In this study, the effect of salinity on the removal of organic matter and nitrogen concentrations in bioreactor was investigated using a hybrid bench scale down-flow hanging sponge (DHS) system for ...145 days of operation. The reactor had three identical sections that were filled to 30% volume with Bio-Bact to serve as attached media. The DHS reactor was fed with domestic wastewater that was mixed with increasing concentration of sodium chloride from 0.5 to 3.0% stepwise. The influent and effluent concentrations of BOD5, CODCr, NH4+-N, and TN were analyzed to evaluate the performance of the DHS reactor during the operational period. Results indicate that when salinity was increased from 0.5 to 3.0%, the removal efficiency gradually decreased from 80.3% to 61.5% for CODCr, 76.4%–65.0% for BOD5, 64.1%–48.4% for NH4+-N, and 50%–36% for TN. Besides, the changes in biofilm characteristics with increasing salinity were observed during the operational period. The results indicate that salinity has a significant influence on the removal of organic matters and nitrogen transformation in the biofilm of the bioreactor. Even so, the DHS reactor revealed a good potential for treating saline wastewater.
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•Effect of salinity on biological treatment of domestic wastewater was investigated.•Removal of CODCr, BOD5, NH4+-N, and TN decreased with increasing salinity.•Salinity influences the removal of nitrogen more than that of organic matter.•Morphology and biomass concentrations in media change with varying salinity.•Relationship between contaminant removal efficiencies and salinities was well-established.
Activated carbon produced from agricultural products and wastes has been applied widely to remove pollutants in the field of waste water treatment. However, the cost of this adsorbent depends so much ...on the raw material sources. Therefore, the approach of producing activated carbon from agricultural waste is strongly recommended due to economic advantages and environmental protection. One of the potential feed-stocks for the activated carbon production is cashew nut shell (CNS) waste which could reduce the negative impacts to the environment from the cashew nut processing industry and simultaneously enhance the values of the related products. This study focused on evaluating the influences of variable factors, such as activation temperature and time, on the properties of the activated carbon obtained from CNS. Methylene blue (MB) adsorption was applied to understand the adsorption mechanism of the products. The results show that increasing the activation temperature led to a rise in the adsorption capacity of the activated carbon within the temperature range of 800 to 850 °C. Otherwise, the values were reduced when the temperature was greater than 850 °C and this was related to the thermal decomposition of carbon. The adsorption capacity also increased when the activation time was changed from 30 min to 50 min. However, in the activation time range from 50 to 70 min, there was a reduction of the adsorption capacity of CNS-based activated carbon. The results also show that the MB adsorption of the activated carbon occurred with one-site-occupancy in the first layer and then layer-by-layer adsorption formation.
Activated carbon produced from agricultural products and wastes has been applied widely to remove pollutants in the field of waste water treatment.
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•Chitosan/gum arabic edible coating was supplemented with antibacterial ZnO nanoparticles.•Antibacterial ZnO nanoparticles were added to chitosan/gum arabic edible coating.•Avocado ...surface with ZnO/chitosan/gum arabic edible coating was characterized.•Physicochemical properties of ZnO- coated avocados were determined.•ZnO/chitosan/gum arabic coating significantly enhanced the freshness of avocado.
Edible coatings or films are considered effective and sustainable in preventing the waste of millions of tons of fruits and vegetables resulting from decay and deterioration. In this study, we propose a new edible coating formulation to preserve avocado. The edible coating consisted of film-forming mixed polysaccharides (chitosan and gum arabic) supplemented with non-toxic zinc oxide (ZnO) nanoparticles using the mixing method. ZnO nanoparticles with diameters ranging from 10 to 40 nm were synthesized using hydrothermal method. The prepared ZnO and ZnO/chitosan/gum arabic edible coatings were characterized by scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The results showed that the edible film coated on the avocado's surface was smooth and uniform with an even distribution of ZnO nanoparticles in the film matrix. The physicochemical properties of avocados, such as appearance and brightness; weight; firmness; and reducing sugar content significantly improved after coating with the ZnO/chitosan/gum arabic edible film as compared to the uncoated samples. The best protective performance was achieved when the coating’s optimum ZnO concentration was 0.3 % w/w. While the uncoated avocados rotted after seven days of storage in room temperature, the coated avocados remained fresh under similar storage conditions.
An effective adsorbent of methylene blue was synthesized from coal fly ash (FA; waste material from a coal power plant) by a denaturing process with an alkaline solution at 90 °C. The denatured fly ...ash (D-FA) has a surface area and pore volume of 66.39 m
g
and 15.33 cm
g
, respectively, whereas the values of the original FA are negligible,
, 3.55 m
g
and 0.02 cm
g
. The removal of methylene blue (MB) in aqueous solution by D-FA was increased in the range of initial MB concentration (10-20 mg L
); contact time (0-120 min); pH (2-8); D-FA dosage (1-4 g L
). However, a larger value of those operational parameters would not improve the removal activity. Furthermore, the methylene blue adsorption on the denatured FA was fitted with the Langmuir model with
= 0.9991; the maximum adsorption capacity was determined as 28.65 mg g
from the model. Overall, the highest removal efficiency of MB using D-FA with the dosage of 4 g L
was 97.1% in 30 mg L
solution of methylene blue at pH = 7. The alkaline hydrothermal denaturation of waste FA is a promising approach to produce an adsorbent with beneficial environmental engineering applications.
Vulvovaginitis is a prevalent gynaecological ailment worldwide, often attributed to bacteria, Candida fungi, or Trichomonas. The synergistic action of antifungal agents and essential oils can enhance ...the efficacy against pathogenic microorganisms. In this study, a simultaneous quantitative method for determining clotrimazole and eugenol in a laboratory-compounded gel product was developed using high-performance liquid chromatography with a photodiode array detector (HPLC-PDA). The HPLC-PDA system utilised in this study was the Shimadzu LC-20AD, with a HiQ Sil RP C18 HS column (250 x 4.6 mm, 5 μm), and a mobile phase consisting of methanol-water in an 80:20 (v/v) ratio, employing isocratic elution at a flow rate of 1.0 ml/min. The injection volume was set at 20 μl, and detection was performed at a wavelength of 229.0 nm. The analytical procedure was validated in accordance with ASEAN guidelines for the validation of analytical procedures, successfully meeting the criteria for specificity, accuracy, system suitability, repeatability, intermediate precision, and linearity within the concentration range of 2.25 to 36.00 ppm for eugenol and 12.00 to 200.00 ppm for clotrimazole. Subsequently, this validated procedure was applied to quantify the clotrimazole and eugenol content in bulk materials and three different lots of gel products. The results for clotrimazole and eugenol content in both the raw materials and the gel product lots fell within an acceptable range, with deviations of less than ±10% compared to the labelled content.
A down-flow hanging sponge (DHS) bioreactor was operated for the treatment of domestic wastewater. The Stover-Kincannon model was applied for kinetic evaluation of the reactor performance during the ...operational period. As a result, the coefficient of determination (R2) for straight lines of effluent concentration from the experimental data and from the predictive data of BOD5; NH4+-N; and TN were 0.9727; 0.9883; and 0.9934, respectively. The calculation of saturation value constant (Umax - g L−1 d−1) and maximum utilization rate constant (KB - g L-1 d-1) were 56.818 and 75.034 for BOD5; 2.960 and 4.713 for NH4+-N; 2.810 and 8.37 for TN, respectively. The study suggests that Stover-Kincannon model can be used for effective evaluation of kinetic removal of BOD5; NH4+-N; and TN from domestic wastewater treated in a DHS bioreactor. KCI Citation Count: 0
The electro-Fenton process (EFP) has been known as an effective process with highly outstanding oxidation power. In this study, the real pharmaceutical wastewater was successfully mineralized via EFP ...by using boron-doped diamond (BDD) anode and carbon-fiber brush cathode (CFB) with Fe2+/Fe3+/Co2+ cocatalysts. The effect of various parameters, including the electrode, ratio of cocatalysts, current density, pH, and O2 flow rate, was investigated. The TOC and COD removal efficiencies of 92% and 93%, respectively, were achieved. For the increase in biodegradability, BOD5/COD ratio increased from 0.1 to 0.69 after 2 h in the presence of Fe2+/Fe3+/Co2+ cocatalysts under optimal conditions in a batch experiment (current density of 17 mA cm−2, initial pH of 3, a Fe2+/Fe3+/Co2+ ratio of 1:1:2, O2 flow rate of 0.5 L min−1). In comparison, TOC and COD removal efficiencies were reached 81% and 85% after 10 h of reaction in a continuous-flow condition, respectively. The oxidation of pharmaceutical organic pollutants was mainly found by the electrochemically produced hydroxyl (OH) and sulfate (SO4−) radicals, followed by pseudo-first-order kinetics. Hence, EFP demonstrated the feasibility of potential technology for the treatment of real pharmaceutical wastewater.
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•TOC and COD removal efficiency reached 92% and 93%, respectively.•The combination of BDD and CFB enhances mineralization and TOC removal.•Differential ratio of Fe2+/Fe3+/Co2+ almost completes mineralization.•Batch and continuous-flow systems were compared in terms of TOC and COD removal.•The mechanism of Fe2+/Fe3+/Co2+ cocatalysts in EFP was proposed.
Yen NTN, Chung DD, Hong NTK, Cham NP, Nhan VT, Linh DTL, Ngoc NLB, Thai NM, Nga ND, Anh NT. 2023. Isolation, phylogenetic analysis and bioprospection of myxobacteria from Vietnam. Biodiversitas 24: ...5653-5663. Myxobacteria have been considered microbial factories for producing secondary metabolites that have a variety of potential biological actions for discovering and isolating new biological molecules. Myxobacteria were isolated from soil samples collected in some provinces/cities in Vietnam. The purified isolates were identified based on morphology, biochemical test and phylogenetic analysis inferred from 16S rRNA gene. High-throughput screening assays including 2,2-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DDPH) for antioxidant properties and microdilution for antimicrobial activity were performed with myxobacterial extracts. Compounds from potential strain were predicted using liquid chromatography coupled with mass spectrometry. Forty-three myxobacterial strains were isolated and classified into seven genera of Angiococcus, Archangium, Chondromyces, Corallococcus, Cystobacter, Melittangium, and Myxococcus. The extract from CT21 strain had the highest total antioxidant activity (IC50 = 52.34 ± 1.47 and 30.28 ± 0.74 ?g/mL for the DPPH and ABTS, respectively). It is worth noting that all strains isolated myxobacterial strains show inhibitory activity against at least one of the tested microorganisms. The most potent antimicrobial strain was Myxococcus stipitatus GL41, which inhibited all tested microorganisms, and the minimal inhibitory concentration (MIC) values were 1 ?g/mL against methicillin-resistant Staphylococcus aureus (MRSA), methicillin-sensitive Staphylococcus aureus (MSSA), Streptococcus faecalis, Candida albicans, and Aspergillus niger. Mass spectrometry analysis revealed the presence of althiomycin - the polyketide antibiotic from ethyl acetate fraction. In the present study, myxobacteria were isolated from soil sample collected from Vietnam, analyzed phylogenetically, and screened for biological activities.
Recently, biochar has attracted tremendous research interest for environmental applications. In this study, biochar-derived watermelon rind (WM) was produced via optimal pyrolysis at 500 °C for 2 h, ...and then improved the adsorption capacity by Zirconium oxide nanoparticles (ZrO2 NPs). The WM@ZrO2 was characterized using X-ray diffraction (XRD), Scanning electron microscopic - Energy-dispersive X-ray spectroscopy (SEM-EDS), and Fourier transform infrared (FTIR). The adsorptive capacities of synthesized ZrO2 NPs were investigated for nitrate as a function of pH, adsorbent dosage, contact time, initial adsorbate concentration, and pyrolysis temperature in the batch experiment. The results showed that a Langmuir isotherm and a pseudo-second-order kinetics model were the best-fit for experimental nitrate data in its non-linear form as correlation coefficients (R2) were 0.985 and 0.998, respectively. The maximum adsorption capacity for the Langmuir isotherm model was 15.196 mg g−1. The proposed mechanism, including electrostatic attraction and ligand exchange, played a dominant role in nitrate adsorption. After testing with the real domestic wastewater, the removal of nitrate for WM@ZrO2 was achieved at 78 %, which was equivalent to the adsorption capacity of 8.1 mg g−1 of adsorbent. Overall, the WM@ZrO2 is proposed as a promising, effective, and environmentally friendly adsorbent in removing nitrate from an aqueous solution.
This study investigated a feasible model for treating actual shrimp farm wastewater at a pilot scale that could be applied to farms in the Mekong Delta area. The research was carried out using a ...hybrid constructed wetlands (HCWs) model, which included a floating constructed wetland (FCW, total area of 1,500 m2) and a horizontal sub-surface constructed wetland (HSCW, total area of 400 m2). The HCWs were cultivated with native plants including: Scirpus littoralis Schrab, Cyperus alternifolius, and Paspalum vaginatum. These plants are all adapted to the high salinity levels of shrimp farm wastewater. The system was operated for 30 days to treat shrimp farm effluent. Results indicated that the model effectively removed organic matter and nitrogen compounds from the wastewater. The treated wastewater had low concentrations of COD (10.0-15.4 mg/L), BOD5 (7.1-12.5 mg/L), NH4+-N (0.04-1.11 mg/L), and TN (0.17-1.83 mg/L), which met the reliable conditions for reuse or safety requirements for discharge to aquatic systems. The findings of this study have significant implications for the sustainable management of shrimp farm wastewater in the Mekong Delta area. The HCWs model is a feasible and effective way to treat this type of wastewater, and it could be adapted to other regions facing similar challenges.
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