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Recycled bed sand from a power plant's fluidized bed reactor was used to remove humic substances (HSs) from surface water samples. The performance of sand samples screened into different size fractions together with unscreened sand was evaluated in removing HSs by performing shaking and column experiments, and by monitoring the quality of the treated water samples in terms of pH, conductivity, chemical oxygen demand (COD), and colour. At the beginning of the column experiments, the used sand fractions removed HSs with over 80% efficiency. However, as the experiments proceeded, the removal efficiency rapidly decreased, reaching a steady state during which a column filled with small-particle-size screened sand removed 20–25% of the COD and colour at a 2.2 kg/h flow speed, and 25–35% of the COD and 30–35% of the colour at a slow 0.5 kg/h flow speed. With unscreened sand, the corresponding COD and colour removal efficiencies were 10–20% (COD) and 10–18% (colour) for fast column experiments, and 22–27% for COD and 25–30% for colour during slow column experiments. Elemental analysis revealed that recycled fluidized bed sand contained several cationic compounds known to form complexes with HSs. Especially calcium together with aluminium and iron are potential candidates for removing colour and COD from the water samples. Highlights Recycled fluidized bed sand could be used as a low-cost adsorbent material for removing HSs from surface water samples Especially the COD and colour of the water samples could be reduced by the sand treatments Fluidized bed sand contained several cationic compounds forming complexes with HSs No significant amounts of heavy metals were leached during the sand treatments [ABSTRACT FROM AUTHOR]

In Jordan, groundwater is the predominant reservoir utilized for human consumption since surface water makes a barely discernible contribution to supply. The investigation of inexpensive and readily accessible adsorbents for heavy metal extraction forms the topic of this research. The aim of this study was to assess the efficacy of a filtration method for the subtraction of heavy metals, i.e. (Fe, Cu, Co, Ni, Zn and Cr), which employed white sand and chlorine as a large filter and oxidizing agent, respectively, and represented a simulation of the clarification procedure. The experiments were performed using pillared sand of varying grain dimensions to explore the impact of particulate size on the adsorption and retention of the heavy metals under examination. Sulfide ions employed as a catalyst. The data revealed that the extraction of Zn, Ni, Cu, Cr, Co and Fe was 75%, 95%, 99%, 65%, 89% and 94%, respectively. Adsorption was conducted using a sand particle dimension of between 50 and 60 μm. Chlorination and sulfide facilitated oxidation, generating fixed oxide compounds. Owing to the notable part performed by the micro-sand particles, the heavy metal fixation was considered a result of hydrogen bonding, electrostatic interaction and ion exchange. This study offers a novel perspective on drinking water clarification using white micro-sand, thus offering a relatively innovative strategy for the efficacious extraction of a number of heavy metals, which is apposite for application to drinking water resources. [ABSTRACT FROM AUTHOR]

A disc filter has been rapidly and widely applied in the irrigation field in recent years owing to its composite three-dimensional filtering and the filtering characteristics of both screen filter and sand filter. Therefore, it has presented a promising application prospect in the very broad filtration system worldwide. However, the head loss of the disc filter can increase sharply within the critical range in a short time, due to the complex channel structure and uneven channel clogging during operation. Therefore, frequent backwashing can increase the water volume and energy consumption, and leading to the low operating efficiency of the whole micro-irrigation system. Thus, it is a high demand to elucidate reasons for the head loss increasing sharply of the disc filter. This study aims to avoid the steep increase in head loss for the higher operation efficiency of the filtering system, the hydraulic and filtration performance of the disc filter was tested on five flow velocities (0.37, 0.40, 0.43, 0.46, and 0.49 m/s), five sand concentrations (0.10, 0.15, 0.20, 0.25, and 0.30 g/L), and five compositions of median particle sizes in sand (49, 66, 82, 100, and 127 μm). Some indexes were determined, including the head loss, the sand interception, the particle size of intercepted sand, and the position distribution of intercepted sand in the laminated channel of the filter under different working conditions. The methods for calculating the head loss were established under the clean and sand water conditions using regression analysis, respectively. A Malvern particle size analyzer was utilized to determine the sensitive particle size, which was caused by the fluctuation of the head loss under the different flow velocities and the particle size of laminated intercepted sand. In addition, the position distribution of intercepted sand was also characterized by an optical microscope. The results showed that the average local head loss coefficient was achieved at 290.60 under the clean water condition. It illustrated that the head loss was only related to the effective water-crossing area. The correlation between the head loss and flow velocity, and sand concentration was high (R ²>0.90) under the sand water with different gradations. Moreover, the sensitive flow velocity of head loss outstandingly increased by 0.37, 0.40, 0.43, 0.46, and 0.49 m/s, respectively, when the sand size in sand water was in the range of 0-50, 50-75, 75-100, 100-125, and 125-150 μm. There was a strong correlation between the head loss and sand interception, and sand size was greater in the sand water, where both were less affected by the flow velocity. Furthermore, the fine sand with 0-65 μm easily passed through the channel without any interception, whereas, the sand with 65-100 μm was intercepted by the laminated channel. There was a ratio of 1:1.8 between the actual filtration accuracy of the lamination and the diameter of the inscribed circle in the minimum section of the channel. Specifically, the sand with the size range of 100-125 μm was possible to enter the laminated channel. Correspondingly, the sand was easily accumulated at the inlet of the channel, indicating the relatively low sand intercepted capacity of the filter. By contrast, the sand with 125-150 μm cannot enter the laminations. In conclusion, the finding can provide a strong reference for the rational configuration and use of disc filters under different irrigation parameters and water quality conditions, such as the flow velocity, sand concentration, and size composition. [ABSTRACT FROM AUTHOR]

The performance of fibrous filter media relies on factors such as particle capture efficiency, pressure drop and clogging time. Fiber diameter, porosity and packing density are important web-based factors to improve final filtration performance. In this study, composite nonwoven webs were produced using spunbonded, meltblown and electroblown mats to obtain filter media with different fiber diameter, porosity and packing density. Such a layered composite approach caused huge differences in porosity and packing density, which resulted with improved clogging performance. The average fiber diameter was found to be 65 ± 19.4 nm for electroblown layer (N), while that was 1.17 ± 0.38 μm for meltblown (M) and 17.64 ± 2.65 μm for spunbond (S) layers. NM (nanofiber+meltblown) configuration provided 12–13% lower mean flow pore size, which resulted in faster clogging compared to NS (nanofiber + spunbond) mats. The thicker nanofibrous layer resulted in lower pore size and quality factor. Additionally, the composite samples showed a faster-rising pressure drop than the thick microfibrous mats due to smaller pores that clogged quickly. It was also shown that nanofiber coating causes a linear increase in pressure drop with dust loading, while microfibrous samples exhibited smooth plateau and linear increase after clogging point. Nanofiber layer facilitates cake formation which causes more difficult airflow, and lower dust holding capacity. Among the layered composite mats, the NM configurations were found to be more advantageous due to higher initial filtration efficiency and almost similar dust loading performance. [ABSTRACT FROM AUTHOR]

Constructed wetlands (CWs) are generally used for wastewater treatment and removing nitrogen and phosphorus. However, the treatment efficiency of CWs is limited due to the poor performance of various substrates. To find appropriate substrates of CWs for micro-polluted water treatment, zeolite, quartz sand, bio-ceramsite, porous filter, and palygorskite self-assembled composite material (PSM) were used as filtering media to treat slightly polluted water with the aid of autotrophic denitrifying bacteria. PSM exhibited the most remarkable nitrogen and phosphorus removal performance among these substrates. The average removal efficiencies of ammonia nitrogen, total nitrogen, and total phosphorus of PSM were 66.4%, 58.1%, and 85%, respectively. First-order continuous stirred-tank reactor (first-order-CSTR) and Monod continuous stirred-tank reactor (Monod-CSTR) models were established to investigate the kinetic behavior of denitrification nitrogen removal processes using different substrates. Monod-CSTR model was proven to be an accurate model that could simulate nitrate nitrogen removal performance in vertical flow constructed wetland (VFCWs). Moreover, PSM demonstrated significant pollutant removal capacity with the kinetics coefficient of 2.0021 g/m2 d. Hence, PSM can be considered as a promising new type of substrate for micro-polluted wastewater treatment, and Monod-CSTR model can be employed to simulate denitrification processes. [ABSTRACT FROM AUTHOR]

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• Dissolved Fe2+ and reactive oxygen species do not affect NH 4 + oxidation. • Fe oxide coating aids sand grain colonization by NH 4 +-oxidizing bacteria. • Fe3+ flocs inhibit NH 4 + oxidation by reducing the NH 4 + oxidation capacity of NH 4 +-oxidizing bacteria. • Changes in transport patterns due to clogging do not play a major role in NH 4 + oxidation. • The inhibition of NH 4 + oxidation is reversible and reduced by backwashing. Rapid sand filters (RSF) are an established and widely applied technology for the removal of dissolved iron (Fe2+) and ammonium (NH 4 +) among other contaminants in groundwater treatment. Most often, biological NH 4 +oxidation is spatially delayed and starts only upon complete Fe2+ depletion. However, the mechanism(s) responsible for the inhibition of NH 4 +oxidation by Fe2+ or its oxidation (by)products remains elusive, hindering further process control and optimization. We used batch assays, lab-scale columns, and full-scale filter characterizations to resolve the individual impact of the main Fe2+ oxidizing mechanisms and the resulting products on biological NH 4 + oxidation. modeling of the obtained datasets allowed to quantitatively assess the hydraulic implications of Fe2+ oxidation. Dissolved Fe2+ and the reactive oxygen species formed as byproducts during Fe2+ oxidation had no direct effect on ammonia oxidation. The Fe3+ oxides on the sand grain coating, commonly assumed to be the main cause for inhibited ammonia oxidation, seemed instead to enhance it. modeling allowed to exclude mass transfer limitations induced by accumulation of iron flocs and consequent filter clogging as the cause for delayed ammonia oxidation. We unequivocally identify the inhibition of NH 4 +oxidizing organisms by the Fe3+ flocs generated during Fe2+ oxidation as the main cause for the commonly observed spatial delay in ammonia oxidation. The addition of Fe3+ flocs inhibited NH 4 +oxidation both in batch and column tests, and the removal of Fe3+ flocs by backwashing completely re-established the NH 4 +removal capacity, suggesting that the inhibition is reversible. In conclusion, our findings not only identify the iron form that causes the inhibition, albeit the biological mechanism remains to be identified, but also highlight the ecological importance of iron cycling in nitrifying environments. [Display omitted] [ABSTRACT FROM AUTHOR]

The capacity for organic micropollutant removal in granular activated carbon (GAC) filters for wastewater treatment changes over time. These changes are in general attributed to changes in adsorption, but may in some cases also be affected by biological degradation. Knowledge on the degradation of organic micropollutants, however, is scarce. In this work, the degradation of micropollutants in several full-scale GAC and sand filters was investigated through incubation experiments over a period of three years, using 14C-labeled organic micropollutants with different susceptibilities to biological degradation (ibuprofen, diclofenac, and carbamazepine), with parallel 16S rRNA gene sequencing. The results showed that the degradation of diclofenac and ibuprofen in GAC filters increased with increasing numbers of bed volumes when free oxygen was available in the filter, while variations over filter depth were limited. Despite relatively large differences in bacterial composition between filters, a degradation of diclofenac was consistently observed for the GAC filters that had been operated with high influent oxygen concentration (DO >8 mg/L). The results of this comprehensive experimental work provide an increased understanding of the interactions between microbial composition, filter material, and oxygen availability in the biological degradation of organic micropollutants in GAC filters. [Display omitted] • Micropollutant degradation and microbial composition in full-scale GAC filters. • Greater micropollutant degradation with increased operation time. • Oxygen availability appears important for micropollutant degradation in GAC filters. • Higher micropollutant degradation with bitumen-based versus coconut-based GAC. • Varying degradation capacities for sand and GAC media, despite similar microbial composition. [ABSTRACT FROM AUTHOR]

• Batch tests using used filter material from waterworks and fresh activated carbon. • (Partial) deiodination increases sorption to filter material and activated carbon. • Sorption to used filter material is very slow due to diffusion through OM layer. • Deiodination of IOP and DTZ strongly increases sorption to activated carbon. • Anoxic/anaerobic conditions contribute to ICM and ICM TPs sorptive removal. Iodinated X-ray contrast media (ICM) and their aerobic transformation products (TPs) are widespread in the aquatic environment due to their persistent and mobile character. In a previous lab study, we have shown that the reductive (partial) deiodination of selected triiodobenzene derivatives increases the sorption to aquifer sand and loam soil, since iodine affects the compounds by steric hindrance, repulsive forces, resonance and inductive effects. These results suggest that the (partial) deiodination generally occurring to ICM and aerobic ICM TPs during anoxic/anaerobic bank filtration has a potential to increase their removal by sorption to natural sorbents. To basically assess the sorption potential to technically applied materials for drinking water treatment subsequent to bank filtration, we investigated the sorption of iopromide, diatrizoate and 5-amino-2,4,6-triiodoisophtalic acid and their di, mono and deiodinated structures to used filter sand from a waterworks and different fresh powdered activated carbons in batch tests using Berlin drinking water. The filter material, coated by iron and manganese oxides as well as organic material (including biofilm), preferentially removed monoiodinated derivatives, but diffusion through the organic layer heavily slowed the sorption. Therefore, the removal potential by sorption in rapid sand filters of waterworks for (partially) deiodinated benzene derivatives is suggested to be low. The deiodination of iopromide and diatrizoate significantly increased the sorption affinity to activated carbon and the competitiveness with regard to drinking water DOC. Despite the large atom radius of iodine, no clear correlation was found between the pore characteristics of the activated carbons and the molecular size of the compounds. This study emphasises the importance of anoxic/anaerobic conditions for the removal of persistent and mobile ICM and ICM TPs during drinking water treatment. [Display omitted] [ABSTRACT FROM AUTHOR]

Adsorption processes are being widely used by various researchers for the removal of heavy metals from waste streams and biochar has been frequently used as an adsorbent. In this study, a MgO-loaded biochar derived from Alternanthera philoxeroides (MAPB) was synthesized for the removal of Cu(II). Compared with other biochar absorbents, MAPB showed a relatively slow adsorption kinetics, but an effective removal of Cu(II) with a maximum sorption capacity of 1, 238 mg/g. The adsorption mechanism of Cu(II) by MAPB was mainly controlled by chemical precipitation as Cu 2 (OH) 3 NO 3 , complexation and ion replacement. Fixed bed column with MAPB packed in same dosage (1, 000 mg) and different bed depth (1.3, 2.6 and 3.9 cm) showed that the increased of bed depth by mixing MAPB with quartz sand could increase the removal of Cu(II). The fitted breakthrough (BT) models showed that mixing MAPB with support media could reduce the mass transfer rate, increase the dynamic adsorption capacity and BT time. Therefore, MAPB adsorbent act as a highly efficient long-term adsorbent for Cu(II) contaminated water treatment may have great ecological and environmental significance. [Display omitted] • The MgO-loaded biochar (MAPB) had a theoretical maximum sorption capacity of 1238 mg/g for Cu(II). • The formation of Cu 2 (OH) 3 NO 3 played a crucial role in adsorption experiments of MAPB. • Clark model best described the breakthrough curves of Cu(II). [ABSTRACT FROM AUTHOR]

Disinfection by-products (DBPs) are prevalent contaminants in drinking water and are primarily linked to issues regarding water quality. These contaminants have been associated with various adverse health effects. Among different treatment processes, nanofiltration (NF) has demonstrated superior performance in effectively reducing the levels of DBPs compared to conventional processes and ozone-biological activated carbon (O 3 -BAC) processes. In this experiment, we systematically investigated the performance of three advanced membrane filtration treatment schemes, namely "sand filter + nanofiltration" (SF + NF), "sand filter + ozone-biological activated carbon + nanofiltration" (SF + O 3 -BAC + NF), and "ultrafiltration + nanofiltration" (UF + NF), in terms of their ability to control disinfection by-product (DBP) formation in treated water, analyzed the source and fate of DBP precursors during chlorination, and elucidated the role of precursor molecular weight distribution during membrane filtration in relation to DBP formation potential (DBPFP). The results indicated that each treatment process reduced DBPFP, as measured by trihalomethane formation potential (THMFP) and haloacetic acid formation potential (HAAFP), with the SF + O 3 -BAC + NF process being the most effective (14.27 μg/L and 14.88 μg/L), followed by the SF + NF process (21.04 μg/L and 16.29 μg/L) and the UF + NF process (26.26 μg/L and 21.75 μg/L). Tyrosine, tryptophan, and soluble microbial products were identified as the major DBP precursors during chlorination, with their fluorescence intensity decreasing gradually as water treatment progressed. Additionally, while large molecular weight organics (60–100,000 KDa) played a minor role in DBPFP, small molecular weight organics (0.2–5 KDa) were highlighted as key contributors to DBPFP, and medium molecular weight organics (5–60 KDa) could adhere to the membrane surface and reduce DBPFP. Based on these findings, the combined NF process can be reasonably selected for controlling DBP formation, with potential long-term benefits for human health. [Display omitted] • The SF + NF, SF + O 3 -BAC + NF, and UF + NF processes help eliminate TCM and DCAA precursors. • Proteins and soluble microbial products are the main precursors for DBP formation. • Small molecular weight organics (0.2–5 KDa) are particularly likely to form DBPs. • The process chosen should consider energy consumption and economic factors. [ABSTRACT FROM AUTHOR]

[Display omitted] • Drum filtration efficiently removes pool water particles above 10 µm. • No clear link between filter cloth permeability and particle rejection was observed. • Particle removal improves over time; after 30 min, most >5 µm particles are removed. • 90 % removal of particles >3 µm was achieved with filter aid. Filtration is an effective method for removing particles larger than 10–15 µm in swimming pool water. However, the removal of smaller particles poses a significant challenge. Tests were conducted to improve the filter's performance. These tests included choice of filter cloth, long-term filtration operation, pre-coating with filter aids (Arbocel and Harbolite). As expected, the choice of filter cloth affects particle rejection, but other strategies can be employed to improve the process. During long-term operation, particle rejection continuously improved for all filter cloths, and after 30 min, 50 % of particles as small as 2 µm were removed. Since, the concentration of particles in swimming pool water is low, only part of the filter cloth is covered by particles even after 30 min. Higher particle rejection could also be achieved by recycling particles from the filter cloth or using filter aids. Additional particles have been removed from the filter cloth by rinsing the filter cloth with water followed by the recirculation of part of the rinse water or the coagulated rinse water. Higher particle removal can also be obtained by using filter aids, whereby it is possible to cover the entire surface of the filter. When using Harbolite as the pre-coat material, more than 80 % of the particles with a size of 2 µm or larger can be removed when 100 g Harbolit was used per m2 filter cloth. [ABSTRACT FROM AUTHOR]

• The combination process of UV/PDS oxidation and BAC (UV/PDS-BAC) was studied in pilot scale. • UV/PDS-BAC performs better than O 3 -BAC in terms of TOC, AOC, and TOXFP removal. • The mechanisms behind the enhanced DOM removal achieved by UV/PDS-BAC was explored. The combination process of UV/peroxydisulfate (UV/PDS) oxidation and BAC (UV/PDS-BAC) is examined as an advanced treatment for conventional drinking water treatment through a continuous flow experimental apparatus with actual sand filter effluent as feed water. The effect of three key parameters (UV dosage, PDS dosage, and water temperature) on dissolved organic matter (DOM) is evaluated via long-term monitoring data. The removal behavior of DOM in the UV/PDS-BAC process is also compared with that in the O 3 -BAC process. Further, this study delves into the mechanisms behind the enhanced DOM removal achieved by UV/PDS-BAC. The achieved results reveal that impressive removal rates of 42.1 % for total organic carbon (TOC) and 62.9 % for UV 254 could be achieved in the presence of specific conditions: a UV input of 200 mJ/cm2 and a PDS dosage of 0.5 mM. The efficiency of DOM removal by UV/PDS-BAC exhibits a positive correlation with the UV dosage ranging from 50 to 200 mJ/cm2, and the water temperature in the range of 4–30 ℃. While increasing the PDS dosage from 0.01 to 0.5 mM results in improved DOM removal, any further increase yields reduced removal efficiency. In comparison, subjected to similar operating conditions, UV/PDS-BAC outperforms O 3 -BAC in removing DOM. The superior DOM removal achieved by the UV/PDS-BAC process can be essentially attributed to several factors: firstly, it exhibits excellent mineralization capacity for low molecular weight organics (<1 kDa) and leads to increased biodegradable fraction of organics by oxidatively degrading DOM with a molecular weight >3 kDa. Secondly, the appropriate exposure of activated carbon pores is chiefly maintained by suitably controlling the biomass. Lastly, the enhanced biodegradability of BAC influent stimulated the growth of bacteria proficient in degrading DOM. [ABSTRACT FROM AUTHOR]

• The most relevant pantoprazole-related compound (M1) for monitoring was identified. • M1 occurs ubiquitously in surface water and wastewaters in Germany. • Environmental concentrations of M1 were much higher than those of parent compound. • Activated carbon filtration considerably improves the removal of M1 from wastewater. • Several ozonation products of M1 in wastewater were characterized. The proton-pump inhibitor pantoprazole (PPZ) is one of the most consumed pharmaceuticals worldwide. Despite its high usage, reported PPZ concentrations in environmental water samples are comparatively low, which can be explained by the extensive metabolism of PPZ in the human body. Since most previous studies did not consider human PPZ metabolites it can be assumed that the current environmental exposure associated with the application of PPZ is substantially underestimated. In our study, 4′- O -demethyl-PPZ sulfide (M1) was identified as the predominant PPZ metabolite by analyzing urine of a PPZ consumer as well as the influent and effluent of a wastewater treatment plant (WWTP) using liquid chromatography coupled to high resolution mass spectrometry (LC-HRMS). M1 was found to be ubiquitously present in WWTP effluents (max. concentration: 3 000 ng/L) and surface waters in Germany. On average, the surface water concentrations of M1 were approximately 30 times higher than those of the parent compound PPZ. Laboratory scale experiments demonstrated that activated carbon can considerably adsorb M1 und thus improve its removal during wastewater and drinking water treatment. Laboratory ozonation experiments showed a fast oxidation of M1, accompanied by the formation of several ozonation products. Certain ozonation products (identities confirmed via synthesized reference standards) were also detected in water samples collected after ozonation in a full-scale WWTP. Overall lower signal intensities were observed in the effluents of a sand filter and biologically active granular activated carbon filter, suggesting that the compounds were significantly removed during these post-ozonation treatment stages. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Batch and column studies establish the application of GO-sand filter for the treatment of Pb(II) and Cr(III) ions. • Significant removal and recovery efficiency (˃ 95 %) at pH = 6. • GO-sand could be effectively employed upto four regeneration cycles. • RSM has successfully optimized the process while developing adequate models. • Cost analysis in terms of synthesis and application of GO-sand is evaluated. The existence of lead and chromium ions in waterbodies severely affects the biological activities of aquatic creatures that directly affect human health. A graphene oxide-sand (GO-sand)-based composite filter has been successfully used as a Rapid Sand Filter (RSF) to remove Lead (II) and Chromium (III) ions in water. Boehm titration, FTIR, RAMAN, XRD, and SEM-EDX analyses confirmed GO-sand's active sites, semicrystalline, and irregular morphology. Moreover, lead and chromium adsorption using a GO-sand composite was established by XPS and SEM-EDX analyses. The results of the batch study showed significant adsorption (289.68 mg g−1 and 258.87 mg g−1) along with significant removal (96.4 % and 95.6 %) of Pb (II) and Cr (III), respectively. Among Langmuir, Freundlich, and Liu isotherms, the adsorption isotherm showed an excellent fit with Liu isotherm. The response surface methodology (RSM) study suggested adequate quadratic models and exceptional covenant between the predicted and actual figures with a significant coefficient determination (R2 > 0.920). The kinetic study finding revealed the best fit for the Elovich kinetic model (R2 = 0.995 (Pb), R2 = 0.967 (Cr)), and the thermodynamics study confirmed endothermic adsorption. Pareto analysis confirmed that solution pH was the most significant parameter towards adsorption. Furthermore, the regenerated adsorbent demonstrated practical reusability up to four adsorption–desorption cycles, revealing the process's sustainability. [ABSTRACT FROM AUTHOR]

The development of an efficient and sustainable separation method for oily wastewater has become a major challenge for industrial development and environmental protection. In this work, the simple special wettability particle preparation method and the hybrid filters construction strategy was reported for enhanced oil/water separation efficiency. Two special wettability quartz sands mixed in a certain proportion could destroy the balance of dispersed droplets in the oil-water emulsion, induce the coalescence of dispersed droplets, and purify the oil-water emulsion by the tortuous channel in the filter. Based on the coupling effect of "size sieving" and "coalescence separation", the special wettability particle hybrid filter with a mass ratio of 3:1 had good droplet coalescence ability, and the separation efficiency of various kinds of oil-water emulsions can reached more than 98%. The hybrid filters exhibited robust mechanical and chemical stability, excellent durability, which enable them to be competent for oil/water separation in multitasking and complex environment. [Display omitted] • The superhydrophilic and superhydrophobic quartz sands hybrid filter was reported. • The screening and coalescence mechanism were used to achieve rapid demulsification. • The hybrid filter possesses excellent oil/water separation efficiency (＞98%). [ABSTRACT FROM AUTHOR]

The aim of the study was to determine the doses of selected bioelements delivered to the body as a result of consuming water from various types of intakes (surface water from the river, water from infiltration wells, treated water directed to the water supply system) and additionally as a result of using bottled water. The present study analysed the content of 33 elements in water, grouped into microelements, ultratrace elements and other elements found in the aquatic environment. The majority of those elements are essential to proper human development and functioning. They can enter the human body together with water: (a) ingested directly, (b) present in food, (c) inhaled or (d) absorbed through skin. The results obtained were compared with the chemical composition of 29 types of bottled water (mineral and spring water) available in the retail market. Reference doses for each of the parameters were calculated in accordance with the US EPA guidelines and compared with the doses recommended in other research studies. Two water treatment plants (WTPs and WTPss) located in southern Poland were selected as research facilities. Water treatment plants treat surface water from rivers and groundwater from infiltration wells using sand filters. It was found that the average mineralisation of water supplied in the water distribution system ranges from 0.15 to 0.2 mg dm-3, which indicates that it has characteristics of natural low-mineral spring water. It provides 0.0001%-0.0003% of the recommended daily intake (RDI) for Al, As, Cd, Co, Cr, Cu, Mn, Mo, Ni, P, and Sn for children and for adults. The novelty of the article is the determination of the doses of microelements in bottled water. Bottled mineral water provides considerably higher doses of microelements than the values stemming from the RDI. The delivered doses of carcinogenic and potentially carcinogenic elements are of particular importance. In the case of Al, Cr, and Ni, the total recommended dose was exceeded 1 to 2 times for children and 1.5-7 times for adults. It was demonstrated that consumers should be careful about drinking water with an elevated content of microelements that are characterized by a very small, yet critical difference between the reference dose and the recommended dose. [ABSTRACT FROM AUTHOR]

In commercial large-scale aquaria, controlling levels of nitrogenous compounds is essential for macrofauna health. Naturally occurring bacteria are capable of transforming toxic nitrogen species into their more benign counterparts and play important roles in maintaining aquaria health. Nitrification, the microbially-mediated transformation of ammonium and nitrite to nitrate, is a common and encouraged process for management of both commercial and home aquaria. A potentially competing microbial process that transforms ammonium and nitrite to dinitrogen gas (anaerobic ammonium oxidation [anammox]) is mediated by some bacteria within the phylum Planctomycetes. Anammox has been harnessed for nitrogen removal during wastewater treatment, as the nitrogenous end product is released into the atmosphere rather than in aqueous discharge. Whether anammox bacteria could be similarly utilized in commercial aquaria is an open question. As a first step in assessing the viability of this practice, we (i) characterized microbial communities from water and sand filtration systems for four habitats at the Tennessee Aquarium and (ii) examined the abundance and anammox potential of Planctomycetes using culture-independent approaches. 16S rRNA gene amplicon sequencing revealed distinct, yet stable, microbial communities and the presence of Planctomycetes (~1–15% of library reads) in all sampled habitats. Preliminary metagenomic analyses identified the genetic potential for multiple complete nitrogen metabolism pathways. However, no known genes diagnostic for the anammox reaction were found in this survey. To better understand the diversity of this group of bacteria in these systems, a targeted Planctomycete-specific 16S rRNA gene-based PCR approach was used. This effort recovered amplicons that share <95% 16S rRNA gene sequence identity to previously characterized Planctomycetes, suggesting novel strains within this phylum reside within aquaria. [ABSTRACT FROM AUTHOR]

The pressurized sand filters used in drip irrigation systems have three zones (the water inlet, sand bed, and water outlet) with different hydraulic behaviors. Previous studies that aimed to improve the hydraulic performance of these filters focused on the water inlet and sand bed by redesigning the diffuser plate and underdrain elements, respectively. In this study, we analyzed the consequences of modifying the water outlet of a commercial porous medium filter without changing its underdrain design. The original design consisted of a horizontal pipe connected to ten horizontal wands. Five additional designs that varied in size, orientation, and number of outlets were numerically studied in four operating modes (including two sand bed heights and two superficial velocities). Comparison with the commercial design indicated that (1) an outlet pipe with twice the cross-sectional area reduced the overall filter pressure drop by up to 12% and increased the flow uniformity within the sand bed; (2) two outlets led to symmetrical behavior for the amount of water drained per wand but did not improve the water volume drained by the central wand, which drained the least amount; and (3) a central vertical outlet of equal diameter as the commercial outlet produced a similar pressure drop but increased the flow uniformity within the porous medium. For completeness, two additional diffuser designs were also studied. In comparison with the original design, the proposed designs improved the flow uniformity and weakened the water vortex above the sand surface. [ABSTRACT FROM AUTHOR]

This study focused on evaluating the feasibility of expanded clay and sand as media types for mainstream partial denitrification‐anammox (PdNA) in deep‐bed single‐media polishing filters under nitrogen and solids loading rates as well as backwash conditions similar to conventional denitrification filters. The surface roughness and iron content of the expanded clay were hypothesized to allow for enhanced anammox retention, nitrogen removal rates, and runtimes. However, under the tested loading rates and backwash conditions, no clear benefit of expanded clay was observed compared with conventional sand. This study showed the feasibility of PdNA in filters with both sand and expanded clay with PdN efficiencies of 76% and 77%, PdNA rates of 840 and 843 g N/m3/d and TIN removal rates of 960 and 964 g N/m3/d, respectively. Glycerol demands were 1.5–1.6 g COD added per g TIN removed, thus indicating potential carbon savings up to 75% compared with conventional denitrification. Overall, this study showed for the first time PdNA filters performing at nitrogen removal rates double that of previous PdNA studies under realistic conditions while providing insights into the media choice and backwashing conditions. Future research on expanded clay backwash conditions is needed to provide its full potential in PdNA filters. Practitioner Points: Hydraulic and TSS loading rates similar to conventional denitrification can be applied in PdNA filters.Conventional sand can be used when retrofitting conventional denitrification filters into PdNA filters.Carbon savings up to 75% can be achieved with glycerol when retrofitting conventional filters into PdNA filters [ABSTRACT FROM AUTHOR]

Fluoride concentration in groundwater above than the prescribed value by WHO (>1.5 mg/L) has led to severe health issues. One of the fluoride removal techniques that are low cost and highly efficient is the coagulation technique. Aluminum salts are used as coagulants along with lime to maintain desired pH. The main drawback of this technique is the large concentration of aluminum in treated water. Therefore, the present study aims to lower down the aluminum concentration in the defluoridated water within the acceptable limits by applying sand filter and ultrafiltration membrane subsequently. Aluminum removal efficiency of ultrafiltration was almost 90% and 70% for sand filtration. In terms of energy consumption, ultrafiltration consumed 60 kWh/m3 and sand filtration consumed 6.2 kWh/m3. Cost analysis was also done and it was observed that sand filter was more cost effective than ultrafiltration. Also, ultrafiltration consumed 10 times higher energy than sand filter for treating 1 m3 of water. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the efficiency of four household slow sand filter (HSSF) models for the removal of microorganisms from river water throughout the development of their biological layers (schmutzdecke). Two models were designed to be operated continuously (HSSF-CC and HSSF-CT) and two intermittently (HSSF-ID and HSSF-IF). Filters were fed daily with 48 L pre-treated river water (24 h sedimentation followed by filtration through a non-woven synthetic blanket). Water samples were quantified by coliform group bacteria and analysed by bright field microscopy to visualize the microorganisms. Total coliform reduction was between 1.42 ± 0.59 log and 2.96 ± 0.58 log, with continuous models showing a better performance (p-values < 0.004). Escherichia coli reduction varied from 1.49 ± 0.58 log to 2.09 ± 0.66 log and HSSF-IF, HSSF-CC and HSSF-CT presented a similar performance (p-values > 0.06), slightly better than the one presented by HSSF-ID (p-value=0.04). Microorganisms, such as algae, protozoa and helminths were detected by microscopy in raw water and pre-treated water. Algae were the most significant group in these samples, although they were not visualized by bright field microscopy in the filtered water. Results showed the potential of HSSF in microbiological risk reduction from river water, which increases the range of point-of-use water treatments in rural communities. However, additional studies of the HSSF biological layer must be performed. [ABSTRACT FROM AUTHOR]

This study evaluated clogging effects on head loss and water quality in sand prefiltration columns, followed by innovative double‐layered slow‐filter filtration technology using anthracite coal and sand. The study was divided into two phases. Phase 1 (filtration rate 11 m3/m2·d) had a layout of a pre‐filter (PF) system followed by a slow filter (SF). In Phase 2 (filtration rates of 5.5 and 11 m3/m2·d), two PF systems (PF1 and PF2) followed by SFs (SF1 and SF2) were monitored, be differed only by filtration rate. Phase 1 presents a mean turbidity removal of 45.6% in PF and 23.9% in SF. PF presented a lower head loss in the superficial layers of the filter media, whereas SF presented a more important contribution in the deeper layers of the bed. In Phase 2, the mean results obtained for turbidity removal in PF1 and SF1 were 84.7% and 22.4%, in that order. PF2 and SF2 promoted mean reductions of 84.5% and 22.0%, respectively. Greater clogging is observed in the PF's surface layers, whereas the SFs dissipate greater clogging with depth. Filtration rates and water quality were similar in filter media of different compositions. Practitioner Points: Double‐layer filters show better use of the porous media in depth.Different materials produce different forms of clogging.Higher filtration rates increase the number of pre‐filter and slow filter runs. [ABSTRACT FROM AUTHOR]

Schmutzdecke, the biofilm formed on the top of the sand bed in household slow sand filters (HSSF) is a key factor for the filters' high efficiency in removing particles and microorganisms from water. This paper aims to investigate the extracellular polymeric substances composition (carbohydrates and proteins), biomass, dissolved oxygen, and microbial community in two types of HSSFs and identify a correlation between them and their efficiency. A continuous- and an intermittent-HSSF (C-HSSF and I-HSSF) were studied to treat river water for 48 days. Their efficiencies for bacteria (E. coli and total coliforms), turbidity, and apparent color removals were analyzed. Results clearly showed an increase of carbohydrates (from 21.4/22.5 to 101.2/93.9 mg·g−1 for C-/I-HSSF) and proteins (from 34.9 to 217/307.8 mg g−1 for C-/I-HSSF), total solids (from 0.03/<0.03 to 0.11/0.19 g L−1 for C-/I-HSSF), dissolved oxygen depletion inside the filter (6.00 and 5.15 mg L−1 for C- and I-HSSF) and diversity of microorganisms over time, pointing out the schmutzdecke development. A clear improvement on the HSSFs' efficiency was observed during operation, i.e., E. coli removal of 3.23 log and 2.98 log for total coliforms, turbidity from 60 to 95%, and apparent color from 50 to 90%. [ABSTRACT FROM AUTHOR]

Objective The efficacy and function of subsurface drain is controlled by materials used to warp it which in turn depends on soil texture in the region where they are installed. The purpose of this paper is to study these for drainage of croplands in the downstream Hetao Irrigation district. Method The materials we used were 68 g/m2 and 90 g/m2 geotextile combined with sand particles with size in ranging from 0.3 to 3.0 mm used in the filtering layer. The experiment was conducted in lab, and the ability of the wrapped drain to drain water was measured using an in-house permeameter, from which we analyzed the effects of combination of different wrapping materials and sand size on permeability, soil retention and anti-clogging. Result The system permeability coefficient of the 68 g/m2 geotextile is higher than that of the 90 g/m2 geotextile; the average permeability coefficient after the system stabilized is 4.5 times that of the stable value of the permeability coefficient of the system. Adjusting the hydraulic gradient can improve the permeability coefficient of the system. The variation of the stability value is small, and each treatment has a good water permeability and stability. Wrapping the drain with 68 g/m2 geotextile combined with 0.8 and 1.0 mm sand particles as the filtering layer improved the permeability coefficient significantly. The average soil loss of wrapping with 90 g/m2 geotextile was 0.5 g, meeting the soil conservation requirements and effectively preventing clogging. The clogging rate showed a high-low-high variation with the increase in sand size, and it was the lowest (26%) for wrapping with 68 g/m2 geotextile combined with 1.0 mm sand particles as the filtering layer. Conclusion Combining 68 g/m2 geotextile with sand particles sized 1 mm as the filtering layer was optimal for subsurface drains in the downstream farmlands of the Hetao Irrigation District. [ABSTRACT FROM AUTHOR]

Background: The Nile River included diverse phytoplankton compositions belonging to five main phytoplankton categories. Algae have been classified and identified through comparative morphology. Results: The Pyrrophyta, Charophyta, Cyanophyta, Chlorophyta, and Bacillariophyta were presented through the full period of investigation with 1, 3, 14, 23, and 28 species, respectively. Therefore, it may be important to note that diatoms were recorded as an abundant group in all investigated samples. The numbers of diatoms ranged between 1.45 × 106 and 1.18 × 107 Organism/l, this was followed by green algae that ranged from 7.0 × 105 to 1.22 × 106 Organism/l. While the lowest count of blue-green algae was ranged between 1.6 × 105 and 7.03 × 105 Organism/l. The treatment of Nile water using two chemical coagulants "aluminum sulfate (Al2(SO4)3⋅16H2O) and aluminum oxide (Al2O3)" removed algae by about 85% and 90%, respectively. As for, the Cyanophyceae species, they were removed completely in treated water using the sedimentation, filtration, and chlorination process. The sedimentation basins removed from 20 to 100% of the total algal count while the rapid sand filters removed from 65 to 100% of the total algal count during the water treatment that depends on the species of algae. Conclusions: This study concluded that the removal of algae from the Nile water may be more or less easy depending on the nature of the prevailing algal group. Water treatment plants must modify alum and chlorine doses in their water treatment processes according to the count and species of the algal groups, to provide an aesthetically acceptable and biologically safe water supply. [ABSTRACT FROM AUTHOR]

Ammonium removal from drinking water to protect human and environmental health is one of the major global concerns. This study evaluates the performance of Purolite C100E, a commercial cation exchange resin, in eliminating ammonium in synthetic and real contaminated groundwater. The results demonstrate that the pH operation range of the resin for better ammonium removal is 3 to 8. Lower ammonium removal at low and high pH occurred due to competition from H+ and loss of ammonium as ammonia gas, respectively. Equilibrium data of ammonium removal fitted both the Langmuir and Freundlich isotherm models with the maximum Langmuir ion exchange capacities for initial ammonium concentrations of 10–200 mg/L and 50–2000 mg/L, reaching 18.37 mg/g and 40.16 mg/g, respectively. The presence of co-ions in the water reduced the ammonium removal efficiencies slightly (< 12%) in the order Mg2+ > Ca2+ > K+. The higher affinity of ammonium to adsorbent is due to its lower hydrated ionic radius and H-bonding. The maximum exchange capacity in the fluidized bed studies of the original Purolite C100E (bed height 27 cm, resin weight 75 g, initial ammonium concentration 17.4 mg/L, filtration velocity 0.5 m/h) was 10.48 mg/g. It progressively reduced slightly after three regeneration cycles to 8.79 mg/g. The column breakthrough data satisfactorily fitted the Thomas model. A household filter cartridge packed with 4 kg Purolite C100E (80 cm height) and operated at a filtration velocity of 1.9 m/h in Vietnam successfully reduced the initial 6 mg NH4+/L in groundwater (after sand filter pre-treatment) to well below the Vietnam drinking water standard (3 mg/L-QCVN 01:2009/BYT) continuously for 1 week, suggesting that such a filter can be adopted in rural areas to successfully remove ammonium from groundwater. [ABSTRACT FROM AUTHOR]

A new model was developed to predict head loss in sand media filters. Sand filters with six different media using reclaimed water were used to measure head losses at different flow rates in the laboratory. The parameters influencing head losses were considered to be the uniformity coefficient, the effective diameter, the sand mass, the filtration velocity, the pollution load, and the water viscosity. A dimensional analysis method was used to develop the model. A comparison between the predicted and the measured head losses showed close agreement with a correlation coefficient of 91.7%, reaching a significance level of p < 0.001. The results showed that the model might give satisfactory predictions within the following range of operational and filter structure parameters: uniformity coefficient 1.48–3.31; effective diameter 0.41–2.1 mm; pollution load 0.0169–4.2049 kg, filtration velocity 0.0038–0.0398 m/s. [ABSTRACT FROM AUTHOR]

With the continuous operation of constructed wetlands, substrate clogging is issue. In order to solve the problem, there is practical significance to understand the causes for clogging in constructed wetlands. Two pilot-scale vertical flow constructed wetlands were established, namely, CW-B and CW-C. By studying the relationship between the accumulation of different substances and the banked-up water area, it was found that the accumulation of non-filter substances and total solids was an important reason for the clogging of the substrate, and the accumulation degree of non-filter inorganic substances was more obvious than that of non-filter organic substances, and the blockage was mainly located in the 10-20 cm layer. In the vertical flow constructed wetland with river sand as the main substrate, water accumulation will occur when the content of total solid and non-filter substances exceeds 67.233 g and 101.228 g per cubic meter of substrate, respectively. Therefore, it is important to pay attention to the substrate particle size matching of 0-20 cm layer to reduce the clogging in the vertical flow constructed wetland. The clogging has little effect on chemical oxygen demand (COD) removal, but great effect on total phosphorus (TP) removal. Compared with the control wetland (CW-C), the biomass content in the CW-B with biochar increased by 334.26 nmol P/g, which can improve the removal efficiency of total nitrogen (TN) and total phosphorus (TP), but also increase the risk of clogging in the vertical flow constructed wetland. Future research should try to combine the anti-blocking research results of biochar constructed wetlands to improve the purification effect, which is of great significance to promote the sustainable development of constructed wetlands. [ABSTRACT FROM AUTHOR]

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 material is a readily available, maintenance is simple and low cost, and installation and operation are effortless. [ABSTRACT FROM AUTHOR]

Green energy production from natural resources can reduce emissions of greenhouse gases and pollutants from burning of fossil fuels in power plants. Recently, groundwater geothermal energy (GGE) is harnessed by deploying closed- and open-loop heat systems. In open-loop geothermal heat pump systems (OLGHPS), groundwater is reinjected into aquifer after harnessing GGE. Nevertheless, OLGHPS face noxious clogging issue because of elusive chemistry (corrosion or precipitation) of chemical species, principally of iron (Fe), in pipes and aquifers during reinjection process via oxidation reactions. Plethora of filtering materials are available for removal of ions, but these are quite expensive and environmentally unsafe. More recently, low-cost, eco-friendly, green filtering materials gain much interest. These materials can remove ions from groundwater that can minimize clogging in heat exchange systems, injection wells, and aquifer. In the present study, three filtering materials, i.e., wooden charcoal (biomaterial), yamazuna fine sand, and volcanic ash, were tested to estimate their Fe removal capacity. In upward flow mode with minimum oxygen-water contact, serial column (each with 6 ports) experiments were conducted under constant pressure head and constant velocity conditions. Columns were connected to well water having dissolved Fe concentration of 10.85 mg L−1. Sampling was done at the well, column inlets, column's six sampling ports and column outlets, and samples were analyzed for Fe by atomic absorption spectroscopy. Related tested parameters include pH, EC, temperature, turbidity, porosity, particle diameter, and dissolved oxygen. Volcanic ash showed less Fe removal, while sand filter showed substantial reduction in velocity. Biomaterial (wooden charcoal) displayed higher Fe adsorption capacity compared to other materials that can be ascribed to its surface chemistry and functional groups. Under different flow rates, maximum Fe content of 3.5 g Fe kg−1 dry charcoal was obtained. By considering a safety factor and influence of groundwater composition, it is possible to design a biomaterial-based iron filter system to minimize Fe-induced chemical clogging in OLGHPS which is an eco-friendly, green energy source. [ABSTRACT FROM AUTHOR]

The mineralogy of beach sand, which was sampled from an island, Jumundo of South Korea, was investigated and beneficiated using gravity and magnetic separation processes. Ilmenite was determined to be a major heavy mineral and, as minor heavy minerals, zircon, monazite, and sphene were observed. Quartz, biotite, microcline, kaolinite, hornblende, and chlorite were present as gangue minerals. The Ilmenite was concentrated with a Humphrey spiral concentrator and shaking table followed by magnetic separators (drum and cross belt types). As a final product, 18% of the Humphrey spiral system concentrate was recovered, and the grade of final product was determined to be 93% ilmenite. The electron probe microscope analysis indicates that ilmenite was a solid solution of major FeTiO3, minor MgTiO3 (geikielite), and MnTiO3 (pyrophanite). [ABSTRACT FROM AUTHOR]

The hunting billbug, Sphenophorus venatus vestitus Chittenden, is an important insect pest of warm-season turfgrass. Larvae and adult S. venatus vestitus feed on turfgrass and affect normal grass growth and development. In sod farms and golf courses, management sprays are typically confined to affected areas because of the high insecticide and application costs. Understanding the walking behavior of S. venatus vestitus adults would help us to refine management tactics. Thus, the objective of this study was to determine the influence of abiotic factors on the walking behavior of adult S. venatus vestitus. A series of laboratory, semifield, and field assays were conducted in 2019 and 2020. For the laboratory assays, field-collected S. venatus vestitus adults were acclimated at 15, 18, 21, 28, and 32°C for 24 h, and the distances walked by these pre-acclimated adults were measured on sand and filter paper substrates using Noldus EthoVision XT software. For the semifield assays, the total and net distances walked by pre-acclimated adults were measured on a paved indoor surface. Sphenophorus venatus vestitus males and females moved farther when the temperature increased from 15 to 28°C in the laboratory and semifield assays. For the field assays, field-collected S. venatus vestitus adults were not acclimated. The total and net distances walked by the adults were documented on a paved surface. Increases in temperature and relative humidity did not affect the distance moved by adults, but an increase in wind speed reduced the distance moved. [ABSTRACT FROM AUTHOR]

Approximately 99.1% of South Koreans have access to drinkable tap water from river basins. Due to such a high access rate, the South Korean government has been running, since 2013, a long-term program for monitoring the quality of tap water for drinking. Under this program, the maximum allowed concentrations of N-nitroso-di-n-methylamine (NDMA) and N-nitrosomethylethylamine (NMEA) are defined and applied. In this study, the data from this monitoring program were used to investigate the changes in six N-nitrosamine substances in the finished water of 33 drinking water treatment plants (DWTPs) in South Korea from 2013 to 2020, based on time and location. The effect of the applied water treatment steps on the appearance of N-nitrosamines was analyzed. The excess cancer risk (ECR) due to the oral intake of these substances was assessed. The results before the maximum allowed concentrations of NDMA and NMEA were defined showed that the oral intake ECR of these substances exceeded the carcinogenesis risk of one per one million people per year. After the maximum allowed concentrations of the substances were applied, the concentrations of the substances in the finished water of the DWTPs significantly dropped. The drinking water treated through sand filtration, and then with granular activated carbon, showed the highest efficiency in preventing the appearance of NDMA. Considering the potency of N-nitrosamines in tap water for drinking, the levels of these substances in the finished water of DWTPs in South Korea should be continuously monitored. [ABSTRACT FROM AUTHOR]

Stormwater best management practices (BMPs) are engineered structures that attempt to mitigate the impacts of stormwater, which can include nitrogen inputs from the surrounding drainage area. The goal of this study was to assess bacterial community composition in different types of stormwater BMP soils to establish whether a particular BMP type harbors more denitrification potential. Soil sampling took place over the summer of 2015 following precipitation events. Soils were sampled from four bioretention facilities, four dry ponds, four surface sand filters, and one dry swale. 16S rRNA gene analysis of extracted DNA and RNA amplicons indicated high bacterial diversity in the soils of all BMP types sampled. An abundance of denitrifiers was also indicated in the extracted DNA using presence/absence of nirS, nirK, and nosZ denitrification genes. BMP soil bacterial communities were impacted by the surrounding soil physiochemistry. Based on the identification of a metabolically-active community of denitrifiers, this study has indicated that denitrification could potentially occur under appropriate conditions in all types of BMP sampled, including surface sand filters that are often viewed as providing low potential for denitrification. The carbon content of incoming stormwater could be providing bacterial communities with denitrification conditions. The findings of this study are especially relevant for land managers in watersheds with legacy nitrogen from former agricultural land use. [ABSTRACT FROM AUTHOR]

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Filters are one of the dam engineer's best tools to prevent internal erosion and control seepage within embankment dams and their foundations. The dam engineering profession developed the current guidance on gradation design and specifications for filters in the 1980s. Still today, not all design engineers fully understand all aspects of this guidance. In addition, filters need to be compacted appropriately to serve their intended purpose, but there is no industry consensus on appropriate compaction methods. This article includes (a) a discussion of filter gradation design and specification, including consideration of flexibility within the current design guidance, and (b) a discussion of filter sand compaction, including recommended practices. This article is a condensed version of a longer paper (France et al., 2020), which includes more information on filter design and construction considerations. [ABSTRACT FROM AUTHOR]

Microorganism was an important part of groundwater pollution, which was related to the safety of drinking water. In rural water supply project, to identify the microbial community structure of groundwater source water and manganese sand filtered water, the structures of the microbial communities were illustrated through 16S rRNA sequencing using the Illumina MiSeq platform. The results showed that, the biodiversity of groundwater samples containing Fe2+ and Mn2+ was higher than those without Fe2+ and Mn2+. In the same water supply project, the biodiversity of source water was higher than that of manganese sand filtered water. When the abundance of genus level was more than 1%, the six water samples have high biodiversity at the genus level, which were composed of 66 genera. Bacteria phylum that may contain pathogenic microorganisms were detected in water source and manganese sand filtered water samples. Although no coliform was detected, disinfection was also necessary. The influence order of water quality factors on microbial community was DO > COD > TN > Mn2+ > Fe2+ (DO – Dissolved oxygen; COD – Chemical oxygen demand; TN – Total nitrogen). In the same water supply project, the correlation between water source and filtered water sample was consistent with water quality factors, that is, DO, Mn2+ and Fe2+ were positively correlated. [ABSTRACT FROM AUTHOR]

This study investigates the capability of a Bacillus flexus strain isolated from decayed cyanobacterial blooms for the bioremediation of Cylindrospermopsis raciborskii and cylindrospermopsin (CYN) toxin. The algicidal activity of this strain was tested by co-cultivation with C. raciborskii cultures. CYN biodegradation was investigated in the presence of living and heat-inactivated bacterial cells or bacterial filtrate. Living bacterial cells inhibited C. raciborskii growth after 2 days of incubation with complete cell death at day 5. Bacterial filtrate caused a rapid reduction in C. raciborskii growth at the first day, with complete cell lysis at day 3. Only living cells of SSZ01 caused reduction in CYN released into the medium during the bacterial decay of C. raciborskii cells. The biodegradation rate of CYN by SSZ01 relied on initial toxin concentrations. The highest rate (42 μg CYN L−1 day−1) was obtained at the higher initial concentration (300 μg L−1), and the lowest (4μg CYN L−1 day−1) was at lower concentration (50 μg L−1). These results suggest that this bacterial strain could be employed to bioremediate cyanobacterial blooms in freshwaters. Also, the application of this bacterium in slow sand filters would give possibilities for degradation and bioremediation of cyanotoxins in drinking water treatment plants. [ABSTRACT FROM AUTHOR]

Synthetic geotextile envelope can be used as a replacement of sand filters for subsurface drainage pipes. However, clogging and blocking can occur if the filter does not match the soils properly. This paper presents a laboratory study on hydraulic performance of nonwoven geotextile as subsurface drain filter for silty loam soil in eastern China. Two selected synthetic geotextiles were tested. Results showed that Typar SF27 satisfied the filtration requirements compared to the traditional sand filters. Typar SF20 exhibited a clogging risk of about 50% more than SF27; it also exposed to soil loss about 10 times more than SF27. The results indicate that choosing geotextile envelope material for the targeted soils need to consider O90 of the geotextile material and soil size distribution. Findings from this study may provide technical reference for selecting proper geotextile filtering material for subsurface drainage pipes in the study area and regions with similar soil conditions. [ABSTRACT FROM AUTHOR]

Using raw water from a shallow water supply reservoir located in the lower Yangtze River region, the removal efficiencies of conventional treatment on dissolved organic matter (DOM) and disinfection by-products formation potential (DBPFP) were compared with an advanced treatment that equipped with ozone-biological activated carbon (O3-BAC) process. The results showed that the advanced treatment was more efficient than the conventional treatment at removing dissolved organic carbon (DOC; 40–67% removal), UV254 (61–81% removal), the trihalomethane formation potential (THMFP; 37–70% removal) and the haloacetic acid formation potential (HAAFP; 35–89% removal). The sand filter in the conventional treatment process was identified as the main contributor to decreasing DOC, UV254 and DBPFP. The O3-BAC in advanced treatment was found to decrease THMFP and HAAFP, with removal rates of 17–40% and 22–59%, respectively. To improve the water quality of effluents, advanced treatment with O3-BAC should be used to treat raw water from the shallow water supply reservoir in lower Yangtze River. However, the increased DBPFP yield, which is proportional to the potential health risks, should not be ignored. [ABSTRACT FROM AUTHOR]

A laboratory study was undertaken in a rectangular filtration chamber having length, width and height as 200 mm, 160 mm and 1200 mm, respectively. Each filter consists of 15 cm thick boulder layer of size 20–40 mm and 15 cm thick gravel layer of size 4.75–10 mm and 10 cm thick. The thicknesses lower course sand (CS) layer of size 0.600–1.18 mm and 10 cm thick upper CS layer each of size 0.425–0.600 mm, 0.300–0.425 mm and 0.150–0.300 mm is placed separately in filters T1, T2 and T3. The influent sediment load prepared by using 0.75–0.15 m soil in terms of concentration as 250, 500, 1000, 1500, 2000, 2500 and 3000 mg/l was used for checking the performance of the filtration system. Various important parameters such as recharge rate, clogging time and removal efficiency of double sand layer filtration system were estimated. The performance of the filter T3 used in present study has also shown better results as compared to filters used in the past for the purpose of artificial recharge of ground water. The proposed filter with treatment T3 is found to be cost effective due to smaller size of the filter as compared to the past studies as well. [ABSTRACT FROM AUTHOR]

Various reactive treatment materials were evaluated to enhance sand filtration of dissolved species common in stormwater runoff: NO3− , PO43− , Cu2+ , Pb2+ , and Zn2+. Fly ash and iron oxyhydroxide mine drainage residuals were blended with sand at 5% (FA5.0) and 7.5% (MDR7.5) by mass and packed into laboratory columns. Additionally, minus 30 mesh particle sizes of proprietary peat products APTsorb and bioAPT were each packed without blending with a succeeding sand layer (APT-S and BIO-S). Pollutant removal performance was evaluated by pumping synthetic stormwater (SS) through packed up-flow columns without recirculation. The control material was 100% sand (SAND). Target SS concentrations included 1.5 mg/L NO3− as N, 0.5 mg/L PO43− as P, 25 μg/L Cu2+ , 30 μg/L Pb2+ , and 100 μg/L Zn2+. FA5.0 and MDR7.5 both removed over 84% of P. SAND, APT-S, and BIO-S removed limited total P and total dissolved P, while BIO showed a net export of up to 30% P. All columns removed greater than 75% and 89% of Cu2+ and Zn2+ , respectively. APT-S removed the greatest Pb2+ , at over 84%. None of the columns exhibited consistent NO3− removal greater than 10%. [ABSTRACT FROM AUTHOR]

Microbially induced calcite precipitation (MICP) is a method based on collaborative knowledge of microbiology, chemistry and geotechnical engineering. The objective of this study was to investigate the increase of the bearing capacity and the unconfined compressive strength (UCS) as well as the reduction of the permeability of sandy soil using MICP. Experiments were carried out using Bacillus Pasteurii, on three different types of sand. The admixture of bacterial culture and cementation (BCC) solution all-in-one with sand by singlephase injection was applied to induce cementation. Three samples of the selected sand were treated with varied concentrations of BCC solution, ranging from 0.05 to 0.2 L/kg, with a curing period of 3, 7 and 14 days. The test results indicated an enhancement of 55% in UCS for sand treated with a BCC content of 0.05 to 0.2 L/Kg and a reduction of 40% in permeability for untreated sand with an effective diameter of 0.5 mm treated with 0.2 L/kg of BCC solution after 14 days of curing. The results of a plate load test (PLT) on MICP treated sand showed an increase in the ultimate bearing capacity (qu) by about 2.95 to 5.8 times and a 1.7 to 3.31-fold reduction in settlement corresponding to the same load applied on untreated footing. Further investigation of the size and shape of the bearing plate on bearing capacity and settlement was carried out through a plate load test. The higher and more favorable results shown by a rectangular plate compared to a circular plate indicate that the first is preferable. [ABSTRACT FROM AUTHOR]

In rural and peri-urban regions of the developing world, many tube wells used as drinking water sources are microbially and chemically polluted. Consequently, hundreds of millions of people lack access to "safe" drinking water worldwide. People drinking tube well water may suffer from preventable water-borne diseases including diarrhea, skin lesions, and cancer. To address this problem, the United Nations have launched the Sustainable Development Goals (UN SDGs) which are regarded as a global urgent call for action by all countries, in a global partnership. The UN SDGs for safe drinking water (Goal 6) aims to achieve universal water supply by 2030. This goal can only be achieved if affordable and efficient water treatment technologies are made available for households and small communities for simultaneous removal of chemicals and pathogens. Ideally, such systems should be constructed using locally available materials and labor. Filtration on metallic iron (Fe0) based beds has been identified as such an appropriate technology and steel wool (SW) a universally available material. Moreover, Fe0-based filters have been designed and disseminated in some parts of the world but have not yet reached global applicability. A critical review on the abundant literature on using Fe0-based filters for safe drinking water provision revealed that existing devices were not designed on the knowledge basis of the science of aqueous iron corrosion (corrosion science). Iron corrosion induces generation of solid iron corrosion products (FeCPs) which are well-documented contaminant scavengers. FeCPs consisting of Fe-oxide hydroxides are formed in the vicinity of the Fe0 surface and act as a diffusion barrier for dissolved species. Iron corrosion is additionally a volumetric expansive process because the volume of each oxide or hydroxide is at least twice larger than that of iron metal (Fe0). These two main characteristics imply that (i) the efficiency of each Fe0-based filter depends on the kinetics of production of FeCPs (reactivity loss), and (ii) Fe0-based filters will experience porosity loss with increasing service life (permeability loss). In other words, reactivity loss and permeability loss are inherent characteristics of Fe0-based filters which should be addressed in the design stage. Moreover, designed systems should be tested for months or years, given the incertitude on the kinetics of iron corrosion. The objective of the present work was to design a science-based household filter and to test it for one year in the coastal city of Douala (Cameroon). The work started with a systematic review of available designs and a presentation of two main potentially durable designs. The one with a Fe0/sand filter sandwiched between two biological sand filters (BSFs) was tested with polluted well water from Logpom (Douala, Cameroon) using 300 g of a commercial SW (grade 000; d = 50 ?m) as Fe0 source. Previous works using Fe0 SW in water filters revealed that grade 00 (d = 25 ?m) was depleted after some 6 months. The used well water was slightly turbid, polluted with pathogens (total coliforms = 1950 UFC mL-1), and contaminated with nitrate ([NO3 -] = 24.0 mg L-1). The following parameters were monitored twice per month for one year in the influent and effluent water of the filter unit: (i) nitrate concentration, (ii) coliform level, (iii) pH value, and (iv) turbidity. The iron concentration and the hydraulic conductivity (permeability) were also determined. Prior to pilot testing, the impact of chloride ions (Cl-) on the efficiency of Fe0 filters was characterized in laboratory column experiments, using the methylene blue discoloration method. Results of laboratory column experiments revealed that the chloride concentrations expected in well waters in Douala would not negatively impact the efficiency of Fe0 filters. The tested design could produce safe drinking water for at least one year. Coliforms (> 99% decrease), nitrate (> 99%) and turbidity (> 96%) were nearly quantitatively removed over the whole testing period and well below the recommended limits of the World Health Organization (WHO). The effluent pH increased continuously from 6.6 to 8.4. The effluent iron concentration was constantly lower than 0.2 mg L-1. These values are within the WHO drinking water quality standards. The initial flow velocity of 20 L h-1 decreased to ~8.33 L h-1 after one year, corresponding to a permeability loss of nearly 41.5 %. At the end, the filter was still producing 200 L of drinking water. These results confirmed the suitability of commercial Fe0 SW as efficient material to construct durable water filters for households. It appears that the success of the design relied on the low ratio of Fe0 SW (10 vol %) dispersed in the matrix of sand (90 vol %). The tested design can be immediately be applied practically, provide that appropriate construction materials are found. Future research should include (i) testing lower Fe0 SW ratios (same grade), (ii) testing other grades of Fe0 SW in parallel experiments (1 year or more); (iii) testing the same systems for the removal of arsenic and uranium which are the most widespread natural pollutants. Fe0 SW based water filters can be considered as one of the best tools for the achievement of Goal 6 of the United Nations sustainable development goals (SDGs), despite the threat of COVID-19. [ABSTRACT FROM AUTHOR]