This study aims at evaluating the improved facultative ponds performance in pilot scale. Wastewater has been collected from primary settling basins of Ahvaz wastewater treatment plant. Treatment efficacy of the four systems (three systems in parallel with a control system) has been evaluated over a period of 12 months at various hydraulic retention times (HRT) and organic loading rates (OLR). There has been no baffle and no attached growth media (AGM) in the control system (S0), while other three systems (S2, S3, and S4) have been equipped with different numbers of baffles and AGM packages, containing the mineral shells. Results show that efficiency of BOD5 removal for S0, S2, S3, and S4 are 53.4%, 60.8%, 64.7%, and 67.6%, respectively, while for COD these rates alter to 28.1%, 37.7%, 45.8%, and 50.1 % and of coliform to 66.7%, 76.6%, 80.7%, and 83.4%. Filtered BOD5 in the effluent of S0, S2, S3, and S4 is 32.5, 27.6, 24.6, and 22.3 mg/l, respectively and 60.2, 52.1, 47, and 44.3 mg/l for TSS. Also the 10-day HRT has been optimum among applied HRTs. As such, attached growth-baffled ponds function better than conventional ones, making the technique, examined in the present paper a low-cost process to establish new wastewater treatment plants or upgrading the existent WSPs, especially in case of warm areas of southwestern Iran.

The aim of this study is to develop analytical solutions for one-dimensional advection-dispersion equation in a semi-infinite heterogeneous porous medium. The geological formation is initially not solute free. The nature of pollutants and porous medium are considered non-reactive. Dispersion coefficient is considered squarely proportional to the seepage velocity where as seepage velocity is considered linearly spatially dependent. Varying type input condition for multiple point sources of arbitrary time-dependent emission rate pattern is considered at origin. Concentration gradient is considered zero at infinity. A new space variable is introduced by a transformation to reduce the variable coefficients of the advection-dispersion equation into constant coefficients. Laplace Transform Technique is applied to obtain the analytical solutions of governing transport equation. Obtain results are shown graphically for various parameter and value on the dispersion coefficient and seepage velocity. The developed analytical solutions may help as a useful tool for evaluating the aquifer concentration at any position and time.

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Solid-solution partitioning of Rare Earth Elements in mine-tailings and soils in China: experimental results and multi-surface modelling. Interfaces Against Pollution

Development of a flux DMT with integrated adsorptive stripping voltammetry for free metal ions detection in solution. Interfaces Against Pollution

The French West Indies face nowadays a diffuse and long term environmental pollution related to historical use of organochlorine insecticide in banana fields, Chlordecone (CLD). Due to its stability, it now pollutes soil, waters, agricultural products and leads to a global exposure of people and ecosystems. We wonder how to manage such a complex pollution system involving all environmental compartments, linked each other. For that, we have been conducting research studies for more than 15 years in the field of agronomy and environment to explore the fate of the molecule in the environment, the impact on food safety, and also the remediation options. Three main points are addressed: i) how to characterize the pollution and to make easier the diagnosis? ii) how to assess the impacts on environmental compartments and agricultural products? iii) How to manage the pollution? The tools we developed make a diagnosis of such pollution easier at different scales (field, farm, watershed, and territory). We built monitoring support systems for the water quality of rivers with models helping to understand variability of water contamination. We built also decision support systems to farmers to manage their soil pollution and choose the crops that will ensure food security. Now CLD content of local crop products on the market complies with the Maximum Residue Limit. Management is more complex for animal products, and further investigations are needed. We investigated alternative solution to enhance CLD soil sequestration, using physical properties of French West Indies volcanic soil and organic matter amendment. Increased organic matter content in soil reduced drastically the CLD transfer from soil to water, but this effect was not perennial and amendment had to be regularly applied. Our results show that an integrative approach is needed to build efficient policies to manage such pollution than to prevent new ones.

The well-informed recycling of organic waste to agricultural land becomes increasingly desirable in dynamic, developing regions worldwide. Pursuing locally optimal benefit-risk ratios, agro-environmental research in support of OW recycling does not focus on avoiding contamination perse, but on the control of dynamics, in soil and other environmental compartments, in order not to exceed risk thresholds. We present a series of empirical research efforts that inform decision making in regions under OW pressure on OW-contained trace contaminant fate under local conditions. Their results illustrate that the present understanding of trace elements fate allows for the ex-ante assessment of fate under specific use scenarios and local conditions, with a limited set of simplifications. A well-established set of analytical tools provides the information required by such assessments. Understanding of OW-borne organic contaminants is less advanced, but the present capacity to project fate under local conditions does allow for the approximate appreciation of risk levels, the major benefit of which is to focus subsequent research on substances of concern. Ongoing long-term field trials may critically advance our understanding of OW-borne contaminant fate in soil. Developing a reasonable capacity to assess biological contaminant fate is one of its priorities.

International audience | Solid-solution partitioning of Rare Earth Elements in mine-tailings and soils in China: experimental results and multi-surface modelling. Interfaces Against Pollution

publishedVersion | Paid Open Access