Current development and future prospect review of freeze desalination

Freeze desalination (FD) is an emerging technology to overcome limitations of membrane- and thermal-energy-based desalination processes. Extant studies concerning FD have primarily focused on ice-quality and productivity enhancement. Numerous crystallizer designs operating under various conditions have been investigated to achieve highest possible fresh-water purity. Few post-treatment techniques have also been developed to boost quality and productivity of fresh water. Some obstacles, have been faced in attempts to scale-up the FD process, and possible remedies to these are discussed in this paper. In addition, there exists a possibility towards combining FD with other desalination technologies, thereby developing a hybrid process. The proposed paper discusses extant research trends in FD as a comprehensive review along with discussion of future prospects concerning utility of the FD process

Investigation of NOM size, structure and functionality (SSF): impact on water treatment process with respect to disinfection by-products formation

This study was undertaken to evaluate existing conventional treatment processes, as opposed to specific membrane processes, to minimize haloacetic acid (HAA) formation, by examining in detail the characteristics of natural organic matter (NOM) size, structure and functionality. Through these evaluations, both size exclusion and charge interaction mechanisms, based on NOM size and functionality analyses, were also used to evaluate the performance of each process in conjunction with NOM structural effects. Such integrated evaluations (beyond a simple combination of the characterizations of NOM size, structure and functionality) were shown to be useful for the selection of advanced alternative membrane processes in order to maximize the removal of hydrophilic NOM fractions, which have a relatively high HAA producing potential, as conventional drinking water treatment processes examined in this study are unable to remove the hydrophilic NOM fraction effectivelyopen111

Effects of two-step cleaning sequences on foulant extraction from multibore ultrafiltration membranes in a pilot-scale membrane filtration system for surface water treatment

The cleaning efficiencies of fouled multibore ultrafiltration membrane (UFMB) operated from a pilot-scale UF process for surface water treatment were systemically investigated according to the sequences of two different cleaning solutions. The experimental results decisively confirmed that HPI DOM and HPO DOM/multivalent ions complexation significantly resulted in the fouling formations on UFMB due to their neutral charge characteristic. The basic cleaning agent effectively extracted the organic foulants attached on UFMB, indicating that the type of cleaning agent was a critical factor influencing on the cleaning efficiency of fouled UFMB. However, the cleaning sequence 1 (CS-1: 0.1 M NaOH > 0.1 M HCl; the total DOC = 725.77 mgC.m(-2); the total TN = 146.35 mgN.m(-2), total inorganic contents = 132.62 mg m-2) much more effectively extracted the foulants on the UFMB surfaces than the cleaning sequence 2 (CS-2: 0.1 M HCl > 0.1 M NaOH; the total DOC = 604.49 mgC.m(-2); the total of TN = 121.79 mgN.m(-2), total inorganic contents = 73.43 mg m-2). The morphological results also clearly showed that the cleaned UFMB surface using CS-1 were effectively recovered, as compared with those using CP-2. Overall, this study implied that the hydroxide ions from the basic cleaning agent promoted the infiltration of the acidic cleaning agent into the densely formed fouling layers on the UFMB surfaces and demonstrated that the cleaning sequences strategy could significantly govern the restoration of UFMB performance during the pilot-scale surface water treatment system operation

Biodegradability, DBP formation, and membrane fouling potential of natural organic matter: Characterization and controllability

Various natural organic matter (NOM) constituents were evaluated in terms of their biodegradability, disinfection byproduct (DBP) formation potentials,and membrane fouling. The biodegradability of NOM was evaluated with respect to biodegradable dissolved organic carbon (BDOC) and its inhibition control. NOM was divided into (i) colloidal and noncolloidal NOM, using a dialysis membrane with a molecular weight cutoff of 3500 Da and (ii) hydrophobic, transphilic, and hydrophilic NOM constituents, using XAD-8/4 resins. The colloidal, and noncolloidal hydrophilic, NOM were identified as being more problematic than the other components, exhibiting relatively higher biodegradability and reactivity toward DBP formation potential. A higher biodegradability especially can provide a high risk of membrane biofouling, if a membrane is fouled by highly biodegradable NOM. Colloidal, and noncolloidal hydrophilic, NOM constituents were also shown as major foulants of negatively charged membranes due to their high neutral fractions. Filter adsorber (F/A) types of activated carbons were evaluated in terms of removals of NOM, DBP formation potential, and BDOC and were compared to conventional processes and a nanofiltration membrane. The F/A process exhibited a comparatively good efficiency, especially in DBP and BDOC control, but was not so good at removing NOM. This suggests that F/A could potentially be combined with a membrane process to minimize the DBP formation potential and bio-/organic-fouling (i.e., F/A process as a pretreatment for a membrane process)close526

Effect of dissolved organic matter on the growth of algae, Pseudokirchneriella subcapitata, in Korean lakes: The importance of complexation reactions

The objective of this study was to investigate the effect of dissolved organic ligands, such as EDTA, humic acids, hydrophobic and hydrophilic fractions of dissolved organic matter (DOM), on the growth of Pseudokirchneriella subcapitata in cultured media and natural lake waters. The growth of algae was gradually increased on the addition of dissolved organic ligands, but markedly declined at high concentrations, due to reduced bioavailable iron concentrations (e.g., Fe3+ and Fe'-inorganic ferric iron). The results demonstrated that the high growth rates of P. subcapitata were correlated with the hydrophobic, but not hydrophilic, DOM from five lakes, spiked under the nutrients-controlled conditions. This was attributed to the role of DOM in controlling the bioavailable iron due to complexation of Fe(III) with -COOH and -OH functional groups on the hydrophobic DOM. Therefore, the hydrophobic DOM, as chelating agent, is a biologically important component in the lake waters, which affects the algal growth by interacting with bioavailable iron in the lake water and can change the results of bioassay experiments. (C) 2008 Elsevier Inc. All rights reservedclose101

Fouling behavior of marine organic matter in reverse osmosis membranes of a real-scale seawater desalination plant in South Korea

The effects of marine organic matter (MOM) characteristics on the fouling layer composition of seven parallelly arranged reverse osmosis (RO) membrane modules were identified to offer valuable insights into the fouling behavior of MOM in a real-scale seawater desalination plant in the South Korea region. Although both hydrophobic (HPO) and hydrophilic (HPI) MOM fractions governed the fouling formation of the RO membranes, HPO MOM fractions complexed with multivalent metal ions (i.e., Al, Ca, Cu, Fe, and Mg) were found to be major contributors to the irreversible fouling of the RO membranes. Despite the efficient recovery of the negative surface zeta potential after the cleaning procedures with deionized water, base and acid solutions, the contact angle of the fouled RO membrane was reduced significantly, which was more pronounced for the cleaned RO1st membranes than the cleaned RO7th membranes. HPI MOM fractions were preferentially deposited onto the membrane surfaces in the RO1st module, while residual HPO MOM fractions strongly contributed to the fouling formation of the RO membranes in the RO7th module. These phenomena might lead to significant differences in the fouling layer composition of the RO membrane modules in the real-scale seawater desalination plant in the South Korea region

Sequential effects of cleaning protocols on desorption of reverse osmosis membrane foulants: Autopsy results from a full-scale desalination plant

The sequential effects of the cleaning protocols on the desorption of the reverse osmosis (RO) membrane foulants related to the recovery of the membrane surface characteristics were examined through the autopsies of the fouled RO membrane module from the full-scale seawater desalination plant in the Gijang province (Pusan, Republic of Korea). Although the types of cleaning agents were found to be a key factor affecting the desorption of the RO membrane foulants, the sequential cleaning protocol I (SCP I; 0.1 N NaOH -> 0.1 N HCl -> deionized (DI) water) more effectively desorbed both the organic and inorganic foulants from the RO membrane surfaces compared to the sequential cleaning protocol II (SCP II: 0.1 N HCl -> 0.1 N NaOH -> DI water). Moreover, the contact angle and the negative surface zeta potential of the cleaned RO membrane with SCP I were higher than those of the cleaned RO membrane with SCP II. These results demonstrated that the strategic pairing of three different cleaning agents governed the desorption efficiencies of the organic and inorganic foulants and the restoration of the membrane surface features in association with the performances of the RO membranes (i.e., permeate flux and salt rejection)

LiberTEM/LiberTEM: 0.2.1

LiberTEM is an open source platform for high-throughput distributed processing of large-scale binary data sets using a simplified MapReduce programming model. The current focus is pixelated scanning transmission electron microscopy (STEM) and scanning electron beam diffraction data. It is designed for high throughput and scalability on PCs, single server nodes, clusters and cloud services. On clusters it can use fast distributed local storage on high-performance SSDs. That way it achieves very high aggregate IO performance on a compact and cost-efficient system built from stock components. LiberTEM is supported on Linux, Mac OS X and Windows. Other platforms that allow installation of Python 3 and the required packages will likely work as well. The GUI is running in a web browser. InstallationThe short version: $virtualenv -p python3.6 ~/libertem-venv/$ source ~/libertem-venv/bin/activate (libertem) $ pip install libertem[torch] Please see our documentation for details! Deployment as a single-node system for a local user is thoroughly tested and can be considered stable. Deployment on a cluster is experimental and still requires some additional work, see Issue #105. Applications Virtual detectors (virtual bright field, virtual HAADF, center of mass , custom shapes via masks) Analysis of amorphous materials Strain mapping Custom analysis functions (user-defined functions) Please see the applications section of our documentation for details! The Python API and user-defined functions (UDFs) can be used for more complex operations with arbitrary masks and other features like data export. There are example Jupyter notebooks available in the examples directory. If you are having trouble running the examples, please let us know, either by filing an issue or by joining our Gitter chat. LiberTEM is suitable as a high-performance processing backend for other applications, including live data streams. Contact us if you are interested! LiberTEM is evolving rapidly and prioritizes features following user demand and contributions. In the future we'd like to implement live acquisition, and more analysis methods for all applications of pixelated STEM and other large-scale detector data. If you like to influence the direction this project is taking, or if you'd like to contribute, please join our gitter chat and our general mailing list. File formatsLiberTEM currently opens most file formats used for pixelated STEM. See our general information on loading data and format-specific documentation for more information! Raw binary files Thermo Fisher EMPAD detector files Quantum Detectors MIB format Nanomegas .blo block files Gatan K2 IS raw format Gatan DM3 and DM4: See Issue #291 Please contact us if you would like to process such data! FRMS6 from PNDetector pnCCD cameras (currently alpha, gain correction still needs UI changes) FEI SER files (via openNCEM) HDF5-based formats such as Hyperspy files, NeXus and EMD Please contact us if you are interested in support for an additional format! LicenseLiberTEM is licensed under GPLv3. The I/O parts are also available under the MIT license, please see LICENSE files in the subdirectories for details