Applicability of pressure retarded osmosis power generation technology in Istanbul

In this study, the applicability of pressure retarded osmosis power generation was investigated in order to meet the electricity demand in Turkey. Pressure retarded osmosis (PRO) is a method that converting salinity gradients to power using a semi-permeable membrane against an applied pressure and PRO is one of the promising candidates to reduce fossil fuel dependency. In PRO, water is transported from a low concentrated feed solution to a high-concentrated draw solution. According to the literature findings, in order to produce 1MW of electricity 1m3/s fresh water flow is needed. Turkey is surrounded on three sides by water and has a big potential to develop this technology. Riva River is investigated in the scope this study. Currently Turkey’s total installed power capacity reached 85.200 MW at the end of 2017.Calculations of PRO power generation reveals that it is possible to generate 25,45 MW, If using 5% of total river flow

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

Pilot scale nanofiltration membrane fabrication containing ionic co-monomers and halloysite nanotubes for textile dye filtration

Wastewater from the textile industry contains high concentrations of pollutants, so the wastewater must be treated before it is discharged. In addition, the reuse of treated wastewater should be considered from an environmental point of view, as large volumes of wastewater are produced. Since textile wastewater mainly contains dyestuffs, it must be treated effectively using environmentally friendly technologies. Membrane processes are widely used in textile wastewater treatment as they have distinct advantages over conventional wastewater treatment methods. This study reports the pilot-scale manufacturing and characterization of three different NF membranes. Three different types of membranes were fabricated. The fabricated membranes were compared through characterization by surface properties, chemical structure and morphology. Membranes were tested for pure water flux. Then the synthetic wastewater (SWW) was tested for flux and rejection. Lastly, the textile wastewater was tested. The textile wastewater flux of pure piperazine (PIP), 60% S-DADPS and 0.04% halloysite nanotubes (HNTs) were 22.42, 79.58 and 40.06 L m-2 h-1. It has been proven that the 60% s-DADPS membrane provides up to four times improvement in wastewater flux and simultaneously. In addition, NF membranes produced using HNT and sDADPS on a pilot scale have brought innovation to the literature with the good results obtained

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

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

<p>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 (MW_PVP = 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 MW_PVP are required to achieve optimal membrane morphology and performance.</p

Thin-film composite nanofiltration membranes with high flux and dye rejection fabricated from disulfonated diamine monomer

Novel nanofiltration (NF) membranes with improved flux, dye rejection, high pH and temperature resistance were developed using a disulfonated diamine co-monomer, disodium-3-3'-disulfone-4-4'-dichlorodiphenylsulfone (S-DADPS). Thin film composite (TFC) NF membranes were fabricated on a porous polysulfonebased ultrafiltration support layer via the interfacial polymerization between trimesoyl chloride (TMC) in the organic phase and S-DADPS/piperazine (PIP) mixture in the aqueous phase. The effect of S-DADPS content was investigated on the structure and properties of fabricated TFC-NF membranes by varying the ratio between SDADPS and PIP from 0/100 to 100/0 (w/w). The chemical structure, surface properties and the morphology of TFC-NF membranes were characterized by Fourier Transform Infrared (FT-IR) spectroscopy, Scanning Electron Microscopy (SEM), optical profilometry, contact angle, and zeta potential measurements. Salt and dye rejection behaviors of fabricated TFC-NF membranes were evaluated using 2000 ppm MgSO4 and NaCl solutions and 100 ppm Setazol Red and Reactive Orange 16 dyes, respectively. Dyes were filtrated in acidic, neutral and alkaline conditions for pH resistance tests. The temperature resistance of membranes was evaluated using pure water and dye solutions at 15 degrees C, 25 degrees C, and 40 degrees C. Among all TFC-NF membranes fabricated by varying the S-DADPS/PIP ratio, the membrane with an 80/20 ratio of S-DADPS/PIP resulted in superior properties such as increased water flux without considerable salt and dye rejection loss compared to the neat TFC-NF membrane without S-DADPS. In addition, the variation of S-DADPS/PIP ratio was demonstrated as a powerful tool to tune the balance of flux, separation and rejection performance of NF membranes for custom purification purposes

Fabrication of halloysite nanotubes embedded thin film nanocomposite membranes for dye removal

Environmental friendly Halloysite nanotubes (HNTs) are used to fabricate novel nanofiltration membranes by in situ interfacial polymerization of piperazine and trimesoyl chloride. The removal of excess amine solution from the porous support membrane surface is a critical step to obtain defect free active layer. Hereby, two main removal tools for the excess aqueous amine solution; a rubber roll or air knife are compared to fabricate a defect free thin film nanocomposite (TFN) nanofiltration (NF) membrane. Removal by the rubber roll is eventuated more favorable than air knife in terms of the reproducibility of NF membranes by comparing salt rejections. By determining the removal step of excess amines, various HNTs concentrations are used to fabricate NF membranes and, these membranes are tested with salt and dye solutions at various pH and temperature ranges. R2 membrane (containing 0.02% [w/v] HNTs) performs the best flux results beside higher rejections of MgSO4 (93.0%) and dye (99.5%). To evaluate the extreme conditionals, further performance tests such as pH and temperature resistance are also performed for R2 membrane. Considering the performances of R2 membrane, HNTs can be demonstrated for tailoring the balance between flux and separation performance of NF membranes