Drinking water treatment *
Jamie Bartram, Rachel Baum, Peter A. Coclanis, David M. Gute, David Kay, Stéphanie McFadyen, Katherine Pond, William Robertson, Michael J. Rouse in Routledge Handbook of Water and Health, 2015
A more advanced method of filtration is provided by one of the different membrane technologies. Membranes come in a variety of types described on the basis of the pore size. Pore size is the spaces in the material which sieve out the particles or substances of concern and so membrane filtration does rely on size exclusion rather than physico-chemical forces to achieve separation of the solid and liquid phases. There are various degrees of size exclusion of particle removal which range from microfiltration (nominal pore sizes in the range 10 microns to 0.03 microns) through ultrafiltration (nominal pore sizes between 0.1 and 0.002 microns) to nanofiltration (nominal pore size 0.001 microns) and reverse osmosis which is capable of removing nearly all inorganic (and organic) contaminants from water. Generally, the water must be further treated to add minerals and to ensure that the water is adequately buffered after reverse osmosis treatment.
Biologic Drug Substance and Drug Product Manufacture
Anthony J. Hickey, Sandro R.P. da Rocha in Pharmaceutical Inhalation Aerosol Technology, 2019
In this step, the cell culture harvest, consisting of target protein in the dissolved state and suspended solids such as cells and cell debris, is subjected to sedimentation, centrifugation, deep bed or depth filtration, and one or more steps of microfiltration. Sedimentation and centrifugation: Gravitational and centrifugal rotational settling of particulate matter allows initial separation of most of the particles from the fluid for initial clarification.Depth filtration or deep bed filtration consists of a porous filtration medium that retains particles throughout the medium, rather than just on the surface. This process is particularly suitable for fluids with high particle load since the filter can retain a large mass of particles before getting clogged. Depth filters provide high surface area and adsorptive surface. In addition to adsorbing impurities from cell culture supernatants, depth filters can also remove viruses (Yigzaw et al. 2006).Microfiltration involves passing the fluid through a specific pore size membrane to effect removal of microorganisms and suspended particles. Suspended particles are retained (“retentate”) on the feed side of the membrane, while the dissolved liquids, including the protein of interest, passes through (“permeate”). A cross-flow filtration process, where the fluid is moved in a direction tangential to the membrane surface, is preferred compared to the dead-end filtration (where the fluid is forced through the membrane surface at a dead end to the direction of flow).
The Study of the Effect of UV-C Radiation on the Current–Voltage Characteristics of Chitosan Membranes
Pandit B. Vidyasagar, Sagar S. Jagtap, Omprakash Yemul in Radiation in Medicine and Biology, 2017
The numerous membranes have been developed for use in reverse osmosis, nanofiltration, ultrafiltration, microfiltration, pervaporation separation, and electrodialysis and in medical use such as artificial kidney [6]. Among these membranes, ion-exchange membranes are one of the advanced separation membranes. It has been used not only as electrodialysis concentration or desalting of solutions, diffusion dialysis to recover acids and electrolysis of sodium chloride solution but also in various fields as a polymeric film having ionic groups [7].
On-line biofilm strength detection in cross-flow membrane filtration systems
Published in Biofouling, 2018
Stanislaus Raditya Suwarno, Wenhai Huang, Y. M. John Chew, Sio Hoong Henrich Tan, Augustinus Elmer Trisno, Yan Zhou
Both the cohesive and adhesive strengths obtained from biofilms in the present study are considerably higher than those from other FDG studies (Möhle et al. 2007; Lewis et al. 2012). Möhle et al. (2007) used FDG to investigate the activated sludge forming biofilm grown on a rotating disc biofilm reactor (rotation speed of <9 min−1 for seven days) and found the cohesive strength of the biofilm was only 6–7 N m−2. Lewis et al. (2012) applied a cross-flow system and formed biofilm by an yeast suspension. Their experiment was conducted for 30 min with a duct flow rate of 0.9 l min−1 under a constant TMP of 3.5 kPa. The highest strength of biofilm was ~55 N m−2. In the present study, the operating conditions applied were harsher and simulated the actual conditions of microfiltration for water treatment. Moreover biofilms formed by Pseudomonas aeruginosa tend to have higher strength as evidenced by other ex situ methods (6,000–15,000 N m−2) (Korstgens et al. 2001; Poppele and Hozalski 2003).
The Rhei radix rhizoma-based carbon dots ameliorates dextran sodium sulphate-induced ulcerative colitis in mice
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2023
Yifan Zhang, Jie Zhao, Yusheng Zhao, Xue Bai, Yumin Chen, Yuhan Liu, Yue Zhang, Hui Kong, Huihua Qu, Yan Zhao
The RRR-CDs were prepared in the muffle furnace (TL0612 muffle furnace; Beijing Zhong Ke Aobo Technology Co., Ltd; Beijing, China) by one-step pyrolysis. First, the RRR samples were placed in separate crucibles and covered with aluminium foil paper with sealed lids. Then, the RRR was carbonised in a preheated muffle furnace at 350 °C for 1h. After cooling to room temperature, the RRR-carbon was ground to a fine powder and boiled twice in a water bath at 100 °C for 1h each time. Thereafter, the decoction solution was filtered (0.22 μm microfiltration membrane), concentrated, and dialysed (1000 Daltons molecular weight cut-off dialysis membrane). The obtained RRR-CDs were stored at 4 °C until further use. The preparation flow chart of RRR-CDs is shown in Figure 1.
Production of CAR T-cells by GMP-grade lentiviral vectors: latest advances and future prospects
Published in Critical Reviews in Clinical Laboratory Sciences, 2019
Mansour Poorebrahim, Solmaz Sadeghi, Elham Fakhr, Mohammad Foad Abazari, Vahdat Poortahmasebi, Asma Kheirollahi, Hassan Askari, Alireza Rajabzadeh, Malihe Rastegarpanah, Aija Linē, Angel Cid-Arregui
Low-speed centrifugation and microfiltration are used in both lab-scale and large-scale capturing processes [92]. Despite the higher efficiency of microfiltration, clogging of the pores with cell debris over time is a critical barrier that results in virus entrapment and, consequently, limited LV recovery [93]. Therefore, most published studies have focused on the use of depth filtration, which has been shown to minimize filter clogging and loss of vector particles during the clarification step [84,94]. The filtration process takes place through a series of membranes of decreasing pore size, typically 0.8 and 0.45 µm. This method has been commonly employed for clarification of several enveloped (e.g. LVs) and non-enveloped (e.g. adenoviral vectors) virus-like particles and viruses with recoveries exceeding 90% [81,95]. The high efficiency of depth-filtration is accomplished by depth-dependent size separation and the charged nature of state-of-the-art depth-filter membranes and their three-dimensional configurations [96]. In addition, much attention has been drawn to the flow rate (mL/min) and shear force (s−1) of the filtration process. For instance, previous studies demonstrated that a higher flow rate (e.g. 100 mL/min compared to 50 mL/min) resulted in a higher LV recovery [94]. However, the flow rate of microfiltration needs to be optimized based on the filter type. The shear force of 5000 s−1 and flux of 10 LMH (L/m2/h) have been established as optimum parameters for the microfiltration step [97]. The higher shear forces may affect the structural integrity of the LV envelope and consequently, reduce LV recovery.
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