•Calibration and validation of an autotrophic denitrification model is proposed.•The batch system used suspended biomass and S0/N at stoichiometric ratio.•The acclimated inoculum contained mainly ...Thiobacillus.•The most sensitive parameters in the model are related to S0 hydrolysis.•The calibrated model can simulate the S0-based autotrophic denitrification.
The inclusion of S0 hydrolysis in a kinetic model of autotrophic denitrification has been recently proposed; however the model has not been calibrated or validated yet. Thus, a new methodology was developed and applied to calibrate and validate this kinetic model for the first time. An inoculum adapted from a poultry wastewater treatment plant at stoichiometric S0/NO3− ratio was used. The model was calibrated with batch data (initial nitrate concentrations of 50 and 6.25 mg NO3−-N/L) at an S0/N ratio = 2.29 mg S/mg N and validated with seven different batch data. The sensitivity analysis showed that the most sensitive parameters are related to S0 hydrolysis. The kinetic model was successfully calibrated with the new methodology and validated, with Theil inequality coefficient values lower than 0.21. Thus, the proposed model and methodology were proved to be well suited for the simulation of elemental sulfur-based autotrophic denitrification in batch systems.
Not only is water an essential source for the existence of humans but also it is a necessity for creatures' life. Reutilizing wastewater is a salient way to conquer this rigor; many physical and ...chemical methods have been developed to treat wastewater, one of which is the advanced oxidation process (AOP). In this study, a heterogeneous Fenton reaction was employed to degrade a non-biodegradable organic contaminant (Direct Blue 71) from synthetic seawater. An unprecedented approach and a novel self-created autoclave were employed to synthesize granulated Fe3O4/Cellulose nanocomposites, which were applied in AOPs as catalysts. Characterization of prepared nanocomposites was investigated by various methods confirming that cellulose is uniformly covered by Fe3O4 nanoparticles. The AOP was carried out in two different kinds of batch and fluidized bed reactors. The impacts of three effectual parameters on the dye removal were weighed using response surface methodology (RSM). The obtained results for both systems demonstrated that exploiting 3.1 g/L catalysts besides the presence of 12.95 mM H2O2 could remove 33.12 mg/L dye entirely. In comparison to the batch reactor, only when the process was conducted in a fluidized bed reactor, did the elimination efficiency increase dramatically. Fluidization results indicated a significant enhancement in dye removal efficiency and a sensitive decrement in the degradation process time. The experimental results were in good agreement with the pseudo-first-order kinetic model and the fluidized bed reactor had a greater K value. The synthesized catalysts were biodegradable and they had an acceptable performance up to 6 cycles after each regeneration process.
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•New method for synthesis of granulated Fe3O4/Cellulose nanocomposite.•Utilizing a novel and self-created rotary autoclave for synthesis.•Conducting the Azo dye degradation process in two various reactors.•Optimizing the degradation process by RSM.•High stability of synthetic catalysts in the heterogeneous Fenton reaction.
The grape surface hosts a complex community of yeast Saccharomyces and non-Saccharomyces species responsible for spontaneous alcoholic fermentation in wine industry. The yeast strains used for this ...study were isolated from ‘Tămâioasă Românească’ and ‘Busuioacă de Bohotin’ grape varieties from Pietroasa vineyard, and the isolates were identified through a molecular method. Identification of yeast strains through the BLASTn analysis of the 5.8S-ITS region revealed that PFE5 strain showed the best sequence match to Saccharomyces cerevisiae (98% similarity) and PFE15 strain to Starmerella bacillaris (99.78% similarity), respectively. In this first micro-pilot study, the differences between Sacharomyces and non-Saccharomyces yeasts in batch (for Starmella bacillaris) and fed-batch fermentation system (for S. cerevisae) and how these regimes influence the culture growth were assessed. The applied fed-batch process was capable for producing two times more S. cerevisae yeast biomass than Starmella bacillaris through a batch process. In addition, the yield of S. cerevisiae converting the substrate into biomass was 42.3%, almost double compared to the yield of Starmella bacillaris. Moreover, the cell wet weight (WCW) for S. cerevisae was 32.5 g/L and for Starmella bacillaris 15.35 g/L, respectively. Both yeast biomass will be used at Pietroasa winery for inoculation separately or mixed as co-culture for ‘Tămâioasă Românească’ and ‘Busuioacă de Bohotin’ grape juice.
In order to make the biosorption process more suitable for industrial applications, soy waste biomass (a low-cost waste, resulted after oil extraction) was functionalized with industrial sulphur ...based chelating agent, which is a precipitation agent used in industrial wastewater treatment, and used for the removal of some heavy metals from aqueous solution. The experimental conditions for biosorbent functionalization were selected considering the efficiency of obtained biosorbent in the removal of Pb(II) ions from aqueous solution, and these were found: a mixing ratio of industrial sulphur based chelating agent solution and SWB of 0.2 mL g−1, and a temperature of 30 °C. The equilibrium and kinetics analysis of Pb(II), Cu(II) and Ni(II) biosorption on functionalized soy waste biomass (SCA-SWB) was examined in batch systems, at room temperature (20 ± 2 °C), compared with raw soy waste biomass. The biosorption capacity of SCA-SWB has increased with 196% for Pb(II) ions, 131% for Cu(II) ions and 128% for Ni(II) ions, respectively. The exhausted biosorbent can be easily regenerated with 0.1 M HNO3 solution, and the regenerated SCA-SWB biosorbent can be used in at least five biosorption/desorption cycles. The tests performed with real wastewater samples and some economic considerations indicate the potential of SCA-SWB as suitable alternative biosorbent for the removal of heavy metal ions with industrial applications.
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•Biosorption of heavy metal ions on SCA-SWB was examined in batch systems.•The functionalization was done to increase the biosorption performances of SWB.•SCA-SWB can be used in at leas five biosorption/desorption cycles.•The applicability of SCA-SWB was tested using wastewater samples.•Economical considerations indicate the low-cost of SWB functionalization.
Sewage output contains a wide range of organic materials, such as pharmaceutical compounds. These compounds have harmful effects on the environment, such as generation of antibiotic-resistant ...bacteria; therefore, their degradation has been considered as one of the environmental challenges. The purpose of this research is to synthesize graphene reinforced with nanocomposites of iron oxide/zinc oxide/tin oxide and evaluate its ability to photocatalytic degradation of azithromycin in the aqueous environment. GO@Fe3O4/ZnO/SnO2 nanocomposite was characterized by various techniques including XRD, FT-IR, TEM and VSM. In the batch system, the effect of pH, contact time, catalyst content and initial concentration of azithromycin was investigated; in this system, under optimal conditions of pH = 3, 120 min with 1 g/L of GO@Fe3O4/ZnO/SnO2, 90.06% of 30 mg/L azithromycin were degraded under UV-C irradiation. In the continuous system, the variables of bed height, flow rate and initial concentration of azithromycin have been investigated. The times to reach the column breakthrough point (Cb = 0.02C0) at heights of 6, 8 and 10 cm are 5, 8 and 14 min, respectively. By increasing the height of the bed from 6 to 10 cm, the azithromycin degradation rate increases; the reason for this increase can be due to the increase in contact time. The results indicate that the degradation of azithromycin in a constant bed column strongly depends on these parameters; actually, the time to reach the breaking point decreased with increase of flow rate and initial concentration of azithromycin while increasing with increase of bed height. Estimating the empty bed residence time showed that this model is in good agreement with laboratory data. Therefore, considering the high ability of GO@Fe3O4/ZnO/SnO2 to eliminate azithromycin, this compound can be used as an effective catalyst for the degradation of antibiotics in aquatic environments.
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•New superparamagnetic GO@Fe3O4/ZnO/SnO2 nanocomposite was synthesized and characterized.•Synthesized nanocatalyst is useful for the treatment of pharmaceutical pollution.•The kinetics of the rate of azithromycin degradation followed pseudo-first-order kinetics.•Bath and continuous system show suitable efficiency for the degradation of azithromycin.•EBRT model approvals a good agreement with laboratory data.
Multiple‐batch production is the most widely practiced method of raising channel catfish. Producers are increasingly adopting intensified production practices in multiple‐batch systems by increasing ...stocking density and aeration rates as a means to improve cost efficiencies. Proven stocking recommendations are required for the efficient implementation of recent developments in multiple‐batch production. Twelve 0.4‐ha ponds were understocked with 17,484, 20,612, and 26,124 fingerlings/ha (mean weight = 40 g/fish) over equal weights of carryover fish (0.46 kg/fish @ 4,589 kg/ha). Fish were fed once daily to apparent satiation with a 28% protein floating feed and aerated with a single 7.4‐kW electric paddlewheel aerator. Density‐dependent significant differences were absent for gross, net, daily net yields, marketable yields (≥0.54 kg), growth (g/day), and survival. Sub‐marketable yield (<0.54 kg) and feeding rate increased significantly with increased understocking density. Economic analysis revealed increased breakeven prices and diminished net returns with increased stocking density when sub‐marketable fish were not considered as revenue. These differences in production costs and profits among the three treatments became minimal when sub‐marketable fish were included as revenue. All three density treatments attained positive annual net cash flows. This study validates channel catfish understocking densities of 17,000–26,000 fish/ha to improve cost efficiency in intensively aerated, multiple‐batch production systems.
Algal biomass possesses tremendous metal binding ability and therefore has great potential for gleaning these pollutants from wastewaters. The algal cell wall and exopolymers contain diverse ...functional groups which confer negative charge to cell surface. Since metal ions in water are generally in cationic form, they are adsorbed onto the cell surface. Biosorption of metal ions from aqueous solution is influenced by various factors, such as, pH, charge density of metal ion, concentration of metal ion, concentration of interfering metal ions, nutrient availability, nature of biomass, culture age, temperature and contact time. Batch studies are very important for collecting information for subsequent application on a large scale. Continuous flow studies, like those conducted in packed bed column, seem more efficient and economically feasible than the batch operation for metal sorption. Various kinds of sorption isotherms have been used for the assessment of maximum sorption capacity. The data of metal sorption obtained from continuous system are generally expressed in the form of breakthrough curves. The shape and size of breakthrough curve is influenced by several factors, such as, metal concentration, flow rate, bed height, size of biosorbent particle, solution composition, and packing of column/density biosorbent in the column. Adam-Bohart, Thomas, mass transfer model, advection–dispersion-reaction equation and bed-depth-service-time model have been developed for elucidating breakthrough curve. However, new approaches, such as artificial neural networking and response surface methodology need adequate attention for modeling of breakthrough curves and metal sorption in multi-metal systems.
•The review focuses on metal sorption by algal biomass.•Cell wall, membranes and biomolecules are major sites of metal sorption.•Of the various factors affecting metal sorption pH is the most important.•Batch studies quickly generate information on metal sorption potential of algae.•Bed height and flow rate are crucial for biomass-packed column in continuous system.
In order to make it more suitable for biosorption process, algae waste obtained after oil extraction, have been activated by alkaline treatment and used for cadmium(II) removal in batch and column ...systems. For batch systems, the effect of initial cadmium(II) concentration and contact time was studied in optimal experimental conditions (pH of 5.0, 8 g biomass·L−1). Langmuir isotherm model and pseudo-second order kinetics model describe the experimental data well. For column studies, the alkaline treated algae waste biomass was mixed with an industrial ion exchanger resin (Purolite A-100) in order to prevent the clogging of column. Bohart-Adams, Thomas and Yoon-Nelson models were used to fit breakthrough curves obtained under varying conditions. Five biosorption/desorption cycles have yielded between 98.83 and 92.39% biosorbent regeneration. The biosorbent could efficient remove cadmium(II) from industrial wastewater, and obtained effluent has better quality characteristics. The results presented in this study indicate that the alkaline treated algae waste biomass can be successfully used for large scale treatment of wastewater.
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•Biosorption of Cd(II) onto AT-AWB was studied in batch and continuous systems.•Alkaline treatment was used to increase the biosorption capacity of AWB.•Cd(II) removal efficiency depends by several experimental parameters.•Column regeneration efficiency reached 99%, using 0.1 mol L−1 HCl solution.•The applicability of AT-AWB was tested using simulated wastewater.
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•Near nano-scale pyrite was formed by iron chloride and sodium hydrosulfide with microwave.•Fast removal kinetic and high removal capacity of pyrite.•Mercury is removed by adsorption ...and complex surface reactions.•HgS was formed on pyrite surface.
Pyrite has been demonstrated to be an excellent adsorbent for removing mercury in many studies. But most of them used natural pyrites that were grinded to micro-scale size or even larger. This study investigated methods to produce near nano-scale pyrite particles. Iron (III) chloride and sodium hydrosulfide were used as the source chemicals to synthesize pyrite. Several aging methods, including hydrothermal, ultrasonic and microwave irradiation, were studied in order to reduce the pyrite particle size. SEM/EDS and TEM/EDS analysis showed that microwave irradiation was the most effective way to produce small pyrite crystals close to the nano-scale. Results of batch kinetic experiments revealed that 0.1g/L pyrite was able to remove about 90% Hg(II) in the first 5min and all Hg(II) has been removed after 12h, although some release of mercury to the solution was observed after 5min. The release could be due to the formation of soluble Hg complexes or by other reactions that tended to increase pH. The mercury loading batch tests showed that the capacity of pyrite for adsorption of Hg(II) could reach 900μmol Hg(II)/g FeS2. The presence of salts (0.01M sodium sulfate and sodium nitrate) decreased the removal efficiency.
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