scholarly journals Stimulatory effects on bacteria induced by chemical cleaning cause severe biofouling of membranes

2020 ◽  
Vol 10 (1) ◽  
pp. 82-94
Author(s):  
Xueye Wang ◽  
Jinxing Ma ◽  
Zhichao Wu ◽  
Zhiwei Wang
Keyword(s):  
Membrane Surface ◽  
Oxygen Species ◽  
Cleaning Efficiency ◽  
Chemical Cleaning ◽  
Physiological Mechanisms ◽  
Homoserine Lactones ◽  
Membrane Surfaces ◽  
Enhanced Production ◽  
Membrane Biofouling ◽  
Microbial Regrowth

Abstract Chemical cleaning with hypochlorite is routinely used in membrane-based processes. However, a high-transient cleaning efficiency does not guarantee a low biofouling rate when filtration is restarted, with the physiological mechanisms largely remaining unknown. Herein, we investigated the microbial regrowth and surface colonization on membrane surfaces after NaOCl cleaning had been completed. Results of this study showed that the regrowth of model bacteria, Pseudomonas aeruginosa, was initially subject to inhibition due to the damage of key enzymes' activity and the accumulation of intracellular reactive oxygen species although the oxidative stress induced by NaOCl had been removed. However, with the resuscitation ongoing, the stimulatory effects became obvious, which was associated with the enhanced production of N-acyl homoserine lactones and the secretion of eDNA that ultimately led to more severe biofouling on the membrane surface. This study elucidates the inhibition–stimulation mechanisms involved in biofilm reformation (membrane biofouling) after membrane chemical cleaning, which is of particular significance to the improvement of cleaning efficiency and application of membrane technologies.

scholarly journals Application of cell entrapping beads for Quorum Quenching technique in submerged membrane bioreactor

2020 ◽  
Vol 81 (4) ◽  
pp. 744-752
Author(s):  
S. Ahmed ◽  
S. Chung ◽  
N. Sohail ◽  
I. A. Qazi ◽  
A. Justin
Keyword(s):  
Sodium Alginate ◽  
Biofilm Formation ◽  
Membrane Bioreactor ◽  
Membrane Surface ◽  
Quorum Quenching ◽  
Chemical Cleaning ◽  
Submerged Membrane Bioreactor ◽  
Membrane Biofouling ◽  
Market Disruption ◽  
Physical And Chemical

Abstract Biofouling is unwanted accumulation of microbial population on the membrane surface which limits the use of membrane bioreactor (MBR) in the market. Disruption of the biofilm formation by Quorum Quenching (QQ) by using cell entrapping beads (CEBs) is an approach with great potential to control membrane biofouling as the beads used provide not only mitigating effect on biofilm formation, by interfering Quorum Sensing, but also physical forces to detach the biofilm from the membrane surface. This research aimed to develop QQ-CEB with locally available chemicals in Pakistan and its application to evaluate the QQ effect together with physical and chemical cleaning. Various CEBs were made of different mixtures of sodium alginate and polyvinyl alcohol (PVA) and their quality was tested considering physical and biological aspects. Rhodococcus sp. BH4 and Pseudomonas putida were entrapped in the CEBs and then introduced in MBR as one of biofouling control methods along with standard backwash and chemical backwash. The CEBs made of specific concentration of PVA were proven to be more durable and helpful in mitigating biofouling as compared to that of sodium alginate. An MBR operated with PVA-alginate QQ CEBs together with chemical backwash showed the best performance without deterioration of effluent quality.

Low-pressure membrane filtration with unconventional coagulation regimes

2005 ◽  
Vol 5 (5) ◽  
pp. 1-8 ◽  
Author(s):  
K.Y. Choi ◽  
B.A. Dempsey
Keyword(s):  
Activated Carbon ◽  
Membrane Filtration ◽  
Membrane Surface ◽  
Cross Flow ◽  
Chemical Cleaning ◽  
Sand Filters ◽  
Charge Neutralization ◽  
Floc Size ◽  
Filtration System ◽  
Pre Treatment

The objective of the research was to evaluate in-line coagulation to improve performance during ultrafiltration (UF). In-line coagulation means use of coagulants without removal of coagulated solids prior to UF. Performance was evaluated by removal of contaminants (water quality) and by resistance to filtration and recovery of flux after hydraulic or chemical cleaning (water production). We hypothesized that coagulation conditions inappropriate for conventional treatment, in particular under-dosing conditions that produce particles that neither settle nor are removed in rapid sand filters, would be effective for in-line coagulation prior to UF. A variety of pre-treatment processes for UF have been investigated including coagulation, powdered activated carbon (PAC) or granular activated carbon (GAC), adsorption on iron oxides or other pre-formed settleable solid phases, or ozonation. Coagulation pre-treatment is often used for removal of fouling substances prior to NF or RO. It has been reported that effective conventional coagulation conditions produced larger particles and this reduced fouling during membrane filtration by reducing adsorption in membrane pores, increasing cake porosity, and increasing transport of foulants away from the membrane surface. However, aggregates produced under sweep floc conditions were more compressible than for charge neutralization conditions, resulting in compaction when the membrane filtration system was pressurized. It was known that the coagulated suspension under either charge-neutralization or sweep floc condition showed similar steady-state flux under the cross-flow microfiltration mode. Another report on the concept of critical floc size suggested that flocs need to reach a certain critical size before MF, otherwise membranes can be irreversibly clogged by the coagulant solids. The authors were motivated to study the effect of various coagulation conditions on the performance of a membrane filtration system.

scholarly journals Down-regulation of NF-κB signalling by polyphenolic compounds prevents endotoxin-induced liver injury in a rat model

2011 ◽  
Vol 18 (1) ◽  
pp. 70-79 ◽  
Author(s):  
Sushma Bharrhan ◽  
Kanwaljit Chopra ◽  
Sunil K Arora ◽  
Jaideep S Toor ◽  
Praveen Rishi
Keyword(s):  
Liver Injury ◽  
Therapeutic Agent ◽  
Polyphenolic Compounds ◽  
Oxygen Species ◽  
Enhanced Production ◽  
Signalling Molecule ◽  
Tnf Α ◽  
Oxide Synthase ◽  
Inducible Nitric Oxide ◽  
Pharmacological Basis

Activation of NF-κB has been reported to play a key role in causing endotoxin-induced hepatic damage through enhanced production of reactive oxygen species and pro-inflammatory mediators. In this context, the potential of polyphenolic phytochemicals in preventing endotoxin-induced liver damage remains unclear. Here, we demonstrate that catechin and quercetin have the potential to down-regulate the initial signalling molecule NF-κB which may further inhibit the downstream cascade including TNF-α and NO. These results were confirmed using N-nitro-L-arginine methyl ester (L-NAME), the inhibitor of inducible nitric oxide synthase (iNOS) along with the biochemical and histological alterations occurring in the presence and absence of supplementation with both the polyphenols. However, catechin was found to be more effective than quercetin against endotoxin-induced liver injury. These findings suggest that these polyphenols may form a pharmacological basis for designing a therapeutic agent against endotoxin-mediated oxidative damage.

Orange juice ultrafiltration: characterisation of deposit layers and membrane surfaces after fouling and cleaning

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Nurul Hainiza Abd-Razak ◽  
Y. M. John Chew ◽  
Michael R. Bird
Keyword(s):  
Shear Stress ◽  
Orange Juice ◽  
Surface Coverage ◽  
Fluid Shear Stress ◽  
Membrane Surface ◽  
Regenerated Cellulose ◽  
Fluid Shear ◽  
Chemical Cleaning ◽  
Membrane Area ◽  
Software Analysis

Abstract The influence of feed condition and membrane cleaning during the ultrafiltration (UF) of orange juice for phytosterol separation was investigated. UF was performed using regenerated cellulose acetate (RCA) membranes at different molecular weight cut-off (MWCO) values with a 336 cm2 membrane area and a range of temperatures (10–40 °C) and different feed volumes (3–9 L). Fluid dynamic gauging (FDG) was applied to assess the fouling and cleaning behaviours of RCA membranes fouled by orange juice and cleaned using P3-Ultrasil 11 over two complete cycles. During the FDG testing, fouling layers were removed by fluid shear stress caused by suction flow. The cleanability was characterised by using ImageJ software analysis. A Liebermann-Buchard-based method was used to quantify the phytosterol content. The results show that RCA 10 kDa filters exhibited the best separation of phytosterols from protein in orange juice at 20 °C using 3 L feed with a selectivity factor of 17. Membranes that were fouled after two cycles showed higher surface coverage compared to one fouling cycle. The surface coverage decreased with increasing fluid shear stress from 0 to 3.9 Pa. FDG achieved 80–95% removal at 3.9 Pa for all RCA membranes. Chemical cleaning using P3-Ultrasil 11 altered both the membrane surface hydrophobicity and roughness. These results show that the fouling layer on RCA membranes can be removed by fluid shear stress without affecting the membrane surface modification caused by chemical cleaning.

scholarly journals Phosphoinositides Regulate Membrane-dependent Actin Assembly by Latex Bead Phagosomes

2002 ◽  
Vol 13 (4) ◽  
pp. 1190-1202 ◽  
Author(s):  
Hélène Defacque ◽  
Evelyne Bos ◽  
Boyan Garvalov ◽  
Cécile Barret ◽  
Christian Roy ◽  
...  
Keyword(s):  
Binding Sites ◽  
Kinase Activity ◽  
Kinase Inhibitors ◽  
Membrane Surface ◽  
Latex Bead ◽  
Actin Assembly ◽  
Wild Type ◽  
Membrane Surfaces ◽  
Organelle Membrane

Actin assembly on membrane surfaces is an elusive process in which several phosphoinositides (PIPs) have been implicated. We have reconstituted actin assembly using a defined membrane surface, the latex bead phagosome (LBP), and shown that the PI(4,5)P2-binding proteins ezrin and/or moesin were essential for this process ( Defacque et al., 2000b ). Here, we provide several lines of evidence that both preexisting and newly synthesized PI(4,5)P2, and probably PI(4)P, are essential for phagosomal actin assembly; only these PIPs were routinely synthesized from ATP during in vitro actin assembly. Treatment of LBP with phospholipase C or with adenosine, an inhibitor of type II PI 4-kinase, as well as preincubation with anti-PI(4)P or anti-PI(4,5)P2 antibodies all inhibited this process. Incorporation of extra PI(4)P or PI(4,5)P2 into the LBP membrane led to a fivefold increase in the number of phagosomes that assemble actin. An ezrin mutant mutated in the PI(4,5)P2-binding sites was less efficient in binding to LBPs and in reconstituting actin assembly than wild-type ezrin. Our data show that PI 4- and PI 5-kinase, and under some conditions also PI 3-kinase, activities are present on LBPs and can be activated by ATP, even in the absence of GTP or cytosolic components. However, PI 3-kinase activity is not required for actin assembly, because the process was not affected by PI 3-kinase inhibitors. We suggest that the ezrin-dependent actin assembly on the LBP membrane may require active turnover of D4 and D5 PIPs on the organelle membrane.

Topology Optimization of Spacers for Maximizing Permeate Flux on Membrane Surface in Reverse Osmosis Channel

2011 ◽  
Author(s):  
Seungjae Oh ◽  
Semyung Wang ◽  
Minkyu Park ◽  
Joonha Kim
Keyword(s):  
Topology Optimization ◽  
Pressure Drop ◽  
Reverse Osmosis ◽  
Membrane Surface ◽  
Design Development ◽  
Permeate Flux ◽  
Membrane Channel ◽  
Initial Attempt ◽  
Membrane Surfaces ◽  
Ro Membrane

The objective of this study is to design spacers using fluid topology optimization in 2D crossflow Reverse Osmosis (RO) membrane channel to improve the performance of RO processes. This study is an initial attempt to apply topology optimization to designing spacers in RO membrane channel. The performance was evaluated by the quantity of permeate flux penetrating both upper and lower membrane surfaces. A coupled Navier-Stokes and Convection-Diffusion model was employed to calculate the permeate flux. To get reliable solutions, stabilization methods were employed with standard finite element method. The nine reference models which consist of the combination of circle, rectangular, triangle shape and zigzag, cavity, submerge configuration of spacers were simulated. Such models were compared with new model designed by topology optimization. The permeate flux at both membrane surfaces was determined as an objective function. In addition, permissible pressure drop along the channel and spacer volume were used as constraints. As a result of topology optimization as the permissible pressure drop changes in channel, characteristics of spacer design development was founded. Spacer design based on topology optimization was reconstructed to a simple one considering manufactuability and characteristics of development spacer design. When a simplified design was compared with previous 9 models, new design has a better performance in terms of permeate flux and wall concentration at membrane surface.

Surface modification of reverse osmosis membranes with zwitterionic polymer to reduce biofouling

2015 ◽  
Vol 15 (5) ◽  
pp. 999-1010 ◽  
Author(s):  
Ahmed E. Abdelhamid ◽  
Mahmoud M. Elawady ◽  
Mahmoud Ahmed Abd El-Ghaffar ◽  
Abdelgawad M. Rabie ◽  
Poul Larsen ◽  
...  
Keyword(s):  
Reverse Osmosis ◽  
Tap Water ◽  
Membrane Surface ◽  
Salt Content ◽  
Cross Flow ◽  
Membrane Properties ◽  
Cleaning Efficiency ◽  
Bacteria Growth ◽  
Cross Flow Filtration

The zwitterionic homopolymer poly[2-(methacryloyloxy)ethyl-dimethyl-(3-sulfopropyl) ammonium hydroxide was coated onto the surface of commercial polyamide reverse osmosis (RO) membranes. Aqueous solutions of the polymer at different concentrations were applied to modify the polyamide membranes through an in situ surface coating procedure. After membrane modification, cross-flow filtration testing was used to test the antifouling potential of the modified membranes. The obtained data were compared with experimental data for unmodified membranes. Each test was done by cross-flow filtering tap water for 60 hours. Yeast extract was added as a nutrient source for the naturally occurring bacteria in tap water, to accelerate bacteria growth. Fourier transform infrared spectroscopy, contact angle, scanning electron microscopy, atomic force microscopy, and permeation tests were employed to characterize membrane properties. The results confirmed that modifying the membranes enhanced their antifouling properties and cleaning efficiency, the fouling resistance to bacteria improving due to the increased hydrophilicity of the membrane surface after coating. In addition, the water permeability and salt rejection improved. This in situ surface treatment approach for RO membranes could be very important for modifying membranes in their original module assemblies as it increases water production and reduces the salt content.

Antibiofilm activity of biomolecules: gene expression study of bacterial isolates from brackish and fresh water biofouled membranes

Biologia ◽  
2016 ◽  
Vol 71 (3) ◽  
Author(s):  
Smita Pal ◽  
Asifa Qureshi ◽  
Hemant J. Purohit
Keyword(s):  
Salicylic Acid ◽  
Fresh Water ◽  
Industrial Process ◽  
Life Time ◽  
Antibiofilm Activity ◽  
Expression Study ◽  
Chemical Cleaning ◽  
Natural Agents ◽  
Membrane Biofouling ◽  
Exopolysaccharides Production

AbstractMembrane biofouling is a common and emerging problem, where cells get cemented and create problems in industrial process. Frequent chemical cleaning used for the treatment of biofouled membrane shortens the membrane life time and creates ‘stress’ to existing microflora to trigger more exopolysaccharides production, which becomes the principle cause of biofouling. To understand safe and environmentally feasible antifouling strategies, key biofilm forming representative bacteria isolated from brackish and fresh water biofouled membranes were subjected to natural agents, such as vanillin (0.05–0.4 mg/mL) and salicylic acid (0.1–0.7 mg/mL). Salicylic acid (0.7 mg/mL) was found to be effective against only

scholarly journals TiO2-Capped Gold Nanorods for Plasmon-Enhanced Production of Reactive Oxygen Species and Photothermal Delivery of Chemotherapeutic Agents

2018 ◽  
Vol 10 (33) ◽  
pp. 27965-27971 ◽  
Author(s):  
Liangcan He ◽  
Chenchen Mao ◽  
Michael Brasino ◽  
Albert Harguindey ◽  
Wounjhang Park ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Gold Nanorods ◽  
Reactive Oxygen ◽  
Chemotherapeutic Agents ◽  
Oxygen Species ◽  
Enhanced Production
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