The INOWAS DSS helps to assess water quality changes in the injected, the recharged water or the ambient groundwater during MAR.
Water quality improvements either of groundwater or the recharged water is often appreciated and can be a key objective during the application of MAR, especially when treated wastewater is infiltrated. During the infiltration of treated wastewater, the degradation of nutrients and other organic contaminants along the flow path is of interest. The soil sediments act as a natural filter removing pathogens, disinfection-by-products (DBP), nutrients and micropollutants such as pharmaceuticals. Especially the infiltration into the unsaturated zone, e.g. via infiltration basins, which is also referred to as Soil Aquifer Treatment (SAT), can improve the recharged water quality. But also during the storage of water in the saturated zone, contaminants can be absorbed, degraded but also mobilized. Water quality changes during the recharge, storage or recovery are dependent on various factors. These include the source water quality, the engineering design of the MAR facility, the degree of mixing with the ambient groundwater, the operational conditions (length of storage time) and the local hydrogeological characteristics (e.g. aquifer redox conditions, temperatures, material).
A thorough process-based understanding of the transport behaviour of organic and inorganic contaminants during the application of MAR typically requires detailed numerical groundwater flow and multi-component reactive transport modeling (Henzler et al., 2014). Henzler et al., 2014 evaluated the depletion by sorption and degradation of emerging organic contaminants during the underground passage at a riverbank filtration site by using the groundwater flow model MODFLOW and the non-reactive as well as reactive transport model MT3DMS. Rahmann et al., 2012 used groundwater flow and transport modeling to assess the degree of attenuation of micropollutants during the surface infiltration of treated wastewater (SAT) and hence to recommend further treatment steps before the recharge of the effluent. Wallis et al., 2011 analyzed the physical and geochemical mechanisms which control the fate of arsenic during ASR with the help of numerical groundwater flow (MODFLOW) and multicomponent reactive transport modeling (PHT3D).
The INOWAS DSS helps to evaluate water quality changes which can occurr during the application of MAR. It encompasses the absorption and degradation of contaminants in the source water, the mixing of the recharged water with the ambient groundwater (dilution) but also the mobilzation of aquifer constituents due to the chemical composition of the source water. For the special case of salinity improvements in brackish aquifers to mitigate seawater intrusion please see application Assessment of seawater intrusion. To quantify the risk of contaminant breakthrough, the user is referred to the application Risk Assessment.
The following INOWAS tools can be used to assess the water quality changes at MAR facilities:
- T03. MODFLOW model setup and editor
- T07. MODFLOW model scenario manager
- T08. One-Dimensional Transport Equation
- T13. Travel Time Through Unconfined Aquifer
- T18. SAT Basin Design
To select a suitable MAR method or a model set for the specific study area, the following tools can be used:
REFERENCES
- Henzler, A.F., Greskowiak, J., Massmann, G., 2014. Modeling the fate of organic micropollutants during river bank filtration (Berlin, Germany). Journal of Contaminant Hydrology 156, 78–92. doi:10.1016/j.jconhyd.2013.10.005
- Rahman, M.A., Ptak, T., Nödler, K., Licha, T., Dimitriadis, K., Soupilas, A., Sauter, M., 2012. Influence of aquifer properties on water quality changes during infiltration of treated effluent, in: Draeger, M. (Ed.), Achieving Groundwater Supply Sustainability & Reliability through Managed Aquifer Recharge – Proceedings of the Symposium ISMAR 7, 9-13 October 2009, Abu Dhabi, UAE. pp. 19–26.
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Wallis, I., Prommer, H., Pichler, T., Post, V., B. Norton, S., Annable, M.D., Simmons, C.T., 2011. Process-Based Reactive Transport Model To Quantify Arsenic Mobility during Aquifer Storage and Recovery of Potable Water. Environmental Science & Technology 45, 6924–6931. doi:10.1021/es201286c