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In the M'zab valley, dry toilets represent an ancestral dry sanitation system, serving as a source of fertilizer thanks to human excrement valorization. However, in the 20th century, local populations began to shun these systems. The objective of this article is to illustrate the importance of dry toilets on agricultural and environmental scales in ancient M'Zab, and the renewal of these systems in response to sanitation problems in the oasis after their decline. The hypothesis put forward is that dry toilets can act as a complementary system to conventional sanitation systems. Data were collected through interviews with the local population. Our results show that the use of dry toilets, and the resulting use of human excrement as fertilizer, has gone through three phases. First, a phase of strong recycling dynamics, followed by a second phase of decline in dry toilet use which is linked to the discovery of the Albian aquifer and flush toilet adoption. The third phase is characterized by dry toilet reuse in response to oasis degradation caused by sanitation and environmental problems. Some oasesians have taken the initiative to revert to dry toilets to ensure oasis system sustainability and to revive the practice of recycling human waste. HIGHLIGHTS Reintroduction of dry toilets in the oases.; Reuse of human excrements for agricultural purposes.; Reduce the discharge of wastewater.; Protection of oases from degradation.; Alternative system of sanitation.

Human urine concentrates 85% of the nitrogen and 65% of the phosphorus excreted by humans, making it a potential alternative crop fertilizer. However, knowledge gaps remain on the fate of nitrogen in situations favouring NH3 volatilisation and on the availability of P from urine. This study aimed at identifying the fate of nitrogen and phosphorus supplied by human urine from source separation toilets in a calcareous soil. To this end, a spinach crop was fertilized with 2 different doses of human urine (170 kgN.ha-1 + 8.5kgP.ha-1 and 510 kgN.ha-1 + 25.5 kgP.ha-1) and compared with a chemical fertiliser treatment (170 kgN.ha-1 + 8.5kgP.ha-1) and a water treatment. The experiment was conducted in 4 soil tanks (50 cm depth) in greenhouse conditions, according to a randomized block scheme. We monitored soil mineral nitrogen over time and simulated nitrogen volatilisation using Hydrus-1D and Visual Minteq softwares. We also monitored soil phosphorus pools, microbial biomass CNP, soil pH and electrical conductivity. Only an excessive input of urine affected soil pH (decreasing it by 0.2 units) and soil conductivity (increasing it by 183%). The phosphorus supplied was either taken up by the crop or remained in the available P pool. Ammonium seemed to be nitrified within about 10 days after application. However, both Visual Minteq and Hydrus models estimated that more than 50% of the nitrogen supplied was lost by ammonia volatilisation. Overall, our results indicate that direct application of urine to a calcareous soil is possible without harming soil properties, but that heavy losses of volatilised nitrogen are to be expected.

International audience; The reuse of wastewater aims to mobilize and treat, for certain uses and under certain conditions, water that has already been used. Rather than discharging wastewater into the natural environment, this practice aims to recover it by replacing the mobilization of water withdrawn from the environment [van Loosdrecht and Brdjanovic, 2014]. By moving from a linear logic of the mobilization and use of water to a circular approach, the objective pursued is to reduce the pressure, qualitative then quantitative, on the resources while limiting, as far as possible, the usage conflicts. It is in fact a question of passing from a simple competitive mode which strongly mobilizes resources, to a complex mode, known as “circular”, of putting in complementarity of uses. This approach initially mainly concerned agricultural uses insofar as agricultural needs represent the majority of the water mobilized, including developed countries [UN Water 2018]. Cities integrate specific issues that are characterized by significantly different options from those that can be found in rural areas. In the city, the recovery of wastewater has both material aspects (water, nutrients, critical metals, biopolymers, etc.) and energy aspects (recovery of heat from the networks, production of energy by biological means and /or thermal,…) which should be integrated on an appropriate scale according to the problems addressed (housing, building, district, city, territory or hydrological basin). To study the conditions under which REUSE can develop and be implemented in a safe and sustainable manner, research is needed [Ait-Mouheb et al., 2018]. If it represents an opportunity in certain territories where wastewater can be mobilized, it is also necessary to underline the limits of this practice in territories where the wastewater discharged into the environment is necessary to maintain the low water levels of rivers and rivers, or where soils may be affected, for example, by the salinity of these waters. In addition, studies of the social, economic and environmental dimensions differ significantly depending on the uses envisaged and the situations considered. To meet these challenges, the REUSE network of INRAE (cf. www6.inrae.fr) proposes to adopt a multidisciplinary and multi-scale approach by mobilizing not only the disciplines that can be considered as falling within the field of technologies and environmental engineering but also all of those relating to the human and social sciences, economics, legal, and participatory sciences.

International audience; Drip irrigation is one of the most efficient irrigation techniques, but it is susceptible to dripper clogging. This study proposes a novel and non-destructive method based on visible and near infrared (Vis/NIR) spectroscopy coupled with chemometric methods for the discrimination and thickness estimation of physical and chemical fouling in drip-irrigation systems. Four representative materials linked to physical and chemical clogging (kaolin, bentonite, sand and calcium carbonate) at different thicknesses were selected to illustrate the potential of the approach. Partial least squares regression (PLSR) and its modification partial least squares with discriminant analysis (PLS-DA) were selected for the modelling of clogging materials. The PLS-DA model was able to predict with 96.97% accuracy all classes of materials. The PLSR models were able to estimate fouling thickness with relative prediction errors comprised between 134 μm and 164 μm. This difference appears mainly to be due to the physical properties of the selected materials. This prediction accuracy enabled the estimation of the clogging thickness between 10 and 21% of dripper channel coverage depending on the dripper channel section and the material under study. The proposed method offers an appropriate approach for clogging studies in drip irrigation systems that could be transferred to field applications.

International audience; This study presents a decision support tool that evaluates the environmental efficiency of reusing treated wastewater for agricultural irrigation, among other options. The developed tool is published as open source at https://doi.org/10.18167/DVN1/YLP1BA. The objective of this decision support tool is to facilitate the interpretation of the Life Cycle Assessment (LCA) results by progressively reducing the non-discriminatory impacts to solve the difficulty of making a decision with a large number of criteria. This framework was applied to a representative case of reuse of reclaimed water for vine irrigation at the Murviel-Les-Montpellier experimental site (Hérault, France). It was then generalized through modeling assumptions to consider different reuse scenarios. To highlight situations in which the supply of recycled water for irrigation may or may not provide significant environmental benefits, four main parameters were varied: (i) tertiary treatment technologies, (ii) availability of conventional water sources, (iii) energy mix composition. The results show that the environmental impact of treated wastewater reuse depends directly on the type of tertiary treatment technology and the location of the treatment plant in relation to the field and other water sources. The decision support tool has identified where wastewater reuse is clearly an environmentally beneficial source of irrigation among surface and groundwater sources (e.g., WWTP closer to field than river, groundwater too deep, tertiary treatment environmentally beneficial). However, there are many situations where the decision support process cannot distinguish between reuse of treated wastewater for agricultural irrigation and conventional water sources, especially when the nutrient content of treated municipal wastewater is insufficient to offset the negative effects of high energy requirements and chemicals of tertiary treatment.

International audience; Filtration is essential in drip irrigation systems to remove physical contaminants carried by water that can clog the emitters, cause wear, or foul components of the system, affecting its performance and lifespan. Automatic flushing strainer-type filters initiate and terminate discrete flushing cycles that are activated automatically by means of differential pressure. The objective of this study is to investigate the hydraulic performance and flow behaviour of an automatic flushing strainer-type filter operated with clean water, using experimental and numerical approaches, to optimise thedimensions of its filter housing and to increase the range of operating flow rates. Pressure drop curves were determined for the filter housing and the filter system equipped with five models of filter elements (woven and non-woven elements). Excessive pressure drop in the filter housing and low filtration rates were identified as the main drawbacks of the original filter system. Numerical simulations enabled the identification of the most critical regions in terms of pressure losses near the transitions between the inlet and outlet segments of the pipe. Four designs of filter housing were simulated to evaluate the possibilities of optimising the filter housing dimensions using a constant filtering area. Larger inlet and outlet diameters combined to a filter housing shorter and wider were improvements in the filter housing dimensions that enabled to decrease the pressure drop in the filter and/or increase the range of operating flow rates. The results provided useful information for enhancing the hydraulic performance of the filtration system

With more than 160 000 confirmed COVID-19 cases and about 30 000 deceased people at the end of June 2020, France was one of the countries most affected by the coronavirus crisis worldwide. We aim to assess the efficiency of global lockdown policy in limiting spatial contamination through an in-depth reanalysis of spatial statistics in France during the first lockdown and immediate post-lockdown phases.To reach that goal, we use an integrated approach at the crossroads of geography, spatial epidemiology, and public health science. To eliminate any ambiguity relevant to the scope of the study, attention focused at first on data quality assessment. The data used originate from official databases (Santé Publique France) and the analysis is performed at a departmental level. We then developed spatial autocorrelation analysis, thematic mapping, hot spot analysis, and multivariate clustering.We observe the extreme heterogeneity of local situations and demonstrate that clustering and intensity are decorrelated indicators. Thematic mapping allows us to identify five "ghost" clusters, whereas hot spot analysis detects two positive and two negative clusters. Our re-evaluation also highlights that spatial dissemination follows a twofold logic, zonal contiguity and linear development, thus determining a "metastatic" propagation pattern.One of the most problematic issues about COVID-19 management by the authorities is the limited capacity to identify hot spots. Clustering of epidemic events is often biased because of inappropriate data quality assessment and algorithms eliminating statistical-spatial outliers. Enhanced detection techniques allow for a better identification of hot and cold spots, which may lead to more effective political decisions during epidemic outbreaks.

International audience; Clogging of drippers due to the development of biofilms weakens the advantages and impedes the implementation of drip irrigation technology. The objective of this study was to characterise the bacterial community of biofilms that develop in a drip irrigation system supplied with treated wastewater. High-throughput sequencing of 16S rRNA gene amplicons indicated that the bacterial community composition differed between drippers and pipes, mainly due to changes in the abundance of the genus Aquabacterium. Cyanobacteria were found to be involved in the biological fouling of drippers. Moreover, bacterial genera including opportunistic pathogenic bacteria such as Legionella and Pseudomonas were more abundant in dripper and pipe biofilms than in the incoming water. Some genera such as Pseudomonas were mostly recovered from drippers, while others (ie Bacillus, Brevundimonas) mainly occurred in pipes. Variations in the hydraulic conditions and properties of the materials likely explain the shift in bacterial communities observed between pipes and drippers.

Drip irrigation is an efficient and safe system for reusing wastewater in agriculture. Since emitter clogging is its main limitation, filtration is needed for preventing it. Media filters are commonly used when irrigation water has a high particle load. However, particle removal through a media bed in media filters used in drip irrigation systems has not been widely studied mainly due to experimental difficulties. To overcome this issue a new methodology using optical coherence tomography (OCT) is presented here. Experiments were carried out on a media filter at laboratory scale using wastewater. Once the filter was clogged, several 20 mm slices were taken and the retained total suspended solids were analysed by gravimetry. Following this, particles retained at six different locations of each slice were also determined using OCT. Results show a good agreement between total suspended solids experimentally determined and particles determined with OCT, especially when pixels attributed to particles were 30–45% of the total. Therefore, OCT could be a useful technique for assessing particle retention at different media depths The authors would like to express their gratitude to Spanish Research Agency and the European Regional Development Fund for their financial support through Grant RTI2018-094798-B-100. They also want to thank the University of Girona for funding the research stages of Miquel Duran-Ros and Carles Solé-Torres at INRAE Montpellier (France). The authors also gratefully acknowledge the financial support of the French Water Agency Rhône Méditerranée Corse, project “Experimental platform for the reuse of reclaimed wastewater in irrigation, Murviel-lès-Montpellier” Open Access funding provided thanks to the CRUE-CSIC agreement with Elsevier

International audience; Milli-channel baffle labyrinths are widely used in drip irrigation systems. They induce a pressure drop enabling drip irrigation. However, with a section thickness that is measured in mm2, they are sensitive to clogging, which reduces the performance and service life of a drip irrigation system. The impact of chlorination (1.5 ppm of free chlorine during 1 h application) and pressure flushing (0.18 MPa) on the biofouling of non-pressure-compensating drippers, fed by real reclaimed wastewater, was studied at lab scale using optical coherence tomography. The effect of these treatments on microbial composition (bacteria and eukaryotes) was also investigated by High-throughput DNA sequencing. Biofouling was mainly observed in the inlet, outlet and return areas of the milli-labyrinth channel from drippers. Chlorination reduced biofilm development, particularly in the mainstream of the milli-labyrinth channel, and it was more efficient when combined with pressure flushing. Moreover, chlorination was more efficient in maintaining water distribution uniformity (CU < 95% compared to less than 85% for unchlorinated lines). It reduced more efficiently the bacterial concentration (≈1 log) and the diversity of the bacterial community in the dripper biofilms compared to the pressure flushing method. Chlorination significantly modified the microbial communities, promoting chlorine-resistant bacteria such as Comamonadaceae or Azospira. Inversely, several bacterial groups were identified as sensitive to chlorination such as Chloroflexi and Planctomycetes. Nevertheless, one month after stopping the treatments bacterial diversity recovered and the chlorine-sensitive bacteria such as Chloroflexi phylum and the Saprospiraceae, Spirochaetaceae, Christensenellaceae and Hydrogenophilaceae families re-emerged in conjunction with the growth of biofouling, highlighting the resilience of the bacteria originating from drippers. Based on PCoA analyses, the structure of the bacterial communities still clustered separately from non-chlorinated drippers, showing that the effect of chlorination was still detectable one month after stopping the treatment.

International audience; The Food-Energy-Water (FEW) nexus for urban sustainability needs to be analyzed via an integrative rather than a sectoral or silo approach, reflecting the ongoing transition from separate infrastructure systems to an integrated social-ecological-infrastructure system. As technology hubs can provide food, energy, water resources via decentralized and/or centralized facilities, there is an acute need to optimize FEW infrastructures by considering cost-benefit-risk tradeoffs with respect to multiple sustainability indicators. This paper identifies, categorizes, and analyzes global trends with respect to contemporary FEW technology metrics that highlights the possible optimal integration of a broad spectrum of technology hubs for possible cost-benefit-risk tradeoffs. The challenges related to multiscale and multiagent modeling processes for the simulation of urban FEW systems were discussed with respect to the aspects of scaling-up, optimization process, and risk assessment. Our review reveals that this field is growing at a rapid pace and the previous selection of analytical methodologies, nexus criteria, and sustainability indicators largely depended on individual FEW nexus conditions disparately, and full-scale cost-benefit-risk tradeoffs were very rare. Therefore, the potential full-scale technology integration in three ongoing cases of urban FEW systems in Miami (the United States), Marseille (France), and Amsterdam (the Netherlands) were demonstrated in due purpose finally.

International audience; The evolution of the COVID-19 pandemic can be monitored through the detection of SARS-CoV-2 RNA in sewage. Here, we measured the amount of SARS-CoV-2 RNA at the inflow point of the main waste water treatment plant (WWTP) of Montpellier, France. We collected samples 4 days before the end of lockdown and up to 70 days post-lockdown. We detected increased amounts of SARS-CoV-2 RNA at the WWTP from mid-June on, whereas the number of new COVID-19 cases in the area started increasing a couple of weeks later. Future epidemiologic investigations shall explain such asynchronous finding.

As drip irrigation develops rapidly worldwide, the need for a standardized method to evaluate emitters’ clogging sensitivity is reinforced. Methodologies for evaluating the sensitivity of e...

In the reclaimed wastewater reuse using drip irrigation, one of the main issues is the bio-clogging of drippers and decrease of water distribution efficiency in field level. However, the relation between the complex flow created along the dripper (in general formed by a milli-channel with labyrinth geometry) and the biofouling development are rarely studied. In order to improve the knowledge of these mechanisms, the objective was to combine the numerical flow simulations to three-dimensional measurements of biofilm along a milli-fluidic system (nominal flow rate 1L/h) fed by treated wastewater. At first, using the Optical Coherence Tomography (OCT) method and based to Qian et al, 2018 studies, the bio-clogging structure was measured at different levels of fouling (up to 77% of channel volume). Secondly, the new fouled dripper geometries were integrated to 3D CFD models (using comsol multiphysics software) to analyse the effect of biofilm on flow topology and the dripper hydraulic parameters (pressure drop, shear stress, turbulence kinetic energy in particular). The results show that the main areas of biofilm growth correspond to vortices zones where fluid velocity, turbulent kinetic energy values and shear stress are lowest. When the level of clogging increases, the numerical plot of stream lines show local perturbation and reduction of vortices areas caused by their interactions with the biofilm structure. There is also a gradual increase in pressure drop along the milli-channel comparing to initial clean dripper. Finally, by characterising the flowrate in function of inlet pressure and according to Karmeli, 1977, the increase of biofilm formation induces also a modification of the global flow regime in the dripper, i.e. the transfer from a turbulent to a laminar regime. Qian, J., Horn, H., Tarchitzky, J., Chen, Y., Katz, S., Wagner, M., (2017). Water quality and daily temperature cycle affect biofilm formation in drip irrigation devices revealed by optical coherence tomography. Biofouling 33, 211–221. Karmeli, D. (1977). Classification and flow regime analysis of drippers. J Agric Eng Res 22:165–173

Effective quantitative and qualitative management of water for irrigation is crucial in many regions and the use of reclaimed water is a possible solution. Quantifying the impact of the use of such water is thus important. Using life cycle assessment methodology, this study analyzes the impact of water reuse irrigation and farmers’ practices in greenhouse cucumber production. Three scenarios concerned sources of water for irrigation and agricultural practices: the first scenario used surface water including reclaimed water, the second used groundwater. The third scenario resembled the first but also accounted for fertilizer application based on theoretical cucumber requirements. The third scenario showed 35% less fertilizer is required than the quantities farmers actually use. Our results show that the higher environmental impact of irrigation using reclaimed water than using groundwater is mainly due to over-fertilization. Comparison of the first and third scenarios also showed that the reduction in the environmental impact under the third scenario was significant. We conclude that LCA is a useful tool to compare the impacts of different water sources and farmers’ irrigation/fertilization management practices, and in particular, that the quantity of nutrients in reclaimed water should be deducted from the actual amount applied by the farmers. HIGHLIGHTS Evaluate the environmental impact of indirect case of reclaimed water reuse versus groundwater for agricultural irrigation using life cycle assessment (LCA).; Our field study was conducted in the Mediterranean region of Tipaza, Algeria focusing on data from farmers' work schedule.; We compared the performance of irrigation using reclaimed water and groundwater to identify which sub-system had the most impact.; Discuss farmers' fertilization practices in the area compared with theoretical recommendations.; Our study could be used as basic data to farmers to respect the doses of fertilizer application with different sources of water irrigation.

Emitters are important components of drip irrigation systems, and the use of labyrinths as a mechanism of energy dissipation stands out in the drippers' design. Relating the geometric characteristics of labyrinths with their operational and hydraulic characteristics is not trivial and generally requires the use of computational simulation tools. This study developed and evaluated models that can predict the discharge of labyrinth channels as a function of their geometry to make possible the rapid prediction of pressure-discharge curves due to modifications in the labyrinth geometry. An empirical mathematical model was developed based on nonlinear regression, and a computational model was trained based on artificial neural networks (ANNs). Twenty-four designs of prototypes were built in polymethyl methacrylate to operate at a discharge of approximately 1.4 L h −1 under 100 kPa. The pressure-discharge curve of each prototype was determined in the laboratory in the range 50-350 kPa. Based on the experimental data, the coefficients of an empirical nonlinear model were fitted, and 11 single-hidden-layer ANN architectures were compared. The best accuracy was provided by an ANN architecture with an input layer with six neurons, six neurons in the hidden layer, and an output layer with a single neuron. The maximum relative errors of the predicted discharges were 9.5% and 9.4% for the ANN and nonlinear models, respectively. Both models were accurate and enabled rapid prediction of the emitter's discharge. An open-source web application was developed to simulate the pressure-discharge curve of labyrinths within a range of geometric and operational characteristics.

Dripper clogging reduces the performance and service life of a drip irrigation system. The impact of chlorination (1.5 ppm of free chlorine during 1 h application) and pressure flushing (0.18 MPa) on the biofouling of non-pressure-compensating drippers fed by real reclaimed wastewater was studied at lab scale using Optical Coherence Tomography. The effect of these treatments on microbial composition (bacteria and eukaryotes) was also investigated by High-throughput DNA sequencing. Biofouling was mainly observed in inlet, outlet and return areas of the drippers. Chlorination limited biofilm development mainly in the mainstream of the milli-labyrinth channel. It was more efficient when combined with pressure flushing. Moreover, chlorination was more efficient in maintaining the water distribution uniformity. It reduced the bacterial concentration and the diversity of the dripper biofilms compared to the pressure flushing method. This method strongly modified the microbial communities, promoting chlorine-resistant bacteria such asComamonadaceaeorAzospira. Inversely, several bacterial groups were identified as sensitive to chlorination such as Chloroflexi and Planctomycetes. Nevertheless, one month after stopping the treatments the bacterial diversity re-increased and the chlorine-sensitive bacteria such as Chloroflexi phylum and the Saprospiraceae, Spirochaetaceae, Christensenellaceae and Hydrogenophilaceae families re-emerged with the growth of biofouling, highlighting the resilience of the bacteria from drippers. Based on PCoA analyses, the structure of the communities still clustered separately from never-chlorinated drippers, showing that the effect of chlorination was still present one month after stopping the treatment.HighlightsThe fouling of drippers is a bottleneck for drip irrigation using reclaimed wastewaterBiofouling was lowest when chlorination was combined with pressure flushingThe β-Proteobacteria and Firmicutes contain chlorine resistant bacteriaThe decrease of Chloroflexi by chlorination was transitoryThe bacterial community was resilient after the interruption of cleaning events

The clogging of drippers due to the development of biofilms reduces the benefits and is an obstacle to the implementation of drip irrigation technology. The geometry of the dripper channel has an impact on the flow behaviours and head loss. The objective of this study was to analyse the influence of hydrodynamic parameters of three types of drippers (flow rates of 1, 2 and 4 l.h-1) fed by reclaimed wastewater on biofilm development kinetics and on the bacterial community. Using optical coherence tomography, we demonstrated that the inlet of the drippers (mainly the first baffle) and vortex zones are the most sensitive area for biofouling. Drippers with the lowest flow rate (1 l.h-1) and the smallest channel section were the favourable areas to biofouling. The low inlet velocity (0.34 m.s-1) in this type of dripper compared to 2 l.h-1 (0.61 m.s-1) and 4 l.h-1 (0.78 m.s-1) drippers can favour the deposition and development of biofilms. In addition, the water velocity influenced the structure of the bacterial communities in the biofilm. Low velocity (0.34 m.s-1) favoured the presence of Hydrogenophaga and Pseudoxanthomonas genera at the early stage of biofilm formation and filamentous bacteria belonging to Chloroflexi phylum at the end. So, maintaining a high flow rate and using drippers with a large flow cross-section is an effective way to control the development of biofilms by limiting the presence of filamentous bacteria.

Climate change, irrigation development, and a growing population across the Mediterranean region are increasing the pressure on water resources in terms of both quantity and quality. High-quality water should be primarily reserved to drinking water while water reuse is, and should be, a growing part of the water mix for other uses. This chapter provides an overview of the current water reuse situation in agriculture across the region, including planned projects and unplanned practices. It highlights the diversity of policy contexts (legal frameworks, national strategies, and governance arrangements) by reviewing the specific experiences of Jordan, France, Morocco, and Algeria. It also highlights the diversity of irrigation practices on the ground, and discusses health-related issues and agronomical performances. It concludes by stressing the potential for planned water reuse, both direct and indirect, while reminding that water reuse should not be primarily perceived as a new resource by policy-makers, but rather as a means to raise water productivity. Finally, an integrated approach is recommended, capable of including environmental, economic, and equity considerations.

The clogging of drippers due to the development of biofilms reduces the benefits and is an obstacle to the implementation of drip irrigation technology in a reclaimed water context. The narrow section and labyrinth geometry of the dripper channel results the development of a heterogeneous flow behaviours with the vortex zones which it enhance the fouling mechanisms. The objective of this study was to analyse the influence of the three dripper types, defined by their geometric and hydraulic parameters, fed with reclaimed wastewater, on the biofouling kinetics and the bacterial communities. Using optical coherence tomography, we demonstrated that the inlet of the drippers (mainly the first baffle) and vortex zones are the most sensitive area for biofouling. Drippers with the lowest Reynolds number and average cross-section velocity v (1 l·h−1) were the most sensible to biofouling, even if detachment events seemed more frequent in this dripper type. Therefore, dripper flow path with larger v should be consider to improve the anti-clogging performance. In addition, the dripper type and the geometry of the flow path influenced the structure of the bacterial communities from dripper biofilms. Relative abundancy of filamentous bacteria belonging to Chloroflexi phylum was higher in 1 l·h−1 drippers, which presented a higher level of biofouling. However, further research on the role of this phylum in dripper biofouling is required.

Clay particles under certain physico-chemical and hydrodynamic conditions can form agglomerates after passing through a filtering system, which favours clogging of the emitters. The main factors interfering with the aggregation potential of clay particles are the type of clay mineral, pH, and ionic strength of the irrigation water. This study analysed the influence of ionic strength and type of clay mineral on clogging, discharge variation, and particle deposition in turbulent-flow non-pressure compensating drippers. Two types of clay (kaolinite and montmorillonite) at a concentration of 500 mg L−1 and four values of ionic strength (0.31, 0.81, 0.02, and 0.01 mol L−1) promoted by the addition of different salts to the solution were used. Clogging tests were conducted with two commercial models of drippers (0.6 and 1.7 L h−1). The deposition zones along the labyrinth channel were analysed using a transparent milli-fluidic system coupled to an optical microscope. Deposition of particles inside dripper labyrinths was observed and this process was strongly influenced by the nature of the clay. The regions of highest particle deposition were vortices zones located in the first baffles of the labyrinths. Kaolinite particles had greater potential of accumulation in the labyrinths than montmorillonite particles. There were fluctuations in the drippers’ discharge during the clogging experiments, but the discharge variations observed were not sufficient to classify the emitters as clogged in any of the test conditions. Clay, as an isolated agent, did not cause full clogging in the emitters evaluated under any of the ionic strength conditions studied. Since particles did not accumulate in the region of the main flow, we suggest that clay particles alone have no potential to cause full clogging of drippers, but may contribute to clogging build-up.

The Food-Energy-Water (FEW) nexus for urban sustainability needs to be analyzed via an integrative rather than a sectoral or silo approach, reflecting the ongoing transition from separate infrastructure systems to an integrated social-ecological-infrastructure system. As technology hubs can provide food, energy, water resources via decentralized and/or centralized facilities, there is an acute need to optimize FEW infrastructures by considering cost-benefit-risk tradeoffs with respect to multiple sustainability indicators. This paper identifies, categorizes, and analyzes global trends with respect to contemporary FEW technology metrics that highlights the possible optimal integration of a broad spectrum of technology hubs for possible cost-benefit-risk tradeoffs. The challenges related to multiscale and multiagent modeling processes for the simulation of urban FEW systems were discussed with respect to the aspects of scaling-up, optimization process, and risk assessment. Our review reveals that this field is growing at a rapid pace and the previous selection of analytical methodologies, nexus criteria, and sustainability indicators largely depended on individual FEW nexus conditions disparately, and full-scale cost-benefit-risk tradeoffs were very rare. Therefore, the potential full-scale technology integration in three ongoing cases of urban FEW systems in Miami (the United States), Marseille (France), and Amsterdam (the Netherlands) were demonstrated in due purpose finally.

[Departement_IRSTEA]Eaux [TR1_IRSTEA]GEUSI [ADD1_IRSTEA]Gestion intégrée de la ressource et des infrastructures; International audience; The labyrinth-channel is largely used in dripper systems. The baffles play an important role to generate the head losses and induce the flow regulation on the drip irrigation network. But they also develop vorticity regions where the velocity is low or zero. These vorticity regions promote the deposition of particles or other biochemical development causing dripper clogging. The flow in the dripper labyrinth-channel must be described to analyze dripper clogging sensibility which drastically reduces its performance. This characterization is performed experimentally using the micro-particle-image-velocimetry (Micro-PIV) method, and numerically using the RSM Simulation. In this study, Micro-PIV experiments allow to analyze the flow in ten-pattern repeating baffles which reproduce the micro-irrigation dripper. The cross section is equal to 1 mm 2 and the inlet Reynolds number varies from 345 to 690. The present study first introduces a global analysis of the flow through the mean velocity modulus, the Reynolds stresses u , 2 v 2 and u v and the turbulence Reynolds number. Then, results for the mean strain rate and the mean spanwise vorticity are presented and discussed. Next, advanced methods of vortex detection are introduced and analyzed to better distinguish the vortex zones and to determine the vortex sizes. Furthermore, the numerical model is used to validate and analyze in a more detailed way the experimental results obtained by Micro-PIV.

[Departement_IRSTEA]Eaux [TR1_IRSTEA]GEUSI [ADD1_IRSTEA]Gestion intégrée de la ressource et des infrastructures; International audience; Treated wastewater in micro-irrigation is a promising approach that could be used to decrease the pressure on good quality water resources. However, the clogging of such systems due to biofilm development and chemical precipitation constitute a constraint with the use of treated wastewater (TWW) and lead to lower irrigation system performance. The objective of this work is to study the development of biofilm and composition of fouling due to TWW under shear stresses of 0.7, 2.2 and 4.4 Pa detected along micro-irrigation systems. For this purpose, a Taylor-Couette reactor (TCR) was specifically calibrated for the cultivation of biofilm. The analysis of fouling composition samples (organic and inorganic) shows that biofilm tends to develop under the highest shear stress value (4.4 Pa). Precipitation of calcium carbonate in the form of calcite was observed in conjunction with biofilm growth using X-ray diffractometry (XRD) and thermogravimetric analysis (TGA). These results can be used to ascertain the origins of chemical and biological clogging of drippers and fouling of pipes related to reclaimed water- irrigation.

potential accumulation in soil and leaves and to assess human health related risks. Lettuce and leek crops were selected as a worse-case scenario since leafy green vegetable has a high potential for organic contaminants uptake. The results revealed limited accumulation of contaminants in soil and plant leaves, their concentration levels being in the range of 1–30 ng/g and 1–660 ng/g range in soil and leaves, respectively. This was likely related to abiotic and biotic transformation or simply binding processes in soil, which limited contaminants plant uptake. This assumption was underpinned by studies of the enantiomeric fractionation of chiral compounds (e.g. climbazole and metoprolol) in soil as pieces of evidence of biodegradation and by the identification of transformation products or metabolites in leaves by means of liquid chromatography - high resolution - mass spectrometry using a suspect screening workflow. The high bioconcentration factors were not limited to compounds with intermediate Dow (100 to 1000) such as carbamazepine but also observed for hydrophilic compounds such as clarithromycin, hydrochlorothiazide and the food additives acesulfame and sucralose. This result assumed that accumulation was not only driven by passive processes (e.g. lipoidal diffusion through lipid bilayer cell membranes or Casparian strip) but might be supported by carrier-mediated transporters. As a whole, this study confirmed earlier reports on the a de minimis human health risk related to the consumption of raw leafy green vegetable irrigated with domestic TWW containing organic contaminants residues., This research was financially supported by the Water and Agriculture, Food Security and Climate Change Joint Programming Initiatives (JPIs) through the research project AWARE “Assessing the fate of pesticides and waterborne contaminants in agricultural crops and their environmental risks”, the French Rhône-Méditerranée-Corse Water Agency for the experimental platform for the reuse of reclaimed wastewater in irrigation (Murviel-lès-Montpellier) project and the Spanish Ministry of Science and Innovation PCIN-2017-067. This work was also supported by the Spanish Ministry of Science and Innovation (Project CEX2018-000794-S). The authors also acknowledge SCIEX for providing the loan instrument LC/HRMS QToF X500R and Bekolut GmbH & Co. KG for the contribution with QuEChERS kits extraction. The EU is not liable for any use that may be made of the information contained therein.

To better understand the physical and biological clogging in drip-irrigation, a study was conducted on the impacts of hydrodynamic conditions on clay particle deposition and biofilm development in drippers using an optical method. A transparent milli-fluidic system composed of labyrinth channels was used to identify areas most susceptible to particle clogging using two different types of clay suspensions: sodium bentonite and kaolin. The impact of salt addition [(NaCl) = 200 mg L− 1] on the clay deposition was also analyzed. Biofilm development was studied using the same methodology using a nutritive solution (chemical oxygen demand, COD = 200 mg L−1). In addition, fluid dynamics simulations were performed along the labyrinth channel to understand the effect of flow behaviour on the fouling. Computational fluid dynamics results show two types of flow topology: high velocity in the main flow (around 1 m s− 1) and low velocity in the vortex zones (less than 0.2 m s− 1) found in the channel corners. Using an optical method, kaolin deposition and biofilm growth in the dripper were observed to occur mainly in the inlet channel and initial vortex zones, which are characterized by lower mean velocity and turbulent kinetic energy values. This part of the dripper can be considered as a bottleneck that amplifies the fouling phenomena and which should be optimized. With the addition of NaCl, kaolin particles tend to form bigger flocs. Therefore, more significant particle deposition is observed, but this is not the case of bentonite for which no fouling is observed along the dripper.

The baffle-fitted labyrinth-channel is largely used in drip irrigation systems. The existing baffles, which play an important role for generating head losses and ensure the flow regulation on the irrigation network, produce vorticity regions where the velocity is low or equal to zero. These vortices are likely to favor the deposition of particles or biochemical development causing dripper clogging which drastically reduces its performance. Flow topology in the dripper labyrinth-channel must be described to analyze dripper clogging sensibility and the effect on irrigation efficiency. Also, a question remains about the regime of this low Reynolds number flow. In the present study, the flow is characterized experimentally by micro-particle image velocimetry (micro-PIV) technique on ten-pattern repeating baffles used in drip irrigation dripper. Square cross-section is of about 1.4 mm $$^2$$ . Studied inlet Reynolds number varies from 345 to 690, which is equivalent to 1.4–2.8 l h $$^{-1}$$ . The mean velocity distribution and turbulence quantities within the labyrinth-channel flow are presented and discussed in this paper. The results underline that flow regime is turbulent and non-isotropic.

Données complémentaireshttps://static-content.springer.com/esm/art%3A10.1007%2Fs10113-018-1292-z/MediaObjects/10113_2018_1292_MOESM1_ESM.docx; International audience; Climate change and a growing population around the Mediterranean Rim are increasing the need for water and, consequently, the pressure on resources in terms of both quantity and quality. High-quality water should be primarily reserved to drinking water while reclaimed water is an alternative for other usages. A review of situations in Tunisia, Jordan, France, and Italy involving the use of reclaimed water highlights the disparity in national regulations governing this alternative water resource and in its management. On the first hand, the use of recycled water for irrigation can have an adverse impact on public health and the environment, depending on treatment and irrigation practices. On the other hand, it may also represent a new source of water: wastewater should no longer be considered as waste but, rather, as a new resource to be handled in a circular economy-type loop. Current scientific knowledge in agronomic and environmental sciences, as well as in the economic and social sciences, can be integrated and used to lower the associated risk through the effective management of irrigation using recycled water and to address the following questions: (i) How can the time-varying nutrient needs of crops be managed to operate safe environmental reuse within an adapted risk assessment framework? (ii) What socio-economic models can render this integrated approach sustainable? (iii) What treatment systems and irrigation technology can be used to support these ideas and with what information? (iv) What changes in the regulations are needed?

National audience; The microtube are emitters of small diameter and there has recently been developed a new type of microtube called of microtube with multiple outputs (MMO) and consists of a pressure regulator microtube attached to a connector with radial arrangement from where are derived six emitters microtubes. The microtubes are highly susceptible to clogging because of its small diameter. The aim of this study was to evaluate the sensitivity of the microtubes to obstruction by physical agents. We used the methodology proposed by Institut National de Recherche en Sciences et Technologies pour l'Environnement et l'Agriculture (IRSTEA) to evaluate the sensitivity of the microtubes to obstruction. In addition, we used the computational program ANSYS Fluent for better visualization of areas more conducive to obstruction of the MMO. Microtubes were assayed with a diameter of 1.074 mm and microtubes with multiple outlets operating with inlet pressure of 5 m. The MMO is less sensitive to clogging than the individual microtubes with internal diameters of 1.074 mm. The use of ANSYS Fluent program identified critical areas in the connector that can contribute to the obstruction of the emitter.

[Departement_IRSTEA]Eaux [TR1_IRSTEA]GEUSI [ADD1_IRSTEA]Gestion intégrée de la ressource et des infrastructures [ADD2_IRSTEA]Équiper l'agriculture; International audience; Emitter clogging is a major problem in microirrigation systems, which may result from the isolated or combined effects of physical, chemical, and biological agents. Clogging caused by suspended solid particles is the most common plugging form of emitters. Water quality and emitter geometry are key aspects in clogging processes. Any suitable test procedure to assess the sensitivity of drippers to clogging should take into account the predominant factors that influence clogging and must reproduce the field conditions. This research set out to assess the performance and suitability of a laboratory clogging test procedure in order to validate a methodology and to provide scientific results that may support the standardization of a clogging test method. The evaluated methodology has been used by the IRSTEA laboratory since 1974 (Platform of Research and experiment on Science and Technology for Irrigation - PReSTI, formerly LERMI) and its contents are currently being discussed by the ISO TC23/SC18 committee. The aim is to define a standardized testing protocol to evaluate the sensitivity of emitters to clogging due to solid particles. Replications analyzing the clogging resistance of four models of emitting pipes were carried out in a laboratory. The clogging test procedure enabled an accurate assessment of the combinations of concentration and size of particles that caused clogging in each model of dripper. However, a significant variability in degree of clogging was identified when the results of replications for each model of dripper were compared. Several requirements, concerns, and improvements related to the clogging test protocol were discussed.

[Departement_IRSTEA]Eaux [TR1_IRSTEA]GEUSI [Departement_IRSTEA]Eaux [TR1_IRSTEA]GEUSI; International audience; Micro-irrigation with treated wastewater has the potential to be the most efficient irrigation technique, especially in water scarce areas. Its main disadvantage is the high sensitivity of the drippers to clog. This study focused only on the chemical precipitation mechanisms. In a batch chemical process in parallel with PHREEQC software, two temperatures (22 and 55°C), four pH (8, 8.5, 9 and 9.5) and CO2 partial pressure were tested. The aim was to analyze the quantity of precipitates and their crystalline nature and calculate the effects of these factors on the behavior of dissolved chemical elements in treated wastewater to be able to validate and calibrate a geochemical software in order to predict chemical precipitation. The amount of precipitate increases by increasing pH and temperature. Precipitates were analyzed using thermo gravimetric analysis (TGA) and X-ray diffraction (XRD). Calcium carbonate (CaCO3) in the form of calcite was found to be the predominant precipitate. Experimental and model results showed that the saturation index (SI) of calcite was found to be the factor that most frequently affected calcite precipitation. Calcite SI is pH, temperature and CO2 partial pressure dependent. In the case of irrigation, water equilibrium with atmospheric CO2 minimizes precipitation of calcite.

International audience; The understanding of physical phenomena such as flow behavior is essential in order to develop appropriate micromixers for industrial or biomedical applications. In this paper, the relevance of an electro-chemical method is demonstrated for a microfluidic diagnostic in the case of high fluctuating flow, over a wide range of Reynolds numbers (300 < Re < 800) corresponding to the engulfment flow regime. An experimental analysis of the signal measured at microprobes embedded to the wall of microsystems is discussed. The power spectral density (PSD) of the wall shear rate is then obtained by discrete Fourier transform of the signal. Information about the interaction flow structures/walls can be obtained by analyzing the PSD of the wall shear rate. The electrochemical technique is applied to flow within a cross-shaped micromixer with channels having square cross-sections of 400 lm in side. The inlet and outlet channels are symmetric. The PSD of wall shear rate fluctuations reveals various flow characteristics depending on the inlet flow rate and the probe positions along the microchannel. A comparison with results previously obtained with this kind of micromixers allows concluding about the length of flow establishment in such systems.

Mass transfer within the T-shaped and cross-shaped micromixers has been studied using CFD and confocal laser scanning microscopy methods. The concentration profiles, based on flow regimes, were used to compare the T- and cross-geometries. The cross-shaped micromixer tends to intensify the mixing and this is occurring for lower flow rates in comparison to the T shape. The improvement made by the cross geometry is attributed to the stronger vortex stretching and high shear rate, which reduces the liquid transfer length. The presence of a single outlet in the T-shaped micromixer induces a smaller degree of freedom for the fluid. A higher pressure drop is calculated in T-shaped micromixer than in cross-shaped micromixer.

The understanding of physical phenomena such as flow behaviour and mass transfer performance is needed in order to develop appropriate micromixers for industrial or biomedical applications. In this article, the flow behaviour of the T-shaped and the cross-shaped micromixers with square cross-section are studied through numerical and experimental investigations. The comparisons are based on identical treated fluxes. From the particle image velocimetry (PIV) measurements, the flow topologies in the T-shaped and cross-shaped micromixers are very different. After liquid impact, it is observed that the vortex structures cover a longer part of the outlet channel in the case of the cross geometry. This result indicates that the cross-shaped micromixer could improve the mixing process in comparison with the micromixers having T geometry. A second experimental technique has been used, the electrochemical one, involving microelectrodes placed at several wall positions of the cross-shaped micromixer. The electrochemical method can locally characterize the formation of swirling flows. The high values of wall shear rate, in the impact zone, confirm the near wall disturbance created by the impingement of the flow and also the appearance of vortices that could enhance fluid mixing.

The understanding of physical phenomena such as flow behaviour and mass transfer performance is needed in order to develop appropriate micromixers for industrial or biomedical applications. In this work, CFD is used to characterize the flow and the liquid mixing quality in a micromixer as a function of the Reynolds number. Two micromixers are studied in steady flow conditions; they are based on two geometries, respectively T-shaped (⊤) and cross-type (+). Simulations allow, in the case of ⊤ micromixers, to chart the topology of the flow and to describe the evolution of species concentration downstream the crossing. The streamlines layout and the mixing quality curves reveal three characteristic types of flow previously reported in the literature, depending on Reynolds number: stratified, vortex and engulfment flows. In the case of cross-type micromixers, the structure of the flow is strongly three-dimensional and is characterized by symmetrical vortices in both output channels. The results show that the + shaped system can improve the mixing process in comparison with the micromixers having ⊤ geometry. The second part of the study is experimental. Two cells are constructed, for both geometries (T-shaped and cross) using square channels with 400 μm hydraulic diameter. In order to use particle image velocimetry (PIV), a system has been adapted to measure velocity fields for various channel plans at different channel depths. This allows observing the evolution of the flow and the vortices development along the microchannels. A second experimental technique, the electrochemical one involving microelectrodes implemented at several positions on the channel wall located near the crossing, has been used. The electrochemical method can locally characterize the formation of swirling flows. These two complementary experimental results will be analysed and a comparison with the CFD results will be performed.Copyright © 2009 by ASME

Computational fluid dynamic simulations are used to characterize the flow and the liquid mixing quality in a micromixer as a function of the Reynolds number. Two micromixers are studied in steady flow conditions; they are based on two geometries, respectively T-shaped and cross-type (⊤ and + shapes). Simulations allow, in the case of ⊤ micromixers, to chart the topology of the flow and to describe the evolution of species concentration downstream the intersection. The streamline layout and the mixing quality curves reveal the three characteristic types of flow, depending on Reynolds number: stratified, vortex and engulfment flows. Vortices appear after impingement, in the exit channel. They become asymmetrical and gain in length with an increase in Re making the flow unsteady, which induces an enhancement of the mass transfer by advection between the two liquids. In the case of cross-type micromixers, the structure of the flow is strongly three-dimensional. It is characterized by symmetrical vortices in both output channels. In the zone close to the impingement, a back flow is observed which induces strong shear stresses. The results show that the + shaped system can improve the mixing process in comparison with the micromixers having ⊤ geometry. The numerical study also allows to select the locations of the most relevant zones of study, from an experimental point of view. It will allow to choose the location of PIV planes and local non intrusive sensors, such as electrochemical microprobes, in order to experimentally investigate the flow.

In the Mediterranean basin, intense and more frequent droughts are expected, as well as a rise in temperatures (+2.2 to 3.5°C by 2040) accompanied by changes in the rainfall regime. The association of the reuse of treated wastewater with drip irrigation systems therefore appears relevant to cope with the scarcity of the resource and help maintain activity. The biological clogging of drip irrigation systems is one of the limits of the use of treated wastewater. The objective was to study the influence of wastewater type and hydrodynamics on the formation of biofilms in complex millifluidic systems, and to test two types of treatment, chlorination and flushing. Colonization kinetics were monitored by optical coherence tomography. The characterization of microbial communities of biofilms growing in irrigation systems and in effluents was performed by high-throughput sequencing using genes coding for 16S rRNA and 18S rRNA as taxonomic markers. Finally, the effect of these parameters (water type, hydrodynamics, treatment) on the microbiological contaminants carried by the treated wastewater was studied.The flow varies along a drip irrigation system (pipe, dripper) but also between the different types of drippers tested. The inlet, return and recirculation areas were the most sensitive to clogging. This is explained by the fact that the turbulence velocities and energy are lower in these areas, favouring the development of biofilms. Drippers with a small hydraulic diameter were the most sensitive to clogging. The differences in flow induce specificities in the structure of the microbial communities of the biofilms that were described for the first time. The influence of lagoon treatment on the communities responsible for clogging was also demonstrated by comparing untreated versus treated wastewater. In particular, the results illustrate the key role of Chloroflexi, and especially filamentous bacteria in the clogging of drippers.Ways commonly used in agriculture to limit clogging were evaluated. Chlorination combined with flushing statistically reduces the level of blockage of drippers, particularly in the main flow of the maze, where the velocity is the highest. Conversely, the use of purging alone does not reduce the level of dripper clogging. Chlorination reduces, but does not completely eliminate biofilms, and bacteria resistant to chlorination have been identified, such as members of the Comamonadaceae or Pseudomonas family. Finally, the opportunistic pathogenic species Pseudomonas aeruginosa and Aeromonas hydrophila and Legionella pneumophila are present in the dripper biofilms, preferentially colonizing the network biofilms compared to the indicators of faecal contamination (Enterococcus spp., E. coli).; Sur le bassin méditerranéen, des sécheresses intenses et plus fréquentes sont attendues, ainsi qu’une hausse des températures (+2,2 à 3,5°C d’ici 2040) accompagnée de la modification du régime des précipitations. L’association de la réutilisation des eaux usées traitées au système d’irrigation goutte à goutte apparaît donc pertinente pour faire face à la raréfaction de la ressource et aider au maintien de l’activité. Le colmatage biologique des systèmes d’irrigation goutte à goutte est une des limites de l’utilisation des eaux usées traitées. L’objectif était d’étudier l’influence du type d’eau usée et de l’hydrodynamique sur la formation des biofilms dans des systèmes complexes millifluidiques, ainsi que de tester deux types de traitement, la chloration et la purge. Les cinétiques de colonisation ont été suivies par tomographie en cohérence optique. La caractérisation des communautés microbiennes des biofilms se développant dans les réseaux d’irrigation et dans les effluents a été réalisée par séquençage haut débit en utilisant les gènes codant pour l’ARNr 16S et l’ARNr 18S comme marqueurs taxonomiques. Enfin, l’effet de ces paramètres (type d’eau, hydrodynamique, traitement) sur les contaminants microbiologiques véhiculés par l’eau usée traitée a été étudié.L’écoulement varie le long d’un système d’irrigation goutte à goutte (conduite, goutteur) mais également entre les différents types de goutteurs testés. L’entrée, la zone de retour ainsi que les zones de recirculation étaient les zones les plus sensibles au colmatage. Ceci s’explique par le fait que les vitesses et l’énergie de turbulence sont plus faibles dans ces zones, favorisant le développement des biofilms. Les goutteurs avec un faible diamètre hydraulique étaient les plus sensibles au colmatage. Les différences d’écoulement induisent des spécificités au niveau de la structure des communautés microbiennes des biofilms qui ont été décrites pour la première fois. L’influence du traitement par lagunage sur les communautés responsables du colmatage a également été mise en évidence par comparaison des eaux usées non traitée versus eaux usées traitées. En particulier, les résultats illustrent le rôle clef des Chloroflexi, et notamment des bactéries filamenteuses dans le colmatage des goutteurs.Des moyens couramment utilisés en agriculture pour limiter le colmatage ont été évalués. La chloration combinée à la purge permet de diminuer statistiquement le niveau de colmatage des goutteurs, notamment dans l’écoulement principal du labyrinthe, où la vitesse est la plus élevée. À l’inverse, l’utilisation de la purge seule ne permet pas de réduire le colmatage des goutteurs. La chloration réduit, mais ne supprime pas totalement les biofilms, et les bactéries résistantes à la chloration ont été identifiées, telles que les membres de la famille des Comamonadaceae ou Pseudomonas. Enfin, les espèces pathogènes opportunistes Pseudomonas aeruginosa et Aeromonas hydrophila et Legionella pneumophila sont présentes dans les biofilms des goutteurs, colonisant préférentiellement les biofilms des réseaux, comparativement aux indicateurs de contamination fécale (Enterococcus spp., E. coli).