This report presents the findings from task 2.1 of the SafeCREW project, which aimed to monitor seasonal microbial quality changes in source waters of near-natural treatment systems, such as managed aquifer recharge (MAR). Two case study locations, Hamburg and Berlin, were examined to understand microbial dynamics over time. Microbial cell counts in source waters were monitored using flow cytometry (FCM), which enables the analysis of bacteria, protozoa, and viruses. In addition, organic matter in source waters and during near-natural treatment was analyzed using techniques such as Liquid Chromatography-Organic Carbon Detection (LC-OCD), fluorescence spectroscopy, and absorption measurements. These methods provided detailed insights into the type and quantity of organic substances, which influence microbial growth. Notably, biopolymers—organic substances produced during microbial degradation—were identified as indicators of microbial activity and surface water influence. By combining microbiological and organic analyses, a comprehensive monitoring system can be developed that provides extensive information not only on seasonal changes in microbial quality, but also on the underlying causes and influencing factors. This enables targeted and effective control of water treatment processes and helps to ensure high water quality.

The objective of the report is to identify enabling and hindering factors for the uptake of ICT solutions to water governance, through the analysis of the process of development and the introduction of three digital applications in three different contexts of water management.
This final deliverable builds on a preliminary (deliverable 3.4) for WP3 which was submitted in November 2020. The report applies the structure proposed in the Guiding Protocol (Deliverable 3.1).

This report describes the main functionalities the SMART-Control web-based tool T1B Quantitative microbial risk assessment. The tool helps to quantify the pathogen occurrence in source water and their removal by various treatment steps at MAR facilities by using a probabilistic approach. The interactive web-based QMRA tool supports the evidence-based risk assessment to minimize water-related infectious diseases.

Subsurface travel time from the area of recharge to the point of abstraction during MAR is a critical parameter to ensure sufficient attenuation for hygienic parameters and other undesired substances. A new simulation tool has been developed by the SMART-Control project partners KWB and TUD for determination of groundwater hydraulic residence time (HRT) using seasonal temperature fluctuations observed in recharge water and MAR recovery wells. This tool represents a proxy for quick, costs-effective and reliable control of travel time during aquifer passage. Time series of seasonal temperature measurements observed in surface water and abstraction wells can be fitted to sinusoidal functions. Peak values represented as local maxima and local minima and turning points from the fitted sinusoidal curves are used for the approximation of travel times between surface water and abstraction well. The calculated values are adjusted by a thermal retardation factor. The developed tool is userfriendly and offers the possibility to use existing hystorical temperature measurements as well as online sensor data. Data acquisition is resolved through the internal connectivity with other web-tools developed within the SMART-Control project, providing thus an integrated simulation environment.

This report summarizes the work for monitoring of hydraulic residence time (HRT) carried out at the Managed Aquifer Recharge (MAR) site Berlin-Spandau waterworks. The newly installed monitoring system consists of realtime online sensor data and evaluation algorithms implemented as a web-based software tool. The combination of online data with processing tools allows time-efficient HRT evaluation. Apart from HRT estimations, the monitoring also included measurements by flow-through cytometry (FCM), meta-genomic DNA sequencing and classical microbial cultivation-based analysis. FCM cell counting allows to quantitatively detect microbial cells after staining with a DNA-binding fluorescent dye. The aim of FCM measurements was to gain insights on microbial dynamics along the flow path from the infiltration basin to the abstraction well. The FCM device was installed to measure in the infiltration basin, groundwater observation well and abstraction well in a continuously flowing sampling line that allowed for automatic and continuous monitoring in water. Microbial indicators of viruses, bacteria and protozoa were sampled and analysed by classical cultivation-based methods in parallel to the FCM measurements. The combination of FCM with cultivation-based methods aimed to establish an indicative reference cell count representing a hygienically safe water. The high-frequency flow cytometry data revealed decreasing order of total cell counts from surface water in the infiltration basin water to groundwater in the abstraction well. The fairly constant measurements in the abstraction well may allow to use FCM fingerprinting as a fast monitoring tool in combination with cultivation based methods. However, long-term measurements of FCM for at least 6 months are recommended to assess seasonal fluctuation in both source water and groundwater. Water samples were in addition characterised by DNA sequencing enabling a complete "meta genomic" analysis and taxonomic profiling including bacterial, archaea, viral, eukaryotic DNA. The DNA sequencing in combination with FCM measurements showed that total cell counts decreased along the flow path while the biodiversity increased.

In 2015, the town of El Port de la Selva in Spain implemented soil-aquifer treatment (SAT) using tertiary treated wastewater effluents to replenish the local potable aquifer. This study evaluated the initial phase of this indirect potable water reuse system including a characterization of hydraulic conditions in the aquifer and monitoring of microbial contaminants and 151 chemicals of emerging concern (CECs). The combined treatment resulted in very low abundances of indicator bacteria, enteric viruses and phages in the monitoring wells after three days of infiltration and a reduction of antibiotic microbial resistance to background levels of local groundwater. After tertiary treatment, 94 CECs were detected in the infiltration basin of which 15 chemicals exceeded drinking water thresholds or health-based monitoring trigger levels. Although SAT provided an effective barrier for many chemicals, 5 CECs were detected above health-based threshold levels in monitoring wells after short hydraulic retention times. However, additional attenuation is expected due to dilution prior to abstraction via downstream drinking water wells and during granular activated carbon (GAC) filtration, which was recently installed to mitigate residual CECs. Overall, the results demonstrate that indirect potable water reuse can be a reliable option for smaller communities, if related risks from microbial and chemical contaminants are adequately addressed by tertiary treatment and subsequent SAT, providing sufficient hydraulic retention times for pathogen decay and CEC removal.

In Berlin wird Trinkwasser ohne aufwändige technische Aufbereitung über naturnahe Verfahren gewonnen. Ca. 80% des geförderten Rohwassers stammen aus Uferfiltration oder künstlich angereichertem Grundwasser (Möller & Burgschweiger 2008). Nach der Entfernung von Eisen und Mangan über Belüftung und Filtration wird im Routinebetrieb grundsätzlich auf eine chemische Desinfektion verzichtet. Zur Gewährleistung der hygienischen Sicherheit haben die Wasserschutzgebiete und hier insbesondere die engere Schutzzone (Zone II) daher eine wichtige Bedeutung. Deren Ausdehnung reicht von der Fassungsanlage bis zu der Linie, von der aus das genutzte Grundwasser 50 Tage im Grundwasserleiter fließt, bevor es über Brunnen zum Wasserwerk gefördert wird (DVGW 2006). Durch die Einhaltung dieser 50-Tage-Richtlinie wird v.a. der Schutz vor mikrobiellen Verunreinigungen angestrebt. Die Aufenthaltszeit des Wassers in der Untergrundpassage kann direkt durch Markierungsversuche ermittelt werden. Da solche Tracer-Untersuchungen zeitlich und technisch aufwändig sind, wurde im Rahmen verschiedener gemeinsamer Forschungsprojekte der Berliner Wasserbetriebe und des Kompetenzzentrums Wasser Berlin geprüft, mit welchen einfachen, kostengünstigen Methoden die Fließzeiten und die Auswirkungen sich ändernder klimatischer Randbedingungen im Betrieb der Grundwasseranreicherung und der Trinkwasserbrunnen überwacht werden können (Sprenger et al. 2016). Dabei wurden unter anderem kontinuierlich messende Temperatur-Druck-Sonden eingesetzt, sowie Geräte zur Quasi-Echtzeitmessung mikrobiologischer Parameter. Parallel wurde für einen Wasserwerksstandort in Berlin ein vereinfachtes numerisches Modell erstellt, mit dem Anreicherungsszenarien in Abhängigkeit der Temperatur des angereicherten Wassers gerechnet und bewertet werden können. Außerdem wurde der Einfluss der Wassertemperatur auf betriebliche Parameter der Oberflächenwasseraufbereitung untersucht. Die Untersuchungen sind ebenfalls Grundlage für risikobasierte Bewertungsansätze für hydraulische und mikrobiologische Parameter und die Ableitung betrieblicher Maßnahmen gegen eine Unterschreitung der 50-Tage-Verweilzeit.