Spiral-wound Ultrafiltration Membrane Research Articles

Application of integrated chemical precipitation and ultrafiltration as pre-treatment in seawater desalination

Chemical precipitation including lime softening, chlorination, clarification and filtration have been long recognized treatment for process water used in various industries because it provides consistent water quality, however these processes were rarely used in pre-treating feed to reverse osmosis desalination systems. The newly developed submerged spiral wound ultrafiltration membranes in conjunction with chemical precipitation or lime softening can be used to treat reverse osmosis feed. Previous studies have proven the feasibility of integrating immersed ultrafiltration (UF) membrane with chemical precipitation and lime softening. This paper describes the relationships of the operating parameters such as pH, membrane flux, trans-membrane pressure (TMP), membrane permeability; optimum dosage of coagulant; to be used as the basis for the design and construction of the full scale plant. A pilot unit consisting of chemical reactor and UF system was operated at various pH conditions, at membrane flux rates ...

Direct drinking water treatment by spiral-wound ultrafiltration membranes

This paper presents the results of a research on direct drinking water treatment through an ultrafiltration pilot plant unit using spiral-wound membranes (3500 MWCO). The source of water is the Guarapiranga Reservoir, an eutrophicated water body located in the metropolitan region of São Paulo, Brazil. The data were collected during a period of almost 3400 h, from August 2005 to January 2006. The main objective of the study was to evaluate the membrane production capacity and contaminant removal efficiency. It was verified that the system was able to produce a high quality permeate with a flow close to the specified by the membrane manufacturer. The average permeate flow was 19.7 L.h −1.m −2, at 467 kPa and 25°C, with a global water recovery of almost 85%. The removal efficiencies for TOC, UV light absorption, and turbidity were 85%, 56%, and 95%, respectively. The results provide substantial evidence of the technical feasibility of spiral-wound UF membranes for direct drinking water treatment from euthrophicated sources, as an alternative for conventional drinking water treatment systems.

Potabilization of low NOM reservoir water by ultrafiltration spiral wound membranes

Membrane technologies such as ultrafiltration offer an interesting alternative to integral treatment of surface water destined for human consumption. With this in mind, a pilot-scale ultrafiltration module was set up, equipped with spiral-wound polyethersulphone membranes (16.6 m 2) with an effective pore size of 0.05 μm. The system operated continuously with a stable production of 0.9 m 3/h (54 lmh) and a constant transmembrane pressure of −0.2 bar. The effluent obtained showed a total absence of faecal contamination indicators of both bacterial and viral origin, and also presented an excellent physico-chemical quality, independently of the quality of influent. Total aerobic bacteria counts revealed the problem of bacterial contamination in the membrane permeate zone, which could be controlled through daily chemical cleansing of the membrane. The chief problem presented by this type of system, applied as exclusive treatment, is low effectiveness in the retention of natural organic matter (NOM), in which respect the quality of the effluent was observed to depend on the quality of influent. This constitutes the principal limitation for applying the system to surface water due to the risk of disinfection by-products formation during the final post-chlorination. However, spiral wound ultrafiltration (SWUF) membranes could be used for low NOM reservoir water total treatment offering several advantages over conventional technologies.

AQUAPOT: Study of the causes in reduction of permeate flow in spiral wound UF membrane. Simulation of a non-rigorous cleaning protocol in a drinkable water treatment facility

In the last two years, international AQUAPOT project has carried out the installation of three drinking water treatment plants based on ultrafiltration (UF), in rural areas of the Andean region of Ecuador without access to drinking water. In addition, the project has carried out an applied parallel investigation in the Naquera Research Centre (CIN) in Valencia that has by objective the anticipation to the problems that can arise in the operation of the drinking water facilities already installed, as a consequence of a non-rigorous cleaning protocol. For the investigation, analogous drinking water treatment plants to the ones installed in Ecuador have been used, working continuously in long-term operation assay and using as feed superficial water with a high microbiological contamination. Cleaning protocol was applied every 7 days using a cleaning solution an basic and acid agent followed by a disinfectant reagent. Results after 6 months of test, showed a progressive decrease of the permeate flow and presence of microbiological contamination. This work exposes main results and conclusions from real assays, and recommendations to achieve a correct operation of the UF plant.

AQUAPOT: study of several cleaning solutions to recover permeate flow in a humanitarian drinking water treatment facility based on spiral wound UF membrane. Preliminary test (I)

Access to safe drinkable water is a basic human right and an international goal. Since 1996, AQUAPOT international project, has researched and developed low cost, easy to use and effective water treatment technologies able to be used in developing countries. Recently, the project has carried out the design of three potabilization units based on membrane technology and its installation in rural areas of Ecuador with no access to safe water. Field experience has shown that maintenance and cleaning of spiral wound ultrafiltration membranes is not done properly what can reduce the membrane’s life due to biofilm growth. In a medium term, this growth would affect the quality and the volume of the pure water produced by the drinkable water treatment facility. An applied research has been initiated to study several cleaning solutions that allow to recover an optimum permeate flow. For the preliminary test, samples from UF membrane were used. Methodology includes static assays in which membrane’s samples were immersed in a cleaning solution for over 12 or 24h at a temperature of 25 to 40°C. The study has allowed to select the most effective membrane’s cleaning solutions and the optimum conditions for its application. In addition, the study has allowed to verify the efficiency of the cleaning reagent in a drinkable water treatment plant.

Recycling the wastewater of the industrial park in Northern Taiwan using UF-RO system: in-situ pilot testing and cost analysis

In Taiwan, every industrial park equips a wastewater treatment plant (WWTP) to collect wastewater streaming from all the factories. These effluents, though showing high total dissolved solids (TDS) and fluctuating composition, would be a valuable water resource for industrial use after large scale purification, especially in the drought seasons. In this study, a pilot plant was installed for reclaiming the effluents from the industrial park WWTP through the membrane process. A modified spiral-wound ultrafiltration (UF) membrane with backwash function was utilized for the pretreatment of the reverse osmosis (RO) system. Evaluation results showed that the pilot plant was performing stably during the two-month operation. After the RO desalination, the quality of the reclaimed water basically met the requirement standards of intermediate-pressure boiler feedwater (150∼ 750psig) of the Environmental Protection Agency, United States (USEPA). The backwashable spiral wound UF membrane provided suitable water quality for RO influent (SDI < 4) and helped reduce the cost compared to using hollow-fibre UF membrane. The total cost of recycling one-ton effluent included US$ 0.35 for construction and US$ 0.45 for operation/maintenance.

Methodology of analysis of a spiral-wound module. Application to PES membrane for ultrafiltration of skimmed milk

This paper investigates a methodology for the characterisation and location of a thin layer of irreversible fouling in a spiral-wound ultrafiltration membrane by using several physico-chemical techniques as SEM-EDX, SEMFEG, FTIR-ATR and AFM. Application to analysis of a spiral-wound PES membrane for UF of skimmed milk, after 4 years of production in a French dairy plant, is detailed. From the analyses, it was evidenced that all parts of the spiral module did not have the same behaviour towards fouling and cleaning. The mapping obtained from SEM-EDX shows that irreversible fouling is located near the collector axis of the permeate and is independent of the inlet and outlet of the membrane. Significant differences are observed between the inner/outer and middle sheets of the spiral membrane. This is probably closely connected with the distribution of the fluid velocity in the spiral membrane. It would be important to compare such analyses with now available computational fluid dynamics (CFD) data related to this complex spiral geometry. Such an approach would lead to improvement of the cleanability of such systems.

Anglian Water membrane hybrid system for the soft drinks industry

This paper examines the general technical aspects of membrane technology when applied to the soft drinks industry. A full scale plant has been installed at Wells Soft Drinks in Northampton, the site is fed from a surface water source within the Anglian Water region. The new water treatment plant installed at Wells Soft Drinks was supplied and commissioned by Anglian Water in 1997. It is a Membrane Hybrid System. Developed by Anglian Water Innovation in the UK, the Membrane Hybrid System is a combination of ultrafiltration and reverse osmosis equipped with spiral wound ultra low pressure reverse osmosis thin film composite membranes and spiral wound ultrafiltration membranes (see Fig.1). For water treatment within the soft drinks industry, membrane applications have many advantages over the conventional ion exchange plants used in the industry.

Evaluation of Three Different Cleaners Recommended for Ultrafiltration Systems by Direct Observations of Commercial-Scale Spiral-Wound Ultrafiltration Membranes

Efficacy of cleaners designed for use with ultrafiltration systems was determined by microbiological evaluation and through visual inspection using scanning electron microscopy. The ultrafiltration system containing two commercial-scale, polysulfone membranes was soiled with sweet whey (40°C) then rinsed with water and membranes were removed. One half of each membrane was soaked for 2 h at 38°C in one of the following solutions: control (no soaking), acid cleaner (pH 2.5), enzyme-based cleaner (pH 11.5) and chlorinated alkaline cleaner (pH 11.5). The membranes were repositioned in the ultrafiltration unit, rinsed with water, then removed and unwound for analysis. Sections of membrane, retentate spacer and permeate mesh were aseptically removed for enumeration of microorganisms remaining and for examination by scanning electron microscopy. Membranes cleaned with chlorinated alkaline cleaner averaged 2 × 103 CFU/50 cm2, enzyme-based cleaner 6 × 106/CFU, acid anionic cleaner 1 × 107 CFU and the control 5 × 107CFU. Scanning electron microscopy found soil and microorganisms present on all membrane materials exposed to all three cleaners.

Performance of a spiral wound ultra-filtration membrane with turbulence promoting net under conditions of strong pressure gradient and fouling

A mathematical model has been developed to predict the performance of a spiral wound ultra-filtration membrane, with turbulence-promoting net. In this analysis the general case which includes fouling of the membrane and strong variation in the transmembrane pressure is considered. The model provides a parameter to describe the degree of fouling.

An analysis of the performance of a spiral-wound ultrafiltration membrane, with a turbulence-promoting net

A mathematical model has been developed to describe the performance of a spiral-wound ultrafiltration module, with a turbulence promoting net. The model requires that certain constants be evaluated from tests on filtration modules and thereafter a simple relation is available to predict performance at varying concentrations and recirculation rates, under conditions of gel polarization.