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Water shortages occur due to several factors, with drought being one of the biggest drivers. Another major environmental issue related to the contamination of freshwater systems worldwide is thousands of micropollutants, although they generally occur at low concentration levels. The provision of safe drinking water to the population in rural developing nations remains a problem, in particular when surface water and shallow wells or non-watertight headworks wells serve as sources of drinking water. Dramatically changing raw water qualities, floods and high rainfall events anthropogenic pollution, lack of electricity supply in developing regions demand new and adapted solutions for treatment and rendering water safe for distribution. Our study aimes to find another source of water supply using riverbank filtration (RBF). The RBF is a water treatment method that removes water from rivers by pumping wells into a nearby alluvial aquifer. Several physical, chemical, and biological processes that occur underground improve the quality of surface water and eliminate the need for traditional potable water treatment. Additional treatment techniques in this process include biological degradation, sorption, and filtration. Physical, chemical, and microbiological variables were used to assess the effectiveness of the RBF system in Upper Egypt. Our study proposes a workable water treatment strategy that replaces RBF treatment or pretreatment technique for high-quality Nile water to eliminate or reduce surface water pollutants without the use of chlorine.

Pharmaceuticals and personal care products (PPCPs) are found in most rivers facing sewage input worldwide. This study investigated the occurence of 116 PPCPs in the Elbe river in Dresden, Germany, as well as the removal efficiency at a riverbank filtration (RBF) site. The data obtained were compared with data from two additional surface water monitoring stations along the Elbe river operated by a state environmental agency. 21 PPCPs were frequently detected in all water samples with concentrations up to 1270 ng/L. Spatial occurrence and sociodemographic aspects are discussed. According to the European Guideline for Environmental Risk Assessment, carbamazepine, diclofenac, iomeprol and venlafaxine indicate a suspected risk for the aquatic environment but not for drinking water quality in the Dresden region. Water treatment using a combination of natural treatment techniques and post-treatment using activated carbon filtration and disinfection proved to be an efficient barrier to drinking water pollution by PPCPs.

Expanding urbanization, socioeconomic factors, and agricultural activities have led to contamination of the natural water resources in Iraq. The objective of this study was to assess the riverbank filtration (RBF) process in purifying the water of Al-Kufa River from pathogens. The riverbank filtration is a natural approach that helps in the enhancement of the quality of river water, and it is a relatively cost-effective, and sustainable process. This study utilized microbiological approaches to monitor the water quality of wells in comparison with river water. In Al-Kufa district of Al-Najaf governorate in Iraq, eight wells were constructed at different locations adjacent to Al-Kufa River. Total plate count, coliform count, fungal count, and fecal coliform count were among the microbiological parameters tested. The findings of the current study showed a difference in the pathogen count between the wells and river water, but the riverbank filtration process did not meet the World Health Organization guidelines. From this, we concluded that, if the pumping well is continuously running, RBF as a preliminary treatment of surface water would be a promising and potentially viable application in purifying water supply. Finally, in future RBF process is supposed to be taken into consideration to protect the security of water supply from waterborne pathogens.

Riverbank filtration (RBF) is an affordable technique to provide drinking water with adequate quality. The ultimate objective of this study is to facilitate the transferability and application of this sustainable technique in Egypt. In this work, a numerical model was constructed using Groundwater Modeling System (GMS) to study the effect of four design parameters on the RBF performance parameters (i.e., river filtrate portion and travel time) with the aid of MODPATH and ZONEBUDGET. The design parameters were: (1) the pumping rates of the RBF wells, (2) number of operating wells, (3) distance between wells and the river, and (4) the spacing between wells. This study was focused on the hydraulic aspects of the technique. The results demonstrated that: (1) the river filtrate portion exceeds 75% regardless of the design conditions, and (2) the hydraulic performance of the RBF technique is highly controlled by the production capacity of the wells and their positions relative to the surface water systems; the spacing between wells has a minimum effect. Two equations were developed to estimate the river filtrate portion and minimum travel time as functions of pumping rate and distance between the pumping well and the river. HIGHLIGHTS Hydraulic aspects of riverbank filtration.; Impact of design parameters on river filtrate portion and travel time.; The relation between over-pumping and river filtrate portion.; Multi-regression analysis for RBF performance.;

Riverbank filtration (RBF) consists of green drinking water production in many regions and is used as a pre-treatment phase. This study investigates the performance of the RBF in the Nile delta, Egypt, for climate change and population growth scenarios of 2030, 2040, and 2050. This study presents a new method for predicting the sharing of riverbanks considering three cases: i) the river stage controlling the water levels in the river, ii) increasing RBF pumping, and iii) changing the groundwater levels. This last scenario is achieved by changing the general head in the MODFLOW model. The results showed that RBF sharing (RBFS) is a proportion of the river leakage inflow, in which the decrease of the river stage due to the influence of climate change reduced the river leakage inflow and RBFS. In addition, increasing RBF pumping, decreasing RBF pumping, and lowering the groundwater levels due to the increase in the future drinking water pumping for the population growth increased the river leakage inflow and RBFS. Finally, combining the three cases decreased RBFS in the coming years of 2030, 2040, and 2050, respectively, due to more groundwater sharing than the river inflow. The results show that the water budget is a good tool to investigate RBFS compared with MT3D results. This technique can reduce the cost of water quality collection and analysis; moreover, it will help with the estimation of RBF and save time compared with solute transport modeling.

Riverbank Filtration (RBF) Technology has been found to be a safe, renewable, sustainable, and cost-effective drinking water treatment or pretreatment technology. The Egyptian government has recently turned to riverbank filtration to conserve drinking and industrial water at a lower cost and higher efficiency. The study aims to assess the hydraulic performance of the riverbank filtration system in west Sohag, Egypt. MODFLOW and MODPATH 10.2.3 were used under the platform of Groundwater Modeling System (GMS) to construct a hydraulic groundwater flow model to simulate the flow of the riverbank filtration system. Six pumping rates with two scenarios were conducted to investigate the system's hydraulic performance. Water samples were collected from the Nile River, abstraction wells, and groundwater to characterize the water quality. The results indicated that the application of riverbank filtration is promising due to the significant hydraulic connection between the Nile and the aquifer. However, the system hydraulic aspects should be taken into consideration during the design phase as they may affect the RBF hydraulic performance and its efficiency. It became apparent how effective RBF is at eliminating pathogens and suspended solids. Infiltrated water, on the other hand, has higher iron and manganese amounts than the Nile water. HIGHLIGHTS New scope in water treatment process in Egypt.; More sustainable and cost effective for water supply.; Green technology.;

The main challenge of water resource management in high-stress regions, especially in developing countries, is in adopting non-traditional methods to obtain safe drinking water in desired quantities. In Egypt, the riverbank filtration (RBF) system is one of the most common solutions to solve rivers’ water quality issues. Several sites have been investigated, and the system has demonstrated tremendous potential. The drinking water plant in Embaba, Giza, Egypt, is considered in this study to improve the quality of the abstracted water through the vertical well system. The numerical code of MODFLOW and MT3D is used to simulate the impact of using the emplacement of the gravel-pack filter (GPF). Three different scenarios were investigated: the first consists of vertical GPF; the second is horizontal GPF for different geometries, depths, widths or thicknesses, lengths, and permeability of the filter material; and, the third is drilling a pipe filter through the riverbed for different pipe numbers, depths, and the material’s hydraulic conductivity. The results revealed that the riverbank filtration sharing (RBFS) rate was increased by increasing the filter width or thickness at the riverside, the filter pipe numbers, the length of the horizontal filter, and the permeability of filter material. At the same time, the thickness of the river bed decreased by increasing the filter width at the groundwater side. Also, the RBFS was increased by increasing the filter width or the thickness in the two directions and the pipe length. However, it returned to decrease again due to groundwater sharing. Thus, the RBF design should carefully consider the gravel-pack, pipe filter geometry, and permeability impact rate of RBFS.

Due to extensive water exchanges and abundant active biochemical compositions, active and complex hydrogeochemical processes often exist in riverbank filtration (RBF). The distribution of microbes is considered to be profoundly affected by these processes and is considered to impact the hydrogeochemical processes and the migration and transformation of water pollutants in turn and then impact the water quality. The distribution of microbes and their response to the physiochemical properties along a vertical RBF profile perpendicular to the Songhua River in Northeast China was explored by using 16 S rRNA and redundancy analysis (RDA). The results showed that various microbes were found in the vertical riparian filter (RBF) curve, including Actinobacteria, Proteobacteria, Acidobacteria, Chloroflexi, and Firmicutes. With increasing depth (vertical) and distance from the river (lateral), the microbial community and diversity in the RBF sediment profile decreased. Nitrospirota, Pseudomonas, Gammaproteobacteria, Ochrobactrum, Acinetobacter and Desulfobacterota of the RBF core taxa were also significantly correlated with the biotransformation behavior of typical groundwater pollutants (ammonia, Fe, Mn and S). The amount of As in the RBF is too low to sustain microbial survival. Some microbes in RBF can also degrade natural organic pollutants. This study not only revealed the spatial distribution of geological microbes under the impact of hydrological processes but also lays a foundation for the further study of the hydrobiogeochemical processes of active biochemical compositions in groundwater and water quality evolution, which is of positive significance to ensure the quality safety of the drinking water supplied by RBFs.

In the present work measurements of chloride concentrations were used to assess the variability of infiltration conditions and contributions of surface water and local groundwater to the discharge of wells at Krajkowo riverbank filtration site (western Poland). Tests were performed on samples from 26 wells located in a well gallery close to the River Warta. Due to higher chloride concentrations in river water in comparison with local groundwater, significant differences in concentrations in samples from individual wells were noted. In particular, lower chloride concentrations in 11 wells were recorded, which can be linked to the local occurrence of low-permeability deposits in the superficial zone; a locally higher degree of riverbed sediment clogging in the highly convex meandering zone, where strong erosion of the riverbed occurred, which in turn led to increased clogging; the occurrence of a more intensive groundwater inflow into the river valley due to water infiltration from a smaller river entering the River Warta valley, as well as unfavourable conditions for the infiltration of surface water to the lower part of the aquifer with a greater thickness. Differences in chloride concentrations observed were also used to quantify approximately river water contribution to the well production. The average contribution of the River Warta to the recharge of the entire well gallery was estimated at 59.8%.

Study region: A riparian zone within the Songhua River Basin in Northeast China, characterized by a continental monsoon semi-humid climate. Study focus: River infiltration is an important part of groundwater recharge at riverbank filtration (RBF) sites and largely depends on the riverbed hydraulic conductivity (RHC). The influence of river scouring and deposition on RHC is not completely clear, resulting in calculation inaccuracies in the rate of river water infiltration to the aquifer. Thus, the study determined the relationship between RHC and sediment particle size using stepwise regression analysis and a genetic algorithm. A hydrodynamic and sediment transport model (Delft3D) was used to simulate the spatial distribution of sediment particle sizes. A numerical groundwater flow model was also established, using Visual MODFLOW, in which the river boundary was generalized into a third type of boundary condition, and RHC zoning was performed to improve the accuracy of the simulation. New hydrological insights: The findings showed that accurate prediction of RHC is essential for the assessment of groundwater resources in riparian zones. This is crucial for RBF managers, as they will be able to adjust the pumping rate according to the hydrological conditions of the river to either access more water resources in wet years or avoid a series of ecological and geological problems caused by excessive groundwater exploitation in dry years.

In drinking water supply, riverbank filtration (RBF) is an efficient and cost-effective way of eliminating pathogens and micropollutants using a combination of biotic and abiotic processes. Microbial communities in the hyporheic zone both contribute to and are shaped by these processes. Microbial water quality at the point of consumption is in turn influenced by the source water microbiome, water treatment and distribution system. Understanding microbial community shifts from source to tap and the factors behind them is instrumental in maintaining safe drinking water delivery. To this end, microbial communities of an RBF-based drinking water supply system were investigated by metabarcoding in a one-year sampling campaign. Samples were collected from the river, RBF wells, treated water, and a consumer’s tap. Metabarcoding data were analysed in the context of physicochemical and hydrological parameters. Microbial diversity as well as cell count decreased consistently from the surface water to the tap. While Proteobacteria were dominant throughout the water supply system, typical river water microbiome phyla Bacteroidota, Actinobacteria, and Verrucomicrobiota were replaced by Nitrospira, Patescibacteria, Chloroflexi, Acidobacteriota, Methylomicrobilota, and the archaeal phylum Nanoarcheota in well water. Well water communities were differentiated by water chemistry, in wells with high concentration groundwater derived iron, manganese, and sulphate, taxa related to iron and sulphur biogeochemical cycle were predominant, while methane oxidisers characterised the more oxic wells. Chlorine-resistant and filtration-associated taxa (Acidobacteria, Firmicutes, and Bdellovibrionota) emerged after water treatment, and no potentially pathogenic taxa were identified at the point of consumption. River discharge had a distinct impact on well water microbiome indicative of vulnerability to climate change. Low flow conditions were characterised by anaerobic heterotrophic taxa (Woesarchaeales, Aenigmarchaeales, and uncultured bacterial phyla MBNT15 and WOR-1), implying reduced efficiency in the degradation of organic substances. High flow was associated the emergence of typical surface water taxa. Better understanding of microbial diversity in RBF water supply systems contributes to preserving drinking water safety in the future changing environment.

Study region: This study focuses on the simulation of flow and transport of potential contaminants at the riverbank filtration (RBF) site at Embaba, Cairo. RBF has a high potential along the Nile in Egypt as a pre-treatment step for drinking water production. As the site in Cairo can be affected by low water quality and spills of contaminants, the aim was to assess the RBF efficiency under various hydrological, geohydraulic and operational conditions. Study focus: MODFLOW, MT3D and MODPATH were used in this study. Three cases were considered to identify the share of bank filtrate in pumped water and the travel time. The first case focused on the river hydrograph and the permeability of the riverbed; the second on clay cap thickness, aquifer and riverbed hydraulic conductivities, and groundwater abstraction downside of the RBF scheme; and the third on different RBF well abstraction rates, depths, screen lengths and distances from the river bank. New hydrological insights for the region: The results indicate that favorable conditions for RBF sites. Good conditions for RBF include high river stage and riverbed permeability, high aquifer hydraulic conductivity and abstraction rates resulting in high portions of bank filtrate. Design and operation analysis indicate that the abstraction wells should be shallow and located close to the river bank to achieve shorter travel times, thus increasing productivity and preventing high manganese concentrations in the pumped bank filtrate. Due to the natural flow gradient from the Nile towards the RBF wells, changing conditions have impact on the portions of bank filtrate, making the site special.

Study region: Poland, Warta River catchment. Study focus: The study aimed to explain the reasons for spatial variability in chloride concentrations at the Mosina-Krajkowo riverbank filtration (RBF) site located along the river. This variability is attributed to RBF’s different intensity along the river sections, related, among others, to clogging development. The RBF effectiveness was studied using groundwater flow modelling by: examining the water balance in zones established on hydrogeological setting and chloride concentrations; travel time of the bankfiltrate investigation; RBF parametrisation (i.e. infiltration per unit area and specific infiltration per unit of riverbank). New Hydrological Insights for the Region: The study identifies zones of the most favourable RBF conditions and establishes the variability causes. The overall share bankfiltrate was found at 75.8 %. Its spatial variation ranged widely from 41.1–89.3%, confirming the usefulness of the RBF performance sectional analysis in managing this type of site. The highest proportion of surface water (>80 %) occurred along the straight river section, where the riverbed was built by fine and medium sands (preventing penetration of organic suspension into the aquifer). In contrast, the lowest values (

Water quality impacts from artisanal and small-scale alluvial (placer) gold mining operations occur in developing economies across several continents including Asia, Africa, and South America. They often occur in remote and/or resource-poor settings in which mitigation strategies must contend with extreme seasonal variation in river flow as well as the economic incentive to periodically churn (mine) alluvial floodplains without riparian restoration. A novel strategy addressing these constraints is herein explored which employs the alluvial floodplain for filtration-driven removal of particulate contaminants and gold from streams. This process of lateral channel filtration is explored in the Rio Nambija of southern Ecuador, in terms of success in achieving the hydraulic objective of passively driven lateral flow, and the corresponding removal of particulate contaminants (e.g., total mercury, lead, iron, and manganese) by filtration. Accumulation of gold was examined to evaluate whether incorporation of this proposed practice in alluvial (placer) mining can reduce particle-bound contaminants in streams and simultaneously increase economic benefit. Excavation of channels lateral to mining-impacted streams was shown to achieve the hydraulic, water quality, and economic (gold accumulation) objectives. The modest flow capture for any given lateral segment, along with the months-long timescale associated with economic gold accumulation and clogging by suspended solids, dictate a “cultivation” process whereby multiple lateral segments are worked annually.

Abstract In analysing the stream–aquifer interactions and riverbank filtration (RBF) systems, it is very crucial to determine the vertical riverbank and streambed hydraulic conductivity. The riverbank and streambed focused in this investigation are a riverbank of six layers with depths of 38 m and streambed with depths of 9 m connected layers of sediments at 22 test locations and 4 test wells in the Muda River, Malaysia. In the analysis, there were a few tests involved to determine riverbank and hydraulic conductivity of vertical streambed, such as analysis of grain size, pumping test and in situ falling head standpipe permeability tests. The approximate K values of 114 samples and 15 samples taken from riverbanks and streambeds, respectively, were then calculated by employing empirical equation methods [Hazen, Hazen K (cm/s) = d10 (mm), Terzaghi, Beyer, Slichter, Sauerbrei, Kruger, Kozeny–Carman, Zunker, USBR, Zamarin, Barr, Alyamani and Sen, Chapuis, and Krumbein and Monk]. The geometric mean of K for six layers, namely the sandy silt (8.30 m/day), silty sand (47.66 m/day), gravelly sand (150.24 m/day), sandy gravel layer (418.48 m/day), gravelly sand (151.09 m/day) and silty clay (9.36 m/day) as identified characteristics by using grain-size analyses, was greater than the K of pumping test (geometric mean) (31.10 m/day) and the mean obtained from K of permeability tests (7.03 m/day). In general, the K values of upper layer of sediments of streambed were recorded to be larger in comparison with their respective lower layer of sediments. The K value for the upper layer of sediments from all tests located at the left, right and middle parts of the river ranged from 7.56 to 54.77 m/day for upper layer, from 39.80 to 128.40 m/day for middle layer and from 9.11 to 49.92 m/day for lower layer, as described by the grain-size analysis. The value of K ranges based on permeability test indicated that the value of K was from 0.036 to 1.09 m/day for the upper layer and 0.16 to 0.68 m/day for the lower layer of hyporheic sediments zone. Based on the acquired results, the conclusion that the aquifer of the focused area shows possibility for RBF and has the potential to improve the water quality and quantity is referable.

In the paper, a comparison of the efficiency of riverbank treatments is outlined for the Krajkowo well field, where different methods of water abstraction are used. The water is extracted from 29 vertical wells that are located at a distance of 60–80 m from the channel of the River Warta and from a horizontal well with radial drains located 5 m below the bottom of the river. The results of a two-year water-quality investigation indicate that the water quality in both types of abstraction system is influenced by the quality of river water. The water quality observed in the horizontal well is closely similar to that of the river water, with similar concentrations of sulphates, nitrates and micropollutants, but a reduction in bacteriological contamination and plankton is clearly seen. The reduction in contaminants is mainly the result of physical processes, such as mechanical entrapment of suspended material and colloids as well as bacteria and plankton. In the vertical wells, the influence of contamination from river water is also visible, but the reduction in contamination is more significant, especially in cases of bacteria, plankton, micropollutants and nitrates, and is determined by both physical and chemical processes, such as sorption, dissolution, red-ox processes and denitrification. The present research shows that river water treatment is more effective in the case of vertical wells. The most favourable distance of a well from the channel of the river, from the perspective of water quality, is 150–200 m, which corresponds to a residence time of about six months.

Riverbank filtration leads to purification of water. For India it can be a simple, economical and effective alternative. A few unanswered questions were: Can it work in Indian mountainous regions? Will it be of any advantage in the case of some of the polluted Indian surface waters? With the goal to evaluate use of riverbank filtration as a sustainable technology under widely varying conditions prevalent in India, the effectiveness of riverbank filtration has been examined over the last 10 years. In the case of cleaner surface waters, the wells deliver water free of turbidity and coliform even during monsoon irrespective of well configuration. In the case of polluted source waters, it results in an overall advantage in terms of improved raw water quality, reduced degree and cost of subsequent treatment and decreased levels of disinfection by-products. The study shows riverbank filtration to be an effective and sustainable option for plains as well as the mountainous region.

Site selection plays a crucial role in riverbank filtration for sustainable water availability and quality. Choosing the most appropriate from among multiple candidate sites requires a complex procedure, involving many tangibles and intangibles. In this study, the Analytic Hierarchy Process (AHP), which selects the optimal alternative by hierarchically classifying various attributes and then quantifying the importance of each attribute, was used to prioritize candidate locations for riverbank filtration. A GIS-based computer program was developed to automate the assessment process. The developed software was applied to the Han River in Korea. Analysis of four candidate sites reveals that a site that has better water quality and connectivity to the neighboring purification facility is more suitable than other locations.

In the Indian metropolis of Delhi, the Yamuna River is highly influenced by sewage water, which has led to elevated ammonium (NH4+) concentrations up to 20 mg/L in the river water during 2012–2013. Large drinking water production wells located in the alluvial aquifer draw high shares of bank filtrate. Due to the infiltrating river water, the raw water NH4+ concentrations in some wells exceed the threshold value of 0.5 mg/L ammonia-N of the Indian drinking water specifications, making the water unfit for human consumption without prior treatment. However, to meet the city’s growing water demand, it might be advantageous to consider the long-term use of the well field. This requires the development of an adapted post-treatment unit in concert with an adjusted well field management. To better understand the groundwater dynamics and contamination and decontamination times at the well field, a theoretical modeling study has been conducted. The results of 2D numerical modeling reveal that the groundwater flux beneath the river is negligible because of the aquifer and river geometry, indicating that infiltrating river water is not diluted by the ambient groundwater. Increasing the water abstraction in the wells closest to the river would result in a larger share of bank filtrate and a decreasing groundwater table decline. Simplified 1D reactive transport models set up for a distance of 500 m (transect from the riverbank to the first production well) showed that the NH4+ contamination will prevail for the coming decades. Different lithological units of the aquifer (sand and kankar—a sediment containing calcareous nodules) have a strong influence on the respective contamination and decontamination periods, as the retardation of NH4+ is higher in the kankar than in the sand layer. Although this simplified approach does not allow for a quantification of processes, it can support decision-making about a possible future use of the well field and point to associated research needs.