Filter Lifetime Research Articles

Assessment of low-cost cartridge filters for implementation in household drinking water treatment systems

In regions where houses are sparsely located, traditional centralized water treatment plants are not economically feasible, with household water treatment (HWT) systems commonly used to provide potable water for a range of household activities. Filtration prior to disinfection is essential, and due to their ease of use and small footprint, cartridge filters are commonly employed. In this work, readily available commercial filter types (spun, wound and pleated) of different micron ratings (10, 5 and 1) were tested for the removal of turbidity either alone or in series via simulated large volume pilot trials. Water with an initial turbidity of 40 ± 10 NTU was prepared using fine test dust (ISO 12103-1, A2) with the turbidity removal efficiency, pressure drop, total capacity and lifespan of the filters evaluated.To increase useable filter lifetime upon reaching the 1 bar pressure limit, a series of washing steps were employed to regenerate the filters. Whilst pleated filters could be efficiently cleaned, spun and wound filters could not, and were discarded after single use. In pilot trials, the volume of turbid water filtered varied from 0.85 m3 with a 1 micron wound filter to 6 m3, with 5 and 1 micron pleated filters in series, which following regeneration could be used for three filtration cycles. For pleated filters, turbidity removal efficiency improved over time as a cake built up resulting in the effluent turbidity reaching acceptable quality (<5 NTU). This criterion continued to be achieved with repeated cycles of washed pleated filters, thereby significantly reducing the cost and improving sustainability of the HWT system. Field trials were carried out with a similar HWT system (5 and 1 micron spun filters) installed in households of rural communities in Curiti, Colombia. Turbidity was effectively removed from natural water (reduction to <1.2 NTU) with improved efficacy in comparison to synthetic water samples due to the large particle size distribution observed in the natural water.

On the influence of pore connectivity on performance of membrane filters

Abstract

Method to Estimate the Remaining Useful Life of a Filter Using a Hybrid Approach Based on Kernel Regression and Simple Statistics

This paper describes the method used by the Uptime team for the estimation of the remaining useful life of a filter during the 2020 PHM Conference Data Challenge. The proposed method is a hybrid of two methods: (1) based on median lifetime of a filter for a particular contamination profile and (2) kernel regression for a sensor-based prediction after a certain threshold of differential pressure is reached. The threshold value was chosen based on visual assessment followed by grid search for fine tuning. Median lifetime of a filter for unseen contamination profiles was estimated using interpolation. Choosing the right interpolation method was a challenge as training data contained samples with only two values of contamination particle size. Interpolation was chosen based on other publicly available information about the relationship between contamination profile and filter lifetime. The results (ranked 1st with the total penalty score of 49.67) showed that an observation made based on one dataset can be useful for solving similar problems in the case of limited data availability. This suggests that there is a potential for using transfer learning in PHM applications.

An optimum design for air filter housing-louver: Enhancing filter life-time

The design of filter housing and louver have been focused on the filter protection from rain. Up till now the effect of air-flow behavior on the filter life-span has not been considered. All filters have to be changed at the same time, which causes expensive maintenance and the plant to be shut down. Sometimes, the filter needs to be changed earlier than its real-life. The main aim of this work is to design a louver shape which obtains a consistent airflow through the filter housing in each channel. The airflow through the filter housing of four different shapes of the louver were simulated in two-dimensional models. The filter size was fixed at 60 × 60 cm. The three filters were set series for the filter housing height at 180 cm. CFD models used in this work to determine the optimum filter housing and louver shape for pressure drop reduction and uniform airflow distribution. The results showed that the optimum filter housing angle was found to be 45° at the largest louver size with the same size of inlet and outlet channels (H/L/Z = 1/1/1). The design of filter housing and louver can be indicated the best airflow behavior and the optimum cost.

Controlling Noise and Gas Emissions by a New Design of Diesel Particulate Filters

A theoretical and numerical studies on Diesel Particulate Filters (DPF) and its working principal in controlling noise and exhaust gasses emissions is presented here. This research includes a study of current Martials types that is used in diesel particulate nowadays and on a new materials and technologies that we can use in future. A new design of DPF is presented here. Unfortunately, in Jordan we face an environmental problems caused by diesel engines and the production of NOx and other exhaust gases and particulate matter. The main reason of this problem is the low specification of diesel fuel that is used in Jordan, which leads to shorten the life time of the Diesel particulate filters and leading to block them in some intensive cases. This problems leads to increasing the pollutant in the air which can harm the people's health, animal and plants, so this research goal is to find a solution for the diesel particulate filter life time and to control the environmental emissions and engines noise resulted from gas dynamics. It is found that the developed design of DPF achieves about 22% increase in its performance in both gas emission and noise reductions comparing with the traditional one.

On the application of photocatalyst-sorbent composite materials for arsenic(III) remediation: Insights from kinetic adsorption modelling

Abstract TiO2–Fe2O3 composites show great promise for the removal of arsenic(III) from drinking water: this single material combines the photocatalytic capabilities of TiO2 for the oxidation of arsenite (i.e. As(III)) with the high adsorption capacity of iron oxides towards the arsenate (i.e. As(V)) subsequently produced. To design an effective treatment, it is necessary to balance high sorbent concentrations, providing long filter lifetimes, with low photocatalyst concentrations, to achieve effective penetration of light into the system. In this work, we construct a predictive model using experimentally determined As(III) adsorption isotherms and kinetics to estimate arsenic treatment plant lifetimes. We considered sorbent loading, treatment time, and batch treatment versus continuous-flow. Our model indicated that batch treatment is more efficient than continuous-flow at low sorbent concentrations ( 100 g L−1 sorbent could operate for an entire year without media replacement. This work highlights the important implications of sorbent concentration when we consider the multifunctional photocatalysts-sorbent system, and highlights the need for further experimental work to design efficient arsenic treatment plants.

The haemodynamic effects of oXiris haemofilter in septic shock patients requiring renal support: A single-centre experience.

Excessive pro-inflammatory and anti-inflammatory cytokines are mediators for haemodynamic alterations, metabolic acidosis, and multi-organ failure in sepsis. Recently, oXiris® haemofilter (Baxter, IL, USA) has been introduced as a novel haemofilter to mitigate inflammatory response during sepsis-associated acute kidney injury requiring renal replacement therapy. In the present case series, the researchers retrospectively reviewed critically ill patients with septic shock with the use of at least one oXiris haemofilter during continuous renal replacement therapy between June 2015 and December 2017. The timing for oXiris initiation was at the nephrologists' discretion. The impact of oXiris haemofilter was evaluated on mean arterial pressure, vasopressor dosage, Sequential Organ Failure Assessment score, lactate and base excess during 72 h after treatment. Thirty-five patients were enrolled in the study. An improvement of haemodynamic status was found, shown by increased mean arterial pressure by 6.1% (p = 0.35), decreased norepinephrine dose by 45.9% (p = 0.02), inotropic score by 26.4% (p = 0.02) and vasopressor dependency index by 40.5% (p = 0.01). Cardiovascular Sequential Organ Failure Assessment scores significantly decreased over 72 h (p = 0.02). Blood lactate levels and base excess also showed statistically significant improvements. The median filter lifetime was 23 (interquartile range = 14-36) hours. The intensive care unit mortality was 82.9%. Treatment with oXiris was safe and well-tolerated with no device-related adverse events. In conclusion, continuous renal replacement therapy with oXiris haemofilter is safe and may improve haemodynamic parameters in septic patients with severe renal dysfunction. Nonetheless, these findings were drawn from a retrospective analysis without a control group, and therefore cannot be generalised. Randomised controlled trials are warranted to confirm these findings.

Regional citrate anticoagulation for continuous renal replacement therapy in newborns and infants: Focus on citrate accumulation

Continuous renal replacement therapy (CRRT) with regional citrate anticoagulation (RCA) in newborns and infants is challenging and accumulation of citrate can occur. There are only a few studies reporting the detailed data on RCA. We aimed to analyze RCA-CRRT at our institution with focus on citrate accumulation. Critically ill newborns and infants up to 11 kg of body weight (BW), treated with RCA-CRRT in the 2011-2016 period were included in this retrospective observational study. Prismaflex(R) and Multifiltrate-CiCa(R) dialysis monitors were used with either automated or manual RCA. Data was collected regarding the circuit lifetime, parameters of RCA, markers of citrate accumulation (total/ionized calcium ratio > 2.5), and metabolic complications. We included 10 children with mean age of 2.6±3.8 months and BW of 4.6±2.7 kg. In-hospital mortality was 60%. RCA-CRRT parameters were: blood flow 46±9 mL/min (12±5 mL/min/kg BW), citrate dose 2.8±0.6 mmol/L of blood resulting in estimated citrate load to the patient of 1.7±0.8 mmol/h/kg BW. In total, 57 dialysis circuits were used with mean filter lifetime of 39±29 h. Citrate accumulation (total/ionized calcium ratio > 2.5) was observed in 7/10 patients and in 14/57 (25%) of circuits; those circuits were performed in children with lower age and BW, had higher relative blood flow and citrate load, while citrate dose was similar. When citrate load to the patient was used to predict citrate accumulation, AUC under the ROC curve was 0.78 and 1.7 mmol/h/kg BW was considered the optimal cutoff value (sensitivity 71% and specificity 72%). CRRT with RCA using equipment, developed for adult population, is feasible in newborns and infants. Signs of citrate accumulation developed relatively often. To prevent it, we suggest avoiding citrate loads above 1.7 mmol/h/kg BW, which can best be achieved by keeping the blood flow below 9 mL/min/kg BW.

Safety and efficacy of citrate anticoagulation for septic patients with liver patients

Objective To evaluate the efficacy and safety of citrate anticoagulation for continuous renal placement therapy (CRRT) in septic patients with liver dysfunction. Methods The data of septic patients who needed to CRRT and were admitted into the department of critical care medicine from January 2016 to December 2017 were enrolled in this study. Liver dysfunction was defined as Child-Turotte-Pugh (CTP) score >4. A total of fifty-six patients met the criteria. According to the patient′s actual condition, they were divided into citrate groups (29 cases) and low molecular weight heparin (LMWH) group (29 cases). Patients in LMWH group were given slow molecular weight heparin. The efficacy and safety were compared between the two groups. The filter lifetime, after treatment the activated partial thromboplastin time (APTT),hemoglobin (Hb) were compared between the two groups. Results The average filter lifetime in citrate group was (25.0±12.2) h which was longer than (13.7±4.5) h in LMWH group (t=13.17, P<0.01). The average service life of each filter was (4.2±1.9) h which was lower than (8.7±3.6) in LMWH group (t=8.395, P<0.05). Conclusions Regional Citrate anticoagulation is a safe and effective option for CRRT in septic patients with liver dysfunction, without causing electrolyte disturbance and internal environment. Key words: Citrate anticoagulation; Liver dysfunction; Septic

Modelling the transport and adsorption dynamics of arsenic in a soil bed filter

Arsenic is among the most hazardous contaminants present in drinking water. Recent increase in agricultural growth and fertiliser use in India and Bangladesh has led to the release of naturally occurring arsenic from the rocks, creating a major public health issue. A novel technology has been developed using naturally abundant laterite soil to filter arsenic, providing potable water to more than 5000 people. To upscale this technology and realise its full potential, a comprehensive understanding of the dependence of filter life on operating regime (flow rate, arsenic concentration and filter size) is essential. We present a mathematical model that characterises arsenic removal, circumventing the need for time-consuming experiments. The model incorporates inter- and intra-particle mass transport within the filter medium. The resulting model enables prediction of a filter lifetime in a specified role, such as on a domestic or community scale, and should assist in future filter deployment and maintenance.

Feasibility and safety of combined cytokine adsorption and continuous veno-venous hemodialysis with regional citrate anticoagulation in patients with septic shock.

Septic shock is characterized by severe metabolic and hemodynamic alterations. It is often accompanied by acute kidney injury. A new adjunct treatment is hemoadsorption using a cytokine adsorber in line with continuous veno-venous renal replacement therapy. We studied the feasibility, efficacy, and safety of cytokine adsorption with citrate-anticoagulated continuous veno-venous hemodialysis (regional citrate anticoagulation-continuous veno-venous hemodialysis). In 11 patients with septic shock and acute kidney injury stage 3, we studied 12 cycles of cytokine adsorption and regional citrate anticoagulation-continuous veno-venous hemodialysis. We monitored parameters of citrate anticoagulation, circuit lifetime, laboratory parameters, hemodynamics, and vasopressor demand. Ten out of 12 adsorber/continuous veno-venous hemodialysis circuits reached the target lifetime of 24 h for the adsorber. One system clotted and one was stopped for non-device-related reasons. Nine of the remaining continuous renal replacement therapy circuits reached 72 h lifetime. With default settings for regional citrate anticoagulation, serum ionized calcium and pH were in the normal range. Urea and creatinine were reduced significantly, and norepinephrine dose decreased from 0.47 (±0.09) to 0.16 (±0.04) µg/kg/min (p = 0.016) after 24 h. We show that combined cytokine adsorption/continuous veno-venous hemodialysis is effective to control pH, to reduce urea and creatinine, and to improve hemodynamics by reducing norepinephrine doses in patients with septic shock. It can be applied safely with standard settings of regional citrate anticoagulation rendering sufficiently long filter lifetimes for the adsorber and the continuous veno-venous hemodialysis circuit. Further studies are on the way to investigate whether these effects translate into improved outcomes in septic shock patients.

Oil-treated pleated fibrous air filters for motor vehicle engine intake application

In this work, oil-treated pleated fibrous air filters were developed, characterized, and evaluated for motorcycle engine intake application. The effect of pleat geometry on the filtration performance was examined. Pleat pitch and pleat height were found to play important roles in determining the filtration efficiency, pressure drop, and dust holding capacity. A pleated fibrous filter prepared with optimum levels of pleat pitch and pleat height showed the best filtration performance. The treatment to the pleated filter by viscous oil yielded remarkably higher dust holding capacity and filtration efficiency, both at cleaned and clogged conditions. A statistical analysis revealed that the weight of oil played a significant role in deciding the filtration performance. The oil-treated pleated filter was installed in a commercial air intake system and its filtration performance was assessed. The filter element displayed a significant delay in evolution of pressure drop during dust loading as compared to the untreated one. However, the difference in filtration efficiency between the oil-treated and untreated filter elements was not found to be too high. Nevertheless, both of them met the standard filtration performance as per the best practices followed by the automotive industry. Overall, the oil treatment to cellulosic filters was found to be highly advantageous for motorcycle application. Practical implications of such air filter system were discussed in terms of service life, fuel consumption, and CO2 emission during filter life time.

Regional citrate anticoagulation for continuous renal replacement therapy.

The delivery of an effective dialysis dose in continuous renal replacement therapy (CRRT) depends on adequate anticoagulation of the extracorporeal circuit. In most patients, either systemic heparin anticoagulation (SHA) or regional citrate anticoagulation (RCA) is used. This review will outline the basics and rationale of RCA and summarize data on safety and efficacy of both techniques. The basic principle of RCA is to reduce the level of ionized calcium in the extracorporeal circuit via infusion of citrate. This way, effective anticoagulation restricted to the extracorporeal circuit is achieved. SHA and RCA were compared in a variety of studies. RCA significantly prolonged filter lifetime, reduced bleeding complications and provided excellent control of uremia and acid-base status. RCA was also safe in the majority of patients with impaired liver function, whereas caution must be exerted in those with severe multiorgan failure and persistent hyperlactatemia. RCA per se is safe and effective for anticoagulation of CRRT. Compared to SHA, efficacy of anticoagulation is improved and adverse effects are reduced. RCA can be recommended as the anticoagulation mode of choice for CRRT in most ICU patients.

Study on Filter Efficiency and Lifetime Enhancement by using Internal Structures

Study on Filter Efficiency and Lifetime Enhancement by using Internal Structures

Membrane filtration with complex branching pore morphology

An idealized first-principles model describing filtration of a feed solution containing small particles in a microstructured porous membrane is presented. Optimal configurations for the pore microstructure are identified in terms of maximizing throughput of filtered fluid and filter lifetime.

Calculation of Filter Lifetime Using Empirical Model Applied to Hydrodynamic Column for Phosphate Removal from Greywater

Greywater is one of the point source pollution that negatively impact water resources if not properly treated. However, improvement of greywater quality can be potentially used for irrigation purpose. The main objective of this study is to calculate the lifetime for calcined waste mussel shell (CWMS) in hydrodynamic column. This study was performed using laboratory scale hydrodynamic column filled with CWMS to determine the breakthrough curve, adsorption capacity, accumulation rate and lifetime using empirical model for the adsorption of PO4-3 onto CWMS from greywater. The bed height and flow rate that used in the experiment are 200 mm and 80 mL/h, respectively. The results demonstrate that breakthrough and exhaustion times are 12h and 18h, respectively. The empirical model was verified using experimental equilibrium data. The values of k1 and qmax calculated using model equations are 0.122 mg/g h2 and 0.0017 mg/g, respectively. On the basis of the results, CWMS can be economically basis media used as an adsorbent for the removal of PO4-3 from greywater in the hydrodynamic column.

Clinical impact of regional citrate anticoagulation in continuous renal replacement therapy in critically ill patients.

Regional citrate anticoagulation (RCA) is being used increasingly in continuous renal replacement therapy (CRRT) as a safer alternative to heparin. However, complex metabolic control to avoid side effects have generated discrepancies about its introduction into everyday practice. We aimed to compare both anticoagulation techniques in terms of efficacy, safety and feasibility. Observational retrospective study performed in 3 specialized ICUs in patients receiving CVVHDF with RCA between January 2013 and May 2016. Heparin-treated patients matched by age, sex and disease severity treated in the preceding year were selected as historic controls. Filter lifetime, number of filters used, haemorrhagic complications and metabolic complications were recorded. 54 patients (27 treated with RCA and 27 with heparin) were included in the study. Filter lifetimes in the first 72 hours were 55.1 ± 21.8 hours in the RCA group compared to 38.8 ± 24.8 hours in the heparin group, (p = 0.004). In addition, the number of filters used in the first 72 hours was significantly higher in the heparin group (2.4 ± 1.3 vs. 1.5 ± 0.7; p = 0.004). There was a trend toward a lower incidence of bleeding in the RCA group, with a significantly lower red blood cell transfusion rate (p = 0.027) in the citrate group. No clinically significant metabolic disturbances were observed in the RCA group. Regarding outcomes, there were no significant differences between groups. These results suggest that the implementation of CVVHDF with RCA using concentrated citrate solutions prolongs filter lifetime, achieves a longer effective hemodiafiltration time and is a safe and feasible method.

Elimination Rates of Electrolytes, Vitamins, and Trace Elements during Continuous Renal Replacement Therapy with Citrate Continuous Veno-Venous Hemodialysis: Influence of Filter Lifetime

Background/Aims: During continuous renal replacement therapy, relevant losses of nutritional substrates, vitamins, and trace elements via the filter may occur. We investigated filter lifetime efficiency during a 72-h treatment period. Methods: This prospective study included 40 patients undergoing citrate continuous veno-venous hemodialysis (CVVHD). The elimination rates were measured at 24, 48, and 72 h. To assess the influence of filter lifetime, we determined substrate loss every 24 h over a 72-h interval. Results: Filter lifetime did not affect the loss of ionized calcium, inorganic phosphate, magnesium, zinc, folic acid, and vitamin B12. Nevertheless, we did observe clinically significant loss of ionized calcium and inorganic phosphate during CVVHD that required supplementation. Conclusions: CVVHD leads to significant loss of ionized calcium and inorganic phosphate that is independent of the filter lifetime.

Characterization of the relationship between ceramic pot filter water production and turbidity in source water

Ceramic pot filters represent a common and effective household water treatment technology in developing countries, but factors impacting water production rate are not well-known. Turbidity of source water may be principal indicator in characterizing the filter's lifetime in terms of water production capacity. A flow rate study was conducted by creating four controlled scenarios with different turbidities, and influent and effluent water samples were tested for total suspended solids and particle size distribution. A relationship between average flow rate and turbidity was identified with a negative linear trend of 50 mLh−1/NTU. Also, a positive linear relationship was found between the initial flow rate of the filters and average flow rate calculated over the 23 day life of the experiment. Therefore, it was possible to establish a method to estimate the average flow rate given the initial flow rate and the turbidity in the influent water source, and to back calculate the maximum average turbidity that would need to be maintained in order to achieve a specific average flow rate. However, long-term investigations should be conducted to assess how these relationships change over the expected CPF lifetime. CPFs rejected fine suspended particles (below 75 μm), especially particles with diameters between 0.375 μm and 10 μm. The results confirmed that ceramic pot filters are able to effectively reduce turbidity, but pretreatment of influent water should be performed to avoid premature failure.

Loading of fibrous filter media and newly designed filter configurations by salt particles: An experimental study

Various fibrous filter media, including surface filter media, depth filter media, woven and nonwoven filter media, were tested and particle loading capacity was calculated using bench‐scale setup via a new estimation approach which was proposed and experimentally verified with Novick‐Kozeny model. Multi‐element structured arrays (MESAs) developed by our research group were evaluated as well for particle loading capacity and filter lifetime on 24″ × 24″ full scale test rig (based on ASHRAE 52.2 Standard). Effects of varying filter media type, filter depth, pleat count and MESAs' element count on salt particle loading performance were experimentally investigated. The experimental studies showed that nonwoven activated carbon fiber filter media have allowed significantly higher salt particle loading capacity and longer useful lifetime compared to woven or nanofiber entrapped media. Furthermore, MESAs were able to significantly enhance loading capacity for salt particles and useful lifetime due to higher filtration area and lower filtration velocity. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3739–3750, 2016