Escenarios de la distribución de plomo en agua, sedimentos y bacterias del lago de Chapala, México

14 p

Reconstrucción de la deposición atmosférica histórica de DDT en la laguna de Zempoala en el centro de México

13 p

Saneamiento del vaso Cencali, Villahermosa, Tabasco. I. Contaminación y reúso de sedimentos

16 p

Saneamiento del vaso Cencali, Villahermosa, Tabasco. II. Diseño del proceso

14 p

Modélisation de la relation entre aération, transfert d'oxygène et performances épuratoires dans les filtres plantés horizontaux aérés

International audienceIn this study, a reactive transport model based on dual-permeability flow and biokinetic formulations of the Constructed Wetland Model No.~1 (CWM1) was developed and extented to 1) simulate oxygen transfer and treatment performance of organic carbon and nitrogen of horizontal flow (HF) aerated wetlands treating domestic sewage, and, 2) to investigate the dependence of oxygen transfer and treatment performance on AFR and water temperature. Conservative tracer transport as well as reactive transport of dissolved oxygen (DO), soluble and total chemical oxygen demand (CODs, CODt), NH4-N and NOx-N measured in pilot--scale experiments were simulated with acceptable accuracy. A prediction equation for the volumetric oxygen transfer coefficient was found to be: kLa,20=0.511 ln(AFR). Treatment performance depended on kLa, 20 in a non-linear manner. A local sensitivity analysis of the calibrated parameters revealed porosity, hydraulic permeability and dispersion length of the fast flow field as well as kLa, 20 as most important. Simulated changes in water temperature from 2.5-20.0 °C did not substantially affect oxygen transfer. An optimal AFR for a spatially and temporally continuous aeration pattern for wetlands treating similar influent was estimated to 150-200 L h-1 m-2. These results can support wetland design in setting the AFR to meet the oxygen demand of a specific influent strength. Furthermore, this study provides insights into aeration mechanisms of aerated wetlands and highlights the benefits of process modeling for in-depth system analysis

La nouvelle normalisation Allemande en terme de traitement des eaux usées domestiques par filtres plantés de roseaux

International audienceThe German Association for Water, Wastewater and Waste e.V. (DWA) has published a new standard for the dimensioning, construction, and operation of constructed wetlands for treatment of domestic and municipal wastewater. The changes to the standard are based on a wide range of experience gained in recent years in Germany and Europe. For the first time ever, the standard has been officially translated and published in English. This paper summarizes the new standard for secondary treatment of domestic wastewater with classical one-stage unsaturated vertical flow (VF) wetlands, VF wetlands with lava sand for treatment of wastewater from combined sewer systems, and actively aerated VF and horizontal flow (HF) flow wetlands. Two-stage unsaturated VF wetlands treating raw wastewater (French VF wetlands), are also included in the new standard. HF wetlands are no longer described in the standard for secondary treatment of domestic wastewater. This does not exclude their application. Existing HF wetland systems in Germany may continue to be operated so long as effluent parameters are met and proper operations and maintenance is ensured. This paper gives an overview of the new design standard, including key information on wastewater type and loading, as well as primary attributes of each wetland design

Remediation of groundwater contaminated with MTBE and benzene: the potential of vertical-flow soil filter systems

Field investigations on the treatment of MTBE and benzene from contaminated groundwater in pilot or full-scale constructed wetlands are lacking hugely. The aim of this study was to develop a biological treatment technology that can be operated in an economic, reliable and robust mode over a long period of time. Two pilot-scale vertical-flow soil filter eco-technologies, a roughing filter (RF) and a polishing filter (PF) with plants (willows), were operated independently in a single-stage configuration and coupled together in a multistage (RF þ PF) configuration to investigate the MTBE and benzene removal performances. Both filters were loaded with groundwater from a refinery site contaminated with MTBE and benzene as the main contaminants, with a mean concentration of 2970 816 and 13,966 1998 mg L 1, respectively. Four different hydraulic loading rates (HLRs) with a stepwise increment of 60, 120, 240 and 480 L m 2 d 1 were applied over a period of 388 days in the single-stage operation. At the highest HLR of 480 L m 2 d 1, the mean concentrations of MTBE and benzene were found to be 550 133 and 65 123 mg L 1 in the effluent of the RF. In the effluent of the PF system, respective mean MTBE and benzene concentrations of 49 77 and 0.5 0.2 mg L 1 were obtained, which were well below the relevant MTBE and benzene limit values of 200 and 1 mg L 1 for drinking water quality. But a dynamic fluctuation in the effluent MTBE concentration showed a lack of stability in regards to the increase in the measured values by nearly 10%, which were higher than the limit value. Therefore, both (RF þ PF) filters were combined in a multi-stage configuration and the combined system proved to be more stable and effective with a highly efficient reduction of the MTBE and benzene concentrations in the effluent. Nearly 70% of MTBE and 98% of benzene were eliminated from the influent groundwater by the first vertical filter (RF) and the remaining amount was almost completely diminished (w100% reduction) after passing through the second filter (PF), with a mean MTBE and benzene concentration of 5 10 and 0.6 0.2 mg L 1 in the final effluent. The emission rate of volatile organic compounds mass into the air fromthe systems was less than 1% of the inflow mass loading rate. The results obtained in this study not only demonstrate the feasibility of vertical-flow soil filter systems for treating groundwater contaminated with MTBE and benzene, but can also be considered a major step forward towards their application under full-scale conditions for commercial purposes in the oil and gas industries

Purification, Stability, and Mineralization of 3-Hydroxy-2- Formylbenzothiophene, a Metabolite of Dibenzothiophene

3-Hydroxy-2-formylbenzothiophene (HFBT) is a metabolite found in many bacterial cultures that degrade dibenzothiophene (DBT) via the Kodama pathway. The fate of HFBT in cultures and in the environment is unknown. In this study, HFBT was produced by a DBT-degrading bacterium and purified by sublimation. When stored in organic solvent or as a crystal, the HFBT slowly decomposed, yielding colored products. Two of these were identified as thioindigo and cis-thioindigo. The supernatant of the DBT-degrading culture contained thioindigo, which has not been reported previously as a product of DBT biodegradation. In mineral salts medium, HFBT was sufficiently stable to allow biodegradation studies with a mixed microbial culture over a 3- to 4-week period. High-performance liquid chromatography analyses showed that HFBT was removed from the medium. 2-Mercaptophenylglyoxalate, detected as benzothiophene-2,3-dione, was found in an HFBT-degrading mixed culture, and the former appears to be a metabolite of HFBT. This mixed culture also mineralized HFBT to CO(2)

Wastewater Treatment and Wood Production of Willow System in Cold Climate

This article studied how wastewater treatment performance of a short rotation forestry system was influenced by the seasonal operational changes under the extreme Mongolian winter conditions. For this reason, two beds planted with Willow (Salix spec.) and Poplar (Populus spec.) trees were operated over a period of two years under two different seasonal conditions: (A) “external winter storage” and (B) “internal winter storage” of pretreated wastewater. For operational condition A, the tree-bed was loaded with wastewater for only 4 summer months. For this operational condition it was considered that the treatment bed was fed with primary treated wastewater, which was stored in a sealed pond during the remaining 8 months. The other Bed B was irrigated throughout the year (12 months) with the same daily loading rate. In winter, the wastewater accumulated as ice in the tree-bed. Bed A, with external winter storage, showed mass removal percentage up to 95%, while the bed with internal winter storage showed mass removal rates up to 86% for pollutants such as COD, BOD5, TN, and TP. A high yield of biomass was recorded for both beds with slight differences. Based on the results, a design recommendation was developed for full-scale systems of short rotation coppice irrigated with wastewater under various operational conditions, which show these systems to be a viable method for treating wastewater and producing biomass for energy production in Mongolia