Abstract
The influence of chlorine on marine bacterial communities was examined in this study. A non-chlorine-adapted marine bacterial community (NCAM) and a chlorine-adapted bacterial community (CAM, bacterial community treated with 0.2 mg-Cl2/L chlorine) were cultivated for 1 month. A distinct difference was observed between the NCAM and CAM, which shared only eight operational taxonomic units (OTUs), corresponding to 13.1% of the total number of identified OTUs. This result suggested that chlorine was responsible for the changes in the marine bacterial communities. Kordiimonas aquimaris was found to be a chlorine-resistant marine bacterium. The effect of intermittent chlorination on the two marine biofilm communities formed on the reverse osmosis (RO) membrane surface was investigated using various chlorine concentrations (0, 0.2, 0.4, 0.6 and 0.8 mg Cl2/L). Although the average number of adherent marine bacteria on the RO membrane over a period of 7 weeks decreased with increasing chlorine concentration, disinfection efficiencies showed substantial fluctuations throughout the experiment. This is due to chlorine depletion that occurs during intermittent chlorination. These results suggest that intermittent chlorination is not an effective disinfection strategy to control biofilm formation.
Key Words
marine bacterial community; intermittent chlorination; terminal restriction fragment length polymorphism (T-RFLP); marine biofilm; qPCR; statistical analysis
Address
Dawoon Jeong: Institute of Environmental Research, Kangwon National University, 1, Gangwondaehak-gil, Chuncheon-si,
Gangwon-do 24341, Republic of Korea
Chang-Ha Lee: Department of Chemical and Biomolecular Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-Gu, Seoul 120-749, Republic of Korea
Seockheon Lee: Center for Water Resource Cycle Research, Korea Institute of Science and Technology, 39-1
Hawolgok-Dong, Seongbuk-Gu, Seoul 136-791, Republic of Korea
Hyokwan Bae: Department of Civil and Environmental Engineering, Pusan National University, 63 Busandeahak-ro,
Geumjeong-Gu, Busan 46241, Republic of Korea
Abstract
Microcystins (MCs) are toxins produced by cyanobacteria causing a major environmental threat to water resources worldwide. Although several MCs have been reported in previous studies, microcystin-LR (m-LR) has been extensively studied as it is highly toxic. Among the several techniques employed for the removal of this toxin, adsorption with AC has been extensively studied. AC has gained wide attention as an effective adsorbent of m-LR due to its ubiquity, high sorption capacity, cost effectiveness and renewability. In this review, the adsorption of m-LR onto AC was evaluated using the information available in existing scientific literature. The effects of the pore volume and surface chemistry of AC on the adsorption of m-LR considering the structural and chemical properties of ACs were also discussed. Furthermore, we identified the parameters that influence adsorption, including natural organic matter (NOM), pH, and ionic strength during the m-LR adsorption process. The effect of these parameters on MCs adsorption onto AC from previous studied is compiled and highlighted. This review may provide new insights into future activated carbon-m-LR adsorption research, and broaden its application prospects.
Key Words
algal bloom; adsorption; activated carbon; cyanobacteria; microcystins
Address
Department of Environmental Engineering, Kumoh National Institute of Technology,
61 Daehak–ro, Gumi 39177, Republic of Korea
Abstract
Poly Sulfone nanofibers were electrospun to fabricate membranes of different characteristics. To fabricate the fiber mats, polymer concentration, flowrate, and current density were determined as the most influencing factors affecting the overall performance of the membranes and studied through Response Surface Methodology. The Box-Behnken Design method (three factors at three levels) was used to design, analyze, and optimize the parameters to achieve the best possible performance of the electrospun membranes in forward osmosis process. Also, internal concentration polarization that characterizes the efficiency of the forward osmosis membranes was determined to better assess the overall performance of the fabricated electrospun membranes. Water flux to reverse salt flux was considered as the main response to assess the performance of the membranes. As confirmed experimentally, best membrane performance with the minimal structural parameter value could be achieved when predicted optimal values were used to fabricate the membranes through electrospinning process.
Key Words
forward osmosis; electrospinning; optimization; structural parameter; design of experiment; response surface methodology
Address
Leila Ghadiri and Alireza Shakeri:School of Chemistry, College of Science, University of Tehran, P.O. Box 14155-6619, Tehran, Iran
Ali Bozorg: Department of Biotechnology, College of Science, University of Tehran, P.O Box: 14176-14411 Tehran, Iran
Abstract
A novel composite membrane was synthesized using crosslinked polyamide and fly ash ceramic substrate for phenol removal. Glutaraldehyde was used as crosslinker. Characterization shows that synthesized membrane possesses good permeability (0.184 l.m-2.h-1.kPa-1), MWCO (1.7 kDa), average pore size (1.08 nm) and good chemical stability. RSM was adopted for phenol removal studies. Box-Behnken-Design using quadratic model was chosen for three operating parameters (feed phenol concentration, pH and applied pressure) against two responses (phenol removal, flux). ANOVA shows that model is statistically valid with high coefficient of determination (R2) value for flux (0.9897) and phenol removal (0.9302). The optimum conditions are obtained as pH 2, 46 mg.l-1 (feed phenol concentration) and 483 kPa (applied pressure) with 92.3% phenol removal and 9.2 l.m-2.h-1 flux. Data validation with deviation of 4% confirms the suitability of model. Obtained results reveal that prepared composite membrane can efficiently separate phenol from aqueous solution.
Abstract
In this study, cellulose acetate (CA) / nylon66 (NYL66) (95/5) blend membranes with different thicknesses were prepared by a solvent evaporation method. The effects of membrane thickness (almost 7-25 micrometre), feed concentration (70- 95 wt.% isopropanol), and feed temperature (30-60 C) were investigated on the performance of membrane in the separation of isopropanol-water mixtures. With regard to the results of sorption experiments, it was found that the increase of feed temperature enhanced the overall sorption while by increasing feed concentration, the overall sorption passed through a maximum value at 70 wt. % isopropanol (IPA) . The best separation factor 3080.51 was gained at high isopropanol concentration 95 wt.%, low feed temperature 30 C, and high membrane thickness 24.62 micrometre. Regarding the pervaporation separation index, the obtained results showed that proper values for the thickness of membrane, feed temperature, and isopropanol concentration in feed were 24.62 micrometre, 40 C, and 70 wt.%, respectively.
Key Words
cellulose acetate/ nylon 66; pervaporation; dehydration; isopropanol-water mixture
Address
Akram Kazemzadeh, Jamshid Mehrzad,
Alireza Motavalizadehkakhky and Malihesadat Hosseiny: Department of Chemistry, Neyshabur Branch, Islamic Azad University, 9319797139 Neyshabur, Iran
Seyed M. Mousavi: Chemical Engineering Department, Faculty of Engineering, Ferdowsi University of Mashhad, 9177948974 Mashhad, Iran
Abstract
Thin film composite membranes incorporated with nano-sized hydrophilic zeolite -A were successfully prepared via interfacial polymerization (IP) on porous blend PES/PAN support for water desalination. The thin film nanocomposite membranes were characterized by SEM, contact angle and performance test with 7000 ppm NaCl solution at 7bar. The results showed that the optimum zeolite loading amount was determined to be 0.1wt% with permeate flux 29LMH.NaCl rejection was improved from 69% to 92% compared to the pristine polyamide membrane where the modified PA surface was more selective than that of the pristine PA. In addition, there was no significant change in the permeate flux of the thin film nanocomposite membrane compared with that of the pristine PA in spite of the formation of the dense polyamide layer. The stability of the polyamide layer was investigated for 15 days and the optimized membrane presented the highest durability and stability.
Key Words
salting water; permeability; TFNCM; zeolite –A; interfacial polymerization
Address
Eman S. Mansor, Tarek S. Jamil and Ahmed M. Shaban: Water pollution Research Department, Environmental Research Division, National Research Centre, 12622, Egypt
Heba Abdallah: Chemical Engineering and Pilot Plant Department, Engineering Research Division, National Research Centre, 12622, Egypt
H.F. Youssef: Refractories, ceramics and building material department, National Research Centre,33 El-Bohouth St., Dokki, Giza, Egypt
Eglal R. Souaya: Chemistry Department, Faculty of Science, Ain Shams University, Cairo, Egypt
Abstract
In the present work, we present a new effective hydrophilicity modifier for polysulfone (PSf) membrane. Firstly, amphiphilic nanocellulose (ANC) with different substitution degrees (SD) was synthesized by esterification reaction with nanocellulose (NC) and dodecyl succinic anhydride (DDSA). The SD and morphology of ANC were characterized by titration method and transmission electron microscopy (TEM). Then, the polysulfone (PSf)/ANC blend membranes were prepared via an immersion phase inversion method. The influence of SD on the morphology, structure and performances of PSf/ANC blend membrane were carefully investigated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), mechanical property test, contact angle measuring instrument and filtration experiment. The results showed that the mechanical property, hydrophilicity and anti-fouling property of all the PSf/ANC blend membranes were higher than those of pure PSf membrane and PSf/NC membrane, and the membrane properties were increased with the increasing of SD values. As ANC-4 has the highest SD value, PSf/ANC-4 membrane exhibited the optimal membrane properties. In conclusion, the prepared ANC can be used as an additive to improve the hydrophilicity and anti-fouling properties of polysulfone (PSf) membrane.
Address
Xue Yang: School of Fashion Technology, Shanghai University of Engineering Science, Shanghai 201620, China
Lifang Liu and Shuai Jiang: College of Textiles, Donghua University, Shanghai 201620, China
Abstract
The complex combination of organic contaminants in the wastewater made water treatment challenging; hence, organic matter in water bodies is usually measured in terms of organic carbon. Since it is important to identify the types of compounds when deciding suitable treatment methods, this study implemented a quantitative and qualitative analysis of the organic matter content in an actual graywater sample from Ulsan, Republic of Korea using mass spectroscopy (MS). The graywater was treated using adsorption to remove the organic contaminants. Using orbitrap MS, the organic matter content between an untreated graywater and the treated effluent were compared which yielded a significant formula count difference for the samples. It was revealed that CHON formula has the highest removal count. Isotherm studies found that the Freundlich equation was the best fit with a coefficient of determination (R2) of 0.9705 indicating a heterogenous GAC surface with a multilayer characteristic. Kinetics experiments fit the pseudo-second order equation with an R2 of 0.9998 implying that chemisorption is the rate-determining step between the organic compounds and GAC at rate constant of 52.53 g/mg•h. At low temperatures, the reaction between GAC and organic compounds were found to be spontaneous and exothermic. The conditions for optimization were set to achieve a maximum DOC and TN removal which yielded removal percentages of 94.59% and 80.75% for the DOC and TN, respectively. The optimum parameter values are the following: pH 6.3, 2.46 g of GAC for every 30 mL of graywater sample, 23.39 hrs contact time and 38.6 Celcius degree.
Key Words
GAC adsorption; organic matter contaminant; Orbitrap MS analysis
Address
Mayzonee Ligaray, Minjeong Kim, Jaegyu Shim, and Kyung Hwa Cho: School of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology,
50 UNIST-gil, Ulsan 44919, Republic of Korea
Jongkwan Park : School of Civil, Environmental and Chemical Engineering, Changwon National University,
Changwon, Gyeongsangnamdo, 51140, Korea
