Water Filtration Process Research Articles

Co-selective effect of dissolved organic matter and chlorine on the bacterial community and their antibiotic resistance in biofilm of drinking water distribution pipes

The proliferation of pathogenic bacteria and antibiotic resistance genes (ARGs) in the biofilm of drinking water distribution pipes poses a serious threat to human health. This work adopted 15 polyethylene (PE) pipes to study the co-selective effect of dissolved organic matter (DOM) and chlorine on the bacterial community and their antibiotic resistance in biofilm. The results indicated that ozone and granular activated carbon (O3-GAC) filtration effectively removed lignins and proteins from DOM, and chlorine disinfection eliminated carbohydrate and unsaturated hydrocarbons, which both contributed to the inhibition of bacterial growth and biofilm formation. After O3-GAC and disinfection treatment, Porphyrobacter, unclassified_d_bacteria, and Sphingopyxis dominated in the biofilm bacterial community. Correspondingly, the bacterial metabolism pathways, including the phosphotransferase system, phenylalanine, tyrosine and tryptophan biosynthesis, ABC transporters, and starch and sucrose metabolism, were downregulated significantly (p < 0.05), compared to the sand filtration treatment. Under such a situation, extracellular polymeric substances (EPS) secretion was inhibited in biofilm after O3-GAC and disinfection treatment, postponing the interaction between EPS protein and pipe surface, preventing bacteria, especially pathogens, from adhering to the pipe surface to form biofilm, and restraining the spread of ARGs. This study revealed the effects of various water filtration and disinfection processes on bacterial growth, metabolism, and biofilm formation on a molecular level, and validated that the O3-GAC filtration followed by chlorine disinfection is an effective and promising pathway to control the microbial risk of drinking water.

Start-up of biofilter for nitrification and effect of filtration rate on the ammonium removal efficiency in drinking water treatment on pilot plant

ABSTRACT Biological filtration is a process that can be used for ammonium removal from water. The removal of ammonium is based on the nitrification process. Nitrification depends on many factors, such as water quality and filtration process parameters. To investigate the influence of filtration rate on the nitrification efficiency, nitrifying biofilters were formed at the pilot plant in the industry for drinking water production from surface water. The new biological filters were started under optimal conditions for biofilm formation. After the biofilm formation, the influence of the filtration rate on nitrification was examined over 3 months (from November to January). The time required for the spontaneous growth of nitrifying bacteria on the new filters was around 70 days. The operating conditions at the start-up period were the continuous flow of water containing γ(NH4+) ≈ 1mg/L, dissolved oxygen in a concentration &amp;gt;9 mg/L, filtration rate &amp;lt;1 m/h, inlet water temperature &amp;gt;12 °C and pH from 7.8 to 8. After the complete formation of the nitrifying biofilm, the percentage of NH4+ removal was greater than 95% for all tested filtration rates, from 0.5 to 8.4 m/h, at γ(NH4+) from 1 to 2.5 mg/L and raw water temperature from 13 to 7°C.

Super hydrophobic PU sponge modified by poly-vinylidene fluoride/SBA-15@NPS hybrid

ABSTRACT In the present work, we try to design and prepare super-hydrophobic, porous, and activated polyurethane (PU) sponge based on physical and chemical surface coating method. The superhydrophobic sponge was effectively modified utilizing nanoporous carbon (NPC), Santa Barbara Amorphous-15 (SBA-15), and polyvinylidene fluoride (PVDF) to separation of oil compounds from water. Incorporating of NPC/SBA nanohybrid with sponge provides a proper functional group and large surface area on 3D structure of the PU sponge. Application of PVDF has been used to change the hydrophobic/hydrophilic properties of PU sponge surface. FT-IR, XRD, BET, SEM, EDS, and contact angle were used for characterization of the prepared modified sponge. To determine the separation efficiency of modified sponge, a set of experiments at different organic solvents, time, and temperatures were designed and performed. Applying NPC/SBA nanohybrid in the role of adsorbent will certainly increase separation efficiency of sponge. We believe that composition of NPC, SBA-15, and PVDF could be a considerable candidate in oil/water separation, especially in oil/gas company waste water treatment and filtration processes.

Polymeric Membranes Doped with Halloysite Nanotubes Imaged using Proton Microbeam Microscopy.

Polymeric membranes are useful tools for water filtration processes, with their performance strongly dependent on the presence of hydrophilic dopants. In this study, polyaniline (PANI)-capped aluminosilicate (halloysite) nanotubes (HNTs) are dispersed into polyether sulfone (PES), with concentrations ranging from 0.5 to 1.5 wt%, to modify the properties of the PES membrane. Both undoped and HNT-doped PES membranes are investigated in terms of wettability (static and time-dependent contact angle), permeance, mechanical resistance, and morphology (using scanning electron microscopy (SEM)). The higher water permeance observed for the PES membranes incorporating PANI-capped HNTs is, finally, assessed and discussed vis-à-vis the real distribution of HNTs. Indeed, the imaging and characterization in terms of composition, spatial arrangement, and counting of HNTs embedded within the polymeric matrix are demonstrated using non-destructive Micro Particle Induced X-ray Emission (µ-PIXE) and Scanning Transmission Ion Microscopy (STIM) techniques. This approach not only exhibits the unique ability to detect/highlight the distribution of HNTs incorporated throughout the whole thickness of polymer membranes and provide volumetric morphological information consistent with SEM imaging, but also overcomes the limits of the most common analytical techniques exploiting electron probes. These aspects are comprehensively discussed in terms of practical analysis advantages.

Surface modification of NF membrane via an environmentally friendly and rapid approach for desalination Process: Performance and stability evaluation

In this study, an environmentally friendly and rapid surface modification method known as surface mineralization was adopted to alter the polyamide (PA) layer of commercial NF270 thin film composite (TFC) membrane, aiming to improve its characteristics for enhanced desalination process. An alternate soaking process was applied on the membrane surface by using barium chloride solution and sodium sulfate solution at varying concentrations (0.01 M, 0.05 M and 0.1 M). The reaction of these two salts can form a layer of barium sulfate (BaSO4) minerals atop the PA layer via an ionic interaction. Our result revealed that the best-performing membrane could be developed using salt solutions at 0.05 M with its water contact angle descended to 33.5° compared to the pristine membrane of 46.4°. Furthermore, the surface roughness of the BaSO4-mineralized membrane was reported to be higher than the pristine membrane. The increase in surface roughness together with improved surface hydrophilicity yielded the BaSO4-mineralized membrane to exhibit 12% higher water flux than the pristine membrane. Nonetheless, the difference in Na2SO4 rejection before and after surface mineralization was not found to be statistically significant owing to the high Na2SO4 rejection of the control membrane. The BaSO4-mineralized membrane also achieved excellent performance in filtering solutions containing sodium alginate and showed very stable salt rejection for multiple cycle of combined chemical cleaning and water filtration process. These results highlighted the potential of the surface mineralization process in overcoming the trade-off effect between water flux and selectivity of TFC membrane.

Exploring the impact of PVC and PVA microplastics on zebrafish tissue using multi-spectral imaging, Optical Coherence Tomography (OCT) and biospeckle OCT (bOCT)

Plastics are widely used in industry and households, but improper disposal has caused their accumulation in aquatic systems worldwide. As a result, mechanical and photochemical processes break down these plastics into microplastics or nano plastics, posing a severe threat to marine organisms and humans as they enter the food chain. This study investigates the effect of Polyvinyl chloride (PVC) and Polyvinyl alcohol (PVA) microplastics in zebrafish by using multi-spectral imaging (MSI), Optical Coherence Tomography (OCT), and Biospeckle OCT (bOCT). These techniques allow for long-term studies in the fish without invasive procedures in real-time. Zebrafish were exposed to Nile red labeled PVC and PVA for 21 days with 500mg/L concentration. Image acquisition and analysis were performed every five days till the end of the study. MSI images revealed deposition of microplastics in the gills region of the fish; some diffused deposition was seen throughout the body in the PVA group towards the end of the experiment. The effect of these MPs on the structure of the gills and their exact location was determined by capturing OCT images. bOCT was used to determine the average speckle contrast for all the OCT images to determine the change in biological activity within the gills region. An increase in bioscpeckle contrast was observed for the MPs treated groups compared to the control group. PVC appeared to cause a more considerable rise in activity compared to PVA. The results indicated that the MPs exert stress on the gills and increase activity within the gills, possibly due to the blockage of the gills and disruption of the water filtration process, which could be monitored non-invasively only by using bOCT. Overall, our study demonstrates the usefulness of non-invasive, robust techniques like MSI, bOCT, and biospeckle for long-term zebrafish studies and real-time analyses.

Effect of molecular dynamics water models on flux, diffusivity, and ion dynamics for polyamide membrane simulations

While molecular dynamics (MD) models for reverse osmosis (RO) and nanofiltration (NF) membranes are useful for studying water filtration processes, the specific water model and force-field parameters have a profound impact on key measures such as flux and diffusivity. Moreover, ensemble related parameters such as temperature and how it is controlled via a thermostat also affect simulation results. To quantify these effects, we investigate the performance of three commonly used water models, SPC/E, TIP3P, and TIP4P, in simulating an NF membrane system at varying temperatures and thermostat settings. All three water models successfully capture the Arrhenius relationship between water diffusivity and temperature as well as the linear relationship between water flux through the membrane and water diffusivity in the membrane. However, SPC/E underpredicts, TIP3P overpredicts, and TIP4P most accurately reproduces the water dynamics, especially water self-diffusivity, compared to experiments. We also investigate the effect of the water model on common salt solutions at various concentrations. TIP4P generally outperforms the other two water models when describing ion diffusivities and water solvation shells around ions. These findings indicate that TIP4P is an appropriate water model to use in polyamide membrane MD simulations.

ОБҐРУНТУВАННЯ ПАРАМЕТРІВ АНКЕРНОГО КРІПЛЕННЯ ПІДГОТОВЧИХ ВИРОБОК В УМОВАХ ІНТЕНСИВНИХ ВОДОПРИПЛИВІВ

Purpose. Improvement of the method of reducing water inflows into mine workings with using com-bined frame-roof bolting to ensure the stability of the mine workings, waterproofing and protection against the collapse of wet contour rocks inside the mine workings. Methods. When solving the problem of water filtration in deformed rock, the method of studying the state of a layered rock massif with a mine working in the presence of water-saturated layers in its vicinity, which was developed by the authors, as well as the finite element method, were used. Research results. As a result of the calculations, the stress values, the zones of inelastic defor-mations, the values of permeability coefficients, water pressure and water inflows have been obtained for the roadways supported with different number of roof bolts. It is shown that the number of roof bolts af-fects all these parameters around the roadway in the rock mass and in the water-saturated seam. If a larg-er number of roof bolts are installed, the processes of crack formation and, accordingly, rock fracturing are slower. After mining, if 3 or more roof bolts installed, intensity of water filtration process is minimal, but after 2-3 days water from the water-saturated seam begins to penetrate deep into the surrounding rocks. Roof bolting significantly reduces these processes, the using of a scheme with 5-9 roof bolts re-strains the movement of water and, most importantly, practically isolates the roadway from water-saturated rocks. Scientific novelty. For the first time, a numerical model has been created and the calculations have been completed for roadways supported with 1-9 roof bolts in conditions of intensive inflows over time from the moment of its building. Practical significance. Research and calculations make it possible to obtain a significant economic effect due to the setting of the optimal number of roof bolts and the reduction of the use of materials for supporting the roadway and, at the same time, to prevent water inflows and increase the stability of road-ways.

Desain Prototype Alat Filtrasi Sederhana dari Limbah Galon Air untuk Pembuatan Penyaringan Air Rumah Tangga

This study reports on the utilization of gallons of water used as containers for household-scale water purification filtration devices. The method of making a filtration device is by making a tap hole (outlet) at the bottom of the gallon and then putting in a filter material consisting of gravel, fine sand, charcoal, coarse sand, sponges, and palm fibre. A water filtration system by entering the water in the top hole of the gallon and the filtered water results are located at the bottom of the gallon that has been given a faucet. Based on the results of this study, it is shown that a gallon waste water-based filtration system is effective in the water filtration process at housing X in Kendari City. Test parameters consisting of turbidity, color, total dissolved solids (TDS), acidity (pH), and iron (Fe) content showed that the decrease in content that occurred in each turbidity test was 56.77%, color 33.33%, TDS 33.61%, the pH level increased by 4.21% (7.37 to 7.68) due to the effect of reduced levels of carbon dioxide (CO2) in water from the filtration process and categorized as water that is suitable for health. Fe levels did not change significantly, where there was an increase of 1.2% (25.7 × 10-4 mg.L-1 to 26.0 × 10-4 mg.L-1). The results of this study illustrate that gallons of water waste can be used as a material for making simple filtration equipment for household-scale water filtration processes.

Synthesis of Magnetic Nanosilica Material Based on River Sand to Improve Water Quality

Research has been carried out on the synthesis of river sand-based nanosilica magnetic material to improve water quality by utilizing iron sand taken from four rivers in the Lombok island region as a natural material for the water filtration process, this study aims to determine whether the iron sand nanosilica magnetic material able to improve the quality of well water or not. This study uses an experimental method where iron sand has gone through the coprecipitation process and the water quality parameters measured are temperature, pH and conductivity. The measurement results showed that well water after being mixed with iron sand decreased for temperature and conductivity parameters and increased for pH parameters. Of the three parameters, only one parameter does not meet the water quality standard requirements, namely the pH value before being mixed with iron sand which is below the standard, which is 6.32. However, after the well water was mixed with the four samples of river iron sand, the pH value increased to 7.99, 7.85, 7.75, and 8.00 so that it was able to meet water quality standards for pH parameters.

Anthracite Releases Aromatic Carbons and Reacts with Chlorine to Form Disinfection Byproducts in Drinking Water Production.

Anthracite is globally used as a filter material for water purification. Herein, it was found that up to 15 disinfection byproducts (DBPs) were formed in the chlorination of anthracite-filtered pure water, while the levels of DBPs were below the detection limit in the chlorination of zeolite-, quartz sand-, and porcelain sandstone-filtered pure water. In new-anthracite-filtered water, the levels of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), and ammonia nitrogen (NH3-N) ranged from 266.3 to 305.4 μg/L, 37 to 61 μg/L, and 8.6 to 17.1 μg/L, respectively. In aged anthracite (collected from a filter at a DWTP after one year of operation) filtered water, the levels of the above substances ranged from 475.1 to 597.5 μg/L, 62.1 to 125.6 μg/L, and 14 to 28.9 μg/L, respectively. Anthracite would release dissolved substances into filtered water, and aged anthracite releases more substances than new anthracite. The released organics were partly (around 5%) composed by the μg/L level of toxic and carcinogenic aromatic carbons including pyridine, paraxylene, benzene, naphthalene, and phenanthrene, while over 95% of the released organics could not be identified. Organic carbon may be torn off from the carbon skeleton structure of anthracite due to hydrodynamic force in the water filtration process.

Analisis Manajemen Rantai Pasok (Supply Chain) Industri Sagu Kabupaten Kepulauan Meranti (Studi Kasus PT. Nasional Sago Prima)

The research objective was to analyze the supply chain of the sago industry in the Meranti Islands Regency. Case Study PT. Nasional Sago Prima (PT. NSP). The research was carried out in March - October 2020. The research method was a survey. The analysis used: qualitative and quantitative. Qualitative analysis to describe the mechanism and flow pattern of the supply chain for the sago industry. Meanwhile, quantitative analysis is used to analyze components and supply chain activities. The results showed: 1). The supply chain mechanism for the sago industry that occurs is the creation of collaboration and coordination between supply chain actors from upstream to downstream. The flow pattern of the supply chain, which consists of raw material flow, product flow, financial flow and information flow, went smoothly. 2). The resistance of the supply chain for the sago flour industry are: A). 70% of the raw material for sago tual is supplied from outside the company, because the nucleus plantations have not yet entered the full harvest period. B). Inefficient processing costs due to: the cost of using electricity and the high cost of water filtration processes.

Predictive modelling of a rapid stratified bed filter for turbidity removal from surface water

The objective of the present work was to evaluate the hydrodynamic behaviour of a stratified bed filtration column consisting of 4 cm of sand and 2 cm of limestone to remove turbidity and measuring the head loss through the filter in several runs. In this study, two types of sand were used as filtering bed material, one fine and one medium. Crushed limestone was also available. These materials were characterized to determine the average particle diameter, porosity, and permeability coefficient. These were respectively 1.7∙10 –4 m, 336.96 and 0.68 m∙day –1 for fine sand, 3.3∙10 –4 m, 654.24 and 2.59 m∙day –1 for the medium sand and 1.26∙10–3 m, 388.8 and 8.64 m∙day–1 for crushed limestone. Using these materials, hydrodynamic analyses were carried out using clean water under rapid filtration conditions. In these analyses, different filtration rates were determined to be used in each experiment. Once the filtration rates were determined, the filtration analysis was performed with synthetic turbid water prepared at 8 NTU using tap water and bentonite. From the results obtained, a predictive model was developed based on total head losses for the evaluated filter, maintaining the rapid filtration condition. As a result, a turbidity removal efficiency of 97.7% was obtained with a total head loss of 17.8 cm at a filtration rate of 153 m·day –1. The developed model predicted head loss as a function of operating time, filtration rate, and filter depth to maximise turbidity removal. The model showed excellent prediction accuracy with R2 of 0.9999, which indicates that the model predictions are not biased. It was concluded that, due to the porosity of these materials, a stratified bed of sedimentary rocks has a great potential to be used in surface water filtration processes, which implies that it could be used at the rural community level as a form of water treatment, since the

A Literature Review of Modelling and Experimental Studies of Water Treatment by Adsorption Processes on Nanomaterials.

A significant growth in the future demand for water resources is expected. Hence researchers have focused on finding new technologies to develop water filtration systems by using experimental and simulation methods. These developments were mainly on membrane-based separation technology, and photocatalytic degradation of organic pollutants which play an important role in wastewater treatment by means of adsorption technology. In this work, we provide valuable critical review of the latest experimental and simulation methods on wastewater treatment by adsorption on nanomaterials for the removal of pollutants. First, we review the wastewater treatment processes that were carried out using membranes and nanoparticles. These processes are highlighted and discussed in detail according to the rate of pollutant expulsion, the adsorption capacity, and the effect of adsorption on nanoscale surfaces. Then we review the role of the adsorption process in the photocatalytic degradation of pollutants in wastewater. We summarise the comparison based on decomposition ratios and degradation efficiency of pollutants. Therefore, the present article gives an evidence-based review of the rapid development of experimental and theoretical studies on wastewater treatment by adsorption processes. Lastly, the future direction of adsorption methods on water filtration processes is indicated.

Analisis Spektrofotometri Serapan Atom pada Penjernihan Air Sumur Bor di Desa Sekernan

Cloudy borehole water if done by filtering method with filtration by sand, charcoal, palm fiber, coral and husks can produce clear water. In the purification process can remove turbidity, color, metal Mn about 98.66 % and Fe around 99,50 %. Zeolite is a mineral that is used as an adsorbent, ion exchanger or catalyst. Zeolite in rice husk ash contains high silica content of 87%-97% and coal ash 50%-69% which is used as an ingredient in the manufacture of zeolite. This study aims to determine the zeolite made from rice husk ash and coal can reduce Fe and Mn levels. Based on the test results of the Health Laboratory Office, samples of water from drilled wells in Sekernan village, RT. 11 with the results of Fe content of 0.475 mg/l and Mn content of 0.380 mg/l. The use of borehole water which has a high metal content for drinking water, bathing and washing can cause a person to suffer from stomach ailments such as diarrhea, skin diseases, such as itching and so on. This research is an experimental study. The results of the water filtration process are left for 30-60 minutes. Furthermore, the water was tested for Fe and Mn levels using Atomic Absorption Spectrophotometry (AAS). The results of the AAS analysis showed that the previous Fe level decreased from 0.475 mg/l to &lt; 0.08 mg/l and the previous Mn level was 0.380 mg/l to &lt; 0.03 mg/l. The purification of borehole water with filtration method can produce clear water. Analysis of the AAS test made from zeolite can reduce the metal content of Mn by about 98.66% and Fe by about 99.50%.

Graphene‐Based Bacterial Filtration via Electrostatic Adsorption

AbstractFlexible graphene oxide (GO) microsheets with attached positively charged polymers, termed GOX microsheets, are efficient at bacterial adsorption, as they bind electrostatically to bacterial membranes’ negative surface charge. The authors explore an antimicrobial water filter application for GOX's extremely high surface area and its previously described efficient bacterial adsorption.Cellulose‐fiber carrier material is functionalized with GOX microsheets to create an adsorption‐based bacteria filtration material. The morphology and charge density (7.8 × 1019 g–1) of the prepared GOX fibers are determined by scanning electron microscopy and dye adsorption assay, and widefield fluorescence microscopy is used to visualize the adsorption of stained Escherichia coli bacterial cells on the fibers. GOX fibers are tested in filtration setups to investigate their bacteria removal performance. The experimental results, with 100 mg of GOX fibers filtering 2.4 × 109 colony‐forming units (CFU) from an E. coli bacterial culture with 99.5% bacterial reduction, demonstrate the fibers’ high bacteria loading capacity. The electrostatic adsorption‐based filtration mechanism allows the filter to be operated at higher flow rates than micropore membrane filters, while maintaining 3‐log bacterial reduction. GOX filter materials removing bacteria via adsorption are a high flow rate alternative to current water filtration processes that rely on size‐exclusion.

A Steady Flow of The Viscous Compressible Liquid in Vertical Pipe

In the study of the flow of gas-liquid mixture over circular vertical pipe rising from the deep zone to ground level, it is observed that, the velocity on surface of tube is much more than in the center of flow. Such a picture is seen also in the water filtration process in sands ordering from high permeability zone to lower. Same phenomena occur in transportation of the water carbon nana-tubes. In order to predict behavior of those processes in this paper, we have studied the compressible liquid flow over the circular vertical pipe ordered from the deep zone to the ground surface for some concrete inlet and outlet regimes of the pipe. The Navier-Stokes equations system as a model of study. For certain inlet and outlet regimes of the flow splitting the equation into the cross section and axes variables, the pressure and velocity distribution are found. The Lane-Emden equation arises for determining the pipe cross section velocity distribution, which is also justified by our calculations on the used model.

Tailoring the properties of polyamide thin film membrane with layered double hydroxide nanoclay for enhancement in water separation

This current paper presented a new candidate and potentially to improve the current membrane materials in water filtration process. With that, the primary materials used in this research study is layered double hydroxides (LDH) nanoclay which can be obtained from earth minerals and self-synthesized from inorganic salts were discussed thoroughly to help a better understanding of these materials. However, the current technologies of water separation were still lagging behind and ineffective especially in removal of divalent metal ions and multivalent salts. Infeasibility of reverse osmosis membrane make it not a viable option for divalent salts filtration. With that, nanofiltration (NF) membrane offered as an alternative to substitute available method. In this study, thin film nanocomposite (TFN) membranes were fabricated by incorporating layered double hydroxides (LDH) nanoclay. The LDH nanoclay with different loading ratio of 0, 0.05, 0.1, 0.15 and 0.2 were impregnated into polyamide layer on top of polysulfone substrates. The fabricated TFN were characterized in terms of physicochemical properties (SEM and FTIR) and membrane hydrophilicity (contact angle). After the addition of LDH, the morphological structures of TFN membranes were changed and the surface hydrophilicity was enhanced significantly. FESEM images displayed a typical ridge and valley morphology with nodule-like structures. As the LDH loading was increased, the contact angle decreased from 34.56° to 15.76° showing the surface hydrophilicity of membrane is improved. The separation performance of membrane was evaluated in terms of salt rejection ability by cross flow filtration system. The best performance NF membrane was found to be TFN 0.05 with high water flux and MgCl2 rejection with values of 24.18 L/m2.h and 91% respectively. This study has experimentally validated the potential of LDH materials in membrane process for improvement in water separation process.

Hydrodynamic evaluation of a filter bed of porous material from stratified sedimentary rocks for the removal of turbidity in surface waters

In this study, the behavior of a filter bed of stratified sedimentary rocks was evaluated through the analysis of turbidity removal efficiency and head losses. Two types of sands were used as materials, fine and medium, as well as crushed limestone. The materials were characterized to determine the average particle diameter, porosity, and permeability coefficient, obtaining respectively 0.17 mm, 0.39, and 1 × 10−3 cm/s for fine sand, 0.33 mm, 0.41, and 3 × 10−3 cm/s for medium sand, and 1.26 mm, 0.45, and 1 × 10−2 cm/s for crushed limestone. Hydrodynamic analyses of the clean filter under conditions of rapid filtration were carried out, by which the different rates of filtration to be used in each experiment were determined, establishing a direct correlation between the rate of filtration and the thickness of the bed; in this way, it was possible to determine the maximum bed thickness that could be used to maintain a rate of rapid filtration higher than 120 m/day. A hydrodynamic study with synthetic turbid water prepared at 8 NTU using tap water and bentonite was also carried out. Total head losses and turbidity removal were studied for each material at a rate of 153 m/day with removal efficiencies of 93.7% for medium sand with a loss of 23 cm and 67.8% for limestone with a loss of 4.5 cm and a rate of 389 m/day. It is recommended to use the medium sand and limestone type material for use in surface water filtration processes.

Heavy metal and organic pollutants removal from water using bilayered polydopamine composite of sandwiched graphene Nanosheets: One solution for two obstacles

The swift and unprogrammed industrial development has engendered several human hazards, including water contamination by heavy metals (Pb2+ and Hg2+) and organic pollutants largely added by agricultural operations (pesticide sprays). The deleterious effects of these contaminants have been extensively studied, highlighting the need for an efficient, quick, and targeted water treatment process. We built a cellulose graphene material sandwiched between double layered polydopamine (PDM) metal–organic framework (MOF). The composite material efficiently removed two water contaminants, i.e., heavy metals (Pb2+, and Hg2+), and persistent organic pollutants-POPs (PCB44 (2,2′,3,5′-tetrachlorobiphenyl), and gamma-HCH (1,2,3,4,5,6-Hexachlorocyclohexane)). The material was proved a highly stable metal–organic MOF composite (FeBT-PDM21/CG20) under dynamic physical conditions (pH 2–12 and temperature 4–65 °C). The extrinsic porosity in the bilayered MOF was due to internally pinned PDM, porous for water, and binds 1758 mg of Hg2+, 488 mg Pb2+, 673 mg PCB 44, and 596 mg gamma-HCH per gram of the composite material. Water samples with a one ppm standard concentration of each contaminant were cleaned up to the drinking level after just one adsorption cycle with the MOF. The material effectively adsorbed persistent organic pollutants (POPs), leaving no detectable graphene traces in water. The novelty of the material lies in the quick water filtration process (1 mL/min by 1 cm2 of material area) up to the drinking water quality. Furthermore, the cleaning property remained persistent at different physical conditions, including pH. Moreover, the material proved stable and robust during lab assays.