Biofilms: their structure, activity, and effect on membrane filtration

2005 ◽  
Vol 51 (6-7) ◽  
pp. 181-192 ◽  
Author(s):  
Z. Lewandowski ◽  
H. Beyenal
Keyword(s):  
Membrane Filtration ◽  
Membrane Separation ◽  
Separation Processes ◽  
Membrane Cleaning ◽  
Underlying Assumption ◽  
Structure Activity ◽  
Membrane Biofouling ◽  
Flux Decline ◽  
Cleaning Procedures ◽  
Near Future

The goal of this presentation is to identify biofouling mechanisms that cause undesirable effects to the membrane separation processes of flux decline and pressure drop. The underlying assumption of this presentation is that biofouling is unavoidable and that the operator cannot eliminate it entirely. This premise justifies research efforts toward understanding the mechanisms by which biofouling affects the membrane processes, rather than expecting that technology can entirely eliminate membrane biofouling in the near future. An improved understanding of biofouling mechanisms may lead to better membrane design, better membrane modules, and better membrane cleaning procedures.

Methods to Reduce Concentration Polarization and Fouling in Membrane Filtration

1994 ◽  
Vol 59 (4) ◽  
pp. 737-755 ◽  
Author(s):  
Petr Mikulášek
Keyword(s):  
Membrane Filtration ◽  
Morphological Analysis ◽  
Concentration Polarization ◽  
Membrane Separation ◽  
Separation Processes ◽  
Membrane Modules

Various methods and concepts that are currently being used and proposed to control or minimize concentration polarization and fouling in membrane separation processes are reviewed. A morphological analysis of hydrodynamic ways to prevent the detrimental influence on fluxes is given. The potentials of these different approaches are analyzed and some examples of module designs resulting from the various approaches with special attention to rotary membrane modules are given.

scholarly journals Permeate Flux in Ultrafiltration Membrane: A Review

2017 ◽  
Vol 14 (1) ◽  
Author(s):  
A. Beicha ◽  
R. Zaamouch ◽  
N. M. Sulaiman
Keyword(s):  
Membrane Filtration ◽  
Membrane Separation ◽  
Size Range ◽  
Membrane Surface ◽  
Separation Performance ◽  
Permeate Flux ◽  
Predictive Capability ◽  
Separation Processes ◽  
Ultrafiltration Pressure ◽  
Rate Limiting

Membrane processes exist for most of the fluid separations encountered in industry. The most widely used is membrane ultrafiltration, pressure driven process which is capable of separating particles in the approximate size range of 0.001 to 0.1 μm. The design of membrane separation processes, like all other processes, requires quantitative expressions relating material properties to separation performance. The factors controlling the performance of ultrafiltration are extensively reviewed. There have been a number of seminal approaches in this field. Most have been based on the rate limiting effects of the concentration polarization of the separated particles at the membrane surface. Various rigorous, empirical and intuitive models exist, which have been critically assessed in terms of their predictive capability and applicability. The decision as to which of the membrane filtration models is the most correct in predicting permeation rates is a matter of difficulty and appears to depend on the nature of the dispersion to separated.

scholarly journals The role of endocrine disrupters in water recycling: risk or mania?

2004 ◽  
Vol 50 (2) ◽  
pp. 215-220 ◽  
Author(s):  
L.D. Nghiem ◽  
J. McCutcheon ◽  
A.I. Schäfer ◽  
M. Elimelech
Keyword(s):  
Steroid Hormones ◽  
Membrane Filtration ◽  
Dynamic Equilibrium ◽  
Steroid Hormone ◽  
Endocrine Disrupting Chemicals ◽  
Water Recycling ◽  
Water Recovery ◽  
Membrane Cleaning ◽  
Endocrine Disrupting ◽  
Cleaning Procedures

The widespread occurrence of endocrine disrupting chemicals (EDCs), such as steroid hormones, in secondary wastewater effluents has become a major concern in the water recycling practice. This paper investigates the risk of steroid hormone breakthrough during nanofiltration membrane filtration in water recycling applications. The results indicate a dynamic equilibrium between adsorption and desorption of steroid hormone with regard to the membrane. This equilibrium can be pH dependent and there is a possibility for release of steroid hormones at high pH during membrane cleaning procedures or erratic pH variations. Increase in water recovery can severely increase the hormone breakthrough concentration. The results also indicate a possibility of accumulation of steroid hormones in the NF membrane, followed by subsequent release.

scholarly journals Manganese in the source of groundwater in Malaysia and the method for the removal process: A review on the adsorption and membrane separation processes

2021 ◽  
Vol 4 (1) ◽  
pp. 1
Author(s):  
Norin Zamiah Kassim Shaari ◽  
Ahmed Qutb Akmal Sajali
Keyword(s):  
Drinking Water ◽  
Membrane Filtration ◽  
Membrane Separation ◽  
Memory Loss ◽  
Motor Dysfunction ◽  
Activated Carbon Adsorption ◽  
Filtration Process ◽  
Separation Processes ◽  
Adsorptive Membrane ◽  
High Level

In Malaysia, the quality of groundwater as one of the main sources drinking water is deteriorated due to the presence of a high level of manganese, which exceeds the allowable values for drinking water consumption. Manganese at concentration higher than 0.1 mg/L causes staining, high turbidity and bad taste problem in drinking water, and eventually can cause a depletion of brain dopamine and a syndrome of motor dysfunction and memory loss resembling Parkinson disease. Several methods have been used to eliminate manganese from the groundwater, which include precipitation, coagulation, ion exchange, oxidation and filtration, aeration, activated carbon adsorption, ionic liquid extraction and biosorption. Among those methods, adsorption is the most efficient and cheaper method to remove heavy metal as the operation is easily be controlled and the reversible adsorbents can be regenerated through a suitable process. Membrane filtration on the other hand particularly reverse osmosis and nanofiltration have been found to be a very effective and economical way to isolate components that are suspended or dissolved in a liquid. In addition to that, the combination of adsorption and membrane filtration process such as polymer enhanced ultrafiltration and adsorptive membrane respectively are currently attracted attentions. This paper provides a review on the adsorption process and membrane filtration process for manganese removal, with subsequently outlining the potential adsorbents to be incorporated in the fabrication of adsorptive membrane.

scholarly journals Purification of Dairy Wastewaters by Advanced Oxidation Processes and Membrane Filtration

2017 ◽  
Vol 11 (1) ◽  
pp. 32-38
Author(s):  
Mihály Zakar ◽  
Erika Lakatos ◽  
Gábor Keszthelyi-Szabó ◽  
Zsuzsanna László
Keyword(s):  
Membrane Fouling ◽  
Membrane Filtration ◽  
Membrane Separation ◽  
Separation Efficiency ◽  
Scale Up ◽  
Separation Processes ◽  
Physicochemical Changes ◽  
Current Trends ◽  
Pre Treatment ◽  
Cost Efficient

Membrane separation processes are space and cost-efficient, easy to scale-up operations, which have proved to treat food industrial wastewaters efficiently. Beside the advantages like high separation efficiency without any chemical changes and low energy-intensity, membrane filtration also has drawbacks, like decreased operational efficiency caused by flux decile resulting from fouling and concentration polarization. Combination of oxidation pre-treatment and membrane filtration is a promising method for decreasing fouling due to the physicochemical changes caused by pre-oxidation of the wastewater in structure of colloidal pollutants and in the interactions between the foulants and the membrane material. The aim of this work is to identify the parameters affecting the membrane fouling during treatment of dairy wastewaters, and present the current trends of research in this field.

scholarly journals Fouling and Chemical Cleaning of Microfiltration Membranes: A Mini-Review

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 846
Author(s):  
Aysegul Gul ◽  
Jakub Hruza ◽  
Fatma Yalcinkaya
Keyword(s):  
Membrane Fouling ◽  
Membrane Separation ◽  
Cleaning Process ◽  
Affecting Factors ◽  
Chemical Cleaning ◽  
Separation Processes ◽  
Membrane Cleaning ◽  
Factors Affecting ◽  
Process Factors ◽  
Cleaning Methods

Membrane fouling is one of the main drawbacks encountered during the practical application of membrane separation processes. Cleaning of a membrane is important to reduce fouling and improve membrane performance. Accordingly, an effective cleaning method is currently of crucial importance for membrane separation processes in water treatment. To clean the fouling and improve the overall efficiency of membranes, deep research on the cleaning procedures is needed. So far, physical, chemical, or combination techniques have been used for membrane cleaning. In the current work, we critically reviewed the fouling mechanisms affecting factors of fouling such as the size of particle or solute; membrane microstructure; the interactions between membrane, solute, and solvent; and porosity of the membrane and also examined cleaning methods of microfiltration (MF) membranes such as physical cleaning and chemical cleaning. Herein, we mainly focused on the chemical cleaning process. Factors affecting the chemical cleaning performance, including cleaning time, the concentration of chemical cleaning, and temperature of the cleaning process, were discussed in detail. This review is carried out to enable a better understanding of the membrane cleaning process for an effective membrane separation process.

Dynamic simulation of sludge blanket movements in a full-scale rectangular sedimentation basin

1996 ◽  
Vol 33 (1) ◽  
pp. 89-99 ◽  
Author(s):  
F. Göhle ◽  
A. Finnson ◽  
B. Hultman
Keyword(s):  
Dynamic Simulation ◽  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Full Scale ◽  
Simulation Studies ◽  
Separation Processes ◽  
Sedimentation Basin ◽  
Near Future ◽  
Sludge Concentration

Bromma sewage treatment plant in Stockholm is the second largest plant in Stockholm and will in the near future have requirements for nitrogen removal. This means that a higher sludge age must be used in the aeration basin. This may be accomplished by an increase of the sludge concentration up to values until the limiting solids flux is exceeded. Measurement of the sludge blanket level is a possibility for better control of the sedimentation basin. Different measurements were performed to evaluate the main factors influencing the level. Dynamic simulation studies were performed at Bromma sewage treatment plant in Stockholm of the sludge blanket level and the return sludge concentration in a full-scale sedimentation basin. The simulations were performed with the help of a Danish simulation package, EFOR (1992), in which both reactions in the aeration basin (mainly based on the IAWPRC model) and separation processes in the sedimentation basin (both clarification and thickening) can be studied. The thickening model is based on the solids flux theory and the Vesilind formula (1979). Different methods were compared for determination and use of characteristic parameters in the Vesilind formula.

Separation of Biologically Active Compounds by Membrane Operations

2017 ◽  
Vol 23 (2) ◽  
pp. 218-230 ◽  
Author(s):  
Xiaoying Zhu ◽  
Renbi Bai
Keyword(s):  
Energy Consumption ◽  
Bioactive Compounds ◽  
Membrane Fouling ◽  
Membrane Separation ◽  
Separation Efficiency ◽  
High Energy ◽  
Separation Processes ◽  
Membrane Processes ◽  
Separation Technology ◽  
Pressure Driven

Background: Bioactive compounds from various natural sources have been attracting more and more attention, owing to their broad diversity of functionalities and availabilities. However, many of the bioactive compounds often exist at an extremely low concentration in a mixture so that massive harvesting is needed to obtain sufficient amounts for their practical usage. Thus, effective fractionation or separation technologies are essential for the screening and production of the bioactive compound products. The applicatons of conventional processes such as extraction, distillation and lyophilisation, etc. may be tedious, have high energy consumption or cause denature or degradation of the bioactive compounds. Membrane separation processes operate at ambient temperature, without the need for heating and therefore with less energy consumption. The “cold” separation technology also prevents the possible degradation of the bioactive compounds. The separation process is mainly physical and both fractions (permeate and retentate) of the membrane processes may be recovered. Thus, using membrane separation technology is a promising approach to concentrate and separate bioactive compounds. Methods: A comprehensive survey of membrane operations used for the separation of bioactive compounds is conducted. The available and established membrane separation processes are introduced and reviewed. Results: The most frequently used membrane processes are the pressure driven ones, including microfiltration (MF), ultrafiltration (UF) and nanofiltration (NF). They are applied either individually as a single sieve or in combination as an integrated membrane array to meet the different requirements in the separation of bioactive compounds. Other new membrane processes with multiple functions have also been developed and employed for the separation or fractionation of bioactive compounds. The hybrid electrodialysis (ED)-UF membrane process, for example has been used to provide a solution for the separation of biomolecules with similar molecular weights but different surface electrical properties. In contrast, the affinity membrane technology is shown to have the advantages of increasing the separation efficiency at low operational pressures through selectively adsorbing bioactive compounds during the filtration process. Conclusion: Individual membranes or membrane arrays are effectively used to separate bioactive compounds or achieve multiple fractionation of them with different molecule weights or sizes. Pressure driven membrane processes are highly efficient and widely used. Membrane fouling, especially irreversible organic and biological fouling, is the inevitable problem. Multifunctional membranes and affinity membranes provide the possibility of effectively separating bioactive compounds that are similar in sizes but different in other physical and chemical properties. Surface modification methods are of great potential to increase membrane separation efficiency as well as reduce the problem of membrane fouling. Developing membranes and optimizing the operational parameters specifically for the applications of separation of various bioactive compounds should be taken as an important part of ongoing or future membrane research in this field.

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