Antifouling strategies in technical systems – a short review

1996 ◽  
Vol 34 (5-6) ◽  
pp. 517-524 ◽  
Author(s):  
Hans-Curt Flemming ◽  
Thomas Griebe ◽  
Gabriela Schaule
Keyword(s):  
Short Review ◽  
Biofilm Reactor ◽  
Cleaning Efficiency ◽  
Cell Counts ◽  
Water Cleaning ◽  
New Strategy ◽  
Efficiency Control ◽  
Biofilm Development ◽  
And Storage ◽  
Wrong Place

The undesired deposition of microorganisms and the formation of biofilms is called “biofouling”. The consequences of biofouling for water purification, transport and storage are considerable both economically and ecologically. Countermeasures against biofouling include three steps: i) detection, ii) sanitization and iii) prevention of biofouling. The detection has to refer to surfaces. Cell counts in water water samples do not reflect the location or the extent of biofilms. Biocides display only limited value in terms of removal of biofouling layers. First, biofilm organisms are protected against biocides and tolerate 10 to 1000-fold higher concentrations. Second, water systems usually cannot be kept sterile. Thus, dead biofilms provide nutrients and suitable surfaces for further growth of cells imported with the raw water. Cleaning of a system is an integral part of sanitization and even more important than disinfection. It has to be based on a designed strategy. Efficiency control is mandatory and has to occur on representative surfaces. The prevention of biofouling is frequently achieved by continuously dosage of biocides. However, this is only possible with suitable raw waters and many failures are reported. Chlorine is still the biocide most frequently used. Concerns about effectivity and environmental protection give rise to other strategies. “Good housekeeping” is recommended as a general countermeasure. It includes frequent cleaning, efficiency control, biofilm monitoring, limitation of nutrients, maintenance of high shear forces, and a cleaning-friendly design. “Biofouling” is operationally defined and refers to biofilm development which exceeds a given “threshold of interference”. Keeping biofilm development below that threshold offers a new strategy, which considers biofouling as a biofilm reactor in the wrong place. Nutrient limitation is an option to curb biofilm development in sensitive areas. If large colonization areas are offered elsewhere than in the system to be protected, biofilms will develop there, sequestering dissolved nutrients and turning them into immobilized biomass in a place where it can be handled more easily than, e.g., inside a heat exchanger or a membrane module. Combined with effective monitoring techniques, a biocide-free antifouling-strategy can be realized.

scholarly journals Conceptual design of portable electrolyzed water cleaning rig using TRIZ method

Food Research ◽  
2021 ◽  
Vol 5 (S1) ◽  
pp. 188-192
Author(s):  
N.A. Jalil ◽  
N.I. Khalid ◽  
N.S. Sulaiman ◽  
S. Sobri ◽  
F.S. Taip ◽  
...  
Keyword(s):  
Conceptual Design ◽  
High Speed ◽  
Food Industry ◽  
Cleaning Efficiency ◽  
Electrolyzed Water ◽  
Limited Budget ◽  
Green Cleaning ◽  
Water Cleaning ◽  
Alkaline Electrolyzed Water ◽  
And Storage

The limited budget allocation and storage chemicals space are the main reasons food SMEs manufacturers took cleaning and sanitation for granted. A portable Electrolyzed Water Cleaning Rig which can generate sanitation solution and at the same time generated high-speed water will ease the cleaning and sanitation process for SMEs. In this study, the theory of inventive problem solving (TRIZ method) is applied in the development of portable electrolyzed water cleaning rig. A new conceptual design for the rig, which is robust and affordable is proposed. The rig could improve cleaning efficiency significantly in SME food industry in Malaysia, which is a major cause of a low number of SME with GMP certification. However, the final conceptual design has to undergo several modifications for assembly and manufacturing purposes, which will be performed in further study. The idea of generation for the portable electrolyzed water cleaning rig design was illustrated based on the TRIZ contradiction matrix. This portable unit will be able to generate both strongly acidic electrolyzed water (AcEW) and strongly alkaline electrolyzed water (AlEW) solution continuously. Both cleaning solutions are green cleaning solutions which can replace the commercial cleaning sanitation solutions. The development of the conceptual design of the portable Electrolyzed Water Cleaning Rig will help food SMEs tremendously.

Quantification of biofilms in a sub-surface flow wetland and their role in nutrient removal

2004 ◽  
Vol 49 (11-12) ◽  
pp. 115-122 ◽  
Author(s):  
E. Larsen ◽  
M. Greenway
Keyword(s):  
Nutrient Removal ◽  
Protein Extraction ◽  
Subsurface Flow ◽  
Sample Volume ◽  
Surface Flow ◽  
Biofilm Reactor ◽  
Biofilm Growth ◽  
Cell Counts ◽  
Significant Difference ◽  
Biofilm Development

Subsurface flow wetlands contain gravel or sand substrates through which the wastewater flows vertically or horizontally. The aims of this study were, firstly, to quantify biofilm development associated with different size gravel in sections of a subsurface flow wetland with and without plants, and secondly, to conduct laboratory experiments to examine the role of biofilms in nutrient removal. Techniques to quantify biofilm included: bacterial cell counts, EPS and total protein extraction. Based on comparative gravel sample volume, only EPS was greater on the smaller 5 mm gravel particles. There was no significant difference between biofilm growth in sections with and without plants. Two vertical flow laboratory-scale reactors, one containing fresh wetland gravel, the other containing autoclaved gravel, were constructed to determine nutrient transformations. The autoclaved gravel in the “sterile” reactor rapidly became colonised with biofilm. Both reactors were dosed with two types of influent. Initially the influent contained 7.25 mg/L NO3-N and 0.3 mg/L NH4-N; the biofilm reactor removed most of the ammonium and nitrite but nitrate concentrations were only reduced by 20%. In the “sterile” reactor there was negligible removal of ammonium and nitrite indicating little nitrification, however nitrate was reduced by 72%, possibly due to assimilatory nitrate reduction associated with new biofilm development. When the influent contained 3 mg/L NO3-N and 16 mg/L NH4-N almost 100% removal and transformation of NH4-N occurred in both reactors providing an effluent high in NO3-N. Organic P was reduced but inorganic soluble P increased possibly due to mineralisation.

Use of a dynamic gassing-out method for activity and oxygen diffusion coefficient estimation in biofilms

1998 ◽  
Vol 37 (4-5) ◽  
pp. 171-175
Author(s):  
Artem Khlebnikov ◽  
Falilou Samb ◽  
Paul Péringer
Keyword(s):  
Diffusion Coefficient ◽  
Oxygen Uptake ◽  
Oxygen Diffusion ◽  
Fixed Bed ◽  
Biofilm Reactor ◽  
Strictly Aerobic ◽  
Comamonas Testosteroni ◽  
Respiration Activity ◽  
Oxygen Diffusion Coefficient ◽  
Biofilm Development

p-toluenesulphonic acid degradation by Comamonas testosteroni T-2 in multi-species biofilms was studied in a fixed bed biofilm reactor. The polypropylene static mixer elements (Sulzer Chemtech Ltd., Switzerland) were used as a support matrix for biofilm formation. Biofilm respiration was estimated using the dynamic gassing-out oxygen uptake method. A strong relation between oxygen uptake and reactor degradation efficiency was observed, because p-toluenesulphonate degradation is a strictly aerobic process. This technique also allowed us to estimate the thickness of the active layer in the studied system. The mean active thickness was in order of 200 μm, which is close to maximum oxygen penetration depth in biofilms. A transient mathematical model was established to evaluate oxygen diffusitivity in non-steady-state biofilms. Based on the DO concentration profiles, the oxygen diffusion coefficient and the maximum respiration activity were calculated. The oxygen diffusion coefficient obtained (2 10−10-1.2 10−9 m2 s−1) is in good agreement with published values. The DO diffusion coefficient varied with biofilm development. This may be, most likely, due to the biofilm density changes during the experiments. The knowledge of diffusivity changes in biofilms is particularly important for removal capacity estimation and appropriate reactor design.

Activity, structure, and stratification of membrane-attached methanotrophic biofilms cometabolically degrading trichloroethylene

1999 ◽  
Vol 39 (7) ◽  
pp. 153-161 ◽  
Author(s):  
Lee W. Clapp ◽  
John M. Regan ◽  
Firdaus Ali ◽  
Jack D. Newman ◽  
Jae K. Park ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Pure Culture ◽  
Competitive Inhibition ◽  
Biofilm Reactor ◽  
Utilization Rate ◽  
Negative Effects ◽  
Loading Rates ◽  
Activity Structure ◽  
Serine Pathway ◽  
Biofilm Development

A membrane-attached methanotrophic biofilm reactor was developed for the cometabolic degradation of trichloroethylene (TCE). In this reactor, CH4 and O2 are supplied to the interior of the biofilm through the membrane, while TCE-contaminated water is supplied to the exterior, creating a “counter-diffusional” effect that minimizes competitive inhibition between TCE and CH4. In addition, this novel design provides 100% CH4 and O2 transfer efficiencies, promotes the development of a thick biofilm, and minimizes the negative effects of TCE byproduct toxicity. The reactor sustained 80-90% TCE removals at TCE loading rates ranging from 100-320 μmol/m2/d. Chloride mass balances demonstrated that 60-80% of the TCE removed was mineralized. The maximum TCE transformation yield was 1.8 mmol of TCE removed per mole of CH4 utilized, although higher transformation yields are expected at higher TCE loading rates. The CH4 utilization rate was 0.20 mol/m2/d. Scanning electron microscopy (SEM) revealed a dense biofilm with a thickness of at least 400 μm. SEM and transmission electron microscopy (TEM) analyses indicated that the “holdfast” material associated with rosette formation in planktonic Methylosinus trichosporium OB3b (M.t. OB3b) cells might also contribute to pure-culture biofilm development. In addition, fimbriae-like structures not commonly associated with methanotrophic bacteria were observed in pure-culture M.t. OB3b biofilms. Finally, fluorescent in situ hybridization (FISH) analyses showed the presence of discrete microcolonies of serine-pathway methanotrophs within mixed-culture biofilms.

scholarly journals Plasmonic nanogap enhanced phase-change devices with dual electrical-optical functionality

2019 ◽  
Vol 5 (11) ◽  
pp. eaaw2687 ◽  
Author(s):  
Nikolaos Farmakidis ◽  
Nathan Youngblood ◽  
Xuan Li ◽  
James Tan ◽  
Jacob L. Swett ◽  
...  
Keyword(s):  
Phase Change ◽  
Phase Change Memory ◽  
Memory Cell ◽  
Communications Technologies ◽  
New Strategy ◽  
On Chip ◽  
Processing And Storage ◽  
Electrical Signaling ◽  
And Storage ◽  
Change Memory

Modern-day computers rely on electrical signaling for the processing and storage of data, which is bandwidth-limited and power hungry. This fact has long been realized in the communications field, where optical signaling is the norm. However, exploiting optical signaling in computing will require new on-chip devices that work seamlessly in both electrical and optical domains, without the need for repeated electrical-to-optical conversion. Phase-change devices can, in principle, provide such dual electrical-optical operation, but assimilating both functionalities into a single device has so far proved elusive owing to conflicting requirements of size-limited electrical switching and diffraction-limited optical response. Here, we combine plasmonics, photonics, and electronics to deliver an integrated phase-change memory cell that can be electrically or optically switched between binary or multilevel states. Crucially, this device can also be simultaneously read out both optically and electrically, offering a new strategy for merging computing and communications technologies.

scholarly journals Evaluation of the automated hematology analyzer Sysmex XT-2000iV™ compared to the ADVIA® 2120 for its use in dogs, cats, and horses. Part II

2012 ◽  
Vol 24 (1) ◽  
pp. 74-89 ◽  
Author(s):  
Natali Bauer ◽  
Julia Nakagawa ◽  
Cathrin Dunker ◽  
Klaus Failing ◽  
Andreas Moritz
Keyword(s):  
Rank Correlation ◽  
Correlation Coefficients ◽  
Differential Count ◽  
Mean Corpuscular Hemoglobin ◽  
Cell Counts ◽  
Hematology Analyzer ◽  
Automated Hematology Analyzer ◽  
The Impact ◽  
And Storage ◽  
Edta Blood

The automated laser-based hematology analyzer Sysmex XT-2000 iV™ provides a 5-part differential count and specific cytograms that are of great interest for large veterinary laboratories. The aim of the study was to validate the Sysmex XT-2000 iV compared to the laser-based hematology analyzer ADVIA® 2120 and manual differential in dogs, cats, and horses as well as the impact of anticoagulant (heparin, ethylenediamine tetra-acetic acid [EDTA], and citrate) and storage at 22°C and 4°C. Consecutive fresh K3–EDTA blood samples from 216 cats, 314 dogs, and 174 horses were included. The impact of anticoagulant and sample storage was assessed in specimens obtained from an additional 9 cats, 10 dogs, and 10 horses. Agreement between both analyzers was excellent to good except for monocytes and canine reticulocytes. Spearman rank correlation coefficients ( rs) between Sysmex XT-2000 iV and manual differential were good to fair and ranged from 0.91 (cat lymphocytes) to 0.44 (cat monocytes). Hematocrit value (Hct), mean corpuscular hemoglobin (MCH), MCH concentration (MCHC; all: P < 0.001), and mean corpuscular volume (MCV; P < 0.01) were higher in canine citrated blood compared to heparin and EDTA. In cats, lymphocytes and monocytes were lower in heparinized blood compared to EDTA ( P < 0.05), whereas in horses no significant effect was seen. Regarding storage time and temperature, white and red blood cell counts, hemoglobin, and MCH were stable. Hct, MCV, and MCHC were influenced by erythrocyte swelling. Differential count remained stable for 24 hr (22°C) and nearly 72 hr (4°C) except for monocytes. The overall performance of the Sysmex XT-2000 iV was excellent and compared favorably with that of the ADVIA 2120. A special strength was the excellent detection of feline eosinophils.

scholarly journals Phenotypic Characterization of Streptococcus pneumoniae Biofilm Development

2006 ◽  
Vol 188 (7) ◽  
pp. 2325-2335 ◽  
Author(s):  
Magee Allegrucci ◽  
F. Z. Hu ◽  
K. Shen ◽  
J. Hayes ◽  
Garth D. Ehrlich ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Biofilm Formation ◽  
Protein Identification ◽  
Development Process ◽  
Developmental Stages ◽  
Developmental Process ◽  
Phenotypic Characterization ◽  
Biofilm Growth ◽  
Cell Counts ◽  
Biofilm Development

ABSTRACT Streptococcus pneumoniae is among the most common pathogens associated with chronic otitis media with effusion, which has been hypothesized to be a biofilm disease. S. pneumoniae has been shown to form biofilms, however, little is known about the developmental process, the architecture, and the changes that occur upon biofilm development. In the current study we made use of a continuous-culture biofilm system to characterize biofilm development of 14 different S. pneumoniae strains representing at least 10 unique serotypes. The biofilm development process was found to occur in three distinct stages, including initial attachment, cluster formation, and biofilm maturation. While all 14 pneumococcal strains displayed similar developmental stages, the mature biofilm architecture differed significantly among the serotypes tested. Overall, three biofilm architectural groups were detected based on biomass, biofilm thickness, and cluster size. The biofilm viable cell counts and total protein concentration increased steadily over the course of biofilm development, reaching ∼8 × 108 cells and ∼15 mg of protein per biofilm after 9 days of biofilm growth. Proteomic analysis confirmed the presence of distinct biofilm developmental stages by the detection of multiple phenotypes over the course of biofilm development. The biofilm development process was found to correlate not only with differential production of proteins but also with a dramatic increase in the number of detectable proteins, indicating that biofilm formation by S. pneumoniae may be a far more complex process than previously anticipated. Protein identification revealed that proteins involved in virulence, adhesion, and resistance were more abundant under biofilm growth conditions. A possible role of the identified proteins in biofilm formation is discussed.

Functional polymer thin films designed for antifouling materials and biosensors

2012 ◽  
Vol 66 (5) ◽  
Author(s):  
Chao Zhao ◽  
Ling-Yan Li ◽  
Ming-Ming Guo ◽  
Jie Zheng
Keyword(s):  
Thin Films ◽  
Biomedical Applications ◽  
Rational Design ◽  
Polymer Thin Films ◽  
Short Review ◽  
Photovoltaic Devices ◽  
Real World Applications ◽  
Energy Conversion And Storage ◽  
And Storage ◽  
Selection Of

AbstractPolymer thin films offer a versatile and ubiquitous platform for a wide variety of real-world applications in biomedicine, nanotechnology, catalysis, photovoltaic devices, and energy conversion and storage. Depending on the chemical composition of the polymers and the associated microenvironment, the physicochemical properties (biocompatibility, stability, wettability, adhesion, morphology, surface free energy, and others) of polymer films can be tuned for a specific application through precisely controlled surface synthesis and the incorporation of desirable and responsive functional groups. In this short review, we first summarise the methods most commonly used for the fabrication of polymer thin films. Then we discuss how these polymer thin films can be used in a selection of biomedical applications in antifouling materials and biosensors. Some directions for the rational design of polymer thin films to achieve a specific function or application are also provided.

A non-covalent peptide-based strategy for siRNA delivery

2007 ◽  
Vol 35 (1) ◽  
pp. 44-46 ◽  
Author(s):  
L. Crombez ◽  
A. Charnet ◽  
M.C. Morris ◽  
G. Aldrian-Herrada ◽  
F. Heitz ◽  
...  
Keyword(s):  
Sirna Delivery ◽  
Active Form ◽  
Short Review ◽  
Clinical Development ◽  
Biologically Active ◽  
Amphipathic Peptide ◽  
New Strategy ◽  
Endosomal Pathway

The major obstacle to clinical development of siRNAs (short interfering RNAs), like for most of the nucleic-acid-based strategies, is their poor cellular uptake and bioavailability. Although several viral and non-viral strategies have been proposed to improve siRNA delivery, their applications in vivo remain a major challenge. We have developed a new strategy, based on a short amphipathic peptide, MPG, that is able to form stable nanoparticles with siRNA. MPG-based particles enter the cell independently of the endosomal pathway and can efficiently deliver siRNA in a fully biologically active form into a variety of cell lines and in vivo. This short review will discuss the mechanism and the potency of the MPG strategy for siRNA delivery both in vitro and in vivo.

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