The Impact of River Discharge and Water Temperature on Manganese Release from the Riverbed during Riverbank Filtration: A Case Study from Dresden, Germany

Abstract

The climate-related variables, river discharge, and water temperature, are the main factors controlling the quality of the bank filtrate by affecting infiltration rates, travel times, and redox conditions. The impact of temperature and discharge on manganese release from a riverbed were assessed by water quality data from a monitoring transect at a riverbank filtration site in Dresden-Tolkewitz. Column experiments with riverbed material were used to assess the Mn release for four temperature and three discharge conditions, represented by varying infiltration rates. The observed Mn release was modeled as kinetic reactions via Monod-type rate formulations in PHREEQC. The temperature had a bigger impact than the infiltration rates on the Mn release. Infiltration rates of <0.3 m3/(m2·d) required temperatures >20 °C to trigger the Mn release. With increasing temperatures, the infiltration rates became less important. The modeled consumption rates of dissolved oxygen are in agreement with results from other bank filtration sites and are potentially suited for the further application of the given conditions. The determined Mn reduction rate constants were appropriate to simulate Mn release from the riverbed sediments but seemed not to be suited for simulations in which Mn reduction is likely to occur within the aquifer. Sequential extractions revealed a decrease of easily reducible Mn up to 25%, which was found to reflect the natural stratification within the riverbed, rather than a depletion of the Mn reservoir.

Oxidation of Selected Trace Organic Compounds through the Combination of Inline Electro-Chlorination with UV Radiation (UV/ECl2) as Alternative AOP for Decentralized Drinking Water Treatment

“…The mean DOC of Elbe river water in Dresden, Germany, is about 5.2 mg/L (4.6-6.0 mg/L, n = 325) [46]. In test settings A and B the river water showed a slightly elevated DOC of 6.7 mg/L, and 5.6 mg/L in test setting C after ultrafiltration.…”

Characterisation of the impact of dissolved organic matter on iron, manganese, and arsenic mobilisation during bank filtration

“…The feed water was introduced to the columns in an up-flow mode (saturated flow), and a variable-speed peristaltic pump was used at the top of the column providing at a constant hydraulic rate (0.5 m/d) to avoid the entrapment of air bubbles in the soil bed. This hydraulic rate has been experienced in many BF fields (Ghodeif et al, 2016;Paufler et al, 2018). The tracer test using NaCl was conducted to estimate the retention time; the empty bed contact time was 16 hours.…”

Water Quality Changes during the Initial Operating Phase of Riverbank Filtration Sites in Upper Egypt

“…The final Fe and Mn concentration depended on the mixing ratio (portion of pumped groundwater commonly having high Fe and Mn concentration) and the redox-dependent Fe and Mn concentration of the bank filtrate. The latter is determined by the river water quality, the composition of the riverbed and the redox conditions within the aquifer [17,18,27,28]. After starting the operations of new RBF wells, the Fe and Mn concentration in the pumped water changed.…”

“…While water quality changes during RBF, redox-zonation, and removal rates have been discussed by many authors (e.g., [14][15][16]), little information is available on the initial operation phase of new RBF schemes. For example, the wash-out effect of iron and manganese in aquifers between the riverbank and the production wells has been described for longer periods (in terms of years) [17,18], based on long-term monitoring, but no description has yet been provided for the initial phase. The new RBF sites in Upper Egypt make it possible to study the behavior of organic compounds and redox sensitive parameters during the initial operation phase and to draw conclusions on the required post-treatment.…”