The sorption of persistent organic pollutants in microplastics from the coastal environment.

Microplastic (MP) pellets were sampled from six sandy beaches around Taiwan in order to investigate the concentrations and compositions of POPs, including: PCDD/Fs, PBDD/Fs, PBDEs, PCBs, PBBs, and their congeners. The concentrations of PCDD/Fs on the surface (Cs) of MP pellets from the six sampling sites were from 1.9 to 14.6 pg∙g-1, while the overall concentrations within MPs (Ct) were from 95.0 to 1110.6 pg∙g-1. As PCDD/Fs were adsorbed into the inner part of MPs, a ratio of the total concentrations to surficial concentration of MPs (Ct/Cs) was as high as 355.2 times. The Ct/Cs of other POPs were also significant, such as PBDEs being found up to 8068 times, which could be attributed to artificial addition during manufacturing processes as flame-retardant substances. Primary compositions of PCDD/Fs, PBDD/Fs, and PBDEs on the MPs in our POP congener analysis were all found containing species with higher number of chlorine or bromine, which were adsorbed on the MP surface more easily due to their relative higher KOW.

A full-scale study of high-rate anaerobic bioreactors for whiskey distillery wastewater treatment with size fractionation and metagenomic analysis of granular sludge.

Two full-scale high-rate bioreactors, i.e. external circulation sludge bed (ECSB) and expanded granular sludge bed (EGSB), were monitored for three years. Their performances for treating wastewater in a whiskey distillery were compared in terms of COD, pH, alkalinity and VFA. Even though feed flowrate highly fluctuated, COD removals of ECSB and EGSB were both excellent (95.7 ± 1.3% and 94.8 ± 3.0%, respectively). The influent and effluent characteristics of ECSB reactor were profiled and urea and urethane were also detected. High-strength properties of raw spent wash were exhibited in TOC, soluble COD and BOD5,20°C of 13500, 37750, and 1950 mg·L-1, respectively and characterized by GC-MS. Anaerobic granular sludge sampled from different heights of ECSB reactor were fractionated for demonstrating vertical size distributions. Moreover, major species found by next-generation sequencing technique were archaea, i.e. Methanosaeta and Methanolinea, while major bacteria were Bacteroidetes with minor Nitrospiraceae. This metagenomic analysis provided an insight of anaerobic microbial consortium.

A full-scale study of external circulation sludge bed (ECSB) system for anaerobic wastewater treatment in a whiskey distillery.

Waste liquid streams from distillery were a hurdle in conventional wastewater treatment due to extreme high chemical oxygen demand (COD) and fluctuating feed conditions. A recently commissioned full-scale external circulation sludge bed (ECSB) was applied at a malt whiskey distillery in northeast Taiwan. Start-up of the new ECSB system, which has a total volume of 490 m3 with diameter of 6.55 m (ø) and height of 15.9 m (H), was performed by gradual increasing influent flow rates from zero to the design value of 300 m3 day-1 in the first 90 days. In the subsequent 204 days, both influent flow rates (0-389 m3 day-1) and COD concentrations (2.8-18.1 kg L-1) were highly fluctuated due to diverse batches from the distillery. However, effective bioremediation (COD removal 95.1 ± 2.4%) and biogas production (1195 ± 724 L day-1) were achieved in this system. Intensively, the Imhoff tests were carried out and shown the settled solids concentration by 0.5 ± 0.4 mL L-1, while size distributions of granular sludge were analyzed and observed by SEM-EDS. In addition, developments of the anaerobic systems (including lab, pilot, and full scale from the simplest reactor to the latest ECSB) applied in whiskey wastewater treatment were reviewed with their operational parameters for comparing performances of various anaerobic systems. In general, real-time monitoring and feasible operation strategies were critical to successfully run the system by producing clean energy simultaneously. It provides more economically attractive and sustainable-to-adopt ECSB not only an end-of-pipe process but also a bioresource technology.

Effects of doping amounts of potassium ferricyanide with titanium dioxide and calcination durations on visible-light degradation of pharmaceuticals.

Acetaminophen (ACT) is one of the most frequently detected pharmaceuticals in aqueous environments, and treatment of ACT were generally carried out by photocatalytic degradations under high energy UV irradiation. In this study, potassium ferricyanide was utilized as a quadruple-elemental dopant in a TiO2 photocatalyst in order to enhance its visible-light activity. Two critical parameters (amounts of dopants and durations of calcination) of the synthesis of the photocatalyst by a sol-gel method were systematically evaluated. Crystal structure of the doping TiO2 was examined by X-ray diffraction while the effects of the two parameters on the photocatalytic activity were elucidated by various characterizations. Increasing the amount of dopant or the duration of calcination red-shifted the UV-vis DRS of the doped TiO2. The estimated band gap energy of the doped TiO2 decreased slightly as the amount of dopant increased, but it increased as the duration of calcination increased. The FT-IR yielded characteristic peaks that revealed the effects of the two parameters, whereas the SEM images revealed the morphological evolutions of each effect. The photocatalyst, synthesized at optimum conditions was able to remove 99.1 % acetaminophen with rate constant of 7.9 × 10-3 min-1, which was 4.88 times greater than virgin TiO2. In general, this study not only optimized synthetic conditions of the new visible-light active photocatalyst for ACT degradation but also presented characterizations conducted by SEM, XRD, UV-vis DRS, and FTIR to elucidate the relationship between modified structure and the photocatalytic activity. Graphical abstract Effects of doping amounts of K3[Fe(CN)6] and calcunation duration on visible light absorbance of TiO2 photocatalysts.

Degradations of acetaminophen via a K2S2O8-doped TiO2 photocatalyst under visible light irradiation.

Acetaminophen (ACT) is a mild analgesic commonly used for relief of fever, headache and some minor pains. It had been detected in both fixed factory-discharged wastewaters, and diverse sources, e.g. surface waters during festival events. Degradation of such trace emergent pollutants by titanium dioxide (TiO2) photocatalysts is a common approach; however, the band gap that can be utilized in the UV range is limited. In order to extend downward the energy required to excite the photocatalytic material, doping with potassium peroxodisulfate (K2S2O8) by a sol-gel method was done in this work. The visible-light active photocatalyst was tested on the degradation of ACT under four parameters including: initial ACT concentration, catalyst dose, initial pH, and system temperature. Optimal conditions, which achieved 100% ACT degradation, were obtained by using 0.1 mM ACT initial concentration, catalyst dose of 1 g L(-1), initial pH of 9.0 and system temperature of 22 °C at the end of 9-h irradiation. Meanwhile, three types of degradation kinetic models (i.e. zero, pseudo first and second order) were tested. The feasible model followed a pseudo-first order model with the computed constant (kapp) of 7.29 × 10(-3) min(-1). The present study provides a better photocatalytic degradation route by K2S2O8-modified TiO2 in comparison with pristine TiO2, in wastewater treatment dealing with ACT and other persistent organic pollutants.

Temporal variation and interaction of full size spectrum Alcian blue stainable materials and water quality parameters in a reservoir.

This paper reports on the fate of different fractions of Alcian blue (AB) stainable material in Pao-Shan reservoir, Taiwan, in a one-year study (2013-2014) and an intensive study during phytoplankton bloom (2014). The interactions between the fractions, including AB stained particles, particle and colloidal transparent exopolymer particles (pTEP and cTEP), dissolved acid polysaccharide (dAPS), and their relationship to other water quality parameters were analyzed. The Flow Cytometer and Microscope (FlowCAM) was for first time used to characterize AB stained particles. The results of the one-year study likely showed relationships of pTEP concentration to phytoplankton count and chlorophyll a, while in the intensive study, AB stained particles abundance and pTEP concentration were correlated neither phytoplankton count nor chlorophyll a, but strongly positively correlated with some phytoplankton species' abundance. The difference indicates that sampling frequency and phytoplankton composition should be addressed for studying the links between AB stained fractions and phytoplankton. The interaction between different AB stained fractions further suggests that the majority of AB stained particles and pTEP would be directly generated by some phytoplankton species, whereas their abiotic generation by cTEP or dAPS may only have contributed partly to their formation. This differs from previous studies which generally posited that pTEP are mainly formed abiotically from dissolved precursors. Successful application of FlowCAM for visualization of AB stained particles recommends this technique by which particle morphologies can be conserved and morphological features of particle can be simultaneously elucidated.

Low density supercritical fluids precipitation of 9-cis and all trans-ß-carotenes enriched particulates from Dunaliella salina.

In this study, supercritical anti-solvent (SAS) pulverization coupled with reverse phase elution chromatography was employed to isolate 9-cis and trans-ß-carotenes from Dunaliella salina. Total concentration of 9-cis (134.7mg/g) and trans-ß-carotene (204.2mg/g) was increased from 338.9mg/g of the ultrasonic extract to 859.7mg/g (338.9 for 9-cis and 520.8 for trans) of the elution fraction. The SAS pulverization of the collected fraction further produced submicron-sized particulates containing 932.1mg/g (355.6 for 9-cis and 576.5 for trans) of total ß-carotenes with a recovery of 86.3% (83.9% for cis and 87.8% for trans). Effects of two SAS operational conditions on the purity, recovery of total ß-carotenes, mean size and morphology of the precipitates were obtained from an experimentally designed method. Generation of micronized particulates enriched with 9-cis and trans-ß-carotenes by low-density SAS was proved to be feasible and environmental benign.

Purification of lignans from Schisandra chinensis fruit by using column fractionation and supercritical antisolvent precipitation.

This study examined the use of ultrasonic-assisted extraction (UAE) coupled with column chromatography (CC) and supercritical antisolvent (SAS) precipitation in purifying five lignans from the dried fruit of Schisandra chinensis. Column fractionation of the ultrasonic extracts and SAS precipitation of the column elution resulted in a ten- and three-fold increase of the five lignans, respectively. Experimental data showed that the concentrations of the five lignans increased from 26.14mgg(-1) in the extraction to 581.85mgg(-1) in the effluent after SAS precipitation with a recovery of 84%. The effluent contained 145.32mgg(-1)of schisandrol B, 56.65mgg(-1)of schisandrin A, 66.38mgg(-1) of γ-schisandrin, 266.70mgg(-1) of gomisin N, and 46.80mgg(-1)of schisandrin C. In addition, our experimental results from a response surface method designed SAS precipitations for the enhancement of the purity of the five lignans, showed that time and carbon dioxide flow rate are significant in altering the purity and the recovery. This work demonstrated that the five lignans of Schisandra chinensis were successfully purified by using the SAS process.

Countercurrent flow of supercritical anti-solvent in the production of pure xanthophylls from Nannochloropsis oculata.

This study examined pilot scaled elution chromatography coupled with supercritical anti-solvent precipitation (using countercurrent flow) in generating zeaxanthin-rich particulates from a micro-algal species. Ultrasonic agitated acetone extract subjected to column fractionation successfully yielded a fraction containing 349.4 mg/g of zeaxanthin with a recovery of 85%. Subsequently, supercritical anti-solvent (SAS) precipitation of the column fraction at 150 bar and 343 K produced submicron-sized particulates with a concentration of 845.5mg/g of zeaxanthin with a recovery of 90%. Experimental results from a two-factor response surface method SAS precipitation indicated that purity, mean size and morphology of the precipitates were significantly affected by the flow type configuration, feed flow rate and injection time.

The effect of feed salinity on the biofouling dynamics of seawater desalination.

A persistent cell labeling dye and a novel microbial counting method were used to explore the effects of salinity on a microbial population in a reverse osmosis (RO) desalination system, and these clearly distinguished microbial cell multiplication from cell adherence. The results indicated that microbial multiplication is more active at the front of a seawater RO pressure vessel, while adhesion dominates the back of the vessel. A severe reduction in RO permeate flux and total dissolved solid (TDS) rejection were detected at low salinity, attributed to marked cell multiplication and release of extracellular polymeric substances, whilst a relatively stable flux was observed at medium and high salinity. The results from PCR-DGGE revealed the variation in microbial species distribution on the membrane with salinity. The results imply the critical role of membrane modification in biofouling mitigation in the desalination process.

Stereological assessment of extracellular polymeric substances, exo-enzymes, and specific bacterial strains in bioaggregates using fluorescence experiments.

This review addresses the introduction of fluorescent molecular tags into exo-enzymes and extra polymeric substances of bioaggregates and the use of confocal laser scanning microscopy (CLSM) to map their role, purpose and quantitative description of the biological processes they undertake. Multiple color staining coupled with CLSM and fluorescent in situ hybridisation (FISH) and flow cytometry have identified the individual polymeric substances, whether they are proteins, lipids, polysaccharides, nucleic acids or antibodies, as well as the microorganisms in the bioaggregate. Procedures are presented for simultaneous multicolor staining with seven different fluorochromes - SYTOX Blue for nucleic acids; Nile red for lipids; Calcofluor white [CW] for beta-polysaccharides; concanavalin A [Con A] for alpha-poly-saccharides; fluorescein-isothiocyanate [FITC] for proteins; SYTO 63 for live microbial cells and Calcium Green for monitoring calcium levels in the microbial cells. For the distribution of certain microbial strains, metabolic enzymes and extrapolymeric substances to be quantitatively described the generated colored images are converted into digital forms under specific predefined criteria. Procedures and computer software programs (Amira; MATLAB) are presented in order to quantitatively establish grid patterns from the CLSM images. The image is digitized using a threshholding algorithm followed by a reconstruction of the image as a volumetric grid for finite element simulation. The original color image is first converted to a grey followed by resizing, detection and modification of bilevel images and finally a total reversal of the image colors. The grid file is then used by specific computer software (Gambit, Fluent) for further numerical studies incorporating chemical reactions, transport processes and computational fluid dynamics including intra-bioaggregate fluid flow, and heat and mass transfer within the bioaggregate matrix.

Application of nanosilver surface modification to RO membrane and spacer for mitigating biofouling in seawater desalination.

Biofouling is one the most critical problems in seawater desalination plants and science has not yet found effective ways to control it. Silver compounds and ions are historically recognized for their effective antimicrobial activity. Nanosilver particles have been applied as a biocide in many aspects of disinfection, including healthcare products and water treatment. This study proposes an innovative biofouling control approach by surface modification of the RO membrane and spacer with nanosilver coating. A chemical reduction method was used for directly coating nanosilver particles on the membrane sheet and spacer. The surface-modified membrane and spacer were tested for their antifouling performance in a cross-flow flat-sheet membrane cell, which is a part of a pilot plant in Wukan desalination plant. The silver-coating membranes and spacers, along with an unmodified membrane sheet, were tested in the membrane cell and compared on the basis of their antifouling performance. Permeate flux decline and salt rejection was continuously monitored through the testing period. Meanwhile regrowth of microbial populations on the membrane cell was quantified by a unique microbial counting every three to four days. The results showed that both silver-coated membrane (Ag-cM) with uncoated spacer and silver-coated spacer (Ag-cS) with uncoated membrane performed better than the unmodified membrane and spacer (Un-MS), in terms of much slower decrease in permeate flux and TDS rejection. However, the effect of silver-coated spacer on antimicrobial activity was more lasting. In the silver-coated spacer test, there was almost no multiplication of cells detected on the membrane during the whole testing period. Besides, the cells adhering to the membrane seemed to lose their activity quickly. According to the RO performance and microbial growth morphology, the nanosilver coating technology is valuable for use in biofouling control in seawater desalination.