Effects of Organic Loading, Influent Concentration, and Feed Time on Biohydrogen Production in a Mechanically Stirred AnSBBR Treating Sucrose-Based Wastewater

An anaerobic sequencing batch biofilm reactor (AnSBBR—total volume 7.5 L; liquid volume 3.6 L; treated volume per cycle 1.5 L) treated sucrose-based wastewater to produce biohydrogen (at 30 °C). Different applied volumetric organic loads (AVOL of 9.0, 12.0, 13.5, 18.0, and 27.0 kg COD m^?3 day^?1), which were varied according to the influent concentration (3,600 and 5,400 mg COD L^?1) and cycle length (4, 3, and 2 h), have been used to assess the following parameters: productivity and yield of biohydrogen per applied and removed load, reactor stability, and efficiency. The removed organic matter (COD) remained stable and close to 18 % and carbohydrates (sucrose) uptake rate remained between 83 and 97 % during operation. The decrease in removal performance of the reactor with increasing AVOL, by increasing the influent concentration (at constant cycle length) and decreasing the cycle lengths (at constant influent concentrations), resulted in lower conversion efficiencies. Under all conditions, when organic load increased there was a predominance of acetic, propionic, and butyric acid as well as ethanol. The highest concentration of biohydrogen in the biogas (24–25 %) was achieved at conditions with AVOL of 12.0 and 13.5 kg COD m^?3 day^?1, the highest daily production rate (0.139 mol H₂?day^?1) was achieved at AVOL of 18.0 kg COD m^?3 day^?1, and the highest production yields per removed and applied load were 2.83 and 3.04 mol H₂?kg SUC^?1, respectively, at AVOL of 13.5 kg COD m^?3 day^?1. The results indicated that the best productivity tends to occur at higher organic loads, as this parameter involves the “biochemical generation” of biogas, and the best yield tends to occur at lower and/or intermediate organic loads, as this parameter involves “biochemical consumption” of the substrate.     

Certified reference material IAEA-418: 129I in Mediterranean Sea water

A certified reference material designed for the determination of ¹²⁹I in seawater, IAEA-418 (Mediterranean Sea water) is described and the results of certification are presented. The median of ¹²⁹I concentration with 95% confidence interval was chosen as the most reliable estimates of the true value. The median, given as the certified value, is 2.28 × 10⁸ atom L^?1 (95% confidence interval is (2.16–2.73) 10⁸ atom L^?1), or 3.19 × 10^?7 Bq L^?1 (95% confidence interval is (3.02–3.82) × 10^?7 Bq L^?1). The material is intended to be used for standardization procedures applied in accelerator mass spectrometric laboratories. It is available in 1 L units and may be ordered via IAEA web side (www.iaea.org).     

Total and inorganic arsenic in dietary supplements based on herbs, other botanicals and algae—a possible contributor to inorganic arsenic exposure

The content of total and inorganic arsenic was determined in 16 dietary supplements based on herbs, other botanicals and algae purchased on the Danish market. The dietary supplements originated from various regions, including Asia, Europe and USA. The contents of total and inorganic arsenic was determined by inductively coupled plasma mass spectrometry (ICP-MS) and anion exchange HPLC-ICP-MS, respectively, were in the range of 0.58 to 5.0 mgkg^?1 and 0.03 to 3.2 mg?kg^?1, respectively, with a ratio between inorganic arsenic and total arsenic ranging between 5 and 100 %. Consumption of the recommended dose of the individual dietary supplement would lead to an exposure to inorganic arsenic within the range of 0.07 to 13 μg?day^?1. Such exposure from dietary supplements would in worst case constitute 62.4 % of the range of benchmark dose lower confidence limit values (BMDL₀₁ at 0.3 to 8 μg kg bw^?1 kg^?1 day^?1) put down by European Food Safety Authority (EFSA) in 2009, for cancers of the lung, skin and bladder, as well as skin lesions. Hence, the results demonstrate that consumption of certain dietary supplements could contribute significantly to the dietary exposure to inorganic arsenic at levels close to the toxicological limits established by EFSA.     

Investigation of <Emphasis Type="Italic">Chlorella vulgaris</Emphasis> UTEX 265 Cultivation under Light and Low Temperature Stressed Conditions for Lutein Production in Flasks and the Coiled Tree Photo-Bioreactor (CTPBR)

Lutein has an increasing share in the pharmaceutical and nutraceutical market due to its benefits to eye health. Microalgae may be a potential source for lutein production while the expense limits the commercialization. In this study, a coiled tubular tree photobioreactor (CTPBR) design was investigated for cultivating the cold tolerant microalgae Chlorella vulgaris UTEX 265 under various conditions for lutein production. The influence and interaction of light irradiance strength, lighting cycle, and temperature on microalgae and lutein production efficiency at low temperature range were also studied in flasks via response surface method (RSM). The results demonstrated that 14 h day-light, 120 μmol photons m^?2 s^?1, and 10 °C was the optimal condition for algae growth and lutein production at low temperature experimental ranges. C. vulgaris UTEX 265 showed good potential to produce lutein in cold weather, and the optimum lutein production was contrary to the specific lutein content but corresponds to the trend of optimum growth. Additionally, fast growth (μ = 1.50 day^?1) and good lutein recovery (11.98 mg g^?1 day^?1) in CTPBR were also achieved at the low irradiance stress condition and the low temperature photo-inhibition conditions.     

Biomethane Production in an AnSBBR Treating Wastewater from Biohydrogen Process

An anaerobic sequencing batch reactor containing immobilized biomass (AnSBBR) was used to produce biomethane by treating the effluent from another AnSBBR used to produce biohydrogen from glucose- (AR-EPHG) and sucrose-based (AR-EPHS) wastewater. In addition, biomethane was also produced from sucrose-based synthetic wastewater (AR-S) in a single AnSBBR to compare the performance of biomethane production in two steps (acidogenic and methanogenic) in relation to a one-step operation. The system was operated at 30 °C and at a fixed stirring rate of 300 rpm. For AR-EPHS treatment, concentrations were 1,000, 2,000, 3,000, and 4,000 mg chemical oxygen demand?(COD)?L^?1 and cycle lengths were 6 and 8 h. The applied volumetric organic loads were 2.15, 4.74, 5.44, and 8.22 g COD L^?1 day^?1. For AR-EPHG treatment, concentration of 4,000 mg COD L^?1 and 4-h cycle length (7.21 g COD L^?1 day^?1) were used. For AR-S treatment, concentration was 4,000 mg COD L^?1 day^?1 and cycle lengths were 8 (7.04 g COD L^?1 day^?1) and 12 h (4.76 g COD L^?1 day^?1). The condition of 8.22 g COD L^?1 day^?1 (AR-EPHS) showed the best performance with respect to the following parameters: applied volumetric organic load of 7.56 g COD L^?1 day^?1, yield between produced methane and removed organic material of 0.016 mol CH₄?g COD^?1, CH₄ content in the produced biogas of 85 %, and molar methane productivity of 127.9 mol CH₄?m^?3 day^?1. In addition, a kinetic study of the process confirmed the trend that, depending on the biodegradability characteristics of the wastewaters used, the two-step treatment (acidogenic for biohydrogen production and methanogenic for biomethane production) has potential advantages over the single-step process.     

Flow Injection Spectrophotometric Determination of N-Acetylcysteine and Captopril Employing Prussian Blue Generation Reaction

A novel flow injection procedure to determine N-acetylcysteine and captopril in pharmaceutical formulations is proposed. The flow procedure developed was based on oxidation of the analytes by Fe(III) in acidic medium and subsequent reaction of the Fe(II) generated with excess hexacyanoferrate(III) to produce soluble Prussian blue (KFe[Fe(CN)₆]) measured at 700 nm. Detection limits of 1.0 × 10^?5 mol L^?1 and 3.0 × 10^?5 mol L^?1 for N-acetylcysteine and captopril, respectively, were found. The sample throughput was 70 h^?1 for both analytes and the results obtained were in agreement at a 95% confidence level with those obtained using reference methods.     

A Fluorescence Spot Test for Salicylate Determination

Abstract

A procedure based on a spot test for salicylate is presented. The method is simple, rugged and is based on the salycilate native fluorescence measurement on the surface of a filter paper by using optical fibers for light conduction. The fluorescence was linear at concentration range of 0.01–0.4 mmol l^?1. The relative standard deviation of 5% (n=10) was observed. Detection and quantification limits were 4 and 14 µmol l^?1, respectively. The results obtained in pharmaceutical salicylate determinations showed that practically no statistical difference existed with the pharmacopeical method (95% confidence level). The recovery studies in biological samples spiked with salicylic acid at overdose concentration levels showed that the matrix sample did not interfere in the method.     

A Flow-Based Analytical Procedure for Salbutamol Determination Exploiting Chemiluminescence in a Liquid-Core Waveguide

Abstract

Salbutamol is a bronchodilator whose use is restricted due to its anabolic effects. A flow-based procedure for salbutamol determination based on the inhibition of chemiluminescence of the luminol/hypochlorite system was developed. A flow cell constructed with a liquid-core waveguide was employed to constrain the emitted radiation, minimizing losses during transport to detector. Linear response was observed within 2.5 × 10^?6 and 1.0 × 10^?5 mol L^?1 with a detection limit estimated as 1 × 10^?7 mol L^?1 at the 99.7% confidence level. The coefficient of variation (n = 20), sampling rate, and luminol consumption per determination were estimated as 2.8%, 164 determinations h^?1, and 50 µg, respectively. Results for pharmaceutical samples were in agreement with those obtained by reference procedures at the 95% confidence level.     

Flow Injection Chemiluminescence Determination of Retinol and α-Tocopherol in Blood Serum and Pharmaceuticals

A simple and sensitive flow-injection method is reported for the determination of retinol and α-tocopherol in human blood serum and pharmaceuticals. The method is based on the reduction of vanadium(V) by retinol and α-tocopherol and subsequent reaction of reduced vanadium with luminol to generate chemiluminescence signal. The optimized conditions allow a linear calibration range of 30–2850 µg L^?1 and 5–4300 µg L^?1 for retinol and α-tocopherol, with relative standard deviations of 1.2–4.6% and 1.5–5.6%, respectively. The detection limits for retinol and α-tocopherol, defined as three times the standard deviation of measured blanks were 23 µg L^?1 and 2.15 µg L^?1, respectively. The proposed method allowed up to 20 determinations h^?1. The tolerance amount of foreign ions/compounds on the determination of retinol and α-tocopherol was also examined. The method was applied to the determination of retinol and α-tocopherol in human blood serum and pharmaceutical samples using hexane extraction with recoveries in the range of 92 ± 2 to 96 ± 1%, and the results obtained were compared with HPLC reference method.     

Determination of Alkylphenols in Water by Dispersive Liquid–Liquid Microextraction Based on Solid Formation without a Disperser

Dispersive liquid–liquid microextraction based on solid formation without a disperser combined with high-performance liquid chromatography has been developed for the determination of 4-tert-butylphenol, 4-n-nonylphenol, and 4-tert-octylphenol. This method is rapid, easy, and uses only 10 µL of a low toxicity organic solvent (1-hexadecanethiol) for the extraction solvent and no disperser solvent. The extraction time and centrifugation time require less than 10 min. The linear range was 1–500 ng mL^?1 for 4-tert-butylphenol, 2–1000 ng mL^?1 for 4-tert-octylphenol, and 5–500 ng mL^?1 for 4-n-nonylphenol with r² ≥ 0.9986. The detection limits were between 0.2 and 1.5 ng mL^?1. The recoveries of lake and river water samples were in the range of 79% to 108%, and the relative standard deviations were 5% to 10%.     

Spectrophotometric Multicommutated Flow System for the Determination of Hypochlorite in Bleaching Products

Abstract

A multicommutation flow system for the spectrophotometric determination of hypochlorite in bleaching products is proposed. In this system, N,N-diethyl-p-phenylenediamine (DPD) reacts with hypochlorite, and the product was monitored at 515 nm. The analytical curve for hypochlorite was linear in the concentration range from 2.68 × 10^?5 to 1.88 × 10^?4 mol L^?1 (2–14 mg L^?1) with a detection limit of 6.84 × 10^?6 mol L^?1 (0.51 mg L^?1). The sampling rate was 45 h^?1, and a relative standard deviation of 1.4% (n = 10) was obtained. The recovery of this analyte ranged from 97.2% to 102.5%, and the results found using the proposed spectrophotometric multicommutated flow system agreed with the data obtained using a reference method (iodometric titration) at the 95% confidence level.     

Determination of the leaching rate of radionuclide 134Cs from the solidified radioactive wastes in Syrian Portland cement and cement–microsilica matrixes

The suitability of Syrian Portland cement for disposal of solidified low-level radioactive waste was assessed by measuring the leaching rate of ¹³⁴Cs. In ordinary cement concrete, a leaching rate of 1.309 × 10^?3 g/cm² per day was measured. Mixing this concrete with microsilica reduced significantly the leaching rate to 3.106 × 10^?4 g/cm² per day for 1% mixing, and to 9.645 × 10^?5 g/cm² per day for 3% mixing. It was also found that the application of a latex paint reduced these leaching rates by about 10%. These results, along with mechanical strength tests (under radiation exposure, high temperature, long water immersion and freeze–thaw cycling) indicate that Syrian Portland cement is suited for the disposal of low-level radioactive waste.     

Environmental gamma background measurements in China Jinping Underground Laboratory

To determine the environmental gamma background levels which affects rare events experiments, we measured in situ gamma spectrum at four locations in the China Jinping Underground Laboratory. The integral background count rates (40–2,700 keV) varied from 3.76 to 74.1 cps. The average count rate of the measurements inside the CJPL was 73.4 cps. The spectrometer was calibrated with a ¹⁵²Eu point source and Monte Carlo simulation to obtain the activity conversion factors for the rock and the air, respectively. The rocks that surrounded the CJPL was characterized by very low activity concentrations of ²³⁸U (3.69–4.21 Bq kg^?1), ²³²Th (0.52–0.64 Bq kg^?1) and ⁴⁰K (4.28 Bq kg^?1).     

LC–MS–MS Determination of Troxerutin in Plasma and Its Application to a Pharmacokinetic Study

A highly sensitive liquid chromatography–tandem mass spectrometry (LC–MS–MS) method for the determination of troxerutin in human plasma using tramadol as internal standard (IS) has been developed and validated. Sample preparation involved liquid–liquid extraction with ethyl acetate–isopropanol (95:5, v/v). The analyte and IS were separated by RP–LC with gradient elution using 10 mM ammonium acetate containing 0.1% formic acid and methanol at a flow rate of 0.9 mL min^?1. LC–MS–MS in the positive ion mode employed multiple reaction monitoring of the transitions at m/z 743.2→435.3 and m/z 264.1→58.0 for troxerutin and IS, respectively. The assay was linear in the concentration range 0.01–10 ng mL^?1 with precision and accuracy within assay variability limits as per FDA guidelines. The assay was successfully applied to a pharmacokinetic study involving oral administration of 300 mg troxerutin to eight healthy Chinese volunteers.     

Carbon ceramic electrodes modified with mixed oxides SiO<Subscript>2</Subscript>/SnO<Subscript>2</Subscript> for determination of levofloxacin

The preparation of a carbon ceramic electrode modified with SnO₂ (CCE/SnO₂) using tin dibutyl diacetate as precursor was optimized by a 2³ factorial design. The factors analyzed were catalyst (HCl), graphite/organic precursor ratio, and inorganic precursor (dibutyltin diacetate). The statistical treatment of the data showed that only the second-order interaction effect, catalyst × inorganic precursor, was significant at 95% confidence level, for the electrochemical response of the system. The obtained material was characterized by scanning electron microscopy (MEV), X-ray diffraction (XRD), RAMAN spectroscopy, XPS spectra, and voltammetric techniques. From the XPS spectra, it was confirmed the formation of the Si–O–Sn bond by the shift in the binding energy values referred to Sn 3d3/2 due to the interaction of Sn with SiOH species. The incorporation of SnO₂ provided an increment of the electrode response for levofloxacin, with Ipa = 147.0 μA for the ECC and Ipa = 228.8 μA for ECC/SnO₂, indicating that SnO₂ when incorporated into the silica network enhances the electron transfer process. Under the optimized working conditions, the peak current increased linearly with the levofloxacin concentration in the range from 6.21×10^?5 to 6.97×10^?4 mol L^?1 with quantification and detection limits of 3.80×10^?5 mol L^?1 (14.07 mg L^?1) and 1.13×10^?5 mol L^?1 (4.18 mg L^?1), respectively.     

Anaerobic Digestion of Sugarcane Vinasse Through a Methanogenic UASB Reactor Followed by a Packed Bed Reactor

The anaerobic treatment of raw vinasse in a combined system consisting in two methanogenic reactors, up-flow anaerobic sludge blanket (UASB) + anaerobic packed bed reactors (APBR), was evaluated. The organic loading rate (OLR) was varied, and the best condition for the combined system was 12.5 kg COD m^?3day^?1 with averages of 0.289 m³ CH₄ kg COD r^?1for the UASB reactor and 4.4 kg COD m^?3day^?1 with 0.207 m³ CH₄ kg COD r^?1 for APBR. The OLR played a major role in the emission of H₂S conducting to relatively stable quality of biogas emitted from the APBR, with H₂S concentrations <10 mg L^?1. The importance of the sulphate to COD ratio was demonstrated as a result of the low biogas quality recorded at the lowest ratio. It was possible to develop a proper anaerobic digestion of raw vinasse through the combined system with COD removal efficiency of 86.7% and higher CH₄ and a lower H₂S content in biogas.     

Semi-continuous Cultivation of Haematococcus pluvialis for Commercial Production

The objectives of the present study on the growth of Haematococcus pluvialis were to indicate the effects of a long-term semi-continuous cultivation, sterilization, carbon dioxide, and different culture media by using artesian well water. This investigation was an enterprise in order to commercialize the production economically. When the effect of CO₂ was investigated in basal culture medium, the influence of sterilization was also researched in Rudic’s culture medium in vertical panel-type photobioreactors for 31 days of semi-continuous cultivation. The maximum cell concentration of 10.55?×?10⁵ cells ml^?1, which corresponds to the growth rate of 0.271 day^?1 with the areal productivity of 3.531 g m^?2 day^?1, was found in non-sterilized RM medium on the 24th day of the third run of semi-continuous cultivation at a renewal rate of 50% in a vertical panel-type photobioreactor.     

Application of ultrasonic-assisted cloud point extraction/flame atomic absorption spectrometry (UA-CPE/FAAS) for preconcentration and determination of low levels of antimony in some beverage samples

Due to be able to migrate or leach from food packaging materials into the foods and/or beverages, development of a new, sensitive and selective analytical methods for low levels of antimony as a food contaminant is of great importance in terms of food safety. In this context, an ultrasonic-assisted cloud point extraction method was developed for the preconcentration and determination of antimony as Sb(III) using 4-(2-thiazolylazo)resorcinol (TAR) and 2-(2-thiazolylazo)-p-cresol (TAC) as chelating agents and sodium dodecyl sulfate as signal enhancing agent at pH 6.0 and mediated by nonionic surfactant, t-octylphenoxypolyethoxyethanol by flame atomic absorption spectrometry. Using the optimized conditions, the calibration curves obtained from Sb(III) with TAR and TAC were linear in the concentration ranges of 0.5–180 and 1–180 μg L^?1 with detection limits of 0.13 and 0.28 μg L^?1, respectively. The precision (as relative standard deviations, RSDs) was lower than 3.9 % (25 and 100 μg L^?1, n: 6). The method accuracy was validated by the analysis of two standard reference materials. The results obtained were statistically in a good agreement with the certified values at 95 % confidence limit. The method has successfully been applied to the determination of Sb(III) and total Sb in selected beverages, milk and fruit-flavored milk products before and after pre-reduction of Sb(V) to Sb(III) with a mixture of KI/ascorbic acid in acidic media. The Sb(V) contents of samples were quantitatively calculated from analytical difference between total Sb and Sb(III) levels.     

On-line spectrophotometric determination of scandium after preconcentration on XAD-4 resin impregnated with nalidixic acid

An on-line scandium preconcentration and determination method was developed with spectrophotometer associated with flow injection. Scandium from aqueous sample solution of pH 4.5 was selectively retained in the minicolumn containing XAD-4 resin impregnated with nalidixic acid at a flow rate of 11.8 mL min^?1 as scandium–nalidixic acid complex. The scandium complex was desorbed from the resin by 0.1 mol L^?1 HCl at a flow rate of 3.2 mL min^?1 and mixed with arsenazo-III solution (0.05 % solution in 0.1 mol L^?1 HCl, 3.2 mL min^?1) and taken to the flow through cell of spectrophotometer where its absorbance was measured at 640 nm. The preconcentration factors obtained were 35 and 155; detection limits of 1.4 and 0.32 μg L^?1 and sample throughputs of 40 and 11 were obtained for preconcentration time of 60 and 300 s, respectively. The tolerance limits of many interfering cations like Th(IV), U (VI), rare-earths and anions like tartrate, citrate, oxalate and fluoride were improved. The method was successfully applied to the determination of scandium from mock seawater samples and good recovery was obtained. The method was also validated on certified reference material IAEA-SL-1 (lake sediment) and the result was in good agreement with the reported value.