Synergetic cleaning procedure for a ceramic membrane fouled by beer microfiltration

Chemical Cleaning Process of Polymeric Nanofibrous Membranes

Membrane fouling is one of the most significant issues to overcome in membrane-based technologies as it causes a decrease in the membrane flux and increases operational costs. This study investigates the effect of common chemical cleaning agents on polymeric nanofibrous membranes (PNM) prepared by polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), and polyamide 6 (PA6) nanofibers. Common alkaline and acid membrane cleaners were selected as the chemical cleaning agents. Membrane surface morphology was investigated. The PAN PNM were selected and fouled by engine oil and then cleaned by the different chemical cleaning agents at various ratios. The SEM results indicated that the use of chemical agents had some effects on the surface of the nanofibrous membranes. Moreover, alkaline cleaning of the fouled membrane using the Triton X 100 surfactant showed a two to five times higher flux recovery than without using a surfactant. Among the tested chemical agents, the highest flux recovery rate was obtained by a binary solution of 5% sodium hydroxide + Triton for alkaline cleaning, and an individual solution of 1% citric acid for acidic cleaning. The results presented here provide one of the first investigations into the chemical cleaning of nanofiber membranes.

Treatment of textile wastewater using monolayered ultrafiltation ceramic membrane fabricated from natural kaolin clay

Fabrication, characterization and application of ceramic membrane developed from Tunisian natural kaolin clay for textile wastewater treatment are presented in this study. The morphology and properties of the resulting membrane sintered at 1000°C for 3 h were then determined by Scanning Electron Microscopy (SEM), mechanical and chemical resistance and water permeability. Separation performance of the membrane was evaluated during the treatment of textile wastewater. SEM images reveal the homogeneous surface of the membrane. The membrane displayed good chemical and mechanical resistances as well. Its permeability was of 21.2 L.h ^-1.m^-2.bar^-1, indicating that separation performance could occur in the domain of Ultrafiltration (UF). Performances of the membrane during the treatment of raw and biologically pretreated textile effluents are promising in terms of the removal of colour (99% for the raw effluent and 100% for the biologically pretreated effluent), chemical oxygen demand (COD) (80% for the raw effluent and 93% for the biologically pretreated effluent) and turbidity (98% for the raw effluent and 100% for the biologically pretreated effluent).

Study of the permeability of tubular mineral membranes: application to wastewater treatment

This research work opens up the possibility of developing tubular mineral membranes from Moroccan clay powders and their use in water permeability tests and wastewater treatment. The aim is to show the possibility of using clay as a low-cost raw material for the production of ceramic membranes with high mechanical and chemical performances. In a first step, we developed ceramic membranes by extruding a prepared plastic paste with the addition of an optimized amount of wood powder as organic matter (OM) to improve the porosity characteristics of the final products after firing. Several parameters are controlled such as the chemical and mineralogical composition of the starting clay powder, the granulometry and the final sintering temperature. The effect of sintering temperature in the range from 800 to 1000 °C, and OM addition (5, 10, 15wt%) on tubular membrane properties such as mechanical and chemical resistance, porosity and permeability were investigated. It was found that the incorporation of OM in the raw clay enhance the pore volume and the permeate flux but it was also accompanied by a decrease in mechanical strength. The membrane sintered at 1000 °C with 15wt% of OM is considered as optimized membrane and it was applied for the second stage of this work. This stage concerns the treatment of wastewater from a thermal complex located 12 km south of the city of Meknes, Morocco, through a treatment by a biological disk microstation. The filtrate obtained then undergoes tangential filtration by the membranes elaborated and optimized following the evolution of the pollution parameters. Based on physicochemical and biological analyses of wastewater after treatment by the coupled system, the membranes obtained have a good permeability and an excellent pollution removal performance.

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

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.

Treatment of biologically treated landfill leachate with forward osmosis: Investigating membrane performance and cleaning protocols

This study presents systematic investigations to evaluate the performance, rejection rate, fouling, cleaning protocols and impact of physical and chemical cleaning strategies on the performance of commercial cellulose triacetate (CTA) membrane. The treatment of landfill leachate (LFL) solution was performed in the active layer facing feed solution and support layer facing the draw solution (AL-FS mode), and active layer facing the draw solution and support layer facing the feed solution (AL-DS mode). Compared to the AL-FS mode, a higher flux for AL-DS mode was achieved, but membrane fouling was more severe in the latter. In both membrane orientations, the rejection rate of the FO membrane to heavy ions and contaminants in the wastewater was between 93 and 99%. Physical and chemical cleaning strategies were investigated to recover the performance of the FO membrane and to study the impact of cleaning methods on the membrane rejection rate. Physical cleaning with hot water at 35 °C and osmotic backwashing with 1.5 M NaCl demonstrated excellent water flux recovery compared to chemical cleaning. In the chemical cleaning, an optimal concentration of 3% hydrogen peroxide was determined for 100% flux recovery of the fouled membrane. However, slight membrane damage was achieved at this concentration on the active layer side. Alkaline cleaning at pH 11 was more effective than acid cleaning at pH 4, although both protocols compromised the membrane rejection rate for some toxic ions. A comparison of the membrane long-term performance found that cleaning with osmotic backwashing and hot water were effective methods to restore water flux without comprising the membrane rejection rate. Overall, it was found that physical cleaning protocols are superior to chemical cleaning protocols for forward osmosis membrane fouled by landfill leachate wastewater.

Innovative Rough Beer Conditioning Process Free from Diatomaceous Earth and Polyvinylpolypyrrolidone

In large-sized breweries, rough beer clarification is still carried out using Kieselguhr filters notwithstanding their environmental and safety implications. The main aim of this work was to test an innovative rough beer clarification and stabilization process involving enzymatic treating with Brewers Clarex^®, centrifuging, rough filtering across 1.4-μm ceramic hollow-fiber membrane at 30 °C, and fine filtering through 0.45-μm cartridge filter. When feeding an enzymatically-pretreated and centrifuged rough beer with permanent haze (H_P) of 2 or 14 European Brewery Convention unit (EBC-U), its primary clarification under periodic CO₂ backflushing yielded a permeate with turbidity of 1.0–1.5 EBC-U at a high permeation flux (2.173 ± 51 or 593 ± 100 L m⁻² h⁻¹), much greater than that typical of powder filters. The final beer was brilliant (H_P = 0.57 ± 0.08 EBC-U) with almost the same colloidal stability of the industrial control and an overall log reduction value (~5.0 for the selected beer spoilage bacterium or 7.6 for the brewing yeast) in line with the microbial effectiveness of current sterilizing membranes. It was perceived as significantly different in flavor and body from the industrial control at a probability level of 10% by a triangle sensory test, as more likely related to the several lab-scale beer-racking steps used than to the novel process itself.

Recent Progresses in Application of Membrane Bioreactors in Production of Biohydrogen

Biohydrogen is a clean and viable energy carrier generated through various green and renewable energy sources such as biomass. This review focused on the application of membrane bioreactors (MBRs), emphasizing the combination of these devices with biological processes, for bio-derived hydrogen production. Direct biophotolysis, indirect biophotolysis, photo-fermentation, dark fermentation, and conventional techniques are discussed as the common methods of biohydrogen production. The anaerobic process membrane bioreactors (AnMBRs) technology is presented and discussed as a preferable choice for producing biohydrogen due to its low cost and the ability of overcoming problems posed by carbon emissions. General features of AnMBRs and operational parameters are comprehensively overviewed. Although MBRs are being used as a well-established and mature technology with many full-scale plants around the world, membrane fouling still remains a serious obstacle and a future challenge. Therefore, this review highlights the main benefits and drawbacks of MBRs application, also discussing the comparison between organic and inorganic membranes utilization to determine which may constitute the best solution for providing pure hydrogen. Nevertheless, research is still needed to overcome remaining barriers to practical applications such as low yields and production rates, and to identify biohydrogen as one of the most appealing renewable energies in the future.

Effective Antiscaling Performance of Reverse-Osmosis Membranes Made of Carbon Nanotubes and Polyamide Nanocomposites

The antiscaling properties of multiwalled carbon nanotube (MWCNT)-polyamide (PA) nanocomposite reverse-osmosis (RO) desalination membranes (MWCNT-PA membranes) were studied. An aqueous solution of calcium chloride (CaCl₂) and sodium bicarbonate (NaHCO₃) was used to precipitate in situ calcium carbonate (CaCO₃) to emulate scaling. The MWCNT contents of the studied nanocomposite membranes prepared by interfacial polymerization ranged from 0 wt % (plain PA) to 25 wt %. The inorganic antiscaling performances were compared for the MWCNT-PA membranes to laboratory-made plain and commercial PA-based RO membranes. The scaling process on the membrane surface was monitored by fluorescence microscopy after labeling the scale with a fluorescent dye. The deposited scale on the MWCNT-PA membrane was less abundant and more easily detached by the shear stress under cross-flow compared to other membranes. Molecular dynamics simulations revealed that the attraction of Ca²⁺ ions was hindered by the interfacial water layer formed on the surface of the MWCNT-PA membrane. Together, our findings revealed that the observed outstanding antiscaling performance of MWCNT-PA membranes results from (i) a smooth surface morphology, (ii) a low surface charge, and (iii) the formation of an interfacial water layer. The MWCNT-PA membranes described herein are advantageous for water treatment.

Towards a Kieselguhr- and PVPP-Free Clarification and Stabilization Process of Rough Beer at Room-Temperature Conditions

In this work, the main constraint (that is, beer chilling and chill haze removing) of the current beer conditioning techniques using Kieselguhr filtration and Polyvinylpolypyrrolidone (PVPP) treatment was overcome by developing a novel higher-throughput conditioning process, operating at room temperatures with no use of filter aids. The effect of filtration temperature (T_F ) in the range of 0 to 40 °C on the hydraulic permeability of ceramic hollow-fiber (HF) membranes with nominal pore size of 0.2 to 1.4 μm, as well as on their limiting permeation flux (J^* ) when feeding precentrifuged rough beer, was preliminarily assessed. When using the 1.4-μm HF membrane operating at T_F ≥ 20 °C, it was possible to enhance the average permeation flux at values (676 to 1844 L/m² /h), noticeably higher than those (250 to 500 L/m² /h) characteristics of conventional powder filtration. Despite its acceptable permanent haze, the resulting beer permeate still exhibited colloidal instability. By resorting to the commercial enzyme preparation Brewers Clarex® before beer clarification, it was possible to significantly improve its colloidal stability as measured using a number of European Brewing Convention forcing tests, especially with respect to that of precentrifuged rough beer by itself. By combining the above enzymatic treatment with membrane clarification at 30 °C across the ceramic 1.4-μm HF membrane module, it was possible to limit the haze development due to chilling, sensitive proteins, and alcohol addition to as low as 0.78, 4.1, and 4.0 EBC-U, respectively, the enzymatic treatment being by far more effective than that using PVPP.

PRACTICAL APPLICATION

A novel Kieselguhr- and PVPP-free rough beer conditioning process at room temperatures was set up. By submitting precentrifuged rough beer to commercial preparation Brewers Clarex ® and then to membrane clarification at 30 °C across a ceramic 1.4-μm hollow-fiber membrane module, it was possible to obtain a clear and stable beer with a throughput (1306 ± 72 L/m² /h) by far higher than that (250 to 500 L/m² /h) characterizing the current powder filters. The haze development due to chilling, sensitive proteins, and alcohol adding was by far lower than that observed when microfiltering PVPP-pretreated rough beer.

A review of reverse osmosis membrane fouling and control strategies

Reverse osmosis (RO) membrane technology is one of the most important technologies for water treatment. However, membrane fouling is an inevitable issue. Membrane fouling leads to higher operating pressure, flux decline, frequent chemical cleaning and shorter membrane life. This paper reviews membrane fouling types and fouling control strategies, with a focus on the latest developments. The fundamentals of fouling are discussed in detail, including biofouling, organic fouling, inorganic scaling and colloidal fouling. Furthermore, fouling mitigation technologies are also discussed comprehensively. Pretreatment is widely used in practice to reduce the burden for the following RO operation while real time monitoring of RO has the advantage and potential of providing support for effective and efficient cleaning. Surface modification could slow down membrane fouling by changing surface properties such as surface smoothness and hydrophilicity, while novel membrane materials and synthesis processes build a promising future for the next generation of RO membranes with big advancements in fouling resistance. Especially in this review paper, statistical analysis is conducted where appropriate to reveal the research interests in RO fouling and control.

Effect of operating conditions on the performances of multichannel ceramic UF membranes for textile mercerization wastewater treatment

Textile wastewaters are rated as one of the most polluting in all industrial sectors, and membrane separation is the most promising technology for their treatment and reuse of auxiliary chemicals. This study evaluates the performance of three types of tubular ceramic ultrafiltration membranes differing by mean pore size (1, 2 and 500 kDa) treating textile mercerization wastewater from a textile mill at different operating conditions: cross-flow velocity (CFV) and temperature. Acceptable results were obtained with 1 kDa ceramic membrane, with rejection efficiencies 92% for suspended solids, 98% for turbidity, 98% for color and 53% for total organic carbon at 20°C and 3 m s^-1 CFV. Highest fouling effect was observed for 500 kDa membrane and lowest CFV. According to the observed results, 1 kDa membrane could be used for the treatment of wastewater from the textile mercerization process in terms of permeate quality.

Membrane processing technology in the food industry: food processing, wastewater treatment, and effects on physical, microbiological, organoleptic, and nutritional properties of foods

Membrane processing technology (MPT) is increasingly used nowadays in a wide range of applications (demineralization, desalination, stabilization, separation, deacidification, reduction of microbial load, purification, etc.) in food industries. The most frequently applied techniques are electrodialysis (ED), reverse osmosis (RO), nanofiltration (NF), ultrafiltration (UF), and microfiltration (MF). Several membrane characteristics, such as pore size, flow properties, and the applied hydraulic pressure mainly determine membranes' potential uses. In this review paper the basic membrane techniques, their potential applications in a large number of fields and products towards the food industry, the main advantages and disadvantages of these methods, fouling phenomena as well as their effects on the organoleptic, qualitative, and nutritional value of foods are synoptically described. Some representative examples of traditional and modern membrane applications both in tabular and figural form are also provided.

Chemical cleaning/disinfection and ageing of organic UF membranes: a review

Membrane separation processes have become a basic unit operation for process design and product development. These processes are used in a variety of separation and concentration steps, but in all cases, the membranes must be cleaned regularly to remove both organic and inorganic material deposited on the surface and/or into the membrane bulk. Cleaning/disinfection is a vital step in maintaining the permeability and selectivity of the membrane in order to get the plant to its original capacity, to minimize risks of bacteriological contamination, and to make acceptable products. For this purpose, a large number of chemical cleaning/disinfection agents are commercially available. In general, these cleaning/disinfection agents have to improve the membrane flux to a certain extent. However, they can also cause irreversible damages in membrane properties and performances over the long term. Until now, there is considerably less literature dedicated to membrane ageing than to cleaning/disinfection. The knowledge in cleaning/disinfection efficiency has recently been improved. But in order to develop optimized cleaning/disinfection protocols there still remains a challenge to better understand membrane ageing. In order to compensate for the lack of correlated cleaning/disinfection and ageing data from the literature, this paper investigates cleaning/disinfection efficiencies and ageing damages of organic ultrafiltration membranes. The final aim is to provide less detrimental cleaning/disinfection procedures and to propose some guidelines which should have been taken into consideration in term of membrane ageing studies. To carry out this study, this article will detail the background of cleaning/disinfection and aging membrane topics in a first introductive part. In a second part, key factors and endpoints of cleaning/disinfection and aging membranes will be discussed deeply: the membrane role and the cleaning parameters roles, such as water quality, storing conditions, cleaning/disinfection/aging agents/conditions/protocols. The third and last part will be developed the parameters, methods and ways of characterization at our disposal and commonly used to develop and implement membrane cleaning and/or ageing studies.

The optimisation of ultrasonic cleaning procedures for dairy fouled ultrafiltration membranes

Ultrafiltration (UF) of whey is a major membrane based process in the dairy industry. However, commercialization of this application has been limited by membrane fouling, which has a detrimental influence on the permeation rate. There are a number of different chemical and physical cleaning methods currently used for cleaning a fouled membrane. It has been suggested that the cleaning frequency and the severity of such cleaning procedures control the membrane lifetime. The development of an optimal cleaning strategy should therefore have a direct implication on the process economics. Recently, the use of ultrasound has attracted considerable interest as an alternative approach to the conventional methods. In the present study, we have studied the ultrasonic cleaning of polysulfone ultrafiltration membranes fouled with dairy whey solutions. The effects of a number of cleaning process parameters have been examined in the presence of ultrasound and results compared with the conventional operation. Experiments were conducted using a small single sheet membrane unit that was immersed totally within an ultrasonic bath. Results show that ultrasonic cleaning improves the cleaning efficiency under all experimental conditions. The ultrasonic effect is more significant in the absence of surfactant, but is less influenced by temperature and transmembrane pressure. Our results suggest that the ultrasonic energy acts primarily by increasing the turbulence within the cleaning solution.