Protection of drinking water resources requires addressing all relevant fecal pollution sources in the considered catchment. A freely available simulation tool, QMRAcatch, was recently developed to simulate concentrations of fecal indicators, a genetic microbial source tracking (MST) marker, and intestinal pathogens in water resources and to conduct a quantitative microbial risk assessment (QMRA). At the same time, QMRAcatch was successfully applied to a region of the Danube River in Austria, focusing on municipal wastewater emissions. Herein, we describe extension of its application to a Danube River floodplain, keeping the focus on fecal sources of human origin. QMRAcatch was calibrated to match measured human-associated MST marker concentrations for a dry year and a wet year. Appropriate performance characteristics of the human-associated MST assay were proven by simulating correct and false-positive marker concentrations, as determined in human and animal feces. With the calibrated tool, simulated and measured enterovirus concentrations in the rivers were compared. Finally, the calibrated tool allowed demonstrating that 4.5 log 10 enterovirus and 6.6 log 10 norovirus reductions must be achieved to convert current surface water to safe drinking water that complies with a health-based target of 10 -4 infections person -1 yr -1. Simulations of the low-and high-pollution scenarios showed that the required viral reductions ranged from 0 to 8 log 10 . This study has implications for water managers with interests in assessing robust catchment protection measures and water treatment criteria by considering the fate of fecal pollution from its sources to the point of abstraction.QMRAcatch: Human-Associated Fecal Pollution and Infection Risk Modeling for a River/Floodplain Environment Julia Derx, Jack Schijven, Regina Sommer, Christa M. Zoufal-Hruza, Inge H. van Driezum, Georg Reischer, Simone Ixenmaier, Alexander Kirschner, Christina Frick, Ana Maria de Roda Husman, Andreas H. Farnleitner, and Alfred Paul Blaschke* S ustainable protection of water resources is a major policy goal worldwide. In recent years, the catchment-to-tap principle has been introduced, and it considers all possible sources of fecal pollution: within the watershed, at the water abstraction, during distribution, and at consumption (WHO, 2011). Inspired by the European Water Framework Directive (EU, 2006) and the Rotorua Declaration (HRWM, 2011), the microbial water quality model QMRAcatch was recently developed (Schijven et al., 2015). QMRAcatch is a completely mixed reactor type model with first-order degradation in a main river with point wastewater discharges, a floodplain river, and a floodplain area with diffuse fecal sources. The main river feeds the floodplain river during flood events. The model structure includes the fate and transport of target microbes and viruses (TMVs), including common fecal indicator bacteria, genetic microbial source tracking (MST) markers, and selected intestinal pathogens originating from wastewater trea...

Characterization of surface water - groundwater interaction in riverbank filtration (RBF) systems is of decisive importance to drinking water utilities due to the increasing microbial and chemical contamination of surface waters. These interactions are commonly assessed by monitoring changes in chemical water quality, but this might not be indicative for microbial contamination. The hydrological dynamics of the infiltrating river can influence these interactions, but seasonal temperature fluctuations and the supply of oxygen and nutrients from the surface water can also play a role. In order to understand the interaction between surface water and groundwater in a highly dynamic RBF system of a large river, bacterial abundance, biomass and carbon production as well as standard chemical parameters were analyzed during a 20 month period under different hydrological conditions. In the investigated RBF system, groundwater table changes exhibited striking dynamics even though flow velocities were rather low under regular discharge conditions. Bacterial abundance, biomass, and bacterial carbon production decreased significantly from the river towards the drinking water abstraction well. The cell size distribution changed from a higher proportion of large cells in the river, towards a higher proportion of small cells in the groundwater. Although biomass and bacterial abundance were correlated to water temperatures and several other chemical parameters in the river, such correlations were not present in the groundwater. In contrast, the dynamics of the bacterial groundwater community was predominantly governed by the hydrogeological dynamics. Especially during flood events, large riverine bacteria infiltrated further into the aquifer compared to average discharge conditions. With such information at hand, drinking water utilities are able to improve their water abstraction strategies and react quicker to changing hydrological conditions in the RBF system.

Riverbank filtration (RBF) systems along rivers are widely used as public water supplies. In these systems, many organic micropollutants (OMPs) are attenuated, but some compounds have shown to be rather persistent. Their fate and transport has been studied in RBF sites along lakes and small rivers, but not extensively along large and dynamic rivers. Therefore, the influence of flood events on OMP behavior in these large and dynamic RBF sites was investigated. Monthly samples were taken from surface- and groundwater up to a distance of 900 m from the riverbank of the Danube from March 2014 till May 2016. Two flood events were sampled more extensively nearby the river. Results showed that changes in flow conditions in the river not only caused changes in OMP concentrations, but also in their load. It was seen that the load of benzotriazole, carbamazepine and sulfamethoxazole in the river increased with increasing river discharges. After a relatively long, oxic groundwater passage, several OMPs were reduced. In contrast to previous work, we found that benzotriazole was almost fully removed under oxic conditions. When entering the aquifer, benzotriazole concentrations were significantly reduced and at a distance of 550 m from the river, >97% was degraded. Carbamazepine and sulfamethoxazole showed relatively persistent behavior in the aquifer. The concentrations measured during flood events were in the same range as seasonal sampling. Furthermore concentrations in the groundwater were higher during these events than in the Danube and can reach further into the aquifer. During flood events some highly degradable compounds (i.e. diclofenac) were found up to a distance of 24 m from the river. These results implied that drinking water utilities with RBF wells in oxic, alluvial aquifers located close to highly dynamic rivers need to consider a potential reduction in groundwater quality during and directly after flood events.

Members of the genus Cryptosporidium are waterborne protozoa of great health concern. Many studies have attempted to find appropriate surrogates for assessing Cryptosporidium filtration removal in porous media. In this study, we evaluated the filtration of Cryptosporidium parvum in granular limestone medium by the use of biotin-and glycoprotein-coated carboxylated polystyrene microspheres (CPMs) as surrogates. Column experiments were carried out with core material taken from a managed aquifer recharge site in Adelaide, Australia. For the experiments with injection of a single type of particle, we observed the total removal of the oocysts and glycoprotein-coated CPMs, a 4.6-to 6.3-log 10 reduction of biotin-coated CPMs, and a 2.6-log 10 reduction of unmodified CPMs. When two different types of particles were simultaneously injected, glycoprotein-coated CPMs showed a 5.3-log 10 reduction, while the uncoated CPMs displayed a 3.7-log 10 reduction, probably due to particle-particle interactions. Our results confirm that glycoprotein-coated CPMs are the most accurate surrogates for C. parvum; biotin-coated CPMs are slightly more conservative, while unmodified CPMs are markedly overly conservative for predicting C. parvum removal in granular limestone medium. The total removal of C. parvum observed in our study suggests that granular limestone medium is very effective for the filtration removal of C. parvum and could potentially be used for the pretreatment of drinking water and aquifer storage recovery of recycled water. W aterborne cryptosporidiosis is mainly caused by Cryptosporidium parvum and Cryptosporidium hominis in humans (1). Cryptosporidium can be found in water contaminated with infected human or animal feces and has a low infectious dose, and ingestion of less than 10 oocysts can lead to infection (2). Cryptosporidium oocysts are sometimes detected in drinking water supplies (3) and in potable groundwater (4), causing disease outbreaks. For example, in the 1993 cryptosporidiosis outbreak in Milwaukee, WI, USA, about 400,000 people were infected and more than 100 people died after contamination of drinking water by C. parvum (5). More recently, a waterborne outbreak of cryptosporidiosis in Ö stersund, Sweden, which infected 27,000 people in 2010, was caused by C. hominis (6).C. parvum can survive in surface water and groundwater for a long period of time (7) and is resistant to chemical disinfection, like chlorination (8) and ozonation (9), due to its thick oocyst wall. UV irradiation with low-and medium-pressure lamps has been found to be effective at inactivating C. parvum (10). However, the efficacy of UV irradiation as well as that of chemical disinfection is hampered by turbidity in the water. Thus, filtration is often used as an essential primary step for drinking water treatment in the course of a multibarrier treatment system because it is effective and cost-efficient.Because it is extremely infectious and highly resistant to chlorination, testing for C. parvum is often used in risk analysis of drin...