Derya Y. Koseoglu-Imer

Enzymatic activation of cellulose acetate membrane for reducing of protein fouling

In this study, the surface of cellulose acetate (CA) ultrafiltration membrane was activated with serine protease (Savinase) enzyme to reduce protein fouling. Enzyme molecules were covalently immobilized with glutaraldehyde (cross-linking agent) onto the surface of CA membranes. The membrane activation was verified using filtration experiments and morphological analysis. Scanning electron microscopy (SEM) images and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy of the activated membrane when compared with raw membrane were confirmed that the enzyme was immobilized onto the membrane surface. The immobilization efficiencies changed from 13.2 to 41.2% according to the enzyme ratios from 2.5 to 10.0 mg/mL. However, the permeability values decreased from 232±6 to 121±4 L/m(2) h bar with increasing enzyme concentration from 2.5 to 10.0 mg/mL. In fouling experiments, bovine serum albumin (BSA) was used as the protein model solution and activated sludge was used as the model biological sludge. Enzyme-activated membranes exhibited good filtration performances and protein rejection efficiencies were compared with raw CA membrane. Also the relative flux reduction (RFR) ratios of membranes were calculated as 97% and 88% for raw CA and enzyme-activated membranes (5 mg/mL savinase), respectively. The membrane activated with Savinase enzyme could be proposed as a surface treatment method before filtration to mitigate protein fouling.

Techno-economic investigation of water recovery and whey powder production from whey using UF/RO and FO/RO integrated membrane systems

AbstractAs a by-product of dairy industry with high pollutant capacity, uncontrolled discharges of cheese whey result in serious pollution problems in the environment. Besides, recovery of water and whey powder in a whey stream has come to the fore as an important one of whey control strategies in environmental pollution. In that sense, the feasibility of water recovery and whey powder production from whey using integrated membrane processes was techno-economically investigated in this study. The study was focused on three case studies including different process scenarios were executed with laboratory-scale experiments in order to determine the technical performances of processes. The process scenarios were selected as following: the ultrafiltration/reverse osmosis (UF/RO), the forward osmosis/reverse osmosis (FO/RO) with NaCl draw solution and forward osmosis/reverse osmosis including thermolysis (FO/T/RO) at 60°C for concentrating NH4HCO3 draw solution. The real-scale costs for the processes were estim...

Effect of sludge retention time on membrane bio-fouling using different type and pore size of membranes in a submerged membrane bioreactor

The objective of this study was to investigate the influence of sludge retention time (SRT) on membrane bio-fouling. An activated sludge reactor was operated at three different SRTs (10, 30, and 50 days). Submerged membrane experiments were performed when the mixed liquor suspended solids (MLSS) concentration reached the steady state conditions. MLSS concentrations reached the steady state at 3,109 ± 194, 6,209 ± 123 and 6,609 ± 280 mg/L for SRTs of 10, 30 and 50 days, respectively. The total soluble microbial products (SMP) were 20.1 ± 3.7, 16.2 ± 7.2 and 28.2 ± 8.4 mg/L at SRTs of 10, 30, and 50 days, respectively. The carbohydrate concentration in the supernatant was about two times more for SRT of 10 days than that for 50 days. The total amount of extracellular polymeric substances (EPS) extracted from the flocs were approximately 74.9 ± 11.9, 67.8 ± 15.0 and 67.5 ± 17.4 mg/g MLSS at three SRTs (10, 30, and 50 days) under the same organic loading rate. The viscosity of the biomass increased with the increasing SRT. The results of flux stepping tests showed that the membrane fouling at SRT 10 days was always higher than that of 30 and 50 days. Four different microfiltration membranes (cellulose acetate, polyethersulfone, mixed ester, and polycarbonate) with three different pore sizes (0.45, 0.22, 0.10 μm) were tested. Filtration resistances were determined for each membrane. Cake resistance was observed to be the most significant fouling mechanism for all membranes.

Influence of membrane fouling reducers (MFRs) on filterability of disperse mixed liquor of jet loop bioreactors.

The effects of membrane fouling reducers (MFRs) (the cationic polyelectrolyte (CPE) and FeCI(3)) on membrane fouling were studied in a lab-scale jet loop submerged membrane bioreactor (JL-SMBR) system. The optimum dosages of MFRs (CPE dosage=20 mg g(-1)MLSS, FeCI(3) dosage=14 mg g(-1)MLSS) were continuously fed to JL-SMBR system. The soluble and bound EPS concentrations as well as MLSS concentration in the mixed liquor of JL-SMBR were not changed substantially by the addition of MFRs. However, significant differences were observed in particle size and relative hydrophobicity. Filtration tests were performed by using different membrane types (polycarbonate (PC) and nitrocellulose mixed ester (ME)) and various pore sizes (0.45-0.22-0.1 μm). The steady state fluxes (J(ss)) of membranes increased at all membranes after MFRs addition to JL-SMBR. The filtration results showed that MFRs addition was an effective approach in terms of improvement in filtration performance for both membrane types.

Immobilization of Acidithiobacillus ferrooxidans on sulfonated microporous poly(styrene-divinylbenzene) copolymer with granulated activated carbon and its use in bio-oxidation of ferrous iron.

The immobilization efficiencies of Acidithiobacillus ferrooxidans cells on different immobilization matrices were investigated for biooxidation of ferrous iron (Fe(2+)) to ferric iron (Fe(3+)). Six different matrices were used such as the polyurethane foam (PUF), granular activated carbon (GAC), raw poly(styrene-divinylbenzene) copolymer (rawSDVB), raw poly(styrene-divinylbenzene) copolymer with granular activated carbon (rawSDVB-GAC), sulfonated poly(styrene-divinylbenzene) copolymer (sulfSDVB) and sulfonated poly(styrene-divinylbenzene) copolymer with granular activated carbon (sulfSDVB-GAC). The sulfSDVB-GAC polymer showed the best performance for Fe(2+) biooxidation. It was used at packed-bed bioreactor and the kinetic parameters were obtained. The highest Fe(2+) biooxidation rate (R) was found to be 4.02 g/L h at the true dilution rate (Dt) of 2.47 1/h and hydraulic retention time (τ) of 0.4 h. The sulfSDVB-GAC polymer was used for the first time as immobilization material for A. ferrooxidans for Fe(2+) biooxidation.

Effect of polymer type on characterization and filtration performances of multi-walled carbon nanotubes (MWCNT)-COOH-based polymeric mixed matrix membranes

ABSTRACT Multi-walled carbon nanotubes (MWCNTs) can be used for the fabrication of mixed matrix polymeric membranes that can enhance filtration perfomances of the membranes by modifying membrane surface properties. In this study, detailed characterization and filtration performances of MWCNTs functionalized with COOH group, blended into polymeric flat-sheet membranes were investigated using different polymer types. Morphological characterization was carried out using atomic force microscopy, scanning electron microscopy and contact angle measurements. For filtration performance tests, protein, dextran, E. coli suspension, Xanthan Gum and real activated sludge solutions were used. Experimental data and analyses revealed that Polyethersulfone (PES) + MWCNT-COOH mixed matrix membranes have superior performance abilities compared to other tested membranes.

Recent developments of electromembrane desalination processes

ABSTRACT Electromembrane processes use the electric potential difference as the driving force to move charged ions through ion-selective membranes. These membranes have negative or positive charged functional groups and can be named as cation- and anion-exchange membranes (CEM and AEM) depending on the sign of the permeating ions. As the electrical force is applied, the membranes allow the permeation of oppositely signed ions and separate the ionic species from an aqueous solution and from other uncharged species. Electromembrane processes are well-established techniques and have gained importance in many areas such as desalination processes, energy production, food processing, molecular separation, water treatment and recovery and membrane concentrate treatment. The desalination with electromembrane process is widely used today for the production of high-quality water from seawater or brackish water. The main electromembrane desalination processes are categorized as electrodialysis (ED), electrodeionization (EDI), capacitive deionization (CDI), reverse electrodialysis (EDR), electrodialysis with bipolar membranes (EDBM). In this review article, the most popular electromembrane desalination processes have been evaluated with their theoretical basis and technological background. The main objectives of the review are (1) to describe the technological background of electromembrane processes (2) to summarize past and present attempts towards scaling up and commercialization of electromembrane desalination process (3) to present a critical review of their advantages and limitations (4) to outline the R&D activities with cost analysis. GRAPHICAL ABSTRACT