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Exploring the distribution of groundwater Crustacea (Copepoda and Ostracoda) to disentangle aquifer type features—A case study in the upper Tajo basin (Central Spain)
No full textOne of the most challenging questions in the assessment of groundwater ecosystem health is whether assemblages of groundwater biota can be used reliably as biomarkers. In this study, we aimed to (a) explore the diversity, distribution, and ecological composition of groundwater
Crustacea, Copepoda, and Ostracoda communities from six aquifers in Central Spain and (b) relate the structure of the species assemblages to the aquifers' hydrogeological conditions, habitat features, and hydrochemistry. The datasets were simultaneously collected from 24 boreholes
drilled in six unconfined aquifers from the upper part of the Tajo catchment. Our results show that the assemblages are primarily influenced by the specific hydrogeological conditions of the aquifer, determined by groundwater flow, supply of organic matter from the surface, and habitat features, whereas the aquifer's hydrochemistry has only a marginal effect. The assemblages from the
Tertiary detrital aquifer were the most diverse, containing a mixture of stygobiont and nonstygobiont species distributed preferentially in the recharge area of the aquifer, characterized by medium hydraulic conductivity, high surface input and relatively high water renewal. The Quaternary alluvial aquifer type was found to have a moderate richness with several hyporheic
dwellers, indicating an active surface/groundwater exchange with the adjacent stream channel. In contrast, the carbonate aquifer type was less diverse but markedly distinct owing to the high occurrence of stygobionts. Our results provide a step forward in exploring the groundwater biodiversity of aquifers in Spain and towards incorporating an ecological perspective into overall
assessments of groundwater status
Fouling in Membrane Distillation, Osmotic Distillation and Osmotic Membrane Distillation
No full textVarious membrane separation processes are being used for seawater desalination and treatment of wastewaters in order to deal with the worldwide water shortage problem. Different types of membranes of distinct morphologies, structures and physico-chemical characteristics are employed. Among the considered membrane technologies, membrane distillation (MD), osmotic distillation (OD) and osmotic membrane distillation (OMD) use porous and hydrophobic membranes for production of distilled water and/or concentration of wastewaters for recovery and recycling of valuable compounds. However, the efficiency of these technologies is hampered by fouling phenomena. This refers to the accumulation of organic/inorganic deposits including biological matter on the membrane surface and/or in the membrane pores. Fouling in MD, OD and OMD differs from that observed in electric and pressure-driven membrane processes such electrodialysis (ED), membrane capacitive deionization (MCD), reverse osmosis (RO), nanofiltration (NF), ultrafiltration (UF), microfiltration (MF), etc. Other than pore blockage, fouling in MD, OD and OMD increases the risk of membrane pores wetting and reduces therefore the quantity and quality of the produced water or the concentration efficiency of the process. This review deals with the observed fouling phenomena in MD, OD and OMD. It highlights different detected fouling types (organic fouling, inorganic fouling and biofouling), fouling characterization techniques as well as various methods of fouling reduction including pretreatment, membrane modification, membrane cleaning and antiscalants application
Mechanism of formation of hollow fiber membranes for membrane distillation: 2. Outer coagulation power effect on morphological characteristics
No full text
Scientific Advice on Guidance Document n°27: Technical Guidance for Deriving Environmental Quality Standards
No full textFollowing a request from the Commission, the Scientific Committee on Health, Environmental and Emerging Risks (SCHEER) reviewed the Guidance Document No. 27:
‘Technical Guidance for Deriving Environmental Quality Standards’ prepared by a collaborative framework (the Common Implementation Strategy) for the Water Framework
Directive.
The SCHEER concludes that the overall scientific quality of the proposed changes is an improvement to the earlier 2011 version. The SCHEER has a number of comments where more practical guidance can be provided or where the current state of knowledge is still insufficient or where it is not being fully utilised
Towards refined environmental scenarios for ecological risk assessment of down-the-drain chemicals in freshwater environments
No full textCurrent regulatory practice for chemical risk assessment suffers from the lack of realism in conventional frameworks. Despite significant advances in exposure and ecological effect modelling, the implementation of novel approaches as high tier options for prospective regulatory risk assessment remains limited, particularly among general chemicals such as down-the-drain ingredients. While reviewing the current state of art in environmental exposure and ecological effect modelling, we propose a scenario-based framework that enables a better integration of exposure and effect assessments in a tiered approach. Global- to catchment-scale spatially explicit exposure models can be used to identify areas of higher exposure and to generate ecologically relevant exposure information for input into effect models. Numerous examples of mechanistic ecological effect models demonstrate that it is technically feasible to extrapolate from individual-level effects to effects at higher levels of biological organisation and from laboratory to environmental conditions. However, the data required to parameterize effect models that can embrace the complexity of ecosystems are large and require a targeted approach. Experimental efforts should, therefore, focus on vulnerable species/traits and ecological conditions of relevance. We outline key research needs to address the challenges that currently hinder the practical application of advanced model-based approaches to risk assessment of down-the-drain chemicals. This article is protected by copyright. All rights reserve
Quantification of potentially cylindrospermopsin-producing Chrysosporum ovalisporum (SOP 7.6)
No full textClinoptilolite and palygorskite as sorbents of neutral emerging organic contaminants in treated wastewater: Sorption-desorption studies
No full textWater reuse for aquifer recharge could be an important route for the introduction of emerging organic
contaminants (EOCs) into the environment. The installation of a Horizontal Permeable Reactive Barrier
(H-PRB) could constitute a tertiary treatment process to remove EOCs from treated domestic wastewater
prior to recharge activities. The sorption-desorption behaviour of six neutral EOCs present in treated
domestic wastewater (acetaminophen, caffeine, carbamazepine, cotinine, 4-acetamidoantipyrine (4-
AAA) and 4-formylaminoantipyrine (4-FAA)) has been evaluated. Clinoptilolite and palygorskite have
been studied as sorbents to be installed in the H-PRB. Batch tests were carried out using an EOC initial
concentration ranging from 5 to 100 mg/L. Apart from acetaminophen and caffeine, both materials
showed a limited sorption capacity of neutral EOCs (Kd = 0.63 - 5.42 L/kg). In general, the experimental
results show that EOCs exhibit a higher sorption affinity for clinoptilolite than for palygorskite. With the
exception of carbamazepine, the sorption of the compounds occurs mainly by interactions with mineral
surfaces as indicated by the comparison of the partition coefficients into organic matter and into mineral
surfaces. According to the molecular geometry of the compounds and the sorption sequences observed, it
appears that the dimensions of the organic molecules play a key role in the sorption process. All the
studied EOCs exhibit irreversible sorption and sorption-desorption hysteresis
Local and regional drivers of headwater stream metabolism: insights from the first AIL collaborative project
No full textExperimental and theoretical investigations on water desalination using direct contact membrane distillation
No full textDirect contact membrane distillation (DCMD) is one of the commonly used configurations of membrane distillation technology for water desalination. In the present study, comprehensive investigations on different parameters affecting the performance of the DCMD system are presented. The investigated variables include the hot feed and the cold permeate temperatures, feed-permeate temperature difference and ratio, feed and permeate flow rates, feed-permeate flow rate ratio, feed concentration, membrane pore size, and membrane degradation with time, etc. An analytical model, based on the heat and mass transfer equations within the DCMD module, was used to predict the system performance at different operating conditions. The model was used to predict the temperature difference across the membrane surfaces and then calculating the vapor pressure difference leading to the permeate flux. The model was validated with the experimental measurements. The permeate flux increases with increasing the feed temperature, feed flow rate, permeate flow rate, and pore size, and decreases with increasing the permeate temperature and feed concentration. The productivity of the system is very promising since a permeate flux of 100 kg/m2·h was achieved at 90 °C for hot feed side and 5 °C for cold side stream. The DCMD system is able to handle feeds with high salt concentration of 100 g/L with remarkably high salt rejection factor and low permeate total dissolved solids (TDS). The SEM micrographs showed the used polytetrafluoroethylene (PTFE) membrane covered with a fouling layer, as compared to the as-received membrane, which attests the need for feed pretreatment and/or membrane washing to recover the membrane performance. The evaporative (thermal) efficiency ranged from 70% to 95% and the GOR values ranged from 0.8 to 1.2 corresponding to feed temperature from 40 °C to 90 °C, depending mainly on the feed temperature