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Managed aquifer recharge is a robust barrier in the multi-barrier approach to supply safe drinking water. The removal performance of gesomin and 2-methylisoborneol through managed aquifer recharge was investigated using batch and column experiments. Batch experiments were carried out to investigate the removal of geosmin and 2-methylisoborneol (MIB) in the presence of different types of biodegradable organic matter using different types of water. Five different types of water spiked with 70--293 ng/L of geosmin and MIB were used in batch reactors, and complete removal of geosmin and MIB (down to the detection limit) was achieved in all cases. Soil column studies showed that biodegradation contributed to the removal of geosmin and MIB by 23 and 31%, respectively (empty bed contact time: 17 hours). The removal of geosmin and MIB appeared to be influenced more by microbial activity than the initial concentrations of geosmin and MIB. Adsorption was found to be the dominant mechanism (major role) followed by biodegradation (minor role) for geosmin and MIB removals during soil passage. Managed aquifer charge can therefore be used as a robust barrier to remove taste and odor (T&O) causing compounds. [ABSTRACT FROM AUTHOR]

A radial collector well is used for the extraction of a large amount of groundwater without causing a deep drawdown at the well's center, and it is appropriate for the supply of municipal water through riverbank filtration (RBF). Flow path changes caused by water extraction through a radial collector well were simulated to estimate the amount of river water induction at a RBF site associated with Nakdong River in South Korea. The structure of the screened horizontal arms of a radial collector well was examined with respect to effective riverbank filtration. The relative ratio of the river water induced to the radial collector well compared to the total groundwater extraction was estimated to be 27-52%. The amount of induced river water varies with the distance of a horizontal arm from the river, indicating that the location and structure of the collector well is significant for RBF. In all simulation cases, the maximum drawdown of the groundwater level near the collector well was 2.1 m, which is not significant considering the substantial pumping rate at the study site. It was concluded that RBF radial collector wells can be used at the study site for a sustainable water supply. [ABSTRACT FROM AUTHOR]

Abstract: One possible consequence of increasing water temperatures due to global warming in middle Europe is the proliferation of cylindrospermopsin-producing species from warmer regions. This may lead to more frequent and increased cylindrospermopsin (CYN) concentrations in surface waters. Hence, efficient elimination of CYN is important where contaminated surface waters are used as a resource for drinking water production via sediment passage. Sediments are often characterized by a lack of oxygen and low temperature (i.e. approx. 10°C). The presence of dissolved organic carbon (DOC) is not only known to enhance but also to retard contaminant degradation by influencing the extent of lag phases. So far CYN degradation has only been investigated under oxic conditions and at room temperature. Therefore, the aim of our experiments was to understand CYN degradation, focusing on the effects of i) anoxic conditions, ii) low temperature (i.e. 10°C) in comparison to room temperature (23±4°C) and iii) DOC on lag phases. We used two natural sandy sediments (virgin and preconditioned) and surface water to conduct closed-loop column experiments. Anoxic conditions either inhibited CYN degradation completely or retarded CYN breakdown in comparison to oxic conditions (T 1/2 (oxic)=2.4 days, T 1/2 (anoxic)=23.6 days). A decrease in temperature from 20°C to 10°C slowed down degradation rates by a factor of 10. The presence of DOC shortened lag phases in virgin sediments at room temperature but induced a lag phase in preconditioned sediments at 10°C, indicating potential substrate competition. These results show that information on physico-chemical conditions in sediments is crucial to assess the risk of CYN breakthrough. [Copyright &y& Elsevier]

Summary: Riverbank filtration (RBF) is a mechanism by which undesired substances contained in infiltrating surface waters are attenuated during their passage across the riverbed and its underlying aquifer towards production wells. In this study, multi-component reactive transport modeling was used to analyze the biogeochemical processes that occur during subsurface passage at an existing RBF system – the Flehe Waterworks located along the Rhine River in Düsseldorf, Germany. The reactive transport model was established on the base of a conservative solute transport model for which temperature and chloride data served as calibration constraints. The model results showed that seasonal temperature changes superimposed by changes in residence time strongly affected the extent of the redox reactions along the flow path. The observed temporal, especially seasonal, changes in the breakthrough of dissolved oxygen were found to be best reproduced by the model when the temperature dependency of the biogeochemical processes was explicitly considered. High floods in the Rhine drastically reduced the travel time to the RBF well from an average travel time of 25–40days to less than 8days. On the other hand, low flow conditions increased the subsurface residence times between the Rhine River and the RBF well to about 60days. The model results revealed that short term changes in the terminal electron acceptor consumption (biodegrdation extent) were solely attributed to fluctuations in residence time, while more gradual changes in biodegradation extent were due to both seasonal variations of the river water temperature and gradual changes in residence time. [ABSTRACT FROM AUTHOR]

Bank filtration (BF) is an attractive, robust and reliable water treatment technology. It has been used in Europe and USA for a long time; however experience with this technology so far is site specific. There are no guidelines or tools for transfer of this technology to other locations, specifically to developing countries. A four-step methodology was developed at UNESCO-IHE to analyse feasibility and to predict the performance of BF for water treatment. This included (I) hydraulic simulation using MODFLOW; (ii) determination of share of bank filtrate using NASRI BF simulator; (iii) prediction of water quality from a BF system using the water quality guidelines developed and (iv) comparison of the costs of BF systems and existing conventional surface water treatment systems for water treatment. The methodology was then applied to assess feasibility of BF in five cities in Africa. It was found that in most of the cities studied BF is a feasible and attractive option from hydraulic, water quality as well as operational cost considerations. Considerable operational and maintenance costs saving can be achieved and water quality can be further improved by switching from conventional chemical-based surface water treatment to BF or at least by replacing some of the treatment units with BF systems. [ABSTRACT FROM AUTHOR]

The article discusses the River Tunnel and Pump Station project of the Louisville Water Co. (LWC), an innovative riverbank filtration (RBF) that provides high-quality water to Louisville and its surrounding areas across Kentucky. It recounts that Lousiville was once referred as the graveyard of the West due to the rampant cases of typhoid fever caused by contaminated water. The move of the LWC in educating the community to embrace the technological innovation is also mentioned.

Nitrate transport in the unsaturated zone of a riverbank filtration (RBF) system in Karany, Czech Republic, was studied. Previous study of the system estimated RBF recharge as 60% riverbank filtrate and 40% local groundwater contaminated by nitrates. Nitrate concentrations observed in RBF recently cannot be explained by simple groundwater contamination and a new conception of groundwater recharge is suggested. A two-component model based on water 18O data modelled recharge of local groundwater. One component of groundwater recharge is rainfall and irrigation water moving through the unsaturated zone of the Quaternary sediments in piston flow. The second component is groundwater from the Cretaceous deposits with a free water table. Both the components of groundwater recharge have different nitrate concentrations, and resulting contamination of groundwater depends on the participation of water from Quaternary and Cretaceous deposits. Nitrates' origins and their mixing in the subsurface were traced by 15N data. Nitrate transport from the unsaturated zone is important and time variable source of groundwater contamination. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A thin layer of fine-grained sediment commonly is deposited at the sediment-water interface of streams and rivers during low-flow conditions, and may hinder exchange at the sediment-water interface similar to that observed at many riverbank-filtration (RBF) sites. Results from a numerical groundwater-flow model indicate that a low-permeability veneer reduces the contribution of river water to a pumping well in a riparian aquifer to various degrees, depending on simulated hydraulic gradients, hydrogeological properties, and pumping conditions. Seepage of river water is reduced by 5-10% when a 2-cm thick, low-permeability veneer is present on the bed surface. Increasing thickness of the low-permeability layer to 0·1 m has little effect on distribution of seepage or percentage contribution from the river to the pumping well. A three-orders-of-magnitude reduction in hydraulic conductivity of the veneer is required to reduce seepage from the river to the extent typically associated with clogging at RBF sites. This degree of reduction is much larger than field-measured values that were on the order of a factor of 20-25. Over 90% of seepage occurs within 12 m of the shoreline closest to the pumping well for most simulations. Virtually no seepage occurs through the thalweg near the shoreline opposite the pumping well, although no low-permeability sediment was simulated for the thalweg. These results are relevant to natural settings that favour formation of a substantial, low-permeability sediment veneer, as well as central-pivot irrigation systems, and municipal water supplies where river seepage is induced via pumping wells. Published in 2011 by John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: Laboratory continuous flow-through riverbank filtration (RBF) models were developed to study the organic substances and ammonia nitrogen removal efficiency in the riverbank filtration process. The results indicated that the priority pollutants, organic substances and ammonia nitrogen, could be removed to a great extent. The results also indicate that the quality of the Huai River water is acceptable to operate the abstraction system with the riverbank filtration. [Copyright &y& Elsevier]

Abstract: Base on the previous study of organic substances and ammonia nitrogen removal efficiency through laboratory continuous flow-through riverbank filtration (RBF) models, field study were carried out to evaluate the results drawn from small model experiments. Five wells were selected to in this riverbank filtration process field study. The results indicated that the priority pollutants, organic substances and ammonia nitrogen, could be removed to a great extent. The results also indicate that the quality of the Huai River water is acceptable to operate the abstraction system with the riverbank filtration. [Copyright &y& Elsevier]

The spatial and temporal variability of riverbed vertical hydraulic conductivity (Kv ) was investigated at a site of induced infiltration, associated with a municipal well field, to assess the impact of high-stage events on scour and subsequently the riverbed Kv . Such impacts are important when considering the potential loss of riverbank filtration capacity due to storm events. The study site, in and along the Great Miami River in southwest Ohio, overlaid a highly productive glacial-outwash aquifer. A three-layer model for this system was conceptualized: a top layer of transient sediment, a second layer comprising large sediment resistant to scour, but clogged with finer sediment (the armor/colmation layer), and a third layer that was transitional to the underlying higher-Kv aquifer. One location was studied in detail to confirm and quantify the conceptual model. Methods included seepage meters, heat-flow modeling, grain-size analyses, laboratory permeameter tests, slug tests and the use of scour chains and pressure-load cells to directly measure the amount of sediment scour and re-deposition. Seepage meter measured riverbed Kv ranged from 0.017 to 1.7 m/d with a geometric mean of 0.19 m/d. Heat-transport model-calibrated estimates were even lower, ranging from 0.0061 to 0.046 m/d with a mean of 0.017 m/d. The relatively low Kv was indicative of the clogged armor layer. In contrast, slug tests in the underlying riverbed sediment yielded Kv values an order of magnitude greater. There was a linear relationship between scour chain measured scour and event intensity with a maximum scour of only 0.098 m. Load-cell pressure sensor data over a 7-month period indicated a total sediment-height fluctuation of 0.42 m and a maximum storm-event scour of 0.28 m. Scour data indicated that the assumed armor/colmation layer almost always remained intact. Based on measured layer conductivities and thicknesses, the overall Kv of this conceptualized system was 1.6 m/d. Sensitivity analyses indicated that even complete scour of the armor/colmation layer would likely increase the overall Kv only by a factor of 1.5. Most scour events observed removed only the transient sediment, having very little effect on the entire system indicating low risk of losing filtration capacity during storms. The research, however, focused on the point bar, depositional side of the river. More research of the entire river profile is necessary. [Copyright &y& Elsevier]

Oocysts of the protozoan pathogen Cryptosporidium parvum are of particular concern for riverbank filtration (RBF) operations because of their persistence, ubiquity, and resistance to chlorine disinfection. At the Russian River RBF site (Sonoma County, CA), transport of C. parvum oocysts and oocyst-sized (3 μm) carboxylate-modified microspheres through poorly sorted (sorting indices, σ1, up to 3.0) and geochemically heterogeneous sediments collected between 2 and 25 m below land surface (bls) were assessed. Removal was highly sensitive to variations in both the quantity of extractable metals (mainly Fe and Al) and degree of grain sorting. In flow-through columns, there was a log-linear relationship (r² = 0.82 at p < 0.002) between collision efficiency (α, the probability that colloidal collisions with grain surfaces would result in attachment) and extractable metals, and a linear relationship (r² = 0.99 at p < 0.002) between α and σ1. Collectively, variability in extractable metals and grain sorting accounted for ∼83% of the variability in α (at p < 0.0002) along the depth profiles. Amendments of 2.2 mg L-1 of Russian River dissolved organic carbon (DOC) reduced α for oocysts by 4-5 fold. The highly reactive hydrophobic organic acid (HPOA) fraction was particularly effective in re-entraining sediment-attached microspheres. However, the transport-enhancing effects of the riverine DOC did not appear to penetrate very deeply into the underlying sediments, judging from high α values (∼1.0) observed for oocysts being advected through unamended sediments collected at ∼2 m bls. This study suggests that in evaluating the efficacy of RBF operations to remove oocysts, it may be necessary to consider not only the geochemical nature and size distribution of the sediment grains, but also the degrees of sediment sorting and the concentration, reactivity, and penetration of the source water DOC. [ABSTRACT FROM AUTHOR]

The objective of this paper was to provide new insights into processes affecting riverbank filtration (RBF). We consider a system with an inflatable dam installed for enhancing water production from downstream collector wells. Using a numerical model, we investigate the impact of groundwater pumping and dam operation on the hydrodynamics in the aquifer and water production. We focus our study on two processes that potentially limit water production of an RBF system: the development of an unsaturated zone and riverbed clogging. We quantify river clogging by calibrating a time-dependent riverbed permeability function based on knowledge of pumping rate, river stage, and temperature. The dynamics of the estimated riverbed permeability reflects clogging and scouring mechanisms. Our results indicate that (1) riverbed permeability is the dominant factor affecting infiltration needed for sustainable RBF production; (2) dam operation can influence pumping efficiency and prevent the development of an unsaturated zone beneath the riverbed only under conditions of sufficient riverbed permeability; (3) slow river velocity, caused by dam raising during summer months, may lead to sedimentation and deposition of fine-grained material within the riverbed, which may clog the riverbed, limiting recharge to the collector wells and contributing to the development of an unsaturated zone beneath the riverbed; and (4) higher river flow velocities, caused by dam lowering during winter storms, scour the riverbed and thus increase its permeability. These insights can be used as the basis for developing sustainable water management of a RBF system. [ABSTRACT FROM AUTHOR]

Riverbank filtration (RBF) has been used for many decades in Europe and the United States to provide drinking water to communities located on riverbanks. In India, the development of RBF has the potential to provide drinking water to many cities located on the Ganga Plains currently using surface water as a source for their public water supply. Water diversion for irrigation and discharge of wastewater to rivers with extremely low flows has aggravated the water supply situation for many Indian cities using surface water. A number of Indian cities, with source waters of significantly varying quality, are already using RBF. In most of these cities no significant additional treatment is provided to the filtrate for their water supply. The objective of this article is to examine selected operating bank filtration sites in India (that have been investigated since 2005) and to elucidate additional potential RBF sites based on water problems and hydrogeologic suitability. A summary of selected operational RBF systems in Ahmedabad, Delhi, Haridwar, Mathura, Medinipur and Kharagpur, Nainital, Patna and Srinagar and their ability to produce potable water is provided. Analysis of the suitability of RBF for Allahabad, Bhubaneswar, Guwahati, and Vijayawada, based on hydrogeology and land use, is also provided. [ABSTRACT FROM AUTHOR]

An evaluation of the efficiency of conventional clariflocculator units with tube settlers has been done in this study within the compact units in Mosul Unified Water Project. Results of bimonthly samples were analyzed before and after treatment in the conventional project with their correspondences in tube settlers within the compact units during period of January 2003 to June 2004 in order to investigate the expected water quality variety in Tigris river. The results have shown that tube settlers are more efficient than conventional clariflocculator units in removing turbidity and phytoplankton alga at a low turbidity level less than (30 NTU) and number of phytoplankton alga between (45-59) cell/ml. (75%) of the residual turbidity and phytoplankton alga after treatment was the best in tube settlers units. Results also showed that conventional clariflocculator units are more efficient than tube settlers at the water turbidity more than(30 NTU) and number of phytoplankton alga between (63-75) cell/ml. (25%) of the total residual turbidity and phytoplankton alga after treatment was the best in the conventional clariflocculator units. [ABSTRACT FROM AUTHOR]

Riverbank filtration, and more recently seabed filtration, has attracted attention as being an effective, low-energy treatment process for water. The process includes filtration of surface water through porous streambed media with a cross flow of water over the streambed, similar to the surface-sweeping mechanism in membrane filtration. The importance of this cross-flow mechanism on the particle removal processes at work in riverbank filtration has not been explored; therefore, this research was initiated to provide insight into this process. Results indicated that the presence of the tangential cross flow of water across a filter surface significantly affects filtrate quality. The unanticipated finding was the apparent concentration of larger particles near the filtration surface, evidence of which was observed in the experimental flume and supported in computer simulations of the process. [ABSTRACT FROM AUTHOR]

Abstract: The three-dimensional groundwater flow patterns in a gravel bar at the Danube east of Vienna were investigated and are discussed in this paper. The observed groundwater level gradients are highly dynamic and respond very quickly to changes in the river water levels. A variably saturated groundwater model was calibrated to the data to describe the complex dynamics of flow in the gravel bar. The model results suggest that short-term (6–48h) fluctuations of river water levels cause variations in the exchange flow rates from −35l/s to 82l/s. The highest rates occur during brief infiltration after rapidly rising river water levels. Simulations of different scenarios indicate that riverbank clogging will decrease the exchange fluxes by up to 80%, while clogging of both riverbank and riverbed essentially stops the flow exchange. The groundwater model is also used to simulate the transport of a conservative tracer. The variation of river water levels over time is shown to increase the extent of the active river–aquifer mixing zone in the gravel bar. These dynamic factors significantly enhance the dilution of conservative tracer concentrations in this zone. [ABSTRACT FROM AUTHOR]

Abstract: There is increasing concern regarding the presence of unregulated trace organic chemicals in drinking water supplies that receive discharge from municipal wastewater treatment plants. In comparison to conventional and advanced drinking water treatment, riverbank filtration represents a low-cost and low-energy alternative that can attenuate total organic carbon (TOC) as well as trace organic chemicals (TOrC). This study examined the role of predominant redox conditions, retention time, biodegradable organic carbon, and temperature to achieve attenuation of TOC and TOrC through monitoring efforts at three full-scale RBF facilities in different geographic areas of the United States. The RBF systems investigated in this study were able to act as a reliable barrier for TOC, nitrogen, and certain TOrC. Temperature (seasonal) variation played an important role for the make-up of the river water quality and performance of the RBF systems. Temperatures of less than 10 °C did not affect TOC removal but resulted in diminished attenuation of nitrate and select TOrC. [ABSTRACT FROM AUTHOR]

Abstract: A new analytic solution approach is presented for the modeling of steady flow to pumping wells near rivers in strip aquifers; all boundaries of the river and strip aquifer may be curved. The river penetrates the aquifer only partially and has a leaky stream bed. The water level in the river may vary spatially. Flow in the aquifer below the river is semi-confined while flow in the aquifer adjacent to the river is confined or unconfined and may be subject to areal recharge. Analytic solutions are obtained through superposition of analytic elements and Fourier series. Boundary conditions are specified at collocation points along the boundaries. The number of collocation points is larger than the number of coefficients in the Fourier series and a solution is obtained in the least squares sense. The solution is analytic while boundary conditions are met approximately. Very accurate solutions are obtained when enough terms are used in the series. Several examples are presented for domains with straight and curved boundaries, including a well pumping near a meandering river with a varying water level. The area of the river bottom where water infiltrates into the aquifer is delineated and the fraction of river water in the well water is computed for several cases. [Copyright &y& Elsevier]

Summary: Understanding the impact of storm events on riverbed hydraulic conductivity is crucial in assessing the efficacy of riverbank filtration as a water-treatment option. In this study, the variability of riverbed hydraulic conductivity and its correlation to river stage during storm events was investigated. Water levels and temperatures were continuously monitored in the river using creek piezometers screened beneath the riverbed, and monitoring wells located on the river bank. The range of values for water levels during the study period was from 161.3 to 163.7m AMSL while temperatures ranged from 3.75°C to 24°C. During the duration of the study the Great Miami River was losing water to the underlying aquifer due to pumping in the adjacent municipal well field. Flow and heat transport were simulated in a groundwater heat and flow program VSH2D to determine the hydraulic conductivity of the riverbed. Hydraulic conductivity was estimated by using it as a calibration parameter to match simulated temperatures to observed temperatures in a monitoring well. Hydraulic heads in the aquifer responded to storm events at the same times but with dampened amplitudes compared to the river stage. The relative responses resulted in increased head gradients during the rising limb of the stage-hydrograph. Heat-flow modeling during five storm events demonstrated that a rise in head gradient alone was not sufficient to produce the temperature changes observed in the wells. Simulated temperatures were fitted to the observed data by varying both river stage (as measured in the field) and riverbed hydraulic conductivity. To produce the best fit temperatures, riverbed hydraulic conductivity consistently needed to be increased during the rising and peak stages of the storm events. The increased conductivity probably corresponds to a loss of fine sediments due to scour during high river stage. Hydraulic conductivity increases during storm events varied from a factor of two (0.0951–0.2195m/d) to almost one order of magnitude (0.0007–0.00658m/d). Despite these predicted changes the highest model-predicted hydraulic conductivity value was 0.66m/d, which is still much lower than the infiltration rate used in sand filtration systems (3.59m/d). These low values suggest that storm events do not pose a significant risk to the water quality at this well field. There was a direct correlation between the duration of rising limb, rate of change of stage and maximum river stage and the magnitude of change of riverbed hydraulic conductivity. [Copyright &y& Elsevier]

Abstract: Utilization of riverbank filtrate water for heating and cooling of buildings can reduce installation costs considerably by using the existing operating facilities for water purification and supply. Changwon city, Korea, has been using riverbank filtrate water for the indoor air-conditioning at its Daesan water treatment plant since 2006. In this method, the most important factor for determining the efficiency of heating and cooling is the temperature of the filtrate water. Numerical simulation of the temperature profile of riverbank filtrate water in the Daesan plant using HydroGeoSphere shows that the primary factor in determining filtrate water temperature is the pumping rate. This is because of the proportion of the river-originated water which increases with pumping rate. It also shows that maintaining the facility operation at the current pumping rate for the next 30 years will not cause any significant change in the water temperature. However, following the new city plan to install an additional 37 wells with a 6 times greater pumping rate than the current system might cause about 2°C decrease in filtrate water temperature 10 years after the extension. This temperature drop will result in a significant change from the original design in heating and cooling performance. [Copyright &y& Elsevier]

Abstract: Riverbank filtration has been shown to be effective for removing viable Cryptosporidium parvum oocysts. Drinking water systems that employ riverbank filtration may receive additional treatment credits beyond that which they can obtain using traditional engineering approaches. In order to develop guidance for removal effectiveness, screening level predictive modeling by colloid filtration theory combined with advection and dispersion modeling is potentially useful. Currently, only few studies have measured basic effective colloid filtration parameters for Cryptosporidium oocysts with naturally occurring riverbank sediments. In the focus of this study we conducted flow column experiments in triplicate and measured effective attachment rate coefficients for sandy river sediments of the Southern Great Plains which are low in organic matter. We found that for sediment sampled from these high-energy rivers there was no apparent dependency of C. parvum removal with carbon content, bacterial colony forming units, or with gross texture properties of the sands. The differences in particle size distribution for the sediments suggested that straining did not play a role in removal efficiency. First-order colloid attachment rate coefficients followed lognormal distribution functions. The coefficients also appeared to be unrelated to the differences in particle size distributions of the sediments, bacterial counts, or levels of total carbon or total organic carbon. Using Monte Carlo analyses, the lowest observed 5th percentile was 8.0 × 10−6 min−1 and the highest observed 95th percentile was 1.6 × 10−3. Total log10 removals ranged from 23 to 200 m−1. These results have application for screening level colloid filtration modeling of riverbank filtration in these systems. [Copyright &y& Elsevier]

The impact of riverbank filtration (RBF) on the treatment of water from the River Yamuna at Mathura, which has disagreeable visual properties, has been investigated. The dissolved organic carbon (DOC) and colour of the river water were 4.0–6.8mg/L and 40–65 colour units (CU), respectively. Pre-chlorination is in practice to improve raw water quality. Chlorine doses as high as 60mg/L ahead of the water treatment units reduced colour by about 78%. Removal of DOC and UV-absorbance was less than 18%. In comparison to direct pumping of the river water, collection of water through RBF resulted in the reduction of DOC, colour, UV-absorbance and fecal coliforms by around 50%. However, riverbank filtrate did not conform to the drinking water quality standards. Therefore, riverbank-filtered water along with the Yamuna water were ozonated for different durations. To reduce DOC to the desired level, the dose of ozone required for the riverbank filtrate was found to be considerably less than the ozone required for the river water. RBF as compared to direct pumping of Yamuna water appears to be effective in improving the quality of the raw water. [Copyright &y& Elsevier]

The Kaoping River Basin, located in southern Taiwan, flows through approximately 171 km and drains toward the South Taiwan Strait. It is the largest and the most intensively used river basin in Taiwan. However, due to the concentrated rainfall in the wet season, short rivers and rapid flows, poor flow conditions, uneven time distribution of flows, and rapid rise of flow peak cause the unevenly distributed water resource in this region. Based on the results from the water resource analysis and water demand evaluation, a shortage of water supply in the basin would occur in 5 years. Sustainable water resource management strategies have been proposed to effectively utilize the limited water resource in the basin. The proposed strategies include construction of water collection gallery system, installation of riverbank infiltration system, installation of groundwater recharge and extraction systems, recycling the effluent from the secondary wastewater-treatment plant, and replacement of old water supply pipes. These measures are more sustainable and more environmentally acceptable compared with other traditional construction measures (e.g., reservoir and long-distance water transportation conduit). Results and experience obtained from this study will be helpful in developing water resource management strategies for other similar river basins. [ABSTRACT FROM AUTHOR]

Abstract: This study assessed the efficacy for removing Cryptosporidium parvum oocysts of poorly sorted, Fe- and Al-rich, subsurface sediments collected from 0.9 to 4.9 and 1.7–13.9 m below land surface at an operating riverbank filtration (RBF) site (Russian River, Sonoma County, CA). Both formaldehyde-killed oocysts and oocyst-sized (3 μm) microspheres were employed in sediment-packed flow-through and static columns. The degree of surface coverage of metal oxides on sediment grain surfaces correlated strongly with the degrees of oocyst and microsphere removals. In contrast, average grain size (D 50) was not a good indicator of either microsphere or oocyst removal, suggesting that the primary mechanism of immobilization within these sediments is sorptive filtration rather than physical straining. A low specific UV absorbance (SUVA) for organic matter isolated from the Russian River, suggested that the modest concentration of the SUVA component (0.8 mg L−1) of the 2.2 mg L−1 dissolved organic carbon (DOC) is relatively unreactive. Nevertheless, an amendment of 2.2 mg L−1 of isolated river DOC to column sediments resulted in up to a 35.7% decrease in sorption of oocysts and (or) oocyst-sized microspheres. Amendments (3.2 μM) of the anionic surfactant, sodium dodecyl benzene sulfonate (SDBS) also caused substantive decreases (up to 31.9 times) in colloid filtration. Although the grain-surface metal oxides were found to have a high colloid-removal capacity, our study suggested that any major changes within the watershed that would result in long-term alterations in either the quantity and (or) the character of the river''s DOC could alter the effectiveness of pathogen removal during RBF operations. [Copyright &y& Elsevier]

The use of soil bio-engineering techniques in developing countries is a relevant issue for disaster mitigation, environmental restoration and poverty reduction. Research on the autochthonal plants suitable for these kinds of interventions and on the economic efficiency of the interventions is essential for the dissemination of such techniques. The present paper is focused on these two issues as related to the realization of various typologies of soil bioengineering works in the humid tropics of Nicaragua. In the area of Río Blanco, located in the Department of Matagalpa, soil bioengineering installations were built in several sites. The particular structures built were: drainages with live fascine mattress, a live palisade, a vegetated live crib wall for riverbank protection, a vegetative covering made of a metallic net and biotextile coupled with a live palisade made of bamboo. In order to evaluate the suitability of the various plants used in these works, monitoring was performed, one on the live palisade alongside an unpaved road and the other on the live crib wall along a riverbank, by collecting data on survival rate and morphological parameters. Concerning economic efficiency, we proceeded to a financial analysis of the works. Once the unit price was obtained, we converted the amount into EPP Dollars (Equal Purchasing Power) in order to compare the Nicaraguan context with the European one. Among the species used we found that Gliricidia sepium (local common name: Madero negro) and Tabebuia rosea (local common name: Roble macuelizo) are adequate for soil bioengineering measures on slopes, while Erythrina fusca (local common name: Helequeme) resulted in successful behaviour only in the crib wall for riverbank protection. In comparing costs in Nicaragua and in Italy, the unit price reduction for Nicaragua ranges from 1.5 times (for the vegetative covering) to almost 4 times (for the fascine mattress), using the EPP dollar exchange rate. Our conclusions with regard to hydrological-risk mitigating actions performed on a basin scale and through naturalistic (live) interventions are that they are not only socially and technically possible, even in hardship areas (by maximizing the contribution of the local labour force and minimizing the use of mechanical equipment), but also economically sustainable. [ABSTRACT FROM AUTHOR]

Abstract: This study explored the effect of different bulk organic carbon matrices on the fate of trace organic chemicals (TOrC) during managed aquifer recharge (MAR). Infiltration through porous media was simulated in biologically active column experiments under aerobic and anoxic recharge conditions. Wastewater effluent derived organic carbon types, differing in hydrophobicity and biodegradability (i. e., hydrophobic acids, hydrophilic carbon, organic colloids), were used as feed substrates in the column experiments. These carbon substrates while fed at the same concentration differed in their ability to support soil biomass growth during porous media infiltration. Removal of degradable TOrC (with the exception of diclofenac and propyphenazone) was equal or better under aerobic versus anoxic porous media infiltration conditions. During the initial phase of infiltration, the presence of biodegradable organic carbon (BDOC) enhanced the decay of degradable TOrC by promoting soil biomass growth, suggesting that BDOC served as a co-substrate in a co-metabolic transformation of these contaminants. However, unexpected high removal efficiencies were observed for all degradable TOrC in the presence of low BDOC concentrations under well adopted oligotrophic conditions. It is hypothesized that removal under these conditions is caused by a specialized microbial community growing on refractory carbon substrates such as hydrophobic acids. Findings of this study reveal that the concentration and character of bulk organic carbon present in effluents affect the degradation efficiency for TOrC during recharge operation. Specifically aerobic, oligotrophic microbiological soil environments present favorable conditions for the transformation of TOrC, including rather recalcitrant compounds such as chlorinated flame retardants. [Copyright &y& Elsevier]

Surface water intakes are a major capital cost for seawater desalination facilities, and their performance can greatly impact the operation of the entire system. Alternative intakes, based on the riverbank filtration concept, are increasingly being implemented because they are less expensive than conventional intakes and can also provide natural filtering of feedwater prior to the entry of water into the treatment plant. The basic concept is to use vertical or horizontal wells or galleries located near the seawater source to produce feed water, while taking advantage of the natural sand filtration provided by the beach sands and other sediments. Although conceptually simple, the successful design of beach gallery intakes must consider a variety of sedimentological and hydrogeological factors. Production rates are dependent upon both the hydraulic conductivity of the beach sediments and the length of the flow path from the seawater source to the gallery. Beach galleries constructed inland above the high tide line thus require relatively great lengths or areas to produce a given amount of seawater. Inasmuch as beach galleries act as slow sand filters, they are subject to clogging at the sediment-water interface. Carbonate scaling has been a major problem in some systems constructed in carbonate sediments in tropical settings because of the supersaturation of seawater with respect to calcite. Beach sedimentation patterns can also impact the long-term performance of beach galleries. Improperly designed or constructed beach galleries may be exposed or damaged in beaches that experience erosion under normal or storm conditions. Prograding beaches are more problematical as the galleries become increasingly distant from the seawater source, which reduces potential production rates. The self-cleaning beach gallery overcomes some of the inherent limitations of beach galleries constructed above high tide line. The gallery is a horizontal collection system within a single trench that is constructed between the low and high tides lines. The normal wave action keeps the sediment-water interface above the gallery clean by mechanically removing fine-grained sediment and marine organisms. The daily tidal cycle keeps the sediment above the gallery saturated and maintains a short travel time. The top of the gallery is set at about 4 m below normal low tide, so erosion should not be a concern and scaling can be managed. However, progradation of the beach may still adversely impact system performance. The design of the self-cleaning beach gallery requires field testing to obtain site-specific data on the hydraulics of surficial sediments. The field testing should involve aquifer performance testing and a small-scale pilot test. Hydraulic flow modeling is necessary to evaluate potential gallery design options and potential water yields. An assessment of shoreline sedimentation dynamics should also be performed, which may involve a literature review or field investigations. [ABSTRACT FROM AUTHOR]

The article presents a research on the geohydraulic and hydrogeochemical processes of a catchment area that is influenced by bank filtration and is exemplified by the case study of Auf dem Grind in Well II, Düsseldorf, Germany. It states that raw water extracted from Well II depicted elevated manganese concentrations. A retrospective modeling shows the principles of long and midterm changes in raw quality, and the processes enable the strategies that optimize the quality of raw water.

Pharmaceutically active compounds (PhACs) and drugs of abuse (DAs) are two important groups of emerging environmental contaminants that have raised an increasing interest in the scientific community. A number of studies revealed their presence in the environment. This is mainly due to the fact that some compounds are not efficiently removed during wastewater treatment processes, being able to reach surface and groundwater and subsequently, drinking waters. This paper reviews the data regarding the levels of pharmaceuticals and illicit drugs detected in wastewaters and gives an overview of their removal by conventional treatment technologies (applying activated sludge) as well as advanced treatments such as membrane bioreactor. The paper also gives an overview of bank filtration practices at managed aquifer recharge sites and discusses the potential of this approach to mitigate the contamination by PhACs and DAs. [ABSTRACT FROM AUTHOR]

Summary: The riverbank filtration technique was initiated in the Republic of Korea in the early 2000s as an additional source of drinking water in preference of usual surface water. In this study, water level, chemical composition, stable isotopes, time series, and factor analyses were used to characterize riverbank-filtered water and river water qualities at a riverbank filtration site in the Daesan-Myeon area (the first riverbank filtration site in the Republic of Korea) adjacent to the Nakdong River. For this study, the riverbank-filtered water and the river water were analyzed in both the field and the laboratory. The inorganic chemical components in the riverbank-filtered water and the river water differed significantly. Based on time series and factor analyses, the nitrate and turbidity concentrations were lower in the riverbank-filtered water than in the river water. The susceptibility to contamination of the riverbank-filtered water was lower than that of the river water. However, the groundwater level rapidly responded to the river level, and this finding was consistent with the irregular variation of the river level due to precipitation. [Copyright &y& Elsevier]

Abstract: Riverbank filtration (RBF) refers to the process of capturing surface water passing through the river-sediment-aquifer system by using a collection technique such as a well or an infiltration gallery. RBF removes nearly all suspended and a large number of dissolved contaminants from the surface water. Therefore, it can function as an effective pretreatment process in drinking-water production. TNT (2,4,6-trinitrotoluene), RDX (1,3,5-trinitro-1,3,5-triazacyclohexane), and HMX (1,3,5,7-tetranitro-1,3,5,7-tetrazocane) are three military explosive chemicals that are considered of concern to human health when present in source waters. This study is to evaluate the ability of the filtration media in RBF systems to remove these chemicals. The results from an anoxic batch test showed that all three chemicals will degrade while passing through streambed sediments. The pseudo first-order degradation-rate constants for TNT, RDX, and HMX were measured to be 0.33, 0.055, and 0.033d−1, respectively. Under aerobic conditions only TNT showed significant degradation. Results from a model RBF system showed that the mobility of the three chemical contaminants in streambed sediments was in the order: HMX>RDX>TNT. The results suggest that RBF is capable of removing TNT and RDX but HMX levels may continue to be of concern—especially when collector wells use laterals running directly beneath the stream or riverbed. [Copyright &y& Elsevier]

River eutrophication and nitrogen pollution poses a potential threat to the groundwater quality in riverbank filtration systems. The river filtration process is often accompanied by complex redox reactions. Therefore, identification of nitrogen biogeochemical processes is essential to scientifically characterize the cause of NO 3 − attenuation and NH 4 + accumulation in groundwater, optimize the design of groundwater pumping wells, and design protection strategies in sudden environmental pollution accidents. Hydrogeochemical and stable isotope tracing techniques were employed in this study at a typical riverbank filtration site located in Songyuan, NE China, to explore the main geochemical reactions controlling the migration and transformation of nitrogen along the groundwater flow path during riverbank filtration. The results indicate that mixing, adsorption, organic nitrogen mineralization, denitrification, and dissimilatory nitrate reduction to ammonium (DNRA) represent the major geochemical reactions. Denitrification primarily occurs within 10–20 m from the riverbed surface along the filtration path and is the primary reaction accounting for NO 3 − attenuation, whereas DNRA typically occurs between 1.5 and 6 m from the riverbed surface along the filtration path and is more active in the wet season, characterized by high temperatures (>15–17 °C), low dissolved oxygen (DO, < 2–4 mg/L), and high carbon load i.e., organic carbon (OC):NO 3 − > 10–15. This work confirms that DNRA is an important nitrogen geochemical reaction during riverbank filtration, and emphasizes its role in NH 4 + enrichment. • Investigation of the nitrogen biogeochemical mechanisms in an RBF system. • Integration of in situ hydrogeochemical and stable isotope monitoring. • Identification of the role of DNRA in the enrichment of NH 4 + during RBF. [ABSTRACT FROM AUTHOR]

Abstract  Riverbank filtration (RBF) is a proven treatment step in a multi-barrier method of drinking-water supply at many sites. RBF wells induce a large amount of river water to infiltrate the river base and travel towards the wells, giving the opportunity for mixing of infiltrated surface water and groundwater. Assessment of raw water quality plays an important role in planning and operating a RBF well field. In this context, the determination of the catchment area (and land uses within the catchment) and the ratio of bank filtrate (BF) to raw groundwater (GW) are two prior steps. Transient model simulations were performed in order to study the hydraulic conditions at the RBF well field at Grind near Düsseldorf, Germany. The BF/GW ratio was determined to be 75/25. The flood events in winter, in particular, showed the BF/GW ratio to have high variation. Transient path lines in the well field were used for delineation of the catchment area. [ABSTRACT FROM AUTHOR]

Summary: Alluvial aquifers are largely used as groundwater resource since large flow rates can be obtained due to infiltration from the neighboring river. Reductive conditions in the infiltration flow path, caused by the degradation of organic matter, can induce effects detrimental to water quality, such as dissolution of Mn and Fe from the aquifer sediments. In the absence of any direct relationship between the redox potential (Eh) and reductive conditions favorable to manganese and/or iron reduction, we propose a quantitative approach, the electron trapping capacity (ETC). It is calculated using dissolved O2 and NO3 concentrations in groundwater, weighted for the quantity of electrons these two species can trap during the oxidation of organic matter. This approach, tested on several field and laboratory investigations, indicates that reductive dissolution of manganese and iron oxyhydroxides occurs for an ETC lower than 0.2mmolL−1. Exceptions to that threshold value are observed when Mn-rich groundwater flows too fast out of a reduced zone into an oxidizing environment to permit equilibrium precipitation of Mn oxyhydroxides. [Copyright &y& Elsevier]

Pilot-scale column experiments were conducted in this study using natural soil and river water from Ohio river to assess the removal of microbes of size ranging over 2 orders of magnitude, i.e., viruses (0.025-0.065 μm), bacteria (1-2 μm), and Cryptosporidium parvum oocysts (4-7 μm) under conditions representing normal operation and flood scour events. Among these different organisms, the bacterial indicators were transported over the longest distances and highest concentrations; whereas much greater retention was observed for smaller (i.e., viral indicators) and larger (i.e., Cryptosporidium parvum oocysts) microbes. These results are in qualitative agreement with colloid filtration theory (CET) which predicts the least removal for micrometer size colloids, suggesting that the respective sizes of the organisms was a dominant control on their transport despite expected differences in their surface characteristics. Increased fluid velocity coupled with decreased ionic strength (representative of major flood events) decreased colloid retention, also in qualitative agreement with CFT. The retention of organisms occurred disproportionately near the source relative to the log-linear expectations of CFT, and this was true both in the presence and absence of a colmation zone, suggesting that microbial removal by the RBF system is not necessarily vulnerable to flood scour of the colmation zone. [ABSTRACT FROM AUTHOR]

Riverbank filtration (RBF) is an efficient and low-cost natural alternative technology for water supply application in which surface water contaminants are removed or degraded as the infiltrating water moves from the river/lake to the pumping wells. The removal or degradation of contaminants is a combination of physicochemical and biological processes. For more than 100 years, RBF has been used in Europe for public and industrial water supply along Rhine, Elbe, and Danube rivers. This paper presents an investigation of a full-scale RBF plant located in Upper Egypt as section of Nile valley to produce drinking water. The studied plant is constructed in 2004 to supply potable water for Sidfa city (30,000 residents), Assiut Governorate. It consists of 6 vertical wells, each about 60 m deep, with distance about 30 m from the west bank of Nile. Water samples from Nile as induced surface water, from background groundwater, and from production wellfield were collected and analyzed at three discrete events. Quality measurements of physical, chemical, and microbiological characteristics were obtained. Comparison of produced water with surface and background natural groundwater for the investigated plant has proven the effectiveness of RBF technique for potable water supply in Upper Egypt. Physicochemical and microbiological characteristics of the produced water are better than the allowable standards for drinking purposes. The results prove the implementation of RBF treatment method for water supply in Nile valley. [ABSTRACT FROM AUTHOR]

Low water consumption in rural areas in Jordan had resulted in the production of concentrated grey water. Average COD, BOD and TSS values were 2568mg/l, 1056mg/l and 845mg/l, respectively. The average grey water generation was measured to be 14L/c.d. Three different treatment options were selected based on certain criterions, and discussed in this article. The examined treatment systems are septic tank followed by intermittent sand filter; septic tank followed by wetlands; and UASB-hybrid reactor. Advantages and disadvantages of each system are presented. It was concluded that UASB-hybrid reactor would be the most suitable treatment option in terms of compactness and simplicity in operation. The volume of UASB-hybrid reactor was calculated to be 0.268m3 with a surface area of 0.138m2 for each house having 10 inhabitants on average. Produced effluent is expected to meet Jordanian standards set for reclaimed water reuse in irrigating fruit trees. [Copyright &y& Elsevier]

Understanding the fate of effluent organic matter (EfOM) and natural organic matter (NOM) through riverbank filtration is essential to assess the impact of wastewater effluent on the post treatment requirements of riverbank filtrates. Furthermore, their fate during drinking water treatment can significantly determine the process design. The objective of this study was to characterise bulk organic matter which consists of EfOM and NOM during riverbank filtration using a suite of innovative analytical tools. Wastewater effluent-derived surface water and surface water were used as source waters in experiments with soil columns. Results showed the preferential removal of non-humic substances (i.e. biopolymers) from wastewater effluent-derived surface water. The bulk organic matter characteristics of wastewater effluent-derived surface water and surface water were similar after 5m soil passage in laboratory column experiment. Humic-like organic matter in surface water and wastewater effluent-derived surface water persisted through the soil passage. More than 50% of total dissolved organic carbon (DOC) removal with significant reduction of dissolved oxygen (DO) was observed in the top 50cm of the soil columns for both surface water and wastewater effluent-derived surface water. This was due to biodegradation by soil biomass which was determined by adenosine triphosphate (ATP) concentrations and heterotrophic plate counts. High concentrations of ATP in the first few centimeters of infiltration surface reflect the highest microbial activity which correlates with the extent of DOC reduction. Good correlation of DOC removal with DO and biomass development was observed in the soil columns. [ABSTRACT FROM AUTHOR]

A 3 year study of the infiltration of Lot River water into a well field located in an adjacent gravel and clay alluvial aquifer was conducted to assess the importance of organic matter regarding the redox processes which influence groundwater quality in a positive (denitrification) or negative (Mn dissolution) manner. Chloride was used to quantify the mixing of river water with groundwater. According to modeling with PHREEQC, the biodegradation of the infiltrated dissolved organic carbon (DOCi) is not sufficient to explain the observed consequences of the redox reactions (dissolved O2 depletion, denitrification, Mn dissolution). Another electron donor source must therefore be involved: we propose solid organic carbon (SOC) as a likely candidate, if made available for degradation by prior hydrolysis. Its contribution to redox reactions could be significant (30-80% of the total organic carbon consumed by redox reactions during river bank filtration). We show here also that even though the first few meters of infiltration are highly reactive, significant redox reactions can take place further in the aquifer, possibly affecting groundwater quality away from the river bank. [ABSTRACT FROM AUTHOR]

Safe drinking water is a top priority in preventing disease outbreaks and is of general concern to everyone. This study examines the occurrence of Cryptosporidium and Giardia in Hungarian drinking water supplies for the first time. A total of 76 raw and drinking water samples were examined using the U.S. EPA Method 1623. From these 15 of 34 (48.4%) raw water samples tested positive for Giardia and 7 (26.6%) for Cryptosporidium. Twelve of 45 (26.7%) drinking water samples were positive for Giardia and 6 (13.3%) for Cryptosporidium. Overall, Giardia cysts and/or Cryptosporidium oocysts were detected in 48% of the raw water samples and 35% of the drinking water samples. The highest levels in drinking water were found to be 3 oocysts/100 litres of Cryptosporidium and 63.6 cysts/100 litres for Giardia, enough to cause giardiasis. The highest levels in raw water were 1,030 cysts/100 litres for Giardia and 50 oocysts/100 litres for Cryptosporidium and higher oocyst densities were associated with source water receiving effluents from sewage treatment plants or originating from a forest environment. In addition to this monitoring, riverbank filtrated water and raw water from the River Danube in Budapest were monitored in order to ascertain protozoan removal efficiency of riverbank filtration (RBF). A total of 157 samples, including 87 samples from the River Danube and 70 samples post RBF, were examined. Cryptosporidium and Giardia were detected regularly in the river water but never in riverbank filtered water suggesting the effectiveness of RBF as a purification method. The occurrence of Cryptosporidium oocysts and Giardia cysts in the investigated water supplies may require the water utilities and water authorities in Hungary to apply additional monitoring and treatment and/or watershed controls. [ABSTRACT FROM AUTHOR]

This study set out to quantify the contributions of subsurface filtration (or underground passage) and groundwater dilution to overall reductions/removals by riverbank filtration (RBF). Samples were collected from four RBF study sites that varied in terms of distance between river sources and extraction wells, river water quality, hydrology, well construction and pumping rate, and subsurface material. Samples were analyzed for removal of dissolved organic carbon, total coliforms, aerobic spore-forming bacteria, and virus indicators. Results indicated that the relative contribution of each removal mechanism was site-specific. Both groundwater dilution and sub-surface filtration appeared to be important reduction/removal processes. Within the United States, RBF is a relatively unfamiliar drinking water treatment. The findings presented here indicate that RBF can be effective as both a primary treatment and a pretreatment process and can significantly improve the quality of river water in terms of particulates, organic precursors, and microbial removals. [ABSTRACT FROM AUTHOR]

Summary: Riverbed clogging is an important issue related to the sustainable exploitation of riverbank filtration well fields. In this research, several complementary field techniques are employed to assess the current state and possible evolution of riverbed clogging at a site in the Saint John River, New Brunswick. The study is conducted in regions of the riverbed that have previously been identified as allowing recharge to the semi-confined aquifer that has been used since 1955 to supply water to the City of Fredericton. Flow velocity measurements, video imaging, and suspended sediment and bed sediment analyses conducted during the low flow (summer) period indicate that part of the recharge area closest to the well field, about 20% of the total area, is affected by bed armoring with cobbles and boulders. Consistent with previous studies, with increasing distance from the riverbank the sediment size decreases and the armor layer disappears. Previous research indicates that turbulent impacting of fine particles into the voids between the cobbles and boulders of the armor layer may reduce infiltration by up to 95%; however, the suspended sediment load in the river is mainly composed of organic matter, and the measured concentrations of suspended sediment (up to 3mg/L) are not considered high enough to create such large reductions in infiltration. Additionally, the mineral fraction of the suspended sediment would not be expected to settle under the calculated average shear velocity of 0.012m/s. Other sources of particulate matter, such as the degradation of aquatic vegetation on the riverbed, may be more significant with respect to riverbed clogging; however, annual peak flows may also create bed shear stresses that serve to limit long-term clogging effects. [Copyright &y& Elsevier]

During the present study, microcystin (MCYST) concentrations in the Nile River and irrigation canal sediments, Egypt, were investigated during the period January–December 2001. Batch experiments were also conducted to confirm the adsorption of MCYSTs on these sediments. The results of field study showed that MCYST concentrations in the sediments were correlated with total count of cyanobacteria, particularly Microcystis aeruginosa, and MCYST within phytoplankton cells in most sites. No detectable levels of MCYSTs were found in the cell-free water of all studied sites in the Nile River and irrigation canals during the entire study period. The data obtained from batch adsorption experiments confirmed the capability of the Nile River and irrigation canal sediments for MCYST adsorption; and that adsorption was sediment weight-dependent and thus fitted the Freundlich adsorption isotherm. The results also revealed that both adsorption capacity (Kf) and intensity (1/n) varied significantly with clay and organic matter contents of these sediments. The results of present study have two implications. First, the presence of cyanobacterial toxins in freshwater sediments can affect benthic organisms inhabiting these sediments, and thus it should be considered during biological monitoring of rivers and streams. Second, the ability of freshwater sediments to adsorb cyanobacterial toxins suggests that bank filtration could be used in developing countries ( e.g., Egypt), which require an inexpensive and low-maintenance method for removing these toxins from drinking water. [ABSTRACT FROM AUTHOR]

Within the scope of the interdisciplinary Natural and Artificial Systems for Recharge and Infiltration research project dealing with riverbank filtration processes at the Berlin water works, a semi-technical column experiment has been ongoing since January 2003. Here, a 30 m long soil column is infiltrated with surface water sampled from Lake Tegel (Berlin, Germany) under saturated flow conditions. Changes in pore water hydrochemistry sampled on 21 non-equidistant distributed points are verified by coupled transport and reaction modelling. The objective of reactive transport modelling was to identify the main biogeochemical processes within the soil column during the flushing experiment as a conceptual model for riverbank filtration. Modelling was done with a combination of MATLAB and PHREEQC. The main processes identified are: (1) biogeochemical degradation due to interaction of natural surface water with the soil matrix; (2) continuous dissolution of refractory air bubbles from the soil column matrix. [ABSTRACT FROM AUTHOR]

The Kuihe River is in Xuzhou, Jiangsu, China. It contains high concentrations of nitrogen. The water in the Kuihe River recharges the groundwater via riverbank filtration (RBF) along the Xucun and Huangqiao reaches, which are characterized by unsaturated and saturated percolations, respectively. The two sections were selected to study the effectiveness of RBF to the nitrogen removal from the infiltrating river water. The results showed that the RBF in the saturated percolation had the potential to remove the nitrogen through biochemical processes. The nitrogen-removal rates were more than 95% over the monitoring period. However, the RBF in the unsaturated percolation resulted mainly from the physical process and thus had no efficacy for nitrogen removal. [ABSTRACT FROM AUTHOR]

Since 1870 Riverbank filtration (RBF) on the river Rhine, Germany has been used successfully by the Düsseldorf waterworks as the first step for treating drinking water. The aim of this article is to present the experience in applying RBF with a focus on the purification efficiency of this natural treatment process. At the Düsseldorf waterworks, the influence of long-term as well as periodic changes of the river water quality on the RBF processes were investigated. While for the first 80 years drinking water treatment was based only on RBF, additional technical treatment became necessary together with the decreasing Rhine water quality in the 1960's. The decontamination of the river was attended successfully by the waterworks along the Rhine. AS a result of the increased river water quality the purification processes during RBF became again more efficient. However, periodic changes of river water quality and hydraulics influence the natural purification processes during RBF and have to be considered. Flood events are accompanied by shorter travel times and less effective natural purification. The changing river water temperature trigger a string of subsequent hydrogeochemical reactions within the aquifer. The performed investigations show that even during flood events and during extreme low water, the multi protective barrier concept including both natural and technical purification has proven to be a reliable method for drinking water production. [ABSTRACT FROM AUTHOR]

Hamburg is a small borough located in Berks County, Pennsylvania. During the 1940s and 1950s, crushed automobile battery casings, containing high levels of lead, were used as fill in and around Hamburg. Several of the fill areas were along the eastern bank of the Schuylkill River and the Schuylkill River Canal. To reduce exposure to human and ecological receptors, the United States Environmental Protection Agency (U.S. EPA) initiated actions at several of the fill areas. Remediation actions at three of these fill areas, the Berry Property, the Hamburg Playground City Playground, and the Port Clinton Avenue site, utilized native plants, slope stabilization, and soil caps. The Berry Property consisted of a flat, wooded area adjacent to the river. The Hamburg Playground consisted of a steep wooded slope between the river and the parking lot for the municipal park. The Port Clinton Avenue site consisted of flat and sloped, wooded, and old-field areas between the canal and Port Clinton Avenue. At each of the three sites, some of the contaminated soils were excavated and the remainder was graded and capped. The clean soil cap was then covered with an erosion control mat, seeded with native grasses, and planted with native shrubs. At the Hamburg Playground and Port Clinton Avenue site, the existing trees and much of the existing vegetation were maintained to preserve the slope stability and the natural environment. Great care was taken to ensure community access to the municipal park. Some of the important considerations included retaining the existing trees, dealing with invasive species, maintaining the plants during a drought, and channeling storm-water runoff. The work was coordinated with the Hamburg Borough Council, the Schuylkill River Greenway Association, and the Pennsylvania Department of Environmental Protection (PADEP). The actions resulted in a stabillized slope with channelized storm water to control erosion and protect the river, a clean soil and plant cover that eliminates exposure to human and animal receptors, and an aesthetically pleasing and usable area that meets the needs of the community and the local conservation/environmental organization. [ABSTRACT FROM AUTHOR]

The Central Wyoming Regional Water System operates 29 groundwater collection devices in an alluvial aquifer adjacent to the North Plane River. These collection devices were previously designated "groundwater under the direct influence of surface water. In lieu of constructing a conventional surface water treatment plant, the utility opted to perform a two-year study to demonstrate that riverbank filtration (i.e., natural filtration) provided the 2.0-log reduction of Cryptosporidium required under the Interim Enhanced Surface Water Treatment Rule (e.g., riverbank filtration is the primary filtration process). Using multiple surrogates of various sizes encompassing those of Giardia and Cryptosporidium, the utility demonstrated 2.0-log reductions in more than 90% of matched data pairs. No Giardia cysts or Cryptosporidium oocysts were found in any of the 170 groundwater samples. This level of removal was achieved during the summer months when infiltration rates are high because of increased river stage and well-field production. [ABSTRACT FROM AUTHOR]

Abstract: Riverbank filtration (RBF) is a low-cost water treatment technology in which surface water contaminants are removed or degraded as the infiltrating water moves from the river/lake to the pumping wells. The removal or degradation of contaminants is a combination of physicochemical and biological processes. This paper illustrates the development and application of three types of artificial neural networks (ANNs) to estimate the effectiveness of two RBF facilities in the US. The feed-forward back-propagation network (BPN) and radial basis function network (RBFN) model prediction results produced excellent agreement with measured data at a correlation coefficient above 0.99 for filtrate water quality parameters, including temperature as well as turbidity, heterotrophic bacteria, and coliform removal. In comparison, the fuzzy inference system network (FISN) predicted only temperature and bacteria removal with reasonable accuracy. It is shown that the predictive performances of the ANNs depend on the model structure and model inputs. [Copyright &y& Elsevier]