As a consequence of the suspended sediments in river water, cake formation on the streambed and clogging of the aquifer may occur, leading to a decline in the production yield of riverbank filtration systems, particularly in highly turbid river waters. However, naturally occurring flow forces may induce sufficient scouring of the streambed, thereby self-regulating the thickness of the formed cake layer. This study assessed the recovery of the infiltration capacity in a simulated physically clogged riverbank filtration system, due to self-cleansing processes. A straight tilting flume, provided with an infiltration column at the bottom, was used for emulating clogging, infiltration and self-cleansing. Based on the presented research it may be concluded that the infiltration of a mixture of different sediments, as found in natural water bodies, can already be recovered at low shear stresses. Clay and silt behaved very differently, due to the difference in cohesiveness. Clay was found to produce a persistent sticky cake layer, whereas silt penetrated deeper into the bed, both resulting in an absence of infiltration velocity recovery. A cake layer of fine sand sediments was easiest to remove, resulting in dune formation on the streambed. However, due to deep bed clogging by fine sand particles in a coarser streambed, the infiltration velocity did not fully recover. The interaction between mixed suspended sediments (5% clay, 80% silt, and 15% fine sand) resulted in uneven erosion patterns during scouring of the streambed and recovery of the infiltration velocity is low. Altogether it may be concluded that natural recovery of infiltration capacity during river bank filtration of highly turbid waters is expected to occur, as long as the river carries a mixture of suspended sediments and the sand of the streambed is not too coarse.

Riverbank filtration (RBF) is a surface water filtration method for drinking water through the banks and bed of a river, using extraction wells located near the water body in order to ensure direct aquifer recharge. As the surface water travels through the sediments, contaminants, such as suspended and colloidal solids and pathogenic microorganisms, are removed. Apart from water quality improvement, RBF has the advantage of reducing peak concentrations which commonly pass through a river. RBF has been widely used in Europe, USA and, nowadays, in some Asian countries (e.g., South Korea, India, China). Latin-American and specifically Colombian river basins, have been suffering a continuous deterioration, leading to high suspended sediment loads being transported by the rivers. The RBF technology has not been proven yet in highly turbid waters, in which the excessive transport of suspended sediments threatens sustainable operation. Clogging of both the riverbed and deeper aquifer may increase flow resistance, reducing water revenues over the course of time. To assess the feasibility of RBF for highly turbid river waters in Colombia, a combination of field and laboratory research was conducted – both in the Netherlands and Colombia. In Colombia, the studies were done at the Cinara institute's Research and Technology Transfer (R&TT) Station for drinking water and at the Fluid Mechanics lab. The station is located at the Northeast of Cali, Colombia, and was built at the premises of the main water treatment plant of Cali, Puerto Mallarino. In the Netherlands, the laboratory work was done at the Delft University of Technology, running infiltration column experiments at the Sanitary Engineering lab and the flume experiments at the Fluid Mechanics lab...

The poor quality of many Colombian surface waters forces us to seek alternative, sustainable treatment solutions with the ability to manage peak pollution events and to guarantee the uninterrupted provision of safe drinking water to the population. This review assesses the potential of using riverbank filtration (RBF) for the highly turbid and contaminated waters in Colombia, emphasizing water quality improvement and the influence of clogging by suspended solids. The suspended sediments may be favorable for the improvement of the water quality, but they may also reduce the production yield capacity. The cake layer must be balanced by scouring in order for an RBF system to be sustainable. The infiltration rate must remain high enough throughout the river-aquifer interface to provide the water quantity needed, and the residence time of the contaminants must be sufficient to ensure adequate water quality. In general, RBF seems to be a technology appropriate for use in highly turbid and contaminated surface rivers in Colombia, where improvements are expected due to the removal of turbidity, pathogens and to a lesser extent inorganics, organic matter and micro-pollutants. RBF has the potential to mitigate shock loads, thus leading to the prevention of shutdowns of surface water treatment plants. In addition, RBF, as an alternative pretreatment step, may provide an important reduction in chemical consumption, considerably simplifying the operation of the existing treatment processes. However, clogging and self-cleansing issues must be studied deeper in the context of these highly turbid waters to evaluate the potential loss of abstraction capacity yield as well as the development of different redox zones for efficient contaminant removal.

The particulate matter composition in the Upper Cauca River section was studied, considering the importance of this river for the water supply of Cali, Colombia, and the implications that the turbidity of this water source has had for the city's water treatment. Additionally, the upstream Palo River was investigated, as this river is a major contributor to the Cauca River. River water samples were taken in both rivers in the period 2012–2014 during dry and rainy seasons. The origin of the particulate matter was studied through measurements of turbidity, total suspended solids (TSS), volatile suspended solids, particle size distribution, Fe3+, PO43−, NO3-N, chlorophyll-a, chemical oxygen demand, and true color. Turbidity and TSS values, measured during this survey, were highly variable, ranging from 25 to 465 NTU and 10 to 490 mg/L in the Cauca River, and from 30 to 840 NTU and 15 to 710 mg/L in the Palo River, respectively. High scattering was obtained in TSS and turbidity relationships in both rivers, potentially due to the different sources contributing to both parameters. It was concluded that the concentration of particulate matter depended merely on precipitation events in the Cauca and Palo River basins, leading to soil erosion due to extensive and intensive agricultural practices. In addition, the South Canal was identified as one of the main contributors to organic particulate matter.