Turker Turken

Biomimetic Approaches for Membrane Technologies

Membrane technology is the dominant process in water treatment. However, the operation cost of membranes cannot be decreased unless the amount of fouling, the “Achilles heel” of membranes, and energy consumed are cut. The high energy requirements in commercial nanofiltration, reverse osmosis and forward osmosis technologies lead researchers to develop new membrane designs having high flux values with high salt rejection values. The purpose of this review is to present the inadequacies of the membrane processes by considering studies related to fouling and energy minimization. In this respect, lipid bilayers, block copolymers, aquaporin Z proteins and aligned carbon nanotubes can be the base to build biomimetic membranes. Such studies are summarized due to their remarkable properties in fouling control. Furthermore, the review describes the membrane design strategies and points the limitations hindering commercialization. Additionally, it is hoped that this review will trigger further needed studies.

CFD modeling of submerged membrane bioreactors (sMBRs): a review

AbstractMembrane bioreactor (MBR) systems are an established technology for the domestic and industrial wastewater treatment, but efficient fouling reduction by air sparging remains an operating problem and design rules still are of a purely empirical nature. Therefore, many modeling approaches have been proposed to solve these operating problems and increase the process efficiency. Several experimental and computational studies have been done to access more efficient separation in different membrane application. Recently, computational fluid dynamics (CFD) has been widely used for hydrodynamic simulation of fluid on the membrane surface and pores, modeling mass transfer rate and further predicting the fouling layer. It provides a method for finding the most effective design features at fundamental level. Especially CFD has been preferred to simulate the fouling problem in MBR systems because these systems have highly energy dependent technologies due to air sparging to control fouling. However, designing...

Manufacturing of antibiofouling polymeric membranes with bismuth-BAL chelate (BisBAL)

AbstractRecent developments indicate an increase in demand of water supply and protection of natural water source quality with a requirement of advanced wastewater treatment systems. Formation of biofilms on the membrane surfaces and in the pores of membranes which are caused by extracellular polymeric substances and soluble microbial products has been identified as the main source of biofouling in membrane operation. The secretion of total polysaccharides and proteins by micro-organisms can be lowered when they are exposed to the bismuth-BAL chelate (BisBAL) at near minimum inhibition concentration. Our study aimed at controlling the population and co-products of micro-organisms that cause biofouling. After successful studies with the inhibition of Escherichia coli and Streptococcus pyogenes in activated sludge, BisBAL-containing membranes were fabricated. The effect of BisBAL on membrane performance was also observed. FTIR, SEM, contact angle, and surface roughness analyses were performed for the charac...

Advances in water treatment by microfiltration, ultrafiltration, and nanofiltration

In this chapter, advances in water treatment by microfiltration, ultrafiltration (UF), and nanofiltration (NF) are explained in detail. General information about membrane processes and the membrane global market is given. In addition, pretreatment methods are compared. Novel membrane materials are explained and compared with conventional membrane materials. Novel membrane module configurations explained in detail. Microfiltration, UF, and NF membrane applications for water treatment are given in the last part of the chapter.

Combined effects of hollow fiber fabrication conditions and casting mixture composition on the properties of polysulfone ultrafiltration membranes

ABSTRACT This study is focused on identifying the combined effects of fabrication conditions and casting mixture composition on the properties of hollow fiber (HF) membranes. Three variables evaluated are air gap (0 and 2.5 cm); coagulation bath temperature (25°C; 35°C; 45°C) and molecular weight of polyvinylpyrrolidone (MWPVP = 10; 40; 65; 360; 1000 kDa). Prepared HF membranes were characterized in terms of specific permeate flux; surface morphology, charge and hydrophilicity; bovine serum albumin (BSA) rejection, Young modulus, and resistance to fouling by BSA. We illustrate that both higher and higher MWPVP are required to achieve optimal membrane morphology and performance.

Hollow fiber nanofiltration membranes: A comparative review of interfacial polymerization and phase inversion fabrication methods

ABSTRACT Membrane-based separation is now established as one of staple technologies used in water treatment and reuse applications. Nanofiltration, in particular, can be a cost-effective solution for removing large ions and low-molecular-weight compounds from water. Nanofiltration membranes have been manufactured mostly as flat sheets and used in spiral wound modules. Hollow fiber geometry, however, offers several advantages over flat sheet and other configurations. This paper overviews recent developments in the design of hollow fiber nanofiltration membranes and provides a comparative analysis of two main methods of their fabrication: interfacial polymerization and phase inversion.

Improvement of anti-biofouling properties of hollow fiber membranes with bismuth-BAL chelates (BisBAL)

ABSTRACT In this study, hollow fiber membranes with and without bismuth dimercaptopropanol (Bis-BAL) additive were fabricated. Membranes were characterized in terms of permeability, surface properties, anti-biofouling and antibacterial properties. Membranes were operated in a lab-scale submerged membrane bioreactor (MBR). During the MBR operation, flux, chemical oxygen demand, volatile suspended solids and suspended solids were calculated for 30 days. Results showed that extracellular polymeric substance and soluble microbial product amounts were decreased in BisBAL-containing membranes. BisBAL-added membranes had the ability to inhibit the growth of Escherichia coli. BisBAL as an additive for membranes was found to be an effective, cheap alternative for enhancing anti-biofouling properties of the membranes.

An Autopsy of Nanofiltration Membrane Used for Landfill Leachate Treatment

Komurcuoda leachate treatment plant, Istanbul, which consists of membrane bioreactor (MBR) and nanofiltration (NF) system, faced rapid flux decline in membranes after 3-year successful operation. To compensate rapid flux decline in membranes, the fouled membranes were renewed but replacement of the membranes did not solve the problem. To find the reasons and make a comprehensive analysis, membrane autopsy was performed. Visual and physical inspection of the modules and some instrumental analysis were conducted for membrane autopsy. Membranes were found severely fouled with organic and inorganic foulants. Main foulant was iron which was deposited on surface. The main reason was found to be the changing of aerator type of MBR. When surface aerators were exchanged with bottom diffusers which led to increasing of dissolved oxygen (DO) level of the basin, iron particles were oxidized and they converted into particulate insoluble form. It was thought that probably this insoluble form of the iron particles was the main cause of decreased membrane performance. After the diagnosis, a new pretreatment alternative including a new iron antiscalant was suggested and system performance has been recovered.

Long-term MBR performance of polymeric membrane modified with Bismuth-BAL chelate (BisBAL)

ABSTRACT An ultrafiltration membrane prepared by polyethersulfone (PES) was modified with Bismuth-BAL chelate (BisBAL) and was used in submerged membrane bioreactor system. Moreover, a control membrane reactor was also tasked to evaluate the effect of BisBAL on the membrane performance. The flux profile, transmembrane pressure, the effect of chemical treatment, cake layer formation, anti-fouling properties against extracellular polymeric substances (EPS) and soluble microbial products (SMP) were studied. The UF modified membrane demonstrated a sustained permeability, low cleaning frequency, and longer filtration time. In terms of anti-EPS and SMP accumulation, the modified membrane showed a lower membrane resistance. It can be illustrated from scanning electron microscopy and confocal laser scanning microscope images that the modified membrane had presented better properties than bare PES membrane, as it was looser and thinner. Thus, the UF membrane proved to be more efficient in terms of permeability and lifetime.