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.

Risk management approach for monitoring UF membrane integrity and experimental validation using MS2-phages

2008 ◽  
Vol 8 (2) ◽  
pp. 239-244 ◽  
Author(s):  
Anne Brehant ◽  
Karl Glucina ◽  
Isabelle Lemoigne ◽  
Jean-Michel Laine
Keyword(s):  
Removal Efficiency ◽  
Membrane Filtration ◽  
Membrane Integrity ◽  
Drinking Water Treatment ◽  
Low Pressure ◽  
Full Scale ◽  
Microbial Pathogens ◽  
Management Approach ◽  
Pathogen Removal ◽  
Bench Scale

Low-pressure membrane filtration systems, such as microfiltration (MF) and ultrafiltration (UF), have received a great deal of attention in the past 15 years due to their ability to remove microbial pathogens, especially Cryptosporidium and Giardia. The major concern for the application of membrane technology is, however, how to ensure integrity of these barriers, since small defects in membranes could result in a significant reduction in pathogen removal efficiency. In order to ensure safe drinking water treatment, a number of environmental agencies request the membrane operators to conduct regular direct integrity tests to control the microbial log removal values (LRV) of the plants. Typically, test conditions must be selected to provide information on defects larger than 3 μm to ensure Cryptosporidium removal. In that context, the objective of this project was to develop and validate, both at bench-scale and full-scale, a model based on the equations proposed by USEPA and ASTM that uses the air flow rate throughout a defect during the air pressure test for predicting the microbial LRV. The project was conducted on a pressurised low-pressure membrane module. MS2-phages were used at bench-scale to validate the model and the selected assumptions with various calibrated defects carried out on the membrane fibres. The validity of the model was then evaluated at full-scale. A user-friendly tool using the Hagen Poiseuille Model proposed by the ASTM was developed to assist membrane operators in the integrity monitoring. The calibration of the model with full-scale tests resulted in adjusting some key-parameters representing air diffusion, flow regime and particles deposition. The numerical applications provide a very reliable result in predicting the pathogen removal efficiency and the equivalent number of broken fibres. This model could detect one complete broken fibre out of more than 700,000 fibres, which guaranteed more than 4 log of microorganism removal efficiency.

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.

scholarly journals Ammonia nitrogen removal and recovery from acetylene purification wastewater by air stripping

2017 ◽  
Vol 75 (11) ◽  
pp. 2538-2545 ◽  
Author(s):  
Lei Zhu ◽  
DeMing Dong ◽  
XiuYi Hua ◽  
Yang Xu ◽  
ZhiYong Guo ◽  
...  
Keyword(s):  
Removal Efficiency ◽  
Flow Rate ◽  
Air Flow ◽  
Ammonia Nitrogen ◽  
Operating Conditions ◽  
H2so4 Solution ◽  
Air Flow Rate ◽  
Air Stripping ◽  
Experimental Conditions ◽  
N Removal

Ammonia nitrogen (NH4-N) contaminated wastewater has posed a great threat to the safety of water resources. In this study, air stripping was employed to remove and recover NH4-N from acetylene purification wastewater (APW) in a polyvinylchloride manufacturing plant. Investigated parameters were initial APW pH, air flow rate, APW temperature and stripping time. The NH4-N removal by air stripping has been modeled and the overall volumetric mass transfer coefficient (KLa) of the stripping process has been calculated from the model equation obtained. In addition, the ability of H2SO4 solution to absorb the NH3 stripped was also investigated. The results indicated that under the experimental conditions, the APW temperature and its initial pH had significant effects on the NH4-N removal efficiency and the KLa, while the effects of other factors were relatively minor. The removal efficiency and residual concentration of NH4-N were about 91% and 12 mg/L, respectively, at the optimal operating conditions of initial APW pH of 12.0, air flow rate of 0.500 m3/(h·L), APW temperature of 60 °C and stripping time of 120 min. One volume of H2SO4 solution (0.2 mol/L) could absorb about 93% of the NH3 stripped from 54 volumes of the APW.

Comparative Bio-sorption of Cadmium and Nickel Ions from Aqueous Solution onto Fibers of Date Palm using Fluidized Bed Column

2019 ◽  
Vol 70 (5) ◽  
pp. 1507-1512
Author(s):  
Baker M. Abod ◽  
Ramy Mohamed Jebir Al-Alawy ◽  
Firas Hashim Kamar ◽  
Gheorghe Nechifor
Keyword(s):  
Aqueous Solution ◽  
Heavy Metal ◽  
Metal Ions ◽  
Fluidized Bed ◽  
Removal Efficiency ◽  
Heavy Metal Ions ◽  
Date Palm ◽  
Operating Conditions ◽  
Initial Concentration ◽  
Bed Height

The aim of this study is to use the dry fibers of date palm as low-cost biosorbent for the removal of Cd(II), and Ni(II) ions from aqueous solution by fluidized bed column. The effects of many operating conditions such as superficial velocity, static bed height, and initial concentration on the removal efficiency of metal ions were investigated. FTIR analyses clarified that hydroxyl, amine and carboxyl groups could be very effective for bio-sorption of these heavy metal ions. SEM images showed that dry fibers of date palm have a high porosity and that metal ions can be trapped and sorbed into pores. The results show that a bed height of 6 cm, velocity of 1.1Umf and initial concentration for each heavy metal ions of 50 mg/L are most feasible and give high removal efficiency. The fluidized bed reactor was modeled using ideal plug flow and this model was solved numerically by utilizing the MATLAB software for fitting the measured breakthrough results. The breakthrough curves for metal ions gave the order of bio-sorption capacity as follow: Cd(II)]Ni(II).

Nitrogen Removal from Anaerobically-Treated Leachate

1984 ◽  
Vol 19 (1) ◽  
pp. 87-100
Author(s):  
D. Prasad ◽  
J.G. Henry ◽  
P. Elefsiniotis
Keyword(s):  
Nitrogen Removal ◽  
Air Flow ◽  
Operating Conditions ◽  
Air Flow Rate ◽  
Flow Rates ◽  
Anaerobic Filter ◽  
Ph Values ◽  
Wide Range ◽  
Ammonia Desorption ◽  
Effects Of Ph

Abstract Laboratory studies were conducted to demonstrate the effectiveness of diffused aeration for the removal of ammonia from the effluent of an anaerobic filter treating leachate. The effects of pH, temperature and air flow on the process were studied. The coefficient of desorption of ammonia, KD for the anaerobic filter effluent (TKN 75 mg/L with NH3-N 88%) was determined at pH values of 9, 10 and 11, temperatures of 10, 15, 20, 30 and 35°C, and air flow rates of 50, 120, and 190 cm3/sec/L. Results indicated that nitrogen removal from the effluent of anaerobic filters by ammonia desorption was feasible. Removals exceeding 90% were obtained with 8 hours aeration at pH of 10, a temperature of 20°C, and an air flow rate of 190 cm3/sec/L. Ammonia desorption coefficients, KD, determined at other temperatures and air flow rates can be used to predict ammonia removals under a wide range of operating conditions.

Removal of trichloroethylene and trichloroethane using a novel hollow-fibre gas-permeable membrane

2003 ◽  
Vol 3 (5-6) ◽  
pp. 67-72
Author(s):  
S. Takizawa ◽  
T. Win
Keyword(s):  
Boundary Layer ◽  
Flow Regime ◽  
Removal Efficiency ◽  
Residence Time ◽  
Flow Rate ◽  
Air Flow ◽  
Hollow Fibre ◽  
Permeation Rate ◽  
Permeable Membrane ◽  
Diffusional Boundary Layer

In order to evaluate effects of operational parameters on the removal efficiency of trichloroethylene and 1,1,1-trichloroethene from water, lab-scale experiments were conducted using a novel hollow-fibre gaspermeable membrane system, which has a very thin gas-permeable membrane held between microporous support membranes. The permeation rate of chlorinated hydrocarbons increased at higher temperature and water flow rate. On the other hand, the effects of the operational conditions in the permeate side were complex. When the permeate side was kept at low pressure without sweeping air (pervaporation), the removal efficiency of chlorinated hydrocarbon, as well as water permeation rate, was low probably due to lower level of membrane swelling on the permeate side. But when a very small amount of air was swept on the membrane (air perstripping) under a low pressure, it showed a higher efficiency than in any other conditions. Three factors affecting the permeation rate are: 1) reduction of diffusional boundary layer within the microporous support membrane, 2) air/vapour flow regime and short cutting, and 3) the extent of membrane swelling on the permeate side. A higher air flow, in general, reduces the diffusional boundary layer, but at the same time disrupts the flow regime, causes short cutting, and makes the membrane dryer. Due to these multiple effects on gas permeation, there is an optimum operational condition concerning the vacuum pressure and the air flow rate. Under the optimum operational condition, the residence time within the hollow-fibre membrane to achieve 99% removal of TCE was 5.25 minutes. The log (removal rate) was linearly correlated with the average hydraulic residence time within the membrane, and 1 mg/L of TCE can be reduced to 1 μg/L (99.9% removal).

scholarly journals Oxidative Extractive Desulfurization System for Fuel Oil Using Acidic Eutectic-Based Ionic Liquid

Processes ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 1050
Author(s):  
Sarrthesvaarni Rajasuriyan ◽  
Hayyiratul Fatimah Mohd Zaid ◽  
Mohd Faridzuan Majid ◽  
Raihan Mahirah Ramli ◽  
Khairulazhar Jumbri ◽  
...  
Keyword(s):  
Ionic Liquids ◽  
Removal Efficiency ◽  
Environmental Effects ◽  
Sulfur Compounds ◽  
Operating Conditions ◽  
Fuel Oil ◽  
Organosulfur Compounds ◽  
Dsc Analysis ◽  
Oil Refineries ◽  
Desulfurization Process

The biggest challenge faced in oil refineries is the removal of sulfur compounds in fuel oil. The sulfur compounds which are found in fuel oil such as gasoline and diesel, react with oxygen in the atmosphere to produce sulfur oxide (SOx) gases when combusted. These sulfur compounds produced from the reaction with oxygen in the atmosphere may result in various health problems and environmental effects. Hydrodesulfurization (HDS) is the conventional process used to remove sulfur compounds from fuel oil. However, the high operating conditions required for this process and its inefficiency in removing the organosulfur compounds turn to be the major drawbacks of this system. Researchers have also studied several alternatives to remove sulfur from fuel oil. The use of ionic liquids (ILs) has also drawn the interest of researchers to incorporate them in the desulfurization process. The environmental effects resulting from the use of these ILs can be eliminated using eutectic-based ionic liquids (EILs), which are known as greener solvents. In this research, a combination of extractive desulfurization (EDS) and oxidative desulfurization (ODS) using a photocatalyst and EIL was studied. The photocatalyst used is a pre-reported catalyst, Cu-Fe/TiO2 and the EIL were synthesized by mixing choline chloride (ChCl) with organic acids. The acids used for the EILs were propionic acid (PA) and p-toluenesulfonic acid (TSA). The EILs synthesized were characterized using thermogravimetry analyser (TGA) differential scanning calorimetry (DSC) analysis to determine the physical properties of the EILs. Based on the TGA analysis, ChCl (1): PA (3) obtained the highest thermal stability whereas, as for the DSC analysis, all synthesized EILs have a lower melting point than its pure component. Further evaluation on the best EIL for the desulfurization process was carried out in a photo-reactor under UV light in the presence of Cu-Fe/TiO2 photocatalyst and hydrogen peroxide (H2O2). Once the oxidation and extraction process were completed, the oil phase of the mixture was analyzed using high performance liquid chromatography (HPLC) to measure the sulfur removal efficiency. In terms of the desulfurization efficiency, the EIL of ChCl (1): TSA (2) showed a removal efficiency of about 99.07%.

Study on De-Nitrification of Improved Step-Feed Progress

2014 ◽  
Vol 703 ◽  
pp. 171-174
Author(s):  
Bing Wang ◽  
Yi Xiao ◽  
Shou Hui Tong ◽  
Lan Fang ◽  
Da Hai You ◽  
...  
Keyword(s):  
Water Quality ◽  
Organic Matter ◽  
Fluidized Bed ◽  
Removal Efficiency ◽  
Nitrogen Removal ◽  
Removal Rate ◽  
Operating Conditions ◽  
Removal Mechanism ◽  
Aerobic Zone

Improved step-feed de-nitrification progress combined with biological fluidized bed was introduced in this study. The progress had good performance and capacity of de-nitrification and organic matter. The experiment result showed that the de-nitrification efficiency of the improved biological fluidized bed with step-feed process was higher than the fluidized bed A/O process under the same water quality and the operating conditions. When the influent proportion of each segment was equal, the system showed good nitrogen removal efficiency with the change of influent C/N ratio, HRT and sludge return ratio. The removal rate of TN reached up to 88.2%. It showed that the simultaneous nitrification and de-nitrification phenomenon happened in the aerobic zone. The nitrogen removal mechanism was also studied.

scholarly journals Evaluation of wet air oxidation variables for removal of organophosphorus pesticide malathion using Box-Behnken design

2016 ◽  
Vol 75 (3) ◽  
pp. 619-628 ◽  
Author(s):  
Melike Isgoren ◽  
Erhan Gengec ◽  
Sevil Veli
Keyword(s):  
Removal Efficiency ◽  
Applied Pressure ◽  
Organophosphorus Pesticide ◽  
Operating Conditions ◽  
Quadratic Model ◽  
Air Oxidation ◽  
Wet Air Oxidation ◽  
Reaction Conditions ◽  
Efficient Treatment ◽  
Optimum Reaction

This paper deals with finding optimum reaction conditions for wet air oxidation (WAO) of malathion aqueous solution, by Response Surface Methodology. Reaction conditions, which affect the removal efficiencies most during the non-catalytic WAO system, are: temperature (60–120 °C), applied pressure (20–40 bar), the pH value (3–7), and reaction time (0–120 min). Those were chosen as independent parameters of the model. The interactions between parameters were evaluated by Box-Behnken and the quadratic model fitted very well with the experimental data (29 runs). A higher value of R2 and adjusted R2 (>0.91) demonstrated that the model could explain the results successfully. As a result, optimum removal efficiency (97.8%) was obtained at pH 5, 20 bars of pressure, 116 °C, and 96 min. These results showed that Box–Behnken is a suitable design to optimize operating conditions and removal efficiency for non-catalytic WAO process. The EC20 value of raw wastewater was measured as 35.40% for malathion (20 mg/L). After the treatment, no toxicity was observed at the optimum reaction conditions. The results show that the WAO is an efficient treatment system for malathion degradation and has the ability of converting malathion to the non-toxic forms.

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