Isolation of Novel Microalgae from Acid Mine Drainage and Its Potential Application for Biodiesel Production

Microalgae were selected and isolated from acid mine drainage in order to find microalgae species which could be cultivated in low pH condition. In the present investigation, 30 microalgae were isolated from ten locations of acid mine drainage in South Korea. Four microalgae were selected based on their growth rate, morphology, and identified as strains of KGE1, KGE3, KGE4, and KGE7. The dry biomass of microalgae species ranged between 1 and 2 g L^?1 after 21 days of cultivation. The growth kinetics of microalgae was well described by logistic growth model. Among these, KGE7 has the highest biomass production (2.05?±?0.35 g L^?1), lipid productivity (0.82?±?0.14 g L^?1), and C16–C18 fatty acid contents (97.6 %). These results suggest that Scenedesmus sp. KGE 7 can be utilized for biodiesel production based on its high biomass and lipid productivity.     

Bioethanol Production from Ipomoea Carnea Biomass Using a Potential Hybrid Yeast Strain

The paper deals with the exploitation of Ipomoea carnea as a feedstock for the production of bioethanol. Dilute acid pretreatment under optimum conditions (3 %H₂SO₄, 120 °C for 45 min) produced 17.68 g L^?1 sugars along with 1.02 g L^?1 phenolics and 1.13 g L^?1 furans. A combination of overliming and activated charcoal adsorption facilitated the removal of 91.9 % furans and 94.7 % phenolics from acid hydrolysate. The pretreated biomass was further treated with a mixture of sodium sulphite and sodium chlorite and, a maximum lignin removal of 81.6 % was achieved. The enzymatic saccharification of delignified biomass resulted in 79.4 % saccharification with a corresponding sugar yield of 753.21 mg g^?1. Equal volume of enzymatic hydrolysate and acid hydrolysate were mixed and used for fermentation with a hybrid yeast strain RPRT90. Fermentation of mixed detoxified hydrolysate at 30 °C for 28 h produced ethanol with a yield of 0.461 g g^?1. A comparable ethanol yield (0.414 g g^?1) was achieved using a mixture of enzymatic hydrolysate and undetoxified acid hydrolysate. Thus, I. carnea biomass has been demonstrated to be a potential feedstock for bioethanol production, and the use of hybrid yeast may pave the way to produce bioethanol from this biomass.     

Determination of Veterinary Pharmaceuticals in Production Wastewater by HPTLC-Videodensitometry

An SPE-HPTLC method for simultaneous identification and quantification of seven pharmaceuticals in production wastewater was optimized and validated. The studied compounds were enrofloxacine, oxytetracycline, trimethoprim, sulfamethazine, sulfadiazine, sulfaguanidine and penicillin G/procaine. The method involves solid-phase extraction on hydrophilic-lipophilic balance cartridges with methanol and HPTLC analysis of extracts on CN modified chromatographic plates followed by videodensitometry at 254 and 366 nm. Optimization of chromatographic separation was performed by systematic variation of the mobile phase composition using genetic algorithm approach and the optimum mobile phase composition for TLC separation was 0.05 M H₂C₂O₄:methanol = 0.81:0.19 (v/v). Linearity of the method was demonstrated in the ranges from 1.5 to 15.0 μg L⁻¹ for enrofloxacine, 100–500 μg L⁻¹ for oxytetracycline, 150–600 μg L⁻¹ for trimethoprim, 300–1100 μg L⁻¹ for sulfaguanidine and 100–400 μg L⁻¹ for sulfamethazine, sulfadiazine and penicillin G/procaine with coefficients of determination higher than 0.991. Mean recoveries ranged from 74.6 to 117.1% and 55.1 to 108.0% for wellspring water and production wastewater, respectively. Only sulfaguanidine showed lower results. The described method has been applied to the determination of pharmaceuticals in wastewater samples from pharmaceutical industry.     

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.     

Swine Manure-Based Pilot-Scale Algal Biomass Production System for Fuel Production and Wastewater Treatment—a Case Study

Integration of wastewater treatment with algae cultivation is one of the promising ways to achieve an economically viable and environmentally sustainable algal biofuel production on a commercial scale. This study focused on pilot-scale algal biomass production system development, cultivation process optimization, and integration with swine manure wastewater treatment. The areal algal biomass productivity for the cultivation system that we developed ranged from 8.08 to 14.59 and 19.15–23.19 g/m²?×?day, based on ash-free dry weight and total suspended solid (TSS), respectively, which were higher than or comparable with those in literature. The harvested algal biomass had lipid content about 1.77–3.55 %, which was relatively low, but could be converted to bio-oil via fast microwave-assisted pyrolysis system developed in our lab. The lipids in the harvested algal biomass had a significantly higher percentage of total unsaturated fatty acids than those grown in lab conditions, which may be attributed to the observed temperature and light fluctuations. The nutrient removal rate was highly correlated to the biomass productivity. The NH₃-N, TN, COD, and PO₄-P reduction rates for the north-located photo-bioreactor (PBR-N) in July were 2.65, 3.19, 7.21, and 0.067 g/m²?×?day, respectively, which were higher than those in other studies. The cultivation system had advantages of high mixotrophic growth rate, low operating cost, as well as reduced land footprint due to the stacked-tray bioreactor design used in the study.     

Cultivation of Chlorella vulgaris in Dairy Wastewater Pretreated by UV Irradiation and Sodium Hypochlorite

There is potential in the utilization of microalgae for the purification of wastewater as well as recycling the resource in the wastewater to produce biodiesel. The large-scale cultivation of microalgae requires pretreatment of the wastewater to eliminate bacteria and protozoa. This procedure is costly and complex. In this study, two methods of pretreatment, UV irradiation, and sodium hypochlorite (NaClO), in various doses and concentrations, were tested in the dairy wastewater. Combining the efficiency of biodiesel production, we proposed to treat the dairy wastewater with NaClO in the concentration of 30 ppm. In this condition, The highest biomass productivity and lipid productivity of Chlorella vulgaris reached 0.450 g L^?1 day^?1 and 51 mg L^?1 day^?1 after a 4-day cultivation in the dairy wastewater, respectively.     

Screening of <Emphasis Type="Italic">Isochrysis</Emphasis> Strains and Utilization of a Two-Stage Outdoor Cultivation Strategy for Algal Biomass and Lipid Production

Isochrysis is a genus of marine algae without cell wall and capable of accumulating lipids. In this study, the lipid production potential of Isochrysis was assessed by comparing 15 Isochrysis strains with respect to their growth rate, lipid production, and fatty acid profiles. Three best strains were selected (lipid productivity, 103.0~121.7 mg L^?1 day^?1) and their lipid-producing capacities were further examined under different controlled parameters, e.g., growth phase, medium nutrient, and light intensity in laboratory cultures. Furthermore, the three Isochrysis strains were monitored in outdoor panel photobioreactors with various initial cell densities and optical paths, and the strain CS177 demonstrated the superior potential for outdoor cultivation. A two-stage semi-continuous strategy for CS177 was subsequently developed, where high productivities of biomass (1.1 g L^?1 day^?1) and lipid (0.35 g L^?1 day^?1) were achieved. This is a comprehensive study to evaluate the lipid-producing capability of Isochrysis strains under both indoor and outdoor conditions. Results of the present work lay a solid foundation for the physiological and biochemical responses of Isochrysis to various conditions, shedding light on the future utilization of this cell wall-lacking marine alga for biofuel production.     

Mixotrophic Cultivation of Microalgae for Biodiesel Production: Status and Prospects

Biodiesel from microalgae provides a promising alternative for biofuel production. Microalgae can be produced under three major cultivation modes, namely photoautotrophic cultivation, heterotrophic cultivation, and mixotrophic cultivation. Potentials and practices of biodiesel production from microalgae have been demonstrated mostly focusing on photoautotrophic cultivation; mixotrophic cultivation of microalgae for biodiesel production has rarely been reviewed. This paper summarizes the mechanisms and virtues of mixotrophic microalgae cultivation through comparison with other major cultivation modes. Influencing factors of microalgal biodiesel production under mixotrophic cultivation are presented, development of combining microalgal biodiesel production with wastewater treatment is especially reviewed, and bottlenecks and strategies for future commercial production are also identified.     

Optimized solid phase extraction based on diethyldithiocarbamate-coated Fe3O4 magnetic nanoparticles followed by ICP-OES for determination of Cd(II) and Ni(II) in rice and water samples

In the present study, application of Fe₃O₄ magnetic nanoparticles (MNPs) coated with diethyldithiocarbamate as a solid-phase sorbent for extraction of trace amounts of cadmium (Cd²⁺) and nickel (Ni²⁺) ions by the aid of ultrasound was investigated. The analytes were determined by inductively coupled plasma-optical emission spectroscopy. Fe₃O₄ MNPs were prepared by solvothermal method and characterized with dynamic light scattering, scanning electron microscope and X-ray diffraction. Response surface methodology was used for optimization of the extraction process and modeling the data. The optimal conditions obtained were as follows: chelating agent, 1.2 g L^?1; pH, 6.13; sonication time, 13 min and Fe₃O₄ MNPs, 10.3 mg. The calibration curves were linear over the concentration range of 1–1,000 μg L^?1 for Cd²⁺ and 2.5–1,000 for Ni²⁺ with the determination coefficients (R ²) of 0.9997 and 0.9995, respectively. The limits of detection were 0.27 μg L^?1 for Cd²⁺ and 0.76 μg L^?1 for Ni²⁺. The relative standard deviations (n = 7, C = 200 μg L^?1) for determination of Cd²⁺ and Ni²⁺ were 2.0 and 2.7 %, respectively. The relative recoveries of the analytes from tap, river and lagoon waters and rice samples at the spiking level of 10 μg L^?1 were obtained in the range of 95–105 %.     

Determination of Total Arsenic in Wastewater and Sewage Sludge Samples by Using Hydride-Generation Atomic Fluorescence Spectrometry Under the Optimized Analytical Conditions

In this work, an improved hydride-generation atomic fluorescence spectrometry (HG-AFS) method for the determination of total arsenic (As) in wastewater and sewage sludge samples was applied. The samples were digested completely with mixtures of HNO₃ and HClO₄. Analytical conditions were studied and optimized through uniform experimental design U*₁₀(10⁸) combined with a single factor test. A mathematical model was established, and a quadratic polynomial stepwise regression analysis by using the DPS software was employed to obtain the factors that impact the fluorescence intensity. This technique is then combined with a single factor test. The optimized experimental conditions were obtained as follows: PMT voltage was 305 V, lamp current was 70 mA, KBH₄ concentration was 2.0% (m/v), carrier liquid (HCl) concentration was 5% (v/v), carrier gas (Ar) flow rate was 300 mL min^?1, and reaction acidity was 10% (v/v) HCl. The pre-reduction of all forms of As to As(III) was performed by using a mixed solution of 1% thiourea and 1% ascorbic acid. The content of total As was determined under the optimized experimental conditions. The detection limits for total As in wastewater and sewage sludge were 0.09 µg L^?1 and 0.01 mg kg^?1, respectively. The linear ranges were 0.24–100 µg L^?1, and the recovery was 91.0–102.0%. The relative standard deviation (RSD, n = 5) for eleven replicate measurements of the certified reference materials containing 60.6 ± 4.2 µg L^?1 As (certified sample of water) and 10.7 ± 0.8 mg kg^?1 As (certified sample of soil) were 3.1% and 1.6%, respectively. The proposed method was validated by the analysis of certified reference materials and was successfully applied to the determination of total As in real samples of wastewater and sewage sludge with satisfactory results.     

Effect of Organic Loading Rate and Fill Time on the Biohydrogen Production in a Mechanically Stirred AnSBBR Treating Synthetic Sucrose-Based Wastewater

This study investigated the feasibility to produce biohydrogen of a mechanically stirred anaerobic sequencing batch biofilm reactor (AnSBBR) treating sucrose-based synthetic wastewater. The bioreactor performance (30 °C) was evaluated as to the combined effect of fill time (2, 1.5, and 1 h), cycle length (4, 3, and 2 h), influent concentration (3,500 and 5,250 mg chemical oxygen demand (COD)?L^?1) and applied volumetric organic load (AVOL_CT from 9.0 to 27.0 g COD L^?1 d^?1). AVOLs were varied according to influent concentration and cycle length (t _C). The results showed that increasing AVOL_CT resulted in a decrease in sucrose removal from 99 to 86 % and in improvement of molar yield per removed load (MYRL_S.n) from 1.02 mol H₂?mol carbohydrate^?1 at AVOL_CT of 9.0 g COD L^?1 d^?1 to maximum value of 1.48 mol H₂?mol carbohydrate^?1, at AVOL_CT of 18.0 g COD L^?1 d^?1, with subsequent decrease. Increasing AVOL_CT improved the daily molar productivity of hydrogen (MPr) from 15.28 to 49.22 mol H₂?m^?3 d^?1. The highest daily specific molar productivity of hydrogen (SMPr) obtained was 8.71 mol H₂?kg TVS^?1 d^?1 at an AVOL_CT of 18.0 g COD L^?1 d^?1. Decreasing t _C from 4 to 3 h decreased sucrose removal, increased MPr, and improved SMPr. Increasing influent concentration decreased sucrose removal only at t _C of 2 h, improved MYRL_S,n and MPr at all t _C, and also improved SMPr at t _C of 4 and 3 h. Feeding strategy had a significant effect on biohydrogen production; increasing fill time improved sucrose removal, MPr, SMPr, and MYRL_S,n for all investigated AVOL_CT. At all operational conditions, the main intermediate metabolic was acetic acid followed by ethanol, butyric, and propionic acids. Increasing fill time resulted in a decrease in ethanol concentration.     

An automated headspace solid-phase microextraction followed by gas chromatography–mass spectrometry method to determine macrocyclic musk fragrances in wastewater samples

A fully automated method has been developed for determining eight macrocyclic musk fragrances in wastewater samples. The method is based on headspace solid-phase microextraction (HS-SPME) followed by gas chromatography–mass spectrometry (GC-MS). Five different fibres (PDMS 7 μm, PDMS 30 μm, PDMS 100 μm, PDMS/DVB 65 μm and PA 85 μm) were tested. The best conditions were achieved when a PDMS/DVB 65 μm fibre was exposed for 45 min in the headspace of 10 mL water samples at 100 °C. Method detection limits were found in the low ng L^?1 range between 0.75 and 5 ng L^?1 depending on the target analytes. Moreover, under optimized conditions, the method gave good levels of intra-day and inter-day repeatabilities in wastewater samples with relative standard deviations (n?=?5, 1,000 ng L^?1) less than 9 and 14 %, respectively. The applicability of the method was tested with influent and effluent urban wastewater samples from different wastewater treatment plants (WWTPs). The analysis of influent urban wastewater revealed the presence of most of the target macrocyclic musks with, most notably, the maximum concentration of ambrettolide being obtained in WWTP A (4.36 μg L^?1) and WWTP B (12.29 μg L^?1), respectively. The analysis of effluent urban wastewater showed a decrease in target analyte concentrations, with exaltone and ambrettolide being the most abundant compounds with concentrations varying between below method quantification limit (<MQL) and 2.46 μg L^?1.

Nutrient Removal Efficiency and Physiological Responses of Desmodesmus communis at Different HRTs and Nutrient Stress Condition Using Different Sources of Urban Wastewater Effluents

The objective of the present study was to evaluate the nutrient removal efficiency and the physiological responses in terms of growth, biochemical composition and photosynthetic activity of the autochthonous freshwater algal strain Desmodesmus communis. Microalgae were grown in a primary municipal effluent under different hydraulic retention times (HRTs) and in a two-phases process using both primary and secondary wastewater effluents. Semi-continuous cultures were operated for 7 day at 5-, 3- and 1.5-day HRT and the different dilution rate showed a greater influence on the biomass composition and nutrient removal efficiency. Removal of N-NH₃ and P-PO₄ was over 99 % and the highest accumulation of polysaccharides (57.2 wt.%) was obtained at high HRT (5 day); the maximum content of proteins (26.9 wt.%) was achieved at 1.5-day HRT, even if, under this condition, a clear inefficiency in terms of ammonia removal was observed. Moreover the accumulation of N-NH₃ occurring at 1.5-day HRT caused the decrease of the photosynthetic response in terms of efficiency of light capture (α) and relative electron transport rate (rETR), both parameters extracted from the rapid light curves (RLC) measurements. No significant differences were observed for the total fatty acids (TFAs), with a content of 2–3.5 wt.% for each HRT condition. On the other hand, in the two-phases process, when a nutrient deprivation condition was induced by diluting the culture with the secondary wastewater effluent, the algal cells accumulated TFAs, achieving a maximum content of 9.7 wt.% and a great increment in terms of biomass (1.64?±?0.02 g L^?1) due to the ability of this algal strain to accumulate intracellular N. The wide and accurate investigation of the different aspects related to the whole process represents a relevant point of novelty in this research field and suggests the operational conditions for the start-up of an open pond system for wastewater treatment and biomass production for further applications.     

Enhancing Carbohydrate Productivity of <Emphasis Type="Italic">Chlorella</Emphasis> sp. AE10 in Semi-continuous Cultivation and Unraveling the Mechanism by Flow Cytometry

Accumulated carbohydrate in microalgae is promising feedstock for bioethanol fermentation. Selection of suitable cultivation conditions in semi-continuous cultivation is critical to achieve a high carbohydrate productivity. In the current study, the effects of macro-nutrient (nitrogen, phosphorus, and sulfur) limitations and light intensity were evaluated for the carbohydrate accumulations of Chlorella sp. AE10 under 10% CO₂ conditions. It was shown that nitrogen limitation and high light intensity were effective for improving carbohydrate productivity. The average carbohydrate and biomass productivity in semi-continuous cultivation with 1/4 N medium and 1000 μmol photons m^?2 s^?1 was 0.673 and 0.93 g L^?1 day^?1, respectively. Sulfur and phosphorus limitations could improve the carbohydrate content but they could not enhance the carbohydrate productivity. The cell cycle progression and chlorophyll a were investigated using flow cytometry (FCM). The results showed that macro-nutrient limitation and high light intensity indeed influenced cell cycle progression and led to the formation of polyploid cells along with the carbohydrate accumulation in a certain range. FCM was rapid and accurate method to investigate the operation conditions why 1/4 N, 2 days as a cycle, and high light intensity were optimal ones. In addition, the remaining high level of photosynthesis activity was also important for achieving a high carbohydrate productivity. Dynamic tracking of carbohydrate accumulation is helpful for establishment of a semi-continuous cultivation for enhancing carbohydrate productivity in microalgae.     

Single-cell Protein and Xylitol Production by a Novel Yeast Strain <Emphasis Type="Italic">Candida intermedia</Emphasis> FL023 from Lignocellulosic Hydrolysates and Xylose

Yeasts are good candidates to utilize the hydrolysates of lignocellulose, the most abundant bioresource, for bioproducts. This study aimed to evaluate the efficiencies of single-cell protein (SCP) and xylitol production by a novel yeast strain, Candida intermedia FL023, from lignocellulosic hydrolysates and xylose. This strain efficiently assimilated hexose, pentose, and cellubiose for cell mass production with the crude protein content of 484.2 g kg^?1 dry cell mass. SCP was produced by strain FL023 using corncob hydrolysate and urea as the carbon and nitrogen sources with the dry cell mass productivity 0.86 g L^?1 h^?1 and the yield of 0.40 g g^?1 sugar. SCP was also produced using NaOH-pretreated Miscanthus sinensis straw and corn steep liquor as the carbon and nitrogen sources through simultaneous saccharification and fermentation with the dry cell productivity of 0.23 g L^?1 h^?1 and yield of 0.17 g g^?1 straw. C. intermedia FL023 was tolerant to 0.5 g L^?1 furfural, acetic acid, and syringaldehyde in xylitol fermentation and produced 45.7 g L^?1 xylitol from xylose with the productivity of 0.38 g L^?1 h^?1 and the yield of 0.57 g g^?1 xylose. This study provides feasible methods for feed and food additive production from the abundant lignocellulosic bioresources.     

A SPE-LC-MS/MS Method for the Detection of Low Concentrations of Pharmaceuticals in Industrial Waste Streams

A SPE-LC-MS/MS method was developed and validated for the determination of three active pharmaceutical ingredients [API A (3-([2-(diaminomethyleneamino)thiazol-4-yl]methylthio)-N′-sulfamoyl propanimid amide, API B 5-[(2 R)-2-[2-(2-ethoxyphenoxy)ethylamino]propyl]-2-methoxybenzenesulfonamide hydrochloride, API C 1-azabicyclo[2.2.2]octan-8-yl (1S)-1-phenyl-3,4-dihydro-1H-isoquinoline-2-carboxylate] in the wastewater of a chemical synthesis production facility. The SPE-LC-MS/MS method was validated in actual influent and effluent samples. Linearity, LOD, LOQ, repeatability, intermediate precision, and recovery were determined. An LOQ of 400 μg · L^?1, 1.0 μg · L^?1, and 6 μg · L^?1, repeatability of 2.5% CV, 14.8% CV, and 11.9% CV, intermediate precision of 7.8% CV, 11.0% CV, and 8.7% CV and SPE recovery of 114%, 103%, and 91% was determined for API A, B, and C, respectively, in influent. An LOQ of 400 μg · L^?1, 0.8 μg · L^?1, and 6 μg · L^?1, repeatability of 2.0% CV, 11.0% CV, and 10.9% CV, intermediate precision of 1.7% CV, 6.8% CV, and 10.2% CV and SPE recovery of 116%, 96%, and 115% was established for API A, B, and C, respectively, in effluent. Coefficients of correlation for each analyte were >0.9301 confirming the linearity of the method. The LC-MS/MS method was used for an on-going monitoring program for these pharmaceuticals in wastewater. The method development techniques, validation procedures, and results from real wastewater samples are presented in this paper.     

Occurrence of cytostatic compounds in hospital effluents and wastewaters,determined by liquid chromatography coupled to high-resolution mass spectrometry

The occurrence of 26 commonly used cytostatic compounds in wastewaters was evaluated using an automated solid-phase extraction (SPE) method with liquid chromatography–high-resolution mass spectrometry (LC–HRMS). Detection was optimized using Oasis HLB SPE cartridges at pH 2. Two hospital effluents and their two receiving wastewater treatment plants were sampled over five days. In hospital effluents, eight cytostatics were detected at levels up to 86.2 μg L^?1 for ifosfamide, 4.72 μg L^?1 for cyclophosphamide, and 0.73 μg L^?1 for irinotecan, the three most relevant compounds identified. Cyclophosphamide and megestrol acetate were found in wastewaters at concentrations up to 0.22 μg L^?1 for the latter. The predicted environmental concentrations (PEC) in sewage effluents of ifosfamide (2.4–4.3 ng L^?1), capecitabine (11.5–14.2 ng L^?1), and irinotecan (0.4–0.6 ng L^?1), calculated from consumption data in each hospital, published excretion values for the target compounds, and wastewater elimination rates, were in agreement with experimental values.     

Use of Surfactant as Mobile Phase Additive in LC for Simultaneous Determination of Metal-Pyrrolidine Dithiocarbamate Chelates

Reversed phase liquid chromatography using UV detection was developed for the simultaneous analysis of Hg(II), Pb(II), Cd(II), Ni(II), Fe(III) and V(V) ions after their complexation with pyrrolidine-dithiocarbamate (PDC). Optimum chromatographic conditions were a μ-Bondapak C₁₈ column and an isocratic mobile phase consisting of 40 mmol L^?1 SDS, 34 mmol L^?1 TBABr and 68% acetonitrile in 10 mmol L^?1 phosphate buffer pH 3.5. The separation of six PDC complexes was achieved within 8 min. Analytical performances and method validation were investigated. The detection limits ranged from 0.16 μg L^?1(Fe(III)) to 5.40 μg L^?1(Pb(II)). Recoveries obtained for all the studied samples including tap water, whole blood and vegetables were 72–98%. The results obtained from the proposed method were not significantly different compared to those obtained from atomic absorption spectrometry (P = 0.05).     

Ethanol Production from Sugarcane Bagasse by Zymomonas mobilis Using Simultaneous Saccharification and Fermentation (SSF) Process

Considerable efforts have been made to utilize agricultural and forest residues as biomass feedstock for the production of second-generation bioethanol as an alternative fuel. Fermentation utilizing strains of Zymomonas mobilis and the use of simultaneous saccharification and fermentation (SSF) process has been proposed. Statistical experimental design was used to optimize the conditions of SSF, evaluating solid content, enzymatic load, and cell concentration. The optimum conditions were found to be solid content (30%), enzymatic load (25 filter paper units/g), and cell concentration (4 g/L), resulting in a maximum ethanol concentration of 60 g/L and a volumetric productivity of 1.5 g L^?1?h^?1.     

Polyhydroxybutyrate (PHB) Synthesis by <Emphasis Type="Italic">Spirulina</Emphasis> sp. LEB 18 Using Biopolymer Extraction Waste

The reuse of waste as well as the production of biodegradable compounds has for years been the object of studies and of global interest as a way to reduce the environmental impact generated by unsustainable exploratory processes. The conversion of linear processes into cyclical processes has environmental and economic advantages, reducing waste deposition and reducing costs. The objective of this work was to use biopolymer extraction waste in the cultivation of Spirulina sp. LEB 18, for the cyclic process of polyhydroxybutyrate (PHB) synthesis. Concentrations of 10, 15, 20, 25, and 30% (v/v) of biopolymer extraction waste were tested. For comparison, two assays were used without addition of waste, Zarrouk (SZ) and modified Zarrouk (ZM), with reduction of nitrogen. The assays were carried out in triplicate and evaluated for the production of microalgal biomass and PHB. The tests with addition of waste presented a biomass production statistically equal to ZM (0.79 g L^?1) (p?<?0.1). The production of PHB in the assay containing 25% of waste was higher when compared to the other cultivations, obtaining 10.6% (w/w) of biopolymer. From the results obtained, it is affirmed that the use of PHB extraction waste in the microalgal cultivation, aiming at the synthesis of biopolymers, can occur in a cyclic process, reducing process costs and the deposition of waste, thus favoring the preservation of the environment.