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Seven biochars (BCs) obtained from pyrolysis or gasification of different vegetal feedstocks were thoroughly characterized in comparison with three commercial activated carbons (ACs) routinely used in drinking water treatment plants. BCs and ACs characterization included the determinations of ash, iodine and methylene blue adsorption indexes, and the release of metals and polycyclic aromatic hydrocarbons, which were performed according to international standards applied for adsorption media to be used in drinking waters. Total specific surface area, micropore and mesopore specific surface area, pH of the point of zero charge, and the release of polychlorinated biphenyls were also determined in all chars. Principal component analysis and cluster analysis were performed in order to summarize the complex set of information deriving from the aforementioned characterizations, highlighting the BC most similar (BC6 from high temperature gasification of woody biomass) and most different (BC7 from low-temperature pyrolysis of corn cob) from ACs. These BCs were studied for their adsorption in ultrapure water towards diiodoacetic acid (an emergent disinfection by-product), benzene, and 1.2-dichlorobenzene, in comparison with ACs, and results obtained were fitted by linearized Freundlich equation. Overall, BC6 showed higher sorption performances compared to BC7, even though both BCs were less performing sorbents than ACs. However, the sorption properties of BCs were maintained also in real water samples collected from drinking water treatment plants.

The objective of this research project was the design and development of an integrated model for odor emission estimation in wastewater treatment plants. The SMAT's plant, the largest wastewater treatment facility in Italy, was used as a case study. This article reports the results of the characterization phase that led to the definition and design of the proposed conceptual model for odor emission estimation. In this phase, concentrations of odor chemical tracers (VOC, H2S, NH3) and odor concentrations were monitored repeatedly. VOC screening with GC-MS analysis was also performed. VOC concentrations showed significant variability in space and magnitude. NH3 and H2S were also detected at considerable concentrations. Results were elaborated to define a spatially variable linear relationship between the sum of odor activity values (SOAV) and odor concentrations. Based on the results, a conceptual operational model was presented and discussed. The proposed system is composed by a network of continuous measurement stations, a set of algorithms for data elaboration and synchronization, and emission dispersion modeling with the application of Lagrangian atmospheric models.

Ambitious energy targets in the 2020 European climate and energy package have encouraged many stakeholders to explore and implement measures improving the energy efficiency of water and wastewater treatment facilities. Model-based process optimization can improve the energy efficiency of wastewater treatment plants (WWTP) with modest investment and a short payback period. However, such methods are not widely practiced due to the labor-intensive workload required for monitoring and data collection processes. This study offers a multi-step simulation-based methodology to evaluate and optimize the energy consumption of the largest Italian WWTP using limited, preliminary energy audit data. An integrated modeling platform linking wastewater treatment processes, energy demand, and production sub-models is developed. The model is calibrated using a stepwise procedure based on available data. Further, a scenario-based optimization approach is proposed to obtain the non-dominated and optimized performance of the WWTP. The results confirmed that up to 5000 MWh annual energy saving in addition to improved effluent quality could be achieved in the studied case through operational changes only.

Disinfection of hot water systems is critical for reducing Legionnaires’ disease in high-risk buildings. The use of neutral electrolysed oxidising water (NEOW) is a promising method for the control of microorganisms in hot water systems. However, full-scale evaluations of the efficacy of NEOW devices to control Legionella pneumophila are currently lacking. The aim of this study was to assess the effectiveness of a NEOW device in reducing L. pneumophila in a hotel water network. Water samples (n = 67) were collected from different sites of a hotel distribution system before and after the installation of the NEOW device at the 1st, 4th, 8th and 12th week. Detection of L. pneumophila was performed comparing culture, qPCR and PMA-qPCR methods. Total bacterial counts (22 °C and 37 °C), Pseudomonas spp. and physico-chemical parameters were also monitored. The NEOW treatment resulted in a reduction of the amount of L. pneumophila positive samples (−32%) and of the number of heavily contaminated points (>104 CFU/L and >103 CFU/L) (−100% and −96%, respectively). Treatment maintained L. pneumophila at low levels ( The NEOW disinfection device appears to be a promising approach to reduce the colonisation of hot water systems by L. pneumophila; however, further investigations are needed to ascertain its efficiency over longer time periods.

This study evaluates nanofiltration as a feasible process to reach low concentrations of chromium in drinking water and provides means for the selection of the most suitable membrane based on the specific treatment needs. Chromium removal is concerning since new stringent limits (10 μg/L) for hexavalent Cr concentration in potable water were recently adopted in various countries. Three commercial nanofiltration membranes were tested against this threshold value: two membranes made of semi-aromatic polyamide and the third having a sulfonated polyethersulfone asymmetric film as the selective layer. The rejection observed as a function of chemical composition in the feed solution suggests that electrostatic effect is an important mechanism of chromium(VI) removal for the membranes with higher surface charge and lower film density. The performance of such membranes is strongly affected by the presence of salts, especially divalent cations, which reduce both Cr(VI) rejection and the permeate flux. The removal of Cr(VI) by denser membranes is dominated by solution-diffusion and is not influenced by feed ionic strength. The exposure of membranes to high chromium concentrations and to hypochlorite, typically employed as an oxidizing agent in water treatment plants, was also investigated. An analysis of the operational membrane life is thus discussed, based on the loss in performance due to active film degradation. All three membranes showed adequate rejection of chromium from tap and well water of diverse chemical composition, suggesting that nanofiltration is an effective process to remove chromium for the production of safe drinking water. However, membranes with different properties should be adopted depending on specific feed water composition and on the productivity required from the system. A final analysis is presented to help with the choice of the most suitable nanofiltration membrane based on initial and target Cr(VI) concentration in feed and product water, respectively.

This paper outlines a hybrid modeling approach to facilitate weather-based operation and energy optimization for the largest Italian wastewater treatment plant (WWTP). Two clustering methods, K-means algorithm and Gaussian mixture model (GMM) based on the expectation-maximization (EM) algorithm, were applied to an extensive dataset of historical and meteorological records. This study addresses the problem of determining the intrinsic structure of clustered data when no information other than the observed values is available. Two quantitative indexes, namely the Bayesian information criterion (BIC) and the Silhouette coefficient using Euclidean distance, as well as two general criteria, were implemented to assess the clustering quality. Furthermore, seven weather-based influent scenarios were introduced to the process simulation model, and sets of aeration strategies are proposed. The results indicate that incorporating weather-based aeration strategies in the operation of the WWTP improves plant energy efficiency.

Water pasteurization has the potential to overcome some of the drawbacks of more conventional disinfection techniques such as chlorination, ozonation and ultraviolet radiation treatment. However, the high throughput of community water systems requires energy-intensive processes, and renewable energy sources have the potential to improve the sustainability of water pasteurization plants. In case of water pasteurization by solar thermal treatment, the continuity of operation is limited by the intermittent availability of the solar irradiance. Here we show that this problem can be addressed by a proper design of the plant layout, which includes a thermal energy storage system and an auxiliary gas boiler. Based on a target pasteurization protocol validated by experiments, a complete lumped-component model of the plant is developed and used to determine the operating parameters and size of the components for a given delivery flow rate. Finally, we report an economic analysis of the proposed plant layout, which allows its optimization for different scenarios based on two design variables, namely the solar multiple and the duration of the thermal energy storage. Based on the analyzed cases, it is found that the proposed plant layouts may yield a unit cost of water treatment ranging from &asymp, 32 EUR-cents m&minus, 3 to &asymp, 25 EUR-cents m&minus, 3.

This study presents an integrated feasibility analysis approach to reduce the carbon footprint in the largest Italian wastewater treatment plant (WWTP). Firstly, a model-based feasibility analysis was carried out to assess the applicability of upgrading scenarios, for an ongoing anaerobic sludge digestion process. Application of dynamic sludge thickener, as well as hybrid thermo-alkali pre-treatment of waste activated sludge, were assessed to enhance the biogas production in the WWTP. Further, an implementation of the selective membranes was proposed and studied to upgrade the produced biogas in sludge treatment units to biomethane with an average efficiency of 98.6%. Model-based sludge pre-treatment and biogas upgrading strategies were developed and evaluated in terms of mass, energy, and greenhouse gas emission balance. The obtained results prove that practicing the proposed upgrading scenario can lead to an 18% improvement in biogas production and a significant reduction of thermal energy auto-consumption and total greenhouse gas emissions. In the second phase, the laboratory-based feasibility analysis was performed about the integration of microalgae technology into the current process of the WWTP. A planar photobioreactor was built to estimate the volumetric mass transfer coefficient (KLa) and CO2 consumption of the reactor. By the use of 44 and 76 μmol/m2/s light intensities, the results show 80% and 70% reductions in total CO2, respectively. The tested configuration guaranteed 11.763 and 27.943 mg/l/h CO2 consumptions, as well as 0.5775 h−1 and 17.7 h−1 KLa values. Overall, the results prove that applications of the technologies proposed in this study can significantly reduce the carbon footprint of the WWTP.

This paper outlines a multi-objective, integrated approach to analyse various possibilities for increasing energy efficiency of the largest Italian wastewater treatment plant (WWTP) at Castiglione Torinese. In this approach, wastewater and sludge treatment units are thoroughly investigated to find the potential ways for improving the energy efficiency of the system. Firstly, a multi-step simulation-based methodology is proposed to make a full link between treatment processes and the energy demand and production. Further, a scenario-based optimization approach is proposed to find the non-dominated and optimized performance of the WWTP. The results prove a potential to save up to 5000 MWh of the annual energy consumption of the plant, in addition to improve the effluent quality through operational changes only. Even for what concerns the sludge line a model was proposed for the optimization of the energy recovery from the processes that in a WWTP are devoted to the management of sewage sludge. The obtained results show that the introduction of an advanced thickening stage and sludge pre-treatment, together with the optimized production and use of biomethane, would have a positive impact on the energy and greenhouse gas balance of the plant. The preliminary tests were conducted with microalgae, under different light intensities (3 and 5 fluorescent lamps equal to 44 and 76 μmol/m2/s), that had shown a total CO2 reduction of 80 and 70%, respectively.

Hydropower remains a key renewable energy source in the pursuit of the decarbonization of the economy, although the relatively high potential impact of the hydro-morphological alterations it may cause poses significant concerns for aquatic ecosystems. In the last years, new technologies and practices have been increasingly adopted to minimize the impacts of hydropower plants, while improving efficiency and flexibility of energy generation. The overall effect of these innovations may be a more sustainable design and operation of hydropower, striking a better balance between the objectives of decarbonization and ecosystem protection. This contribution presents and discusses a few representative examples of hydropower installations from companies in Italy, France, Switzerland, Belgium and the USA, where solutions have been adopted in this direction. The case studies cover (1) ecologically improved and low head hydropower converters (Vortex turbine, Hydrostatic Pressure Machine, VLH and Girard-optimized turbines, hydrokinetic turbines), hydropeaking reduction (2) new control systems, governors and digitalization, (3) hydropower as a strategy for local sustainable development and (4) energy recovery in existing hydraulic infrastructures and aqueducts. It was found that better-governing systems can extend the life span of runners, for example avoiding the runner uplift during a trip. Digitalization can improve efficiency by 1.2%. New sustainable practices and turbines with better ecological behavior can minimize environmental impacts, like the reduction of fish mortality, improvement of fish habitat availability, reduction of oil for lubrication purposes and generation of economic incomes for local development. The use of existing structures reduces the total installation cost: examples are the total saving of 277 €/kW by reusing irrigation pipes and reservoirs, or the reduction of the investment period from 9 years to 6 years by turbining the environmental flow. Innovative low head hydropower converters can exhibit good ecological behavior, with reduced costs (

This study proposes an integrated approach by combining a pattern recognition technique and a process simulation model, to assess the impact of various climatic conditions on influent characteristics of the largest Italian wastewater treatment plant (WWTP) at Castiglione Torinese. Eight years (viz. 2009–2016) of historical influent data namely influent flow rate (Qin), chemical oxygen demand (COD), ammonium (N-NH4) and total suspended solids (TSS), in addition to two climatic attributes, average temperature and daily mean precipitation rates (PI) from the plant catchment area, are evaluated in this study. Following the outlier removal and missing-data imputation, five influent climate-based scenarios are identified by K-means clustering approach. Statistical characteristics of clustered observations are further investigated. Finally, to demonstrate that the proposed approach could improve the process control and efficiency, a process simulation model was developed and calibrated. Steady-state simulations were conducted, and the performance of the plant was studied under five influent scenarios. Further, an optimization scenario-based method was conducted to improve the energy consumption of the plant while meeting effluent requirements. The results indicate that with the adaptation of suitable aeration strategies for each of the influent scenarios, 10–40% energy saving can be achieved while meeting effluent requirements.

Data scarcity can be considered as the main limitation for a more widespread utilization of mathematical models in the design, optimization and control of biological nutrient removal activated sludge systems (BNRAS). High cost and demanding workload related to experimental data and sufficient sampling campaigns make the data collection process an unpleasant necessity for managing stakeholders in modelling projects. Complicated use of online-sensors leading to frequent erroneous readings and dynamic nature of wastewater treatment processes can intensify the data scarcity problems. This paper investigates the influence of data scarcity on the development and calibration of wastewater treatment plant (WWTP) models. A straightforward methodology is proposed to address the challenges associated with data quality and quantity problems in modelling of a BNRAS in the largest Italian WWTP located in Castiglione, Italy. The plant operational modes, weather condition and sensor performance during the sampling campaigns were the main sources of the data scarcity. Influent, biokinetic, aeration, hydraulic and transport, clarifier, energy consumption and effluent sub-models were calibrated by use of the proposed extensive step-wise calibration process. The Monte Carlo analysis was performed to quantify the uncertainty of the modelling results. The proposed methodology could be implemented in engineering practice to develop and calibrate the WWTP models while it increases the awareness about modelling robustness and its characterized uncertainty to avoid bad modelling practice.

According to the recent proposal released by the European Commission for the revision of the 98/83/EC Directive, water suppliers will be requested to monitor the nine bromine- and chlorine congeners of haloacetic acids, HAAs, as well as the oxyhalides chlorite and chlorate, as disinfection by-products (DBPs) originated during the potabilization process. In this work, we propose a direct-injection method based on ion chromatography and mass spectrometric detection for the determination of the mentioned DBPs as well as bromate (already included in the 98/83/EC), implemented also for the following emerging HAAs monoiodo-, chloroiodo- and diiodo-acetic acids. The method was optimized to include the fifteen compounds in the same analytical run, tuning the chromatographic (column and gradient) and detection conditions (suppression current, transitions, RF lens settings and collision energies). To avoid matrix effect and to manage the instrumental conditions, optimization was performed directly in drinking water matrix. The method quantitation limits satisfy the new limits imposed by the future directive and range from 0.08 μg/L (monobromoacetic acid) to 0.34 μg/L (trichloroacetic acid). The performance of the method was checked along different strategic sampling points of three potabilization plants serving the city of Turin (Italy), including intermediate treatments and finished waters. Recovery was checked according to the ±30% limit of acceptability set by EPA regulations. The effect of disproportionate concentrations of chlorite and chlorate in respect to HAAs on HAA signals was studied; this aspect is underestimated in literature. The method is routinely applied by the potabilization plant of the city of Turin to confirm the effectiveness of all control measures in abstraction, treatment, distribution and storage. This study represents the first example in Italy of development and use of a cutting-edge technique for HAAs analysis along the potabilization processes.

Energy consumption represents a significant part of the operative costs of a wastewater treatment plant but, with a correct design and a careful management model, there are important possibilities for its limitation. The proposed research presents a multi-step methodology for the evaluation of the energetic aspects of wastewater treatment, which was implemented on the largest facility in Italy (2.7 M population equivalents as organic load), managed by Societa Metropolitana Acque Torino (SMAT). The study initially took into account each phase of the process scheme, in order to obtain specific electricity consumption values for all the electro-mechanic devices. Data from tele-control system and direct measurements in field have both been acquired. The total electric energy demand of the plant was evaluated (66.78 GW h/y, about 50% from aeration in oxidation tanks). In account of large contribution the energy efficiency of the blowers was verified with positive results. Four specific energy consumption indexes were considered to carry out a critical analysis of SMAT wastewater treatment plant with other facilities performing biological oxidation processes and of a different order of magnitude about design capacity, and congruent values were obtained. The considered indexes related the electric energy demand to the equivalent population, to the volume of treated water and to the amount of removed COD and total Nitrogen. Furthermore the thermal energy demand of the plant was estimated (49.15 GW h/y, more than 93% from sludge line). An energy balance for the whole plant was finally evaluated, and some energy optimization solutions to decrease the corresponding costs were suggested.

Nanofiltration is an emerging technology applied to increase the availability of safe drinking water. This study evaluates nanofiltration as a feasible process to reach the new regulatory concentration limit for hexavalent chromium (0.01 mg/L) in potable water. Real well water contaminated with chromium was treated using two types of membranes of different selectivity in bench-scale and pilot-scale experiments. The pilot system comprised two modules in series and was run for 42 days without chemical cleaning, at an applied pressure of 98%) for the denser membrane, while it decreased from 95% to 70% for the less selective membrane. This result may be attributed to the impairment of charge-based rejection of chromate ions. Based on these results, a full-scale plant is proposed to treat the contaminated well water, equipped with the more selective membranes. The optimal plant configuration would consist of two stages, with a total number of 96 modules to produce 30 L/s of potable water. Based on equations developed to describe contaminant concentrations in the streams entering and exiting a generic plant, guidelines are also provided to perform a preliminary system analysis. An economic assessment showed an average cost of

Legionella pneumophila is a ubiquitous microorganism widely distributed in aquatic environments and can cause Legionellosis in humans. A promising approach to detect viable cells in water samples involves the use of quantitative polymerase chain reaction (qPCR) in combination with photoactivatable DNA intercalator propidium monoazide (PMA). However, the PMA efficiency could be different depending on the experimental conditions used. The aim of this study was to compare two PMA exposure protocols: (A) directly on the membrane filter or (B) in liquid after filter washing. The overall PMA-induced qPCR means reductions in heat-killed L. pneumophila cells were 2.42 and 1.91 log units for exposure protocols A and B, respectively. A comparison between the results obtained reveals that filter exposure allows a higher PMA-qPCR signal reduction to be reached, mainly at low concentrations (p < 0.05). This confirms the potential use of this method to quantify L. pneumophila in water with low contamination.

This study analyze the urban water cycle in the Turin Metropolitan Area (Northwestern Italy), with a focus on quantifying the annual life cycle energy consumption and greenhouse gas emissions, using Material Flow Analysis and Life Cycle Assessment methods. The annual direct and indirect energy consumption and greenhouse gas emissions have been quantified as related to system-wide energy consumption and production and transportation of chemicals used in water/wastewater treatment plants. Results says that the wastewater treatment consumes the biggest share of the total energy (44%), but a significant part of this energy demand is provided by the energy in biogas produced from wastewater sludge.

SOFCOM is an applied research project (FCH JU Grant Agreement 278798) devoted to demonstrate the technical feasibility, the efficiency and environmental advantages of CHP plants based on SOFC fed by different typologies of biogenous primary fuels (locally produced), integrated by a process for the CO2 separation from the anode exhaust gases. The research activity is devoted to the scientific, technical and economic management of the proof-of-concept of a complete energy systems based on SOFCs, integrated in a waste water treatment plant (WWTU), with CO2 management. Several issues are addressed, like high efficiency integration designs, impact of the fuel pollutants on the SOFC and fuel processing units operation, gas cleaning, carbon sequestration module, operation in CHP configuration, maintenance and repair strategies, lessons learned for pre-normative issues and scale-up analysis. The paper develops general presentation of the SOFCOM project, and outlines the WWTU–SOFC–CO2 management demonstration plant.

Several studies have noted that treated and untreated wastewaters are primary contributors of a variety of pathogenic microorganisms to the aquatic ecosystem. Conventional wastewater treatment may not be sufficient to achieve microbiologically safe effluent to be discharged into natural waters or reused, thus requiring wastewater effluents to be disinfected. In recent years, peracetic acid (PAA) has been adopted as a disinfectant for wastewater effluents. The aim of this study was to evaluate the disinfection efficiency of PAA at low doses (range 0.99–2.10 mg/L) against microbial indicators and pathogenic bacteria in a municipal wastewater plant. Samples of untreated sewage and effluents before and after PAA treatment were collected seasonally for 1 year and were analysed for pathogenic Campylobacter, Salmonella spp., E. coli O157:H7 and E. coli virulence genes using molecular methods; moreover, the detection of specific microbial indicators (E. coli, faecal coliforms, enterococci, C. perfringens) and Salmonella spp. were carried out using culturing methods. Salmonella spp. DNA was found in all untreated sewage and effluent before PAA treatment, whereas it was recovered in 50% of the samples collected after PAA treatment. Although E. coli O157:H7 was never identified, the occurrence of Shiga-like toxin I amplicons was identified in 75% of the untreated sewage samples, in 50% of the effluents assayed before PAA treatment, and in 25% of the effluents assayed after PAA treatment, whereas the stx2 gene was never found. Campylobacter coli was only detected in one effluent sample before PAA treatment. In the effluents after PAA treatment, a lower load of indicator bacteria was observed compared to the effluents before treatment. The results of this study highlight that the use of low doses of PAA seems to lead to an improvement of the microbiological quality of the effluent, although it is not sufficient to guarantee its suitability for irrigation. These results underscore the need for additional studies to further assess the efficiency of PAA disinfection in municipal wastewater plants.

Human enteric viruses are a major cause of waterborne diseases, and can be transmitted by contaminated water of all kinds, including drinking and recreational water. The objectives of the present study were to assess the occurrence of enteric viruses (enterovirus, norovirus, adenovirus, hepatitis A and E virus) in raw and treated wastewaters, in rivers receiving wastewater discharges, and in drinking waters. Wastewater treatment plants’ (WWTP) pathogen removal efficiencies by adenovirus quantitative real-time PCR and the presence of infectious enterovirus, by cell culture assays, in treated wastewaters and in surface waters were also evaluated. A total of 90 water samples were collected: raw and treated wastewaters (treated effluents and ultrafiltered water reused for industrial purposes), water from two rivers receiving treated discharges, and drinking water. Nested PCR assays were used for the identification of viral DNA/RNA, followed by direct amplicon sequencing. All raw sewage samples (21/21), 61.9 % of treated wastewater samples (13/21), and 25 % of ultrafiltered water samples (3/12) were contaminated with at least one viral family. Multiple virus families and genera were frequently detected. Mean positive PCRs per sample decreased significantly from raw to treated sewage and to ultrafiltered waters. Moreover, quantitative adenovirus data showed a reduction in excess of 99 % in viral genome copies following wastewater treatment. In surface waters, 78.6 % (22/28) of samples tested positive for one or more viruses by molecular methods, but enterovirus-specific infectivity assays did not reveal infectious particles in these samples. All drinking water samples tested negative for all viruses, demonstrating the effectiveness of treatment in removing viral pathogens from drinking water. Integrated strategies to manage water from all sources are crucial to ensure water quality.

The aim of this study was the evaluation of the occurrence of pathogenic Campylobacter, Escherichia coli O157:H7, E. coli virulence genes and Salmonella spp. in different wastewater treatment plants (WWTPs) using a method based on an enrichment step and PCR. This method was sensitive enough to detect low levels (∼2 CFU100 ml(-1) of raw sewage) of all the investigated pathogens. In the WWTP samples, E. coli O157:H7 DNA and the eae gene were never found, but 33 % of influents and effluents exhibited amplicons corresponding to Shiga-like toxin I. Twenty-five percent of the influent and 8 % of the effluent exhibited the presence of Shiga-like toxin II. Campylobacter jejuni and C. coli DNA were identified in 50 and 25 % of the influents and in 8 and 25 % of the effluents, respectively. Salmonella spp. DNA was present in all the samples. Considering the results obtained, the method tested here offers a reliable and expeditious tool for evaluating the efficiency of the effluent treatment in order to mitigate contamination risk. Influent contamination by Salmonella spp. and Campylobacter spp. provides indirect information about their circulation; moreover, their presence in effluents underlines the role of WWTPs in the contamination of the receiving surface waters, which affects public health directly or indirectly.

The drinking water treatment plant (WTP) of the city of Turin (NW Italy), with a treatment capacity of 40 × 106 m3/year, has a basin that is employed as a lagooning pretreatment facility. This study aims to assess the effect of the basin on several environmental parameters (temperature, dissolved oxygen (DO), turbidity, pH, chloride, nitrite, and total chlorophyll) of the river water before entering the WTP and monitor the changes inside the basin caused by the seasonal hydrological and biological cycles. Sampling was carried out on 16 dates over 3 years at the inlet and outlet channel of the basin and in five locations along three depth values (1, 6, and 12 m, i.e., at the bottom). The results of the 3-year monitoring campaign demonstrated that the basin had an effect on pH (p = 6.6 × 10−9), DO (p = 0.000072), turbidity (p = 0.011), and chlorophyll (p = 0.033). No significant changes regarding nitrite (p = 0.11), chloride (p = 0.94), and temperature (p = 0.66) were detected. The results gathered from the sampling campaign inside the basin demonstrated that, during the year, the basin experienced the following: two states of complete mixing in early spring and fall, when the differences in temperature between the surface and the bottom of the basin were less than 1 °C; a condition of late spring/summer stratification with a temperature difference between the surface and the bottom of 4–5 °C and a difference in DO, pH, and total chlorophyll concentration that increased throughout the spring season; and one or more states of summer circulation due to the weak stability of the warm season stratification. During the states of circulation, the persistent algae photosynthetic activity tended to cause a quick change in the concentration of DO, total chlorophyll, and pH value in the most superficial layer of the basin. The results of the principal component analysis (PCA) showed a strong direct relationship between the weight of the first component and the hydrodynamic states of the basin (stratification/circulation) and an inverse relationship between the weight of the second component and the intensity of photosynthetic activity of algae species.

Potable water is undoubtedly one of the most critical resources for the International Space Station (ISS) crews. The amount and quality of this resource, mainly provided to the ISS by the Space Shuttle and Progress, and in the near future by logistic vehicles Automated Transport Vehicle (ATV) and HTV, must be compatible with the crew consumption needs and health-related requirements. For this purpose, potable water must satisfy very stringent quality requirements from chemical and bacteriological point of view. The definition of such requirements, resulting from medical studies, lessons learned, technical constraints, is reached in agreement among ISS International Partners. Two different quality standards are defined, one for the ISS Russian Segment, the other for the US Segment and other International Partners. The ATV, a program under European Space Agency (ESA) contract and EADS Space Transportation (EST) prime contractor-ship, is the only logistic vehicle requested to transport and deliver potable water to ISS according to both quality standards. Significant efforts have been spent in Alenia Spazio, responsible for the ATV Integrated Cargo Carrier, to define all the activities necessary to accomplish this task. The main aspects under consideration have been: selection of materials in contact with water, identification of suitable potable water sources, water preparation and disinfection, and pre-conditioning of equipment. This paper focuses on preparation and quality of potable water as obtained in dedicated ground facilities. The quality and stability of source water are an essential pre-requisite to attain the required standards. Disinfection techniques using colloidal silver and iodine are discussed, and their implementation in the ATV Water Preparation Facility at Societa Metropolitana Acque Torino (SMAT) premises is presented. The results of chemical and micro-biological analyses performed on potable water batches treated with the defined techniques show that the requirements are fully satisfied.