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.

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>