Monitoring membrane integrity using high sensitivity laser turbidimetry

2001 ◽  
Vol 1 (5-6) ◽  
pp. 273-276 ◽  
Author(s):  
A. Banerjee ◽  
M. Lambertson ◽  
J. Lozier ◽  
C. Colvin
Keyword(s):  
Drinking Water ◽  
Membrane Filtration ◽  
Membrane Integrity ◽  
High Sensitivity ◽  
Particle Counter ◽  
Pressure Decay ◽  
Particle Counting ◽  
Decay Test ◽  
Microfiltration Membranes ◽  
Decay Testing

Membrane filtration plants for drinking water typically use pressure decay testing in conjunction with particle counting and turbidity to monitor membrane integrity. Pilot plants offer the capability of monitoring permeate quality with both intact and intentionally compromised membranes. We compare data from a particle counter, a pressure decay test and a laser turbidimeter on pilot plants from two different manufacturers of microfiltration membranes.

Monitoring and maintaining the integrity of immersed ultrafiltration membranes used for pathogen protection

2002 ◽  
Vol 2 (5-6) ◽  
pp. 307-311
Author(s):  
P. Côté ◽  
J. Cadera ◽  
N. Adams ◽  
G. Best
Keyword(s):  
Drinking Water ◽  
Membrane Filtration ◽  
Ultrafiltration Membranes ◽  
Vacuum Decay ◽  
Integrity Monitoring ◽  
Pressure Decay ◽  
Decay Test ◽  
Conventional Technology ◽  
Water Borne

Membrane filtration has become the preferred alternative to conventional technology to remove water-borne pathogens in the preparation of drinking water. This paper presents the integrity monitoring and maintenance options for the ZeeWeed® immersed membrane. Results from two versions of air-based tests, a pressure decay test and a vacuum decay test are presented and shown to be conservative when compared to challenge results from independent studies.

Assessing pathogen removal efficiency of microfiltration by monitoring membrane integrity

2001 ◽  
Vol 1 (4) ◽  
pp. 43-48 ◽  
Author(s):  
S.K. Hong ◽  
F.A. Miller ◽  
J.S. Taylor
Keyword(s):  
Removal Efficiency ◽  
Air Flow ◽  
Membrane Integrity ◽  
Operating Conditions ◽  
Pathogen Removal ◽  
Membrane Pore ◽  
Pressure Decay ◽  
Particle Counting ◽  
Integrity Tests ◽  
Microbial Challenge

This study was conducted to investigate the ability of various methods of monitoring membrane integrity to respond to changes in actual membrane integrity imposed by the compromised fibers within the microfiltration unit. In addition, the pilot-scale MF unit was challenged with high concentrations of coliform, Cryptosporidium, and spore, in order to assess the pathogen removal capability of microfiltration. A correlation between the integrity tests and microbial challenge data was also made. The integrity tests investigated in this study were pressure decay and diffusive air flow tests (direct integrity tests), and turbidity and particle counting (indirect integrity tests). Both pressure decay (PDT) and diffusive air flow (DAF) tests were sensitive enough to detect one damaged fiber out of 66,000. The extent of fouling did not affect the sensitivity of the PDT and DAF, showing that PDT and DAF tests are a simple, reliable means to monitor membrane integrity under field conditions. Indirect integrity monitoring using turbidity and particle counting, however, responded poorly to changes in membrane integrity. Microbial challenge study demonstrated that microfiltration was capable of removing various pathogens including Cryptosporidium, at the level required by drinking water regulations, under even adverse operating conditions. Finally, PDT and DAF tests showed a better correlation with actual microbial removal efficiency of microfiltration than turbidity and particle counting. The turbidity and particle counting grossly underestimated the removal of pathogen larger than MF membrane pore size due to poor sensitivity.

scholarly journals A Novel Model of Pressure Decay in Pressure-Driven Membrane Integrity Tests Based on the Bubble Dynamic Process

2019 ◽  
Vol 9 (2) ◽  
pp. 273
Author(s):  
Songlin Wang ◽  
Jiaqi Ding ◽  
Han Xu ◽  
Pengchao Xie ◽  
Junfeng Wu ◽  
...  
Keyword(s):  
Dynamic Process ◽  
Accurate Determination ◽  
Membrane Integrity ◽  
Defect Size ◽  
Chamber Pressure ◽  
Bubble Dynamic ◽  
Pressure Decay ◽  
Chamber Volume ◽  
Decay Test ◽  
Gas Chamber

The membrane integrity is estimated using a pressure decay test based on the bubble dynamic process of membrane defects. The present work builds a schematic diagram for a bubble formation model of a pressure decay test, proposes a simulation model of pressure decay rate (PDR) in the membrane gas chamber by means of numerical simulation using microdefect bubble dynamic behavior, and tries to establish the main factors influencing the back-calculated defect size resolution. Results obtained from the variations in the membrane gas chamber pressure and the PDR allowed for accurate determination of the membrane defect size, and the PDR was found to be relatively dependent on the gas chamber volume and the initial applied test pressure. The measured data about PDR using controlled experimental parameters was in good agreement with the trend found in the prediction model, proving that the pressure decay test process is in essence a bubble dynamic process. Furthermore, the back-calculated defect size resolution was found to decrease with the increase in gas chamber volume and PDR as well as with the decrease in applied pressure.

Enhancing the particle removal efficiency of a drinking water treatment plant by membrane filtration

2001 ◽  
Vol 1 (5-6) ◽  
pp. 377-380
Author(s):  
G. Hagmeyer ◽  
O. Kiepke ◽  
W. Dautzenberg ◽  
R. Gimbel
Keyword(s):  
Drinking Water ◽  
Water Treatment ◽  
Pressure Vessel ◽  
Membrane Filtration ◽  
Treatment Plant ◽  
Drinking Water Treatment ◽  
Pressure Vessels ◽  
Particle Removal ◽  
Reservoir Water ◽  
Particle Counter

In the first step of the project funded by the German Federal Ministry for Education and Research (BMBF) three UF pilot systems (about 10 m3/h) were evaluated for drinking water treatment of reservoir water. In the second step a 150 m3/h pilot plant with 12 6 m long pressure vessels was installed in the waterworks of Roetgen. One of the unique features of the pilot is, that the inlet and outlet flows of every pressure vessel are monitored. Further on a particle counter is installed. With this particle counter the filtrate of every pressure vessel can be monitored automatically by switching magnetic valves.

Improvement of the resolution in direct membrane integrity test by controlling solution surface tension

2009 ◽  
Vol 59 (11) ◽  
pp. 2205-2211 ◽  
Author(s):  
J. H. Lee ◽  
S. K. Hong ◽  
H. C. Hur ◽  
Y. J. Choi
Keyword(s):  
Surface Tension ◽  
Membrane Integrity ◽  
Membrane System ◽  
Point Theory ◽  
Initial Test ◽  
Integrity Test ◽  
Pressure Decay ◽  
Decay Test ◽  
Test Pressure ◽  
Solution Surface

Membrane-based treatment technologies have been introduced as a promising tool for the removal of water-borne pathogens. To ensure successful application of membrane processes, the integrity of the membrane system should be maintained. Related with evaluation of the membrane integrity, USEPA guidance recommends pressure-based membrane integrity (MIT). Based on the bubble point theory, the ability of detecting smallest integrity breakage during the MIT is defined as “Resolution”. However, the response to remarkably small breach demands significantly high initial test pressure of the pressure decay test. In this study, the surface tension of the test liquid was controlled to improve the resolution without increasing the corresponding test pressure. Three common chemicals were chosen to control the solution surface tension. It is concluded that 0.1 M of the citric acid can decrease the initial test pressure significantly for the same pore size. Subsequently, the improvement of the resolution with controlled surface tension was confirmed by the results of pressure decay test and marker test.

Coagulation/flocculation/ultrafiltration for natural organic matter removal in drinking water production

2004 ◽  
Vol 4 (5-6) ◽  
pp. 215-222 ◽  
Author(s):  
A.R. Costa ◽  
M.N. de Pinho
Keyword(s):  
Drinking Water ◽  
Organic Matter ◽  
Natural Organic Matter ◽  
Membrane Fouling ◽  
Membrane Filtration ◽  
Membrane Surface ◽  
Water Production ◽  
Cellulose Acetate Membranes ◽  
Wide Range ◽  
Drinking Water Production

Membrane fouling by natural organic matter (NOM), namely by humic substances (HS), is a major problem in water treatment for drinking water production using membrane processes. Membrane fouling is dependent on membrane morphology like pore size and on water characteristics namely NOM nature. This work addresses the evaluation of the efficiency of ultrafiltration (UF) and Coagulation/Flocculation/UF performance in terms of permeation fluxes and HS removal, of the water from Tagus River (Valada). The operation of coagulation with chitosan was evaluated as a pretreatment for minimization of membrane fouling. UF experiments were carried out in flat cells of 13.2×10−4 m2 of membrane surface area and at transmembrane pressures from 1 to 4 bar. Five cellulose acetate membranes were laboratory made to cover a wide range of molecular weight cut-off (MWCO): 2,300, 11,000, 28,000, 60,000 and 75,000 Da. Severe fouling is observed for the membranes with the highest cut-off. In the permeation experiments of raw water, coagulation prior to membrane filtration led to a significant improvement of the permeation performance of the membranes with the highest MWCO due to the particles and colloidal matter removal.

Viruses and Water: Problems, Detection, and Control

1993 ◽  
Vol 27 (7-8) ◽  
pp. 127-133 ◽  
Author(s):  
H. Dizer ◽  
J. Dürkop ◽  
A. Grohmann ◽  
H. Kopecka ◽  
J. M. López-Pila
Keyword(s):  
Drinking Water ◽  
Surface Waters ◽  
Membrane Filtration ◽  
Wastewater Treatment Plants ◽  
Health Hazard ◽  
Primary Source ◽  
Detection Methods ◽  
Secondary Effluent ◽  
Naturally Occurring ◽  
Water Problems

Secondary effluent of wastewater treatment plants contains a high number of viruses and other pathogens, which pose a health risk to the population, (especially when receiv ng waters are used for bathing and swimming, or for growing shellfish. In areas with a high density of population, where drinking water supply is dependent on surface waters and contaminated rivers are the primary source of drinking water, failure of the filtration or of the disinfection step, or of any other “barriers” supposed to warrant safe potable water, will increase the risk of health hazard for the consumer. We have compared the efficiency of viral elimination in secondary effluent by flocculation, uv rradiation and membrane filtration taking naturally occurring, or additionally seeded f2 phages, as indicator for viruses. Flocculation decreased the number of phages present in secondary effluent by more than two logs. If combined with uv irradiation, the elimination reached five additional logs. Membrane filtration eliminated essentially all naturally occurring phages. Improvement of the quality of surface waters calls for a refinement of detection methods for viruses. We have found that the polymerase chain reaction (PCR) might be used for detecting viruses in surface waters.

Rapid detection and enumeration of total bacteria in drinking water and tea beverages using a laboratory-built high-sensitivity flow cytometer

2015 ◽  
Vol 7 (7) ◽  
pp. 3072-3079 ◽  
Author(s):  
Muxin Yu ◽  
Lina Wu ◽  
Tianxun Huang ◽  
Shuo Wang ◽  
Xiaomei Yan
Keyword(s):  
Drinking Water ◽  
Rapid Detection ◽  
High Sensitivity ◽  
Flow Cytometer ◽  
Total Bacteria

This paper describes a method for the rapid detection and enumeration of total bacteria in drinking water and tea beverages.

scholarly journals One-step removal of lead from water using an electricity-free and sustainable membrane filtration

2021 ◽  
Vol 27 (4) ◽  
pp. 166-172
Author(s):  
Junwei Zhang ◽  
Yan Tung Lo ◽  
Hao Guo ◽  
Chuyang Tang
Keyword(s):  
Drinking Water ◽  
Removal Efficiency ◽  
Membrane Filtration ◽  
High Water ◽  
Water Safety ◽  
Drinking Water Contamination ◽  
Emergency Situations ◽  
Drinking Water Safety ◽  
Effective Removal ◽  
Volumetric Loading

Lead (Pb) is a typical contaminant in water with adverse effects on human health. Hong Kong’s incident of drinking water contamination by Pb in 2015 caused severe public concerns regarding drinking water safety. Conventional treatment methods for Pb removal generally require electricity, chemical dosage, and considerable time and space, which significantly restrict their use for rapid water purification under emergency situations. In this study, a polyvinyl alcohol/polyacrylic acid (PVA/PAA) composite nanofibrous membrane was developed for the rapid and effective removal of Pb from water. The PVA/PAA membrane had a high water permeability of 550 L/m2/h/kPa - 710 L/m2/h/kPa, which allowed the filtration to be driven by gravity (e.g. with a water height of 10.0 cm). The membrane showed consistently high removal efficiency of Pb (> 95%) with a volumetric loading up to 3000 L/m2. This high removal efficiency was attributed to the combined effects of complexing and electrostatic attraction between Pb and PAA. An esculent citric acid was used to regenerate the exhausted PVA/PAA membrane. The regenerated membrane maintained its removal efficiency of Pb over a five-cycle filtration. These results imply that the PVA/PAA composite membrane can be repeatedly used in electricity-free filtration devices for rapid elimination of Pb under emergency situations.

Sign in / Sign up

Export Citation Format

Share Document