Removal Efficiency Of Filter Research Articles

Comparison of Test Methods for Determining the Particle Removal Efficiency of Filters in Residential and Light-Commercial Central HVAC Systems

Central heating, ventilating, and air-conditioning (HVAC) filters are often the dominant mechanism for particle removal in buildings. However, little is known about filter performance in real environments, particularly in residential and light-commercial buildings where particle concentrations and compositions can be very different from laboratory test conditions. This article explores differences in HVAC filter test protocols and refines a whole-house method for in situ testing of filters for size-resolved particle removal efficiencies. Results from the in situ method are compared with those from a simple upstream–downstream method for three types of commercially available filters in an unoccupied test house. Results from both field methods are compared with standardized laboratory test results as measured by an independent laboratory and as reported by the manufacturer. In general, comparisons between filter efficiency as measured by the refined whole-house method and as measured by the upstream–downstr...

Turbulent transport of airborne pollutants in a residential room with a novel air conditioning unit

Modeling on indoor air quality is performed considering the effect of a new window-type air conditioner, which is a promising way toward compromising energy consumption and residential air environment. Sensitivity analysis of the actual operating situations has been implemented, including the total fresh air supply and the full room air recirculation. The effects of supplying air flow rate, pollutant filtration efficiency, and indoor thermal buoyancy on the airborne pollutant transports are also illustrated. The numerical results demonstrate that the reduction of indoor pollutant levels can be accomplished either by increasing the fresh air ratio, or by increasing filtered removal efficiency, or by increasing the supplying airflow rate, or by decreasing the strength of indoor heating source. The indoor contaminant concentration asymptotically approaches to a small value for the situation of full fresh air supply, which agrees well with the analytical solutions of indoor contaminant concentration under the extreme operations.

Removal of Microbe-Carrying Particles by High Efficiency Air Filters in Cleanrooms

The removal efficiency of high efficiency air filters against microbe-carrying particles (MCPs) in the air supply of occupied rooms, such as cleanrooms, was determined. Knowing the size distribution of MCPs in the air to be filtered, and the removal efficiency of a filter against individual particle diameters, the overall removal efficiency was ascertained. A variety of filters were investigated, and it was found that a filter 90% efficient, when tested against sub-micrometre particles, used in standard classification methods such as EN 1822, was greater than 99.99% efficient in removing MCPs. The effect of filter efficiency on the quality of the air supply, and the concentration of MCPs in cleanroom air was also studied. No practical improvement in airborne concentrations was obtained by filters that had a removal efficiency greater than 99.99% against MCPs. Use of a filter suitable for removing MCPs, rather than sub-micrometre particles, would give a reduction of about 6 to 8-fold in the pressure drop over a filter, and a substantial reduction in the cost of running a cleanroom.

Removal of Cryptosporidium and polystyrene microspheres from swimming pool water with sand, cartridge, and precoat filters

Cryptosporidium has caused the majority of waterborne disease outbreaks in treated recreational water venues in the USA for many years running. This research project evaluated some common US swimming pool filters for removing Cryptosporidium oocysts, 5-µm diameter polystyrene microspheres, and 1-µm diameter polystyrene microspheres. A 946 L hot tub with interchangeable sand, cartridge, and precoat filters was used at room temperature for this research. Simulated pool water for each experiment was created from Charlotte, NC (USA) tap water supplemented with alkalinity, hardness, chlorine, and a mixture of artificial sweat and urine. Precoat (i.e., diatomaceous earth and perlite) filters demonstrated pathogen removal efficiencies of 2.3 to 4.4 log (or 99.4-99.996%). However, sand and cartridge filters had average Cryptosporidium removals of 0.19 log (36%) or less. The combined low filter removal efficiencies of sand and cartridge filters along with the chlorine-resistant properties of Cryptosporidium oocysts could indicate a regulatory gap warranting further attention and having significant implications on the protection of public health in recreational water facilities. The 5-µm microspheres were a good surrogate for Cryptosporidium oocysts in this study and hold promise for use in future research projects, field trials, and/or product testing on swimming pool filters.

A Fast Predicting Neural Fuzzy Model for Suspended Solid Removal Efficiency in Multimedia Filter

Modeling of filter performance is very difficult because of complexity of the defining physical and chemical events in the filtration system whereas the knowledge of functionality of filter coefficient. The main objective of this study is to predict the performance of multimedia filter and to evaluate both the initial and transient stage of suspended solid removal efficiency depending on experimental data. Fuzzy logic has been used to build a model of multi input and one output (MISO) for the removal efficiency of multimedia filter which it consists from sand and granular activated carbon (GAC) mediums. The control parameters of (FLC) of Sugeno model are seven parameters which are media depths, media grains size for both sand and GAC, filtration rate, diameter of suspension particle, feed concentration, and operation time. The output parameter is removal efficiency of media filter whereas these data are collocated from pilot scale deep bed filter, thus, the removal efficiency of filter was modeled by 575 rules as a function of different control parameters. An adaptive of neuron fuzzy inference system (ANFIS) had used to simulate the experimental data. The simulation results were evaluated using mean absolute percentage error (MAPE), whereas the results showed that the prediction of ANFIS model has a good agreement with experimental data when the MAPE is equal to 7.0458 and fuzzy rule -based modeling proved a reliable and flexible tool to study the performance of multimedia filter. The conclusion showed that there is a relationship between flow rate, effective size and optimum bed depth for all filter media, the increment of effective size generates a higher value of optimum filter bed depth for a lower value of filtration rate. It was concluded that the optimal removal efficiency (95-100) achieved by (0.5-0.7 mm) grain size of sand, (1.5-1.9) mm grain size of granular activated carbon (GAC), with media depths should range from 0.3 to 0.6 m.

Characterizing Shape of Effluent Particles by Image Analysis

Particle shape of wastewater effluents were investigated by implementing a dynamic particle image analyzer which provided data on the particle count, size, shape and circularity concurrently with images. The goals of this study were to characterize removal efficiency based on size and shape parameters for an in‐line filtration process and to study correlation between size and shape parameters. Results showed that filter removal efficiency can be determined by various size and shape parameters, where different information is obtained for each analysis. This method has potential in evaluating treatment process efficiencies by coupling size and shape parameters into a meaningful tool.

Numerical analysis of two contaminants removal from a three-dimensional cavity

This paper reports the results of a numerical study on removal of two contaminants from a three-dimensional enclosure with one inlet, one exhausting port and one returning port. In the formation of the problem, use is made of Reynolds stress model (RSM). The governing equations are solved by means of the SIMPLE algorithm. Lots of cases have been studied for the sensitivity analysis, including more practical cases from the total fresh air supplying to the total recirculation situations. The influence of inlet velocity, fresh air ratio, recirculating air filtered removal efficiency and contaminant property is investigated. The indoor contaminant is studied parametrically as a function of governing dimensionless numbers (Reynolds number and Schmidt number). The results show the above parameters have complex influence to indoor contaminant removal.

Evaluation of Operation of Submerged Aerated Filters in Wastewater Treatment and Excess Sludge Production

The aims of this study were to evaluate the SCOD removal efficiency in submerged biological aerated filters (BAFs) and subsequently to assess the relationship between the specific surface area (Ss) and Excess Sludge Production (ESP) rate in such filters. Accordingly, four filters with different porosity and specific surface (647, 295, 175 and 136 m2 m(-3)) have been loaded with synthetic wastewater based on low fat dry milk powder with COD of 1500 mg L(-1) in different hydraulic retention time (8, 4, 2, 1 and 0.5 h). In this study, it was shown that specific surface increase of the filters initially increases the efficiency of the filters and after a certain value, the filter efficiency remains uncharged or decreases, as in HRT of 8 h the SCOD removal efficiency of filters 1 and 2 (Ss = 647 m2 m(-3) and Ss = 295 m2 m(-3)) were 89.8 and 91% at VOL of 3.195 and 3.727 kg COD m(-3) d(-1), respectively. Also, the results showed that in all the filters, the production rate of suspended sludge increases inversely with the hydraulic retention time and the media with higher porosity (90.5%) produced less suspended sludge (8-57 g m(-3)) despite having lower efficiency in the SCOD removal.

Enhanced Coagulation for Satisfying the Arsenic Maximum Contaminant Level under Variable and Uncertain Conditions

This study evaluated the effects of influent variability and model parameter uncertainty when utilizing enhanced coagulation modification to bring existing treatment plants into compliance with a stricter arsenic regulation. Enhanced coagulation modification options include: (1) increased ferric chloride dose, (2) addition of an acid dose, and (3) a combination of the individual options. Arsenic removal is described by adsorption to hydrous ferric oxide with a surface complexation model and subsequent removal through sedimentation and filtration. The least-cost modification for reliably satisfying the arsenic regulation is determined using an optimization algorithm that explicitly includes variability and uncertainty. The ferric chloride only modification is always the least-cost treatment modification. The ferric chloride and acid modification could be the least-cost option when considering waste handling processes due to a tradeoff between modification cost and sludge production. By inclusion of variability and uncertainty, the relative importance of individual parameter distributions for determining whether the arsenic regulation is reliably satisfied is assessed. Influent arsenic concentration variability is always critical, while variability in the influent pH and sulfate concentrations and uncertainty in the filter removal efficiency and equilibrium adsorption constant for the triple bond Fe(s)OHCa2+ surface species are critical or important, depending on influent conditions.

Optimizing Trout Farm Effluent Treatment by Stabilizing Trout Feces: A Field Trial

AbstractThe following study investigates the effect of adding guar gum binder to a commercial extruded trout diet (Select P/Trouvit) in a land‐based water‐flow‐through trout farm, analyzing the effects of binder‐mediated fecal stabilization with respect to particle size distribution, nutrient retention, and the effectiveness of drum filtration of effluent. The experiments took place in a facility with two raceways of similar size and water flow rate and with similar stocks of rainbow trout Oncorhynchus mykiss. Fish in one raceway were fed Select P, while those in the other raceway received the same diet with the addition of guar gum. When the fish were given feed containing the dietary binder, feces were discharged in visibly and significantly larger particles. Furthermore, in effluent from the raceway in which fish were fed the diet plus binder, the particle‐bound fractions of phosphorus and Kjeldahl nitrogen were increased at the expense of the respective dissolved fraction by about 18% and 8%, respectively, possibly reflecting a reduced leaching of nutrients from the larger particles. Drum filter removal efficiency was significantly higher for the effluents from the fish fed the binder‐containing diet; for both total suspended solids and total phosphorus there was an improvement of about 40%. For total Kjeldahl nitrogen the improvement was about 17%. For the particulate fraction, removal values were even higher, efficiency improving about 47% for particulate phosphorus and 34% for particulate Kjeldahl nitrogen. The addition of the binder to the trout diet proved to be an effective means of improving mechanical effluent treatment and thus to developing environmentally sound fish production opportunities.

Deposition of submicron particles in deep bed filtration under unfavorable surface conditions

Deterioration in the filter removal efficiency of submicron particles (λ/λo) under unfavorable surface con- ditions is affected by the number of deposited particles per filter grain. In the case of above micron particles, the dete- rioration of filter removal efficiency has been mainly due to the blocking effect of deposited particles and not by the number of deposited particles. Deposition of large number of submicron particles changed the surface characteristics of collectors (filter grain associated with deposited particles) and enhanced unfavorable surface conditions. Filtration experiments were conducted with monodispersed suspensions of known sizes of submicron latex particles at different ionic strengths, using glass beads as filter grains. The filtration performance was predicted by using a mathematical model, assuming a linear relationship between λ/λo and σ (i.e. λ/λo=1−kσ). For both particles, k was found to decrease and λo was found to increase with the increase in the ionic strength. A comparison was made of the importance of block- ing effect for the filtration of submicron particles.

Properties of Catalytic Filter for the Hot Gas Cleaning

Porous filter was manufactured using cordierite powder and it was loaded with V2O5 catalyst by vacuum impregnation method. The removal efficiency of NOX and simultaneous removal efficiency of NOX /Dust were measured by passing NO and dust through catalystloaded ceramic filter. The cordierite porous filter had the apparent porosity of 61.6%, the compressive strength of 12.3 MPa and the pressure drop of 1200 Pa at the face velocity of 5 cm/sec, at 400oC. NOX removal efficiency of filter loaded only V2O5 catalyst was 80% and it could be improved up to 90% by the acid treatment (which increased specific surface area of filter elements); then this result is equal to the removal efficiency of the commercial V2O5/TiO2 catalyst, which was used at SCR(Selective Catalytic Reduction) process. Dust & NOX simultaneous removal efficiency of filter loaded V2O5 catalyst was about 99.6% of dust and 90% of NOX. Crack generated by thermal shock or pressure was not found. We found that catalytic cordierite filter is good candidate for simultaneous removal of particulate and hazardous gas from this result.

Performance evaluation of slow sand filters using fuzzy rule-based modelling

The main objective of this study is to evaluate and predict the performance of slow sand filters used for wastewater treatment. The uncertainties in the control parameters and processes require fuzzy sets to be used when modelling system performance. Fuzzy logic if– then rules were used to build a model for the removal efficiency (total coliforms) of slow sand filters. The data were collected from three pilot-scale slow sand filters at the Alkhobar (Saudi Arabia) wastewater treatment plant. The removal efficiency of filters was modelled using three input control parameters—filtration rate, sand bed depth and grain size. Based on available data, fuzzy logic if– then rules were established. The fuzzy rule-based model was validated using experimental data of three case studies reported in the literature. The results were also compared with a multiple regression model. A possibilistic risk analysis was performed using optimal removal efficiency of the slow sand filters. The risk is estimated with respect to non-compliance of unrestricted agricultural reuse standards (100 total coliform/100 ml). In addition to slow sand filters, post- or pre-chlorination of wastewater is recommended to improve wastewater quality for conforming agricultural reuse standards.

An overview of arsenic contamination in groundwater of Nepal and its removal at household level

A recent test result of about 17000 terai tube wells of Nepal on Arsenic, as published by the National Steering Committee on Arsenic, show that nearly 31% of the tested tube wells have exceeded the WHO standard of 10 μg/L and 4% have exceeded the Bangladesh, China, India, and Interim Nepal Standard of 50 μg/L. One of the best treatment options at household levels is a 3-Gagri (Pitcher) filter to remove arsenic and iron since no foreign materials and chemicals are required in this method. The arsenic removal efficiency of 3-gagri filters installed at Tilakpur and Thulokunuwar villages of Nawalparasi (Hotspot) district have been observed initially as 84.5% and 76.5% (Day 0) and reached maximum upto 94.8% (Day 2) and 85.2% (Day 14), respectively. The iron and turbidity removal efficiency of these filters are very promising as in both cases the initial iron content of 1.9 mg/L reduced to zero. Likewise, initial turbidity of 25 NTU reduced to less than 5 NTU in Thulokumuwar. The filter can produce about 160-170 liters of water per day.

Secondary Effluent Treatment by Slow Sand Filters: Performance and Risk Analysis

The objective of this study is to examine the reuse of wastewaterfor beneficial purposes. To accomplish this objective, the efficiency of slow sand filters in removing total coliforms (TC) was studied using a probabilistic method. Three pilot scale slowsand filters were constructed at Alkhobar wastewater treatment plant, Dhahran, Saudi Arabia. The removal efficiency of filters was estimated under different operating control parameters, which included filtration rate (q), sand bed depth (d) and sand grain size (c). The Type III extreme value distribution best fitted theremoval efficiency data. A multiple linear regression analysis was performed to develop a relationship for mean removal efficiency as a function of control parameters. The predicted mean response and experimental results of previous studies werecompared to validate the empirical regression model. The controlparameters and influent concentrations of total coliform were used in Monte Carlo (MC) simulations for calculating the reliability index (β). The reliability index and corresponding risk were calculated for lognormally distributedsafety margins (SM). An effluent standard of 100 total coliform/100 mL was defined as capacity of the filter to ascertainthe risks of exceedence, which was approximately less than 50 for95% of the time. Pre and/or post disinfection would be necessaryto meet the stipulated effluent standards for unrestricted agriculture use.

Transient stage deposition of submicron particles in deep bed filtration under unfavorable conditions

Deterioration in the filter removal efficiency of submicron particles ( λ/ λ 0) under unfavorable surface conditions is affected by the number of deposited particles per filter grain. In the case of above micron particles, the deterioration of filter removal efficiency has been mainly due to the blocking effect of deposited particles and not by the number of deposited particles. Deposition of large numbers of submicron particles changed the surface characteristics of collectors (filter grain associated with deposited particles) and enhanced unfavorable surface conditions. Filtration experiments were conducted with monodispersed suspensions of known sizes of submicron latex particles at different ionic strengths, using glass beads as filter grains. The filtration performance was predicted using a mathematical model assuming a linear relationship between λ/ λ 0 and σ (i.e. λ/ λ 0=1− kσ). For both particles, k was found to decrease and λ 0 was found to increase with the increase in the ionic strength. Charge accumulation on the filter grain for deposition of submicron particles was calculated and was found significant at all the ionic strengths studied. For monodispersed suspensions of 0.816 μm particles, charge accumulation was found to decrease with the increase in the ionic strength of the suspensions. A comparison was made on the relative importance of blocking effect and charge accumulation for the filtration of submicron particles.

527. 活性炭による放射性ヨウ素の除去に関する研究,(III)

To evaluate the performance of a large charcoal filter, a full sized charcoal filter unit (600mm×600mm) was constructed, and the removal efficiency of each filter for iodine was determined under various conditions, using radioactive iodine as tracer. The principal variables applied in this test were selected so as to be analogous with those of the previous experiment.The results of the test indicate no significant variation in the removal efficiency of the charcoal filter due to increased filter size And it was found that in the range covered by the present tests the efficiency for iodine plus methyl iodine determined by the present experiment agreed with the value determined by empirical formula.

ELECTROKINETIC PHENOMENA IN THE FILTRATION OF ALGAL SUSPENSIONS

Modification of sand and suspended particle surface properties, the authors assert, is an effective means of increasing filter removal efficiencies beyond those possible with normal doses of coagulants and with minimal head loss buildup.