to 800 mg l−1. Effects of the C/N ratio on granule performance were identified. The granules cultivated in the sulfide-laden medium have Pseudomonas spp . and Azoarcus sp. presenting the heterotrophs and autotrophs that co-work in the high-rate EGSB-SDD (simultaneous desulfurization and denitrification) reactor. [ABSTRACT FROM AUTHOR]

Heavy metals and arsenic contamination in municipal solid waste (MSW) and its treatment products has garnered increasing attention. This study investigated the heavy metals and arsenic flows in organic fractions of MSW (OFMSW) in Shanghai, China, through a one-year monitoring program. The OFMSW separated directly from the source (source- separated, pure organic waste), obtained from the treatment facilities were sampled and compared with pure foodstuffs. The heavy metals and arsenic contents in the source-separated OFMSW resembled those in foodstuffs, whereas the OFMSW from the treatment facilities was significantly contaminated with heavy metals and arsenic and failed to meet the government standards for land use. Using flow analysis, >80% of heavy metals and arsenic were from extrinsic inorganic waste with high ash content that was combined with OFMSW during MSW collection, transfer, transportation, and storage stages. Based on source analysis of heavy metals and arsenic, suggestions for reducing heavy metals and arsenic contents in the current MSW management system in Shanghai are presented. [ABSTRACT FROM AUTHOR]

This study quantified the activities of enzymes in extracellular polymeric substances (EPS) and in pellets. Seven commonly adopted extraction schemes were utilized to extract from aerobic flocs the contained EPS, which were further categorized into loosely bound (LB) and tightly bound (TB) fractions. Ultrasonication effectively extracted the EPS from sludge flocs. Enzyme assay tests showed that the protease activity was localized mainly on the pellets, α-amylase and α-glucosidase activities were largely bound with LB-EPS, and few protease, α-amylase, or α-glucosidase activities were associated with the TB-EPS fraction. There exists no correlation between the biochemical compositions of EPS and the distribution of enzyme activities in the sludge matrix. The 44–65% of α-amylase and 59–100% of α-glucosidase activities noted with the LB-EPS indicate heterogeneous hydrolysis patterns in the sludge flocs with proteins and carbohydrates. [ABSTRACT FROM AUTHOR]

We report a breakthrough discovery involving supramolecular-based strategies to construct novel core–shell heterojunction nanoparticles with hydrophilic adenine-functionalized polythiophene (PAT) as the core and hydrophobic phenyl-C61-butyric acid methyl ester (PCBM) as the shell, which enables the conception of new functional supramolecular assemblies for constructing functional nanomaterials for applications in optoelectronic devices. The generated nanoparticles exhibit uniform spherical shape, well-controlled tuning of particle size with narrow size distributions, and excellent electrochemical stability in solution and the solid state owing to highly efficient energy transfer from PAT to PCBM. When the PAT/PCBM nanoparticles were fabricated into a photoconducting layer in an electronic device, the resulting device showed excellent electric conduction characteristics, including an electrically-tunable voltage-controlled switch, and high short-circuit current and open-circuit voltage. These observations demonstrate how the self-assembly of PAT/PCBM into specific nanostructures may help to promote efficient charge generation and transport processes, suggesting potential for a wide variety of applications as a promising candidate material for bulk heterojunction polymer devices. [ABSTRACT FROM AUTHOR]