Evaluation of the river bank filtration technology in water purification in Iraq

Water purification of pollutants is a major challenge to the sustainable development of health in arid and arid regions of the world. Organization of water purification by the river bank filtration is a natural technique. Therefore, this survey was conducted to evaluate the shoulder of the Kufa River in purifying water from pollutants in an inexpensive and natural way. Six water samples were taken from six different locations of the river course, and six corresponding water samples were taken from the well locations near the river. The chemical analyzes of the samples were conducted during the month of December of the year 2020. The statistical analysis was carried out using the SAS program. The results showed that there were significant differences, as they showed the superiority of the concentration of phosphorous, cadmium, lead, copper, iron, manganese, chromium, molybdenum, and the total number of bacteria in river water compared to their concentration in well water. While it was observed that the concentration of total dissolved salts, sulfate, nickel and chlorine was superior in well water compared to river water. From this, it is clear that the effectiveness of the river shoulder technology in purifying the water of the Kufa River is low because the process of pumping water from wells is not continuous. It is assumed that to achieve the effectiveness of this technology, we need continuous months of pumping until the work of the river shoulder technology is achieved.

A review of seventeen years of bank filtration in Brazil: results, benefits and challenges - Part 1: state of Santa Catarina

This work is the first part of a national review about Bank Filtration (BF) that began in 2003, in Brazil. These studies were conducted in the laboratory and in the field with water and natural sediment from the study regions, showing how BF has been efficient worldwide for the treatment of water for public supply as an alternative treatment. It aims to show the synthesis of results to date and point out its main benefits and challenges; that is, the state of the art at the national level. The review is concentrated in Santa Catarina (part 1), Pernambuco and Minas Gerais (part 2). BF demonstrates efficiency in reducing parameters such as turbidity and coliforms (total and fecal), pesticides and toxins. However, BF showed low capacity in reducing parameters such as salinity and true color. BF is highly dependent on local geological conditions, so parameters such as iron, manganese, fluorine, alkalinity, hardness, and chlorides can be added to the treated water. Keywords: Water Treatment. Bank Filtration. Public Supply Systems. Natural Sediment. Water Quality.

A review of seventeen years of bank filtration in Brazil: results, benefits and challenges - Part 2: states of Pernambuco and Minas Gerais

This work is the second part of “A Review of seventeen years of bank filtration in Brazil: results, benefits, and challenges”. Part 2 describes the research on water treatment carried out in the states of Pernambuco (Olinda city, metropolitan region of Recife and region of Garanhuns) and Minas Gerais (Viçosa city). The main benefit of bank filtration (BF) is that it is an alternative way of obtaining a higher quality raw water compared to the traditional water supply methods when local geological conditions are favorable. BF technology highlights other relevant aspects: it may become one of the main water pretreatments in rivers or lakes with sandy sediments; it is possible to obtain quality water in a well up to the first impenetrable layer (30 m deep); the technology removes 100% of total and fecal coliforms; it may reduce water turbidity at high levels; its pretreatment application may reduce the amount of inputs in the water and, consequently, the generated sludge. Keywords: Bank Filtration. Water Treatment. Local Geological Conditions. Pretreatment. Impenetrable Layer.

The effect of biochar amendment on chlorinated phenols retention in alluvial sediments during river bank filtration

<p>Amendment of alluvial sediments with carbon rich materials such as biochars can be an effective method for controlling the penetration of hazardous substances from river water into drinking water sources during river bank filtration (RBF). In this work, the transport of chlorinated phenols (CPs) during simulated RBF through Danube alluvial sediment with and without biochar amendment was studied. In order to assess the effect of the biochar amendment on CPs retention in the alluvial sediment, column experiments were carried out, with the addition of biocide to exclude the influence of biodegradation. Four CPs that differ in polarity were used as sorbates: 4-chlorophenol (4-CP), 2,4-dichlorophenol (2,4-DCP), 2,4,6-trichlorophenol (2,4,6-TCP) and pentachlorophenol (PCP). For the column packing, Danube alluvial sediment was used, characterized as a mesoporous sandy material with low organic carbon content (1.57 %) and small specific surface area (1.65 m<sup>2</sup>/g). In contrast, the material used as the amendment in the column experiment is a biochar with high organic carbon content (89.8 %) and large specific surface area (341 m<sup>2</sup>/g). The breakthrough curves obtained for the alluvial sediment column without biochar amendment showed poor retention of all investigated CPs. Retardation factors (<em>R</em><sub>d</sub>) for 4-CP, 2,4-DCP and 2,4,6-TCP were 1.65, 1.98 and 1.48, respectively, whereas for PCP, <em>R</em><sub>d</sub> was somewhat higher (4.28) most likely due to the fact that it’s nonpolar nature greatly affects its distribution between the solid and aqueous phase. The addition of biochar into the alluvial sediment at a 0.5 % mass ratio significantly increased the retardation of all investigated CPs. The obtained <em>R</em><sub>d</sub> values for 4-CP, 2,4-DCP, 2,4,6-TCP and PCP were 102, 83, 78 and 92, respectively. The general increase in retardation of all investigated CPs can be explained by the increase of organic carbon content in the alluvial sediment by the addition of biochar, which is known to be the main fraction for organic components sorption in sediments and soils. In addition, the enhanced affinity of the alluvial sediment to retain the more polar CPs after biochar amendment indicates that sorption is carried out not only through nonpolar interactions, but also by electrostatic interactions between the CPs and functional groups on the surface of the biochar. The results show that biochar amendment of alluvial sediments could have a great potential for organic contaminants retention in the RBF zone, thus decreasing the risk of groundwater and drinking water sources contamination.</p><p><strong>Acknowledgement: </strong>The authors acknowledge financial support of the Ministry of Education, Science and Technological Development of the Republic of Serbia (Grant No. ‪451-03-68/‪2020-14/ 200125). The authors want to express their gratitude to Basna d.o.o. Čačak for providing the biochar.</p>

Reducing the risk for contamination of river bank filtration systems using inverse modelling and anthopogenic traces

<p>Many drinking water systems worldwide are based on river bank filtration. From a quantitative point of view river bank filtration systems are highly reliable because of the high permeability of alluvial aquifers linked to high production rates. However, there might be an increased risk of contamination because of the short residence time between the river and the production well, especially during flood events.</p><p>Flood events change the river-aquifer hydraulic interactions and may increase infiltration rates (e.g., due to an increased hydraulic head, larger river infiltration widths, or erosion of a siltation layer). This leads to changes in groundwater flow paths and production wells might abstract water with a shorter residence time and lower quality. Groundwater quality may degrade during flood events due to the presence of undesirable chemicals (e.g., wastes water treatment plant overflow) and the occurrence of faecal indicator bacteria such as <em>E.Coli</em>.</p><p>Groundwater modelling can assist in developing strategies to protect river bank filtration from such undesired contamination by predicting optimal operation conditions. The key impediment of this approach is significant uncertainties in subsurface properties and the associated uncertainties of the groundwater flow paths. To reduce uncertainties in model predictions, anthropogenic tracers including the MRI contrast agent gadolinium and artificial sweeteners were used in this study. They revealed sources and flow patterns, and have been used to derive mixing ratios representing different temporal and spatial scales. Including anthropogenic tracers into the objective function of the calibration process also lead to more accurate estimation of groundwater flow paths. This was critical to predict the best water works operation strategy during flood events.</p>

Impact of seasonal variations and transient colmation layer properties on bacteria and virus transport in bank filtration

<p>Bank filtration is a sustainable source for drinking water production in urbanized regions but is increasingly at risk by contamination with pathogenic bacteria and viruses from surface water receiving wastewater discharge. While recent advances have improved our process understanding for pathogen transport on laboratory scale, simulations and predictions on field scale under transient conditions, as in bank filtration, are still highly uncertain. To improve our understanding on field scale, we performed a sampling survey over 16 months at an observation well transect in a heterogeneous sand-gravel aquifer of an active bank filtration waterworks at the river Rhine in Germany. Water samples were collected from the river, the production well, and 4 multi-level observation wells. Samples were analysed for main anions/cations, and hygienic indicators (E. coli and coliform bacteria via plate counts, coliphages via plaque assay, and adenoviruses via ddPCR). A two-dimensional reactive transport model was set up using PFLOTRAN to simulate the transport of heat and dissolved species, aerobic respiration, denitrification, and colloid-based transport of bacteria and viruses. For the latter, adsorption to and desorption from the sediment, straining, blocking, and inactivation are considered. Model parameters were estimated from prior knowledge of the site or calibrated with the obtained data using particle swarm optimization.</p><p>Field observations show a strong seasonal variation of river hydraulics with up to 8 m difference in water level, a prolonged low in the summer/fall and short-termed river level increases in the winter. Aerobic respiration was strongly controlled by the temperature variation (6-24°C in groundwater), leading to an increase in oxygen consumption and limited denitrification during the warm summer/fall. Bacteria and virus concentrations in the groundwater were elevated following a flood in the first winter (up to 500 MPN/100mL coliforms, 2 PFU/100mL coliphages, 1000 copies/100mL adenovirus). Measurable concentrations were still observed during the summer (e.g., up to 10 MPN/100mL coliforms, 0.7 PFU/100mL coliphages, 500 copies/mL adenovirus), but concentrations were below the detection limit for most of the second winter, where no significant flood occurred. In the well closest to the river (40 m distance), the concentration reduction compared to the river varied over time between 1 to ≥4 log-units for coliforms, 1.5 to ≥3 log-units for coliphages, and 0.5 to ≥3 log-units for adenoviruses. The model results suggest the main driving processes for the variation in the bacteria and virus concentrations are (i) the changing groundwater velocity (driven by river level variations and pumping rate), (ii) occurrence of low dissolved oxygen concentrations which lower inactivation, and (iii) transient colmation layer properties (permeability and effective grain size). The colmation layer is affected by reworking of riverbed sediments during floods, bio-clogging during summer, and physical clogging due to constant forced infiltration caused by the bank filtration plant. This is supported by the observation of high bacteria concentrations in the aquifer for a short duration after pumps were reactivated following a 40-day maintenance period. Overall, bacteria and virus attenuation during bank filtration was high, only a strong flood resulted in significantly higher contaminant concentrations in the aquifer.</p>