115 research outputs found
Production of Hydrogen and Volatile Fatty Acid by Enterobacter sp T4384 Using Organic Waste Materials
No full textIn a study of hydrogen-producing bacteria, strain T4384 was isolated from rice field samples in the Republic of Korea. The isolate was identified as Enterobacter sp. T4384 by phylogenetic analysis of 16S rRNA and rpoB gene sequences. Enterobacter sp. T4384 grew at a temperature range of 10-45 degrees C and at an initial pH range of 4.5-9.5. Strain T4384 produced hydrogen at 0-6% NaCl by using glucose, fructose, and mannose. In serum bottle cultures using a complete medium, Enterobacter sp. T4384 produced 1,098 ml/l H-2, 4.0 g/l ethanol, and 1.0 g/l acetic acid. In a pH-regulated jar fermenter culture with the biogas removed, 2,202 ml/l H-2, 6.2 g/l ethanol, and 1.0 g/l acetic acid were produced, and the lag-phase time was 4.8 h. Strain T4384 metabolized the hydrolysate of organic waste for the production of hydrogen and volatile fatty acid. The strain T4384 produced 947 ml/l H-2, 3.2 g/l ethanol, and 0.2 g/l acetic acid from 6% (w/v) food waste hydrolysate; 738 ml/l H-2, 4.2 g/l ethanol, and 0.8 g/l acetic acid from Miscanthus sinensis hydrolysate; and 805 ml/l 112, 5.0 g/l ethanol, and 0.7 g/l acetic acid from Sorghum bicolor hydrolysate.This work was supported by a grant from the R&D Program of MKE/KEIT (10037331, Development of Core Water Treatment Technologies based on the Intelligent BT-NT-IT Fusion Platform). This work was also the outcome of a Manpower Development Program for Energy supported by the Ministry of Knowledge and Economy (MIKE). Prof. Hyunook Kim was partially supported by the 2011 sabbatical year research grant of the University of Seoul
Electrophoresis Characterization of Nanoplastic Particle Surface Charge in Dilute Aqueous Electrolytes
No full textThis is the accepted version of the following article: Lin, Jui-Yen, Ingyu Lee, Cuijuan Feng, Hyunook Kim, and Chin-Pao Huang. “Electrophoresis Characterization of Nanoplastic Particle Surface Charge in Dilute Aqueous Electrolytes.” Environmental Engineering Science, July 8, 2024. https://doi.org/10.1089/ees.2024.0076, which has now been formally published in final form at Environmental Engineering Science at https://doi.org/10.1089/ees.2024.0076. This original submission version of the article may be used for non-commercial purposes in accordance with the Mary Ann Liebert, Inc., publishers’ self-archiving terms and conditions. © 2024, Mary Ann Liebert, Inc., publishers.Aggregation, adsorption, and biofilm formation are involved in the fate and transport of nanoplastics in the aquatic environment. These interfacial processes are closely related to surface charge and electrical double layer (EDL) structure. As it is experimentally difficult to obtain surface potential, laser doppler electrophoresis is currently the most popular technique to measure zeta potential, or the potential at shear plane. However, the determination of zeta potential by laser doppler electrophoresis is not a trivial undertaking. Inaccurate zeta potential values could potentially lead to misleading conclusions. This study aims to present a comprehensive method tailored for nanoplastics to accurately measure zeta potential and convert it to surface charge and potential with classical EDL theory. The effect of particle size and number concentration on zeta potential measurement was investigated using monodisperse polystyrene (PS) latex. An optimal number concentration was between 1010 and 1012 #/L to generate sufficient scattered light with minimal interparticle interaction. Six nanoplastics were synthesized from major polymers to acquire the zeta potential at various pH, including low-density polyethylene, high-density polyethylene, polypropylene, PS, polyvinyl chloride, and polyethylene terephthalate. Based on classical EDL theory, the zeta potential measured at various ionic strength was converted to surface potential, revealing that the shear plane was 0.4 to 2.1 nm away from the surface. Finally, the surface charge density of nanoplastics was acquired, which is essential to describe interfacial processes of nanoplastics in the environment.This work is supported by the National Research Foundation of Korea in a grant funded by the Korea government (MSIT) (No. 2020R1A2C2101347) and the Graduate Program for Plastic-free Society funded by Korea Environmental Industry and Technology Institute. Additional support was provided by the Ministry of Science and Technology, Taiwan, to Jui-Yen Lin, under contract No. MOST-110–2917-I-564-033
pH and Oxidation–Reduction Potential Control Strategy for Optimization of Nitrogen Removal in an Alternating Aerobic–Anoxic System
No full textRemoval of selected pharmaceuticals spiked in the secondary effluent of a wastewater treatment plant (WWTP) by potassium ferrate(VI)
No full textThis study investigated the ferrate(VI) performance in the removal of pharmaceuticals spiked in the secondary effluent taken from a wastewater treatment plant (WWTP). In the raw secondary effluent samples, seven of 12 target pharmaceuticals were detected with a maximum concentration of 500.0 ± 28.3 ng/L for ibuprofen. 70% of carbamazepine could be reduced in the raw effluent samples by ferrate(VI) when the dose exceeded 4 mg/L. In the modified effluent samples spiked with detected target pharmaceuticals, approximately 40% of naproxen was removed, whereas other target compounds were removed less than 30%. Raising the ferrate(VI) dose improved the removal of pharmaceuticals to some extent, while acidic conditions were more preferable for drugs’ reduction. The study demonstrated that ferrate(VI) can efficiently remove pharmaceuticals containing electron-rich moieties (ERMs), and the coagulation of iron(III) colloids resulted from the reduction of Fe(VI) also influenced the treatment performance
Ferrate(VI): novel compound for removal of natural organic matter in water
No full textThis chapter presents examples of the effectiveness of the novel ferrate treatment technology in the removal of dissolved organic matter from contaminated water
Development of Software Sensors for Determining Total Phosphorus and Total Nitrogen in Waters
No full textTotal nitrogen (TN) and total phosphorus (TP) concentrations are important parameters to assess the quality of water bodies and are used as criteria to regulate the water quality of the effluent from a wastewater treatment plant (WWTP) in Korea. Therefore, continuous monitoring of TN and TP using in situ instruments is conducted nationwide in Korea. However, most in situ instruments in the market are expensive and require a time-consuming sample pretreatment step, which hinders the widespread use of in situ TN and TP monitoring. In this study, therefore, software sensors based on multiple-regression with a few easily in situ measurable water quality parameters were applied to estimate the TN and TP concentrations in a stream, a lake, combined sewer overflows (CSOs), and WWTP effluent. In general, the developed software sensors predicted TN and TP concentrations of the WWTP effluent and CSOs reasonably well. However, they showed relatively lower predictability for TN and TP concentrations of stream and lake waters, possibly because the water quality of stream and lake waters is more variable than that of WWTP effluent or CSOs
Determination of NH4+ in Environmental Water with Interfering Substances Using the Modified Nessler Method
No full textNitrogen is an essential element in the environment. If excess nitrogen including NH4 + is present in water, however, it can result in algae blooming and eventually the destruction of the aquatic ecosystem. Therefore, the determination of NH4 + in streams, lakes, and effluents of the treatment facilities has long been carried out. The Nessler method is the most common spectrophotometric method to measure NH4 + in water. However, the result of the method becomes inaccurate if there are interfering substances such as Cl2, Cl−, hardness-causing compounds (e.g., Mg2+), and Fe2+ in target water samples. In this study, therefore, the traditional Nessler method has been modified to eliminate the effects of interfering substances; the so-called MS was added to water samples. In addition, the polyvinyl alcohol reagent as a dispersing agent was added to water samples to increase the sensitivity and reproducibility of the method. The modified method could successfully analyze NH4 + of water samples even with the interfering substance at high concentration
Understanding the molecular mechanisms of odorant binding and activation of the human OR52 family
No full textAbstractStructural and mechanistic studies on human odorant receptors (ORs), key in olfactory signaling, are challenging because of their low surface expression in heterologous cells. The recent structure of OR51E2 bound to propionate provided molecular insight into odorant recognition, but the lack of an inactive OR structure limited understanding of the activation mechanism of ORs upon odorant binding. Here, we determined the cryo-electron microscopy structures of consensus OR52 (OR52cs), a representative of the OR52 family, in the ligand-free (apo) and octanoate-bound states. The apo structure of OR52cs reveals a large opening between transmembrane helices (TMs) 5 and 6. A comparison between the apo and active structures of OR52cs demonstrates the inward and outward movements of the extracellular and intracellular segments of TM6, respectively. These results, combined with molecular dynamics simulations and signaling assays, shed light on the molecular mechanisms of odorant binding and activation of the OR52 family.</jats:p
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