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CONTENTS
Volume 12, Number 5, September 2021
 


Abstract
Natural disasters such as earthquakes can cause damage to water distribution pipe, resulting in water interruption. For a contingency plan for earthquakes, calculating the possibility of failure and the consequence of failure are necessary. The empirical formula for the vulnerability of water distribution pipe after earthquake was developed considering deterioration effect with aging in this study. The degree of water outage was assumed to be a consequence of failure. The earthquake risk with pipe aging was obtained through the product of them. Although the risk alone might be used to prioritize pipe network improvement, it was recommended to consider the construction cost as well. It was also proposed to use a score-based method by graphically tabulating construction cost and risk. The methodology proposed was demonstrated on a real-scale water distribution pipe in Korea. The improved prioritization using the scoring method will help create a future earthquake preparedness plan for a water distribution system.

Key Words
fragility curve; pipe renewal prioritization; repair rate; seismic risk; water distribution pipe; water outage risk

Address
Hyeyeon Youn and Dooil Kim: Department of Civil and Environmental Engineering, Dankook University, 152, Jukjeon-ro, Suji-gu, Yongin-si, Gyeonggi-do, 16890, Republic of Korea

Hyun Je Oh: 2Department of Land, Water and Environment Research, KICT,
283, Goyang-daero, Ilsanseo-gu, Goyang-si, Gyeonggi-do, 10223, Republic of Korea



Abstract
In this work, the performance of a mixed matrix membrane in the removal of crystal violet from aqueous solutions is reported. This membrane was fabricated by adding a nanocomposite (fMWNTs/GO/MnO2 NC) synthesized with functionalized multi-walled carbon nanotubes, graphene oxide, and manganese dioxide nanoparticles, to polysulfone. Details pertaining to the preparation and characterization of the membrane, evaluation of its performance in the removal of crystal violet, and antifouling properties of the membrane are reported in this paper. The membranes were fabricated by embedding varying concentrations of fMWNTs/GO/MnO2 NC (from 0 to 0.3wt%) in the Psf matrix. Incorporation of fMWNTs/GO/ MnO2 NC was found to enhance hydrophilicity, equilibrium water content, porosity, mean pore radius, pure water permeability and antifouling properties of the membrane. Analyses of surface morphology of the fabricated membranes revealed the presence of macro-voids in the matrix of the membrane after addition of fMWNTs/GO/MnO2 NC, resulting in an increase in pure water flux and permeability. It was observed that 0.1wt% is the optimum concentration of fMWNTs/GO/ MnO2 NC in the Psf matrix since the membrane exhibited maximum hydrophilicity, equilibrium water content, porosity, pure water permeability and dye rejection at this concentration. Also, it was observed that the polysulfone membrane exhibited enhanced antifouling properties at this concentration of the nanocomposite.

Key Words
antifouling; crystal violet; membrane filtration; nanocomposite

Address
Sabna V, Santosh G Thampi and S Chandrakaran: Department of Civil Engineering, National Institute of Technology Calicut, Kozhikode, Kerala, India-673 601

Sasina E P and Resmi P: Department of Environmental Science, University of Calicut, Kerala, India-673 635

Abstract
Pore blocking is considered to dominate the hydraulic conductivity in solute transport processes. Biomass accumulation is effective in reducing the hydraulic conductivity of porous medium. In this paper, the sphere model and the cut-and-random-rejoin-type model were adopted to establish mathematical equations for hydraulic characteristics of porous media caused by biological clogging. A new mathematical correlation was proposed to address the coupling effect of hydraulic, biofilm growth fields on the basis of thorough review on Kozeny-Carman equation relevant researches. The time-dependent solution were investigated with the consideration of a series of different model factors. The study found that there are similar phenomena both in the sphere model and in the cut-and-random-rejoin-type model. When the pores of the porous media are filled with biofilms, the pore volume is continuously reduced, and the porosity of the porous media continues to decrease. Macroscopically, it is manifested as a decrease in permeability. The model image analysis shows that growth of biofilm in a porous medium reduces the total volume and the average size of the pores and directly affects the permeability of pores. But this effect is not permanent, the pores will not be completely blocked, and the permeability will not drop to zero.

Key Words
biofilm growth; microbial clogging; relative hydraulic conductivity; relative permeability

Address
Shenjie Shi: School of Rail Transportation, Soochow University, Yangchenghu Campus, Xiangcheng District, Suzhou, 215131, China

Yu Zhang and Qiang Tang: School of Rail Transportation, Soochow University, Yangchenghu Campus, Xiangcheng District, Suzhou, 215131, China/ Graduate School of Global Environmental Studies, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan

Jialin Mo: Graduate School of Global Environmental Studies, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan/ National Institute for Environmental Studies, Fukushima Branch, Fukushima 963-7700, Japan



Abstract
In this research, we study recent advances in the use of graphene, graphene oxide, and boron nitride nanosheets for the water treatment processes. The perfect nanostructured membranes are impermeable to ions or molecules. Therefore, for using them in the selective separation processes, they should be drilled and so, the created pores will be functionalized using appropriate chemical functional groups. Up to now, numerous research articles have been done on the use of functionalized chemical groups on the nanostructured membranes but the results of those works have not been compared with each other. Therefore, a comprehensive review of the structural property and application of functional groups at the edge of membranes pores was performed. To the best of our knowledge, no review study has been reported in the literature on the effect of functionalized groups on the separation of molecules or ions by nanostructured membranes. This review paper aims to draw the attention of the theoretical as well as the experimental researchers working on the functionalized materials towards the recent developments probing the permeation of various species such as atoms, ions, and small molecules through graphene, graphene oxide, and boron nitride nanosheets.

Key Words
boron nitride, graphene, graphene oxide, membrane, water treatment

Address
Jafar Azamat: Department of Basic Sciences, Farhangian University, Tehran, Iran

Abstract
Bentonites contain a large amount of montmorillonite and this nano-structured and nano-porous member of the smectite group determines the adsorption properties of bentonites. In this study, four types of Iranian commercial bentonite clays have been examined to determine the adsorption capacity of cesium and strontium. The physicochemical and mineralogical properties of the four types have been experimentally analyzed with the focus on the moisture content, pH, dry (granulometric) and wet screen analyses; swell, sediment and Methylene Blue (M.B.) indices; cation exchange capacity (C.E.C) measurements. The pH and C.E.C values of B3 were 9.48 and 71.9 mEq/100g, respectively. The high values of C.E.C; swell, sediment and M.B. indices along with the high amount of granulometric values (particles finer than 36 um) showed that the B3 had a high amount of montmorillonite. X-Ray Fluorescence (XRF) analysis showed that the major of competing cations such as Ca2+ and K+ existing in B2 affects the Sr adsorption. The experimental analysis also showed that B2 had almost high pH and C.E.C values as well. The results of the separation process of Cs and Sr indicate that the B3 and B2 have the highest adsorption capacity of 59.75 and 45.5 for Cs and Sr adsorption, respectively.

Key Words
adsorption; metal removal; montmorillonite; nano-structured bentonite

Address
Mohammad-Ali Ostovaritalaba and Majid Hayati-Ashtiani: Department of Chemical Engineering, Faculty of Engineering, University of Kashan, Iran

Abstract
Controlling non-point source pollutants (NPSPs) is critical in achieving good surface water quality; the contribution of road runoff has recently received increased attention. This study monitored the runoff characteristics of NPSPs, including suspended solids, particle size distribution, heavy metals, organic matter, and nutrients, from asphalt and concrete roads. Water quality parameters, including biochemical oxygen demand (BOD), chemical oxygen demand (COD), and nutrients of the receiving reservoir, were also investigated. During the first flush, the changes in pollutant concentrations over time were higher on concrete roads than asphalt roads. Concentrations peaked over a short period, while an increased pollutant concentration may be present several days after rain. The runoff concentration and particle size distribution were higher on concrete roads, whereas the concentrations of heavy metals were similar in asphalt and concrete roads. The organic matter concentration of asphalt roads was higher, or identical, to that in the first flush from concrete roads; this may be associated with the road location. Water quality analysis of the reservoir showed relatively good results for BOD, COD, and nutrient concentrations. Road construction was a factor that determined the characteristics of NPSPs in road runoff.

Key Words
asphalt; concrete; non-point source pollutant; road runoff

Address
Seongbeom Kim, Muhammad Yaqub, Jaehyun Lee, Wontae Lee: Department of Environmental Engineering, Kumoh National Institute of Technology, 61 Daehak–ro, Gumi 39177, Republic of Korea


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