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Microplastics (MPs) have been detected in drinking water and raw water sources. Therefore, it is important to know the performance of drinking water treatment process. The rapid sand filter (RSF) is one of the water treatments that can be an alternative treatment in removing MPs after several configuration processes (pre-sedimentation, coagulation-flocculation, and sedimentation). This study aims to determine the effectiveness of RSF to remove MPs. The artificial samples were made from plastics bags and tyre flakes, with sizes from 10 μm to more than 500 μm. Bentonite was added to represent turbidity in the water. The average removal efficiency of plastics flakes before entering the filter was 50.48% (using bentonite) and 47.78% (without bentonite). Overall, the removal efficiency for the tyre flakes was 90.72% (using bentonite) and 93.03% (without bentonite). The filtration used in this study was varied between 4 and 10 m/h. Removal efficiency using RSF for plastic flakes on which the Effective Size (ES) filter media 0.39 mm was 97.7% and on which ES 0.68 mm was 94.3%. Meanwhile, the removal efficiency of the tyre flakes for ES 0.39 mm were 90.6% and ES 0.68 mm was 85.2%. However, in this study, RSF mostly removed MPs particles greater than 200 μm in size.

Helicobacter pylori is a microorganism that infects 60% of the population and is considered the main cause of atrophic gastritis, gastric and duodenal ulcers, and gastric cancer. Different emerging pathogens have been found in drinking water and their presence is considered to be an important public health problem. For this reason, it is necessary to carry out the validation of reliable technologies for this type of pathogens and evaluate their performance. This paper reports, for the first time, H. pylori reduction in a drinking water pilot plant of two slow sand filters (SSF). Inlet water was taken from a gravel filtration system of a rural water supply in Colombia and then inoculated with viable cells of H. pylori . By determining the Genomic Units (GU) through quantitative Polymerase Chain Reaction (qPCR), the concentration of GU/sample was measured. In the inlet water amplification for SSF1 and SSF2 were 5.13 × 10 2  ± 4.48 × 10 2 and 6.59 × 10 2  ± 7.32 × 10 2 , respectively, while for the treated water they were 7.0 ± 5.6 and 2.05 × 10 1  ± 2.9 × 10 1 GU/sample for SSF1 and SSF2, respectively. The SSF pilot plant reached up to 3 log reduction units of H. pylori ; therefore, since there is not an H. pylori contamination indicator and its periodic monitoring is financially complicated, the SSF could guarantee the drinking water quality necessity that exists in rural areas and small municipalities in developing countries, where infection rates and prevalence of this pathogen are high.

Among the available technologies, the dyna-sand filter has gained attention due to its continuous filtration and sand washing mechanism, which provides an advantage in maintaining stable operation. Nevertheless, its performance under variable heights of washout weir with constant solid loads and the optimization of its washing system remain areas that require further study. This study investigates the use of the dyna-sand filter in water treatment facilities, focusing on the alteration of the washout weir to improve efficiency and reduce washout water amount. The study evaluates the filter’s performance under fixed influent total suspended solids (TSS) concentration and constant filtration rate (ROF), aiming to demonstrate the advantages of this alteration in enhancing removal efficiency, operational stability, and water saving through a laboratory-scale pilot. The average washout discharge fell from 0.788 to 0.486 L/min, a 38.3% reduction in washout water amount. As a result, filtered water production rose by nearly 2.2%, indicating more efficient hydraulic operation. These findings confirm that raising the washout weir by 4 cm improved filtration and reduced washout water loss. This, in turn, enhanced system productivity and the quality of washwater produced, assuming a consistent flow rate and solid load.

This study investigated the performance of a granular filtration system (GFS) composed of a rock filter (RF), a rapid sand filter (RSF), and an activated carbon filter (ACF), applied to the post-treatment of an anaerobic reactor effluent. Four filtration rates (FR) were applied to the GFS (in m 3 ·m −2 ·d −1 ): 100–60-60, 100–90-90, 200–120-120, and 200–160-160, for RF-RSF-ACF, respectively. A clarified final effluent with low turbidity (~ 10 NTU), solids (~ 6.5 mg TSS.L −1 ), and organic matter content (~ 40 mg COD.L −1 ) was obtained when the GFS worked with FR up to 100–90-90 m 3 ·m −2 ·d −1 . For higher FR, the effluent quality was a little poorer. Principal component analysis showed when the RSF operated at 120 or 160 m 3 ·m −2 ·d −1 , it presented an effluent with higher turbidity which did not affect negatively the ACF performance. The hydraulic load limits in the RSF were reached in periods of 45, 30, and 24.5 h for the FR of 60, 120, and 160 m 3 ·m −2 ·d −1 , respectively, and head loss analysis depicted a more distributed solid retention through the sand depth with the lower FR. Thus, the results revealed that the RF-RSF-ACS system is a promising alternative for effluent polishing of anaerobic reactor, especially when the FR is set at 90 m 3 ·m −2 ·d −1 or even higher.

Despite the United Nations 2030 agenda, large number of both urban and rural dwellers in low-income countries continue to lack access to improved water. Thus, increased effort is required towards enhancing low-cost drinking water treatment technologies especially for developing countries. Slow sand filter (SSF) is one of the most commonly used low-cost and efficient technologies for treating household drinking water. However, effectiveness of SSF is substantially affected by very high turbidity and relatively large amounts of dissolved heavy metals. To enhance removal of both turbidity and heavy metals, this study optimized sand bed depth (SBD) of SSF and investigated the potential of natural zeolite from Uganda for removal of lead, arsenite (As(III)) and fluoride ions from water. To remove lead ions, the zeolite was used in its natural form. However, to remove As(III) and fluoride, the natural zeolite was modified using hexadecyltrimethylammonium bromide solution. Removal of high turbidity was found to require a large optimal SBD. Furthermore, efficiency of treating synthetic turbid water increased with increasing initial turbidity. Variation of final turbidity with SBD was found to be best described by an exponential function. Optimal SBDs on top of an underdrain gravel layer of 0.2 m were 453, 522, 561, and 580 mm for turbidity of 60, 80, 100, and 120 NTU, respectively. Optimized SBD used achieve at least 95% efficiency in removing suspended particles from water with turbidity 120 NTU was found to save up to 35% of the total cost for acquiring sand volume required by a conventional SSF. For a particular zeolite mass, removal efficiencies of lead, As(III) and fluoride generally increased with increasing contact time. Removal efficiencies of lead, As(III), and fluorides were also shown to increase with increasing zeolite mass. Lead removal efficiencies using natural zeolite were 75 and 98% under 20 and 40 min, respectively. Removal of As(III) using modified zeolite mass was 91% within contact time of 10 min. Adsorption of fluoride on modified zeolite was 80% within 5 min. Adsorption of lead, As(III), and fluorides indicated promising potential of natural zeolites from Uganda for treating polluted water.

Primary stage of water treatment for the human drink or for the consumption of the industry is sand filtration. This study aimed to examine the potential use of the Bakari quarzitic rocks in Lom series (Adamawa–Cameroon) as sand filters usable as import-substitute materials. Petrographically, two types of quartzite notably quartzite with coarse-grained of quartz and quartzite with fine-grained of quartz were localized in the field. These quarzitic rocks have silica contents higher than 80%. Their sand fraction is characterized physicochemical by effective size (D10) equal to 0.9 mm and uniformity coefficient (UC) equal to 1.6 mm. Their water content ranges from 0.25 to 0.51 wt%, whereas loss on ignition (LOI) and acid loss are less than 2%. With those characteristics and the smallest turbidity values after sand filtration, the Bakari quarzitic sands are efficient and are suitable as sand filters for water for human drink or for the consumption of the industries.

This study has assessed the efficiency of sand filter basins in treating urban stormwater runoff by analyzing available data in the literature, the International Stormwater BMP Database, and data collected in a sand filter basin located in the main campus of the University of Texas at San Antonio (UTSA). Ten storm events were monitored starting in March 2016 until February 2017. Total suspended solids, volatile suspended solids, nitrate, ortho-phosphate, copper, zinc, lead, pH, and conductivity were measured in the inlet and the outlet of the basin. Statistical analysis, including linear regression modeling, scatter plotting, and non-parametric testing, using data from the literature and the International Stormwater BMP Database was performed. The sand filter basin removed, on average, 94% and 86% of TSS and VSS, respectively. Such high removal rates were not observed for other constituents, with exception of lead (79%) that already showed a low mean concentration in the inlet of the basin (41.47 ± 27.41 μg/L). Nitrate and ortho-phosphate mean concentrations were not significantly different in the outlet than inlet. The basin effluent concentration of zinc was higher than acceptable stormwater benchmarks defined by EPA. The results indicated that the monitored sand filter basin met its primarily design criteria, which is TSS removal by at least 80% of mass. Better stormwater treatment practices, however, are needed to remove other pollutants more efficiently, in particular, because this area is located on top of the recharge zone of the Edwards Aquifer, a major source of water supply for the region.

The present study aimed to evaluate the water purifying capacity of three filters (local ceramic filter, imported ceramic filter and bio-sand filter) to promote the production of local filters in order to resolve not only economical but, above all, health problems. Findings from the study showed that the filtration rate of bio-sand filters (25.5 ± 2.3 l/h) was significantly higher than those of imported (1.12 ± 0.3 l/h) and local (1.23 ± 0.2 l/h) ceramic filters l/h). The results of laboratory analyses showed that ceramic filters, whether imported or locally produced, were highly effective in retaining bacteria such as total coliforms, fecal coliforms, fecal streptococci, E. coli , Shigella sp , and Salmonella sp , with retention rates between 99 and 100%. As for bio-sand filters, their capacity to retain bacteria was considerable but not consistent with guaranteeing safe water quality as defined by WHO. The three categories of filters were also effective in improving the physicochemical parameters (pH, Turbidity, Electrical Conductivity, TDS, Iron, Chlorine, Ammonia, and Aluminum) of water, to a standard accepted by WHO. However, imported ceramic filters and bio-sand filters were found to be more effective than local ceramic filters in improving certain chemical parameters. Promoting the production and effective use of locally manufactured filters could therefore constitute a logical alternative, that may contribute to solving several socio-economic, health, and environmental problems in Cameroon.

In this study, the arsenic (As) removal characteristics of a Mn–Fe binary coating formed on waste sand filter of an acid mine drainage treatment facility are investigated. Owing to the Mn–Fe binary coating forming on the surfaces of the sand grains, its potential for arsenic removal, particularly As(III), was evaluated and characterized through batch experiments and x-ray absorption spectroscopy. Sorption isotherms reveal that the Mn–Fe binary coating exhibits comparable removal efficiencies for As(III) and As(V) under low initial As concentrations. However, at higher initial As(III) and As(V) concentrations, the As(III) removal efficiency increases because of newly formed active adsorption sites from reductive dissolution of Mn. The oxidation of the As(III) and reduction of the Mn oxide phases are verified through As K-edge and Mn K-edge X-ray absorption near edge fine structure analysis. The outstanding As(III) removal efficiency of the Mn–Fe binary coating suggests synergy of Fe- and Mn-oxides, highlighting a potential application for this coating system. The natural formation of binary coating through acid mine drainage treatment reported in this study indicates that similar coating can form naturally in other environments, thus, providing plausible natural attenuation processes for arsenic immobilization.

In the present study, a simple, low-cost and user-friendly hybrid system composed of coagulation chamber (chemical treatment) followed by multi-stage filtration unit (physical treatment) was used to treat greywater for reducing organic chemical compounds and turbidity to reach the required quality standards for irrigation water. First, the optimum coagulant concentration for greywater treatment was determined. Then, the hybrid system was used to investigate the removal efficiencies of chemical oxygen demand (COD) and turbidity of greywater in optimum coagulant dose for developing the filtration unit through 49 experiments in different configurations and thicknesses varying from one to four-layer. Multilayer nonlinear machine learning model was utilized to evaluate the performance of this hybrid system and adaptive heuristic search algorithm was used to achieve the optimal configuration of multilayer sand filter using optimization technique. Results show that coagulation followed by three stages filtration unit composed of 15 cm of medium sand, 15 cm of fine sand, and 30 cm of activated carbon had the best performance with the maximum reduction of COD (90.8%) and turbidity (98.9%). Also, electrical conductivity and pH of treated greywater have been in the normal range for irrigation use. Based on the optimization-simulation model and experimental results, coagulation process followed by a filtration unit consisting of 17 cm of fine sand, 9 cm of medium sand and 34 cm of activated carbon results in the maximum efficiency and can reduce the COD and turbidity of greywater by 90.12% and 99.03%, simultaneously.