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CONTENTS
Volume 9, Number 4, July 2018
 

Abstract
In this study, we investigated coagulants such as polyaluminum chloride (PACl) and ferric chloride (FeCl3) and the combination of a coagulant and powdered activated carbon (PAC) for the removal of dissolved organic matter (DOM) from fish processing effluent to reduce membrane fouling in microfiltration. The efficiency of each pretreatment was investigated through analyses of dissolved organic carbon (DOC) and ultraviolet absorbance at 254 nm (UVA254). Membrane flux and silt density index (SDI) analyses were performed to evaluate membrane fouling; molecular weight distributions (MWD) and fluorescence excitation-emission matrix (FEEM) spectroscopy were analyzed to assess DOM characteristics. The results demonstrated that FeCl3 exhibited higher DOC and UVA254 removals than PACl for food processing effluent and a combination of FeCl3 and PAC provided comparatively better results than simple FeCl3 coagulation for the removal of DOM from fish processing effluent. This study suggests that membrane fouling could be minimized by proper pretreatment of food processing effluent using a combination of coagulation (FeCl3) and adsorption (PAC). Analyses of MWD and FEEM revealed that the combination of FeCl3 and PAC was more efficient at removing hydrophobic and small-sized DOM.

Key Words
adsorption; coagulation; food processing wastewater; microfiltration; organic matter

Address
Haenam Jang:Department of Energy Engineering, Gyeongnam National University of Science and Technology,
Jinju, Gyeongnam 52725, Republic of Korea
Wontae Lee: Department of Environmental Engineering, Kumoh National Institute of Technology, Gumi, Gyeongbuk 39177, Republic of Korea

Abstract
Incorporating nano-materials in thin-film composite (TFC) membranes has been considered to be an approach to achieve higher membrane performance in various water treatment processes. This study investigated the rejection efficiency of three target compounds, i.e., reserpine, norfloxacin and tetracycline hydrochloride, by TFC membranes with different graphene oxide proportions. Graphene oxide (GO) was incorporated into the polyamide active layer of a TFC membrane via an interfacial polymerization (IP) reaction. The TFC membranes were characterized with FTIR, FE-SEM, AFM; in addition, the water contact angle measurements as well as the permeation and separation performance were evaluated. The prepared GO-TFC membranes exhibited a much higher flux (3.11+-0.04 L/m2 h bar) than the pristine TFC membranes (2.12+-0.05L/m2 h bar) without sacrificing their foulant rejection abilities. At the same time, the GO-modified membrane appeared to be less sensitive to pH changes than the pure TFC membrane. A significant improvement in the anti-fouling property of the membrane was observed, which was ascribed to the favorable change in the membrane\'s hydrophilicity, surface morphology and surface charge through the addition of an appropriate amount of GO. This study predominantly improved the understanding of the different PA/GO membranes and outlined improved industrial applications of such membranes in the future.

Key Words
graphene oxide; polyamide membrane; thin-film composite; interfacial polymerization; PPCPs

Address
1. State Key laboratory of Pollution Control and Resources Reuse, Tongji University, Shanghai, 200092, China
2. Key laboratory of Yangtze River Water Environment, Ministry of education, Tongji University, Shanghai, 200092, China


Abstract
A new procedure to produce poly(vinylidene fluoride)/boron nitride hybrid membrane is presented for application in membrane distillation (MD) process. The influence of hexagonal boron nitride (h-BN) incorporation on the performance of the polymeric membranes is studied through the present investigation. For this aim, h-BN nanopowders were successfully synthesized using the simple chemical vapor deposition (CVD) route and subsequent solvent treatments. The resulting h-BN nanosheets were blended with poly(vinylidene fluoride) (PVDF) solution. Then, the prepared composite solution was subjected to phase inversion process to obtain PVDF/h-BN hybrid membranes. Various examinations such as scanning electron microscopy (SEM), wettability, permeation flux, mechanical strength and liquid entry pressure (LEP) measurements are performed to evaluate the prepared membrane. Moreover, Air gap membrane distillation (AGMD) experiments were carried out to investigate the salt rejection performance and the durability of membranes. The results show that our hybrid PVDF/h-BN membrane presents higher water permeation flux (~18 kg/m2 h) compared to pristine PVDF membrane. In addition, the experimental data confirms that the prepared nanocomposite membrane is hydrophobic (water contact angle: ~103 degree),has a porous skin layer (>85%), as well competitive fouling resistance and operational durability. Furthermore, the total salt rejection efficiency was obtained for PVDF/h-BN membrane. The results prove that the novel PVDF/h-BN membrane can be easily synthesized and applied in MD process for salt rejection purposes.

Key Words
membrane distillation; polymers; salt rejection; water treatment; flux

Address
Rasoul Moradi,Nazila Pourkhalili,Masoud Mehrizadeh and Hassan Niknafs:Department of Chemical Engineering, School of Engineering and Applied Science, Khazar University, Azerbaijan
Rasoul Moradi, Mojtaba Shariaty-Niassar:Transport Phenomena & Nanotechnology Laboratory, School of Chemical Engineering, College of Engineering, University of Tehran, Iran

Abstract
In this manuscript, 35 m3/d NF unit was designed and applied for surface water treatment of the River Nile water. Intake of Embaba drinking water treatment plant was selected to install that unit at since; it has the lowest water quality index value through the examined 6 sites in greater Cairo area. The optimized operating conditions were feed and permeate flow, 40 and 7 m3/d, feed pressure 2.68 bar and flux rate 37.7 l/m2h. The permeate water was drinkable according to Egyptian Ministerial decree 458/2007 for the tested parameters (physic-chemical, heavy metals, organic, algal, bacteriological and parasitological). Single and double sand filters were used as pretreatment for NF membranes but continuous clogging for sand filters moved us to use UF membrane as pretreatment for NF membrane.

Key Words
River Nile; NF membrane; pretreatment; water; treatment

Address
Water Pollution Control Department, National Research Center, 33 El-Behouth St., Cairo, Egypt, 12622

Abstract
The aim of this study is to investigate the membrane fouling in a thermophilic membrane bioreactor (TMBR) operated different sludge retention times (SRTs). For this purpose, TMBR was operated at four different SRTs (10, 30, 60 and 100 days). Specific cake resistance, cake resistance, gel resistance, total resistance, MFI (modified fouling index) and FDR (flux decrease ratio) were calculated for all SRTs. It was observed that flux in the membrane increases with rising SRT although the sludge concentrations in the TMBR increased. The steady state flux was found to be 31.78; 34.70; 39.60 and 43.70 LMH (Liter/m2/h) for the SRTs of 10, 30, 60 and 100 days respectively. The concentrations of extracellular polymeric substance (EPS) and soluble microbial product (SMP) decreased with increasing SRT. The membrane fouling rate was higher at shorter SRT and the highest fouling rate appeared at an SRT of 10 d. Both the sludge cake layer and gel layer had contribution to the fouling resistance, but the gel layer resistance value was dominant in all SRTs.

Key Words
EPS; flux; fouling; MBR; resistance; SMP; SRT; thermophilic

Address
Mahir İnce: Gebze Technical University, Department of Environmental Engineering, Kocaeli, Turkey
Alikemal Topaloğlu: Bulent Ecevit University, Department of Environmental Engineering, Zonguldak, Turkey

Abstract
This study attempted to evaluate the process of self-forming dynamic membrane formation on mesh filter in membrane bioreactor with a two-stage method of batch (agitation) and continues (aeration) stage at different sludge concentrations. Four concentrations of activated sludge including 6+-0.4, 8+-0.5, 10+-0.3, 14+-0.3 g/L were used to demonstrate the optimal concentration of sludge for treating municipal wastewater and reducing fouling in dynamic membrane bioreactor. The formation time and effluent turbidity were decreased in the batch stage when increasing the activated sludge concentration. The minimum values of formation time and effluent turbidity were 14 min and 43 NTU for the optimum mixed liqueur suspended solids of 8+-0.5 g/L, respectively. To improve operational condition and fouling reduction in the aeration stage, critical fluxes were measured for all concentrations by flux-step method. With increasing the sludge concentration, the relevant critical fluxes reduced. The optimum subcritical flux of 30 L/m2/h was applied as operating flux in the second stage. The maximum COD removal efficiency of 98% was achieved by the concentration of 8+-0.5 g/L. Compressibility index of self-forming dynamic membrane and transmembrane pressure trend remained somewhat constant until the optimal concentration of 8+-0.5 g/L and thereafter they increased steeply.

Key Words
mesh filter; self-forming dynamic membrane; membrane bioreactor; critical flux; wastewater treatment; different sludge concentrations

Address
Department of Chemical Engineering, Biotechnology Group, College of Engineering, University of Tehran, P.O.Box 11155-4563, Tehran, Iran

Abstract
The objective of this work was to analyze organic matter removal, nitrification, biomass growth and membrane fouling in a submerged flat-sheet membrane bioreactor, fed with synthetic wastewater, of similar composition to the effluents generated in a fish meal industry. After biomass acclimatization with saline conditions of 12 gNaCl/L and COD/N ratio of 15 in the bioreactor, results showed that the organic matter removal was higher than 90%, for all organic loading rates (0.8, 1, 1.33 and 2 gCOD/L∙d) and nitrogen loading rates (0.053, 0.067, 0.089 and 0.133 gN/L∙d) tested during the study. However, nitrification was only carried out with the lowest OLR (0.8 gCOD/L∙d) and NLR (0.053 gN/L∙d). An excessive concentration of organic matter in the wastewater appears as a limiting factor to this process\'operating conditions, where nitrification values of 65% were reached, including nitrogen assimilation to produce biomass. The analysis of membrane fouling showed that the bio-cake formation at the membrane surface is the most impacting mechanism responsible of this phenomenon and it was demonstrated that organic and nitrogen loading rates variations affected membrane fouling rate.

Key Words
membrane bioreactor; nitrification; aerobic biodegradation; saline wastewater; fouling

Address
Guadalupe López, Francisco J. Almendariz: Department of Chemical Engineering and Metallurgy, Universidad de Sonora, Blvd. Luis Encinas, Col. Centro, 83000 Hermosillo, Sonora, México
Marc Heran, Geoffroy Lesage: IEM, Univ Montpellier, CNRS, ENSCM, Place Eugène Bataillon, 34095 Montpellier cedex 5, France
Sergio Pérez:Environmental Engineering Technology, Universidad Politécnica de Chiapas,
Eduardo J. Selvas s/n y Avenida Manuel de J. Cancino. Col. Magisterial, 29082. Tuxtla Gutiérrez, Chiapas, México


Abstract
Due to the lack of water in arid and semi-arid areas, reuse of wastewater can be a suitable way to compensate for water scarcity. Therefore, in this research, evaluation of the quality of wastewater of Kashan Treatment Plant to use for irrigation was studied. This descriptive cross-sectional study was conducted in 2016. pH, TSS, TDS, turbidity, COD, BOD5, Total Kjeldahl Nitrogen, Total Phosphorus, Total Coliform, fecal coliform, nematode eggs of inlet and outlet of wastewater treatment plant in Kashan were studied. Mean and standard deviation and wastewater quality parameters before and after treatment were tested with SPSS 22 (2014) software. The mean wastewater output of COD, BOD5, TSS, TDS and turbidity were respectively 86.6, 41.2, 11.11, 1095 mgL-1 and 17.5 NTU and the pH was equal to 7.22. Also, the average of Total Kjeldahl Nitrogen and phosphorus were 22.4 and 2.2 mgL-1 respectively. The mean of Total Coliform and fecal coliform were 225, 161 MPN / 100 ml respectively. In addition, no nematode eggs were found in final effluent. The results indicated that the treatment plants had a significant role in the control of microbial and organic pollution load of wastewater. Also, it is concluded that all parameters were in accordance with the standards of Iran\'s Department of Environment, so, it can be used for unrestricted irrigation.

Key Words
sewage; treatment; reuse; agriculture

Address
Rouhullah Dehghani, Mohammad Bagher Miranzadeh:Social Determinants of Health (SDH) Research Center and Department of Environmental Health Engineering,
Faculty of Health, Kashan University of Medical Sciences, Kashan, Iran
Ashraf Mazaheri Tehrani: Department of Environmental Health Engineering, School of Public Health, Hamadan University of Medical Sciences, Hamadan, Iran
Hossein Akbari, Leila Iranshahi and Abbas Zeraatkar: Department of Biostatistics and Public Health, Faculty of Health, Kashan University of Medical Sciences, Kashan, Iran

Abstract
Membrane biofouling is a critical operational problem that hinders the rapid commercialization of MBRs. Quorum quenching (QQ) has been investigated widely to control membrane biofouling and is accepted as a promising anti-fouling strategy. Various QQ strategies based on bacterial and enzymatic agents have been identified and applied successfully. Whereas, this study aimed to compare indigenously isolated QQ strain i.e., Enterobacter cloaca with well reported Rhodococcus sp. BH4. Both bacterial species were immobilized in polymeric beads and introduced to two different MBRs keeping the overall beads to volume ratio as 1%. Efficiencies of these strains were monitored in terms of prolonging the membrane filtration cycle of MBR, release of extra-cellular polymeric substances, membrane resistivity measurements and mineralization of signal molecules and permeate quality. Indigenous strain (Enterobacter cloaca) was added to QQ-MBRE while Rhodococcus sp. BH4 was introduced to QQ-MBRR. QQ bacterial embedded beads showed enhanced filtration cycles up to 1.4 and 2.3 times for QQ-MBRE and QQ-MBRR respectively as compared to control MBR (C-MBR). Soluble EPS concentration of 52 mg/L was observed in C-MBR while significantly lower EPS concentration of 20 and 10 mg/L was witnessed in QQ-MBRE and QQ-MBRR, respectively. Therefore, substantial reduction in biofouling showed the effectiveness of indigenous strain.

Key Words
membrane bioreactor; biofouling control; quorum quenching; filtration cycle

Address
Saimar Pervez, Sher Jamal Khan, Hira Waheed, Imran Hashmi: Institute of Environmental Sciences and Engineering, School of Civil and Environmental Engineering,
National University of Sciences and Technology, H-12 Sector, Islamabad, Pakistan
Chung-Hak Lee: School of Chemical and Biological Engineering, Seoul National University, Seoul, Korea

Abstract
In the following study, Artificial Neural Network (ANN) is used for prediction of permeate flux decline during oily wastewater treatment by hybrid powdered activated carbon-microfiltration (PAC-MF) process using mullite and mullite-alumina ceramic membranes. Permeate flux is predicted as a function of time and PAC concentration. To optimize the networks performance, different transfer functions and different initial weights and biases have been tested. Totally, more than 850,000 different networks are tested for both membranes. The results showed that 10:6 and 9:20 neural networks work best for mullite and mullite-alumina ceramic membranes in PAC-MF process, respectively. These networks provide low mean squared error and high linearity between target and predicted data (high R2 value). Finally, the results present that ANN provide best results (R2 value equal to 0.99999) for prediction of permeation flux decline during oily wastewater treatment in PAC-MF process by ceramic membranes.

Key Words
artificial neural network; ceramic membranes; oily wastewater treatment; microfiltration; powdered activated carbon

Address
Department of Chemical Engineering, School of Chemical and Petroleum Engineering, Persian Gulf University, Bushehr,75169, Iran


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