IRH Ingenieur Conseil

Vandœuvre-lès-Nancy, France

IRH Ingenieur Conseil

Vandœuvre-lès-Nancy, France
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Fernandez-Rojo L.,IRD Montpellier | Hery M.,IRD Montpellier | Le Pape P.,CNRS Institute of Mineralogy, Materials Physics and Cosmochemistry | Braungardt C.,IRD Montpellier | And 13 more authors.
Water Research | Year: 2017

Passive water treatments based on biological attenuation can be effective for arsenic-rich acid mine drainage (AMD). However, the key factors driving the biological processes involved in this attenuation are not well-known. Here, the efficiency of arsenic (As) removal was investigated in a bench-scale continuous flow channel bioreactor treating As-rich AMD (∼30–40 mg L−1). In this bioreactor, As removal proceeds via the formation of biogenic precipitates consisting of iron- and arsenic-rich mineral phases encrusting a microbial biofilm. Ferrous iron (Fe(II)) oxidation and iron (Fe) and arsenic removal rates were monitored at two different water heights (4 and 25 mm) and with/without forced aeration. A maximum of 80% As removal was achieved within 500 min at the lowest water height. This operating condition promoted intense Fe(II) microbial oxidation and subsequent precipitation of As-bearing schwertmannite and amorphous ferric arsenate. Higher water height slowed down Fe(II) oxidation, Fe precipitation and As removal, in relation with limited oxygen transfer through the water column. The lower oxygen transfer at higher water height could be partly counteracted by aeration. The presence of an iridescent floating film that developed at the water surface was found to limit oxygen transfer to the water column and delayed Fe(II) oxidation, but did not affect As removal. The bacterial community structure in the biogenic precipitates in the bottom of the bioreactor differed from that of the inlet water and was influenced to some extent by water height and aeration. Although potential for microbial mediated As oxidation was revealed by the detection of aioA genes, removal of Fe and As was mainly attributable to microbial Fe oxidation activity. Increasing the proportion of dissolved As(V) in the inlet water improved As removal and favoured the formation of amorphous ferric arsenate over As-sorbed schwertmannite. This study proved the ability of this bioreactor-system to treat extreme As concentrations and may serve in the design of future in-situ bioremediation system able to treat As-rich AMD. © 2017 Elsevier Ltd

For the refurbishment of a water treatment plant, an ion exchange carbonate removal unit was implemented. The regeneration of the ion exchange resins involved in the process required hydrochloric acid. A few months after commissioning, failure of one of the two hydrochloric acid dosing pumps resulted in a serious discharge of hydrochloric acid into the plant. This led to irreversible damages to the newly refurbished plant. It was finally decided to build a new plant on the same site and to deconstruct the existing one.

Boisson J.,IRH Ingenieur Conseil | Humbel X.,IRH Ingenieur Conseil | Pottecher G.,Groupe IRH Environnement | Sadowski A.G.,Ecole Nationale du Genie de lEau et de lEnvironnement de Strasbourg | And 3 more authors.
Eau, l'INDUSTRIE, les Nuisances | Year: 2010

The study presented here has taken place in the light of a LIFE Environment project directed by the Water and Waste Water Service of Angers Loire Metropole. The treatment of a part stream of recycled sludge (Waste water treatment plants of 6300 population equivalents) has reduced sludge production by about 26 %. The treatment by ultrasounds seems to have no impact on the water treatment performance, on the quality of thickened sludge, neither on the direct emission of greenhouse gases. The only exception is a decrease of the treatment performance of phosphorus. The treatment is not valuable from an economical point for this small waste water treatment plant with low sludge handling costs (10 /ton). Extrapolation of the results show that after some modifications, the process could be economically feasible for waste water treatment plants with a sizee ≥ 100 000 population equivalent and with final sludge eliminution costs > 11 /ton (DM 20%). If a digestor is present, it is preferable to apply ultrasounds to the sludge file in order to increase biogas production. This final application has proved itself all over the world (Hein, 2008; Nickel, 2008).

Gobert A.,IRH Ingenieur Conseil | Pottecher G.,IRH Ingenieur Conseil | Deberles F.,Veolia | Ravenel H.,Meteo - France | Genin N.,Syndicat Mixte pour lAssainissement de lAgglomeration Granvillaise SMAAG
Techniques - Sciences - Methodes | Year: 2010

The Mareclean project includes the implementation of active management of the sewerage system of the Granville urban area. The sewerage system contains seven basins situated at the overflow of the main pumping stations. The objective of the project is to optimise the use of storage capacities by a centralised control of the pumps. The approach has been tested on four basins during summer 2009. The partners of the Mareclean project involved in this « active management » are Veolia Eau, Météo-France and IRH. The active management consists of real time testing of different management strategies (on/off for each pump) by means of hydraulic modelling. The scenarios are evaluated by the volume of the overflow in combination with a coefficient taking into account the variable sensibility of the bathing water according to the emplacement of the outlet. The best strategy is then applied for the coming hour. Data and instructions are updated every 15 minutes. The model integrates real time data of MétéoFrance: Antilope, hourly water layer with a kilometric resolution, and PIPEC, prevision of the precipitation during periods of 5 minutes for the coming hour. The model is also receiving real time data from the remote processing system (water level, rainfall, flow rates). The real time management has been tested on four basins selected for their hydraulic pertinence and for the relative facility to put in place the control system. The control system is composed of telecommunication material, local automates and the software for remote processing (Lerne).

Choosing the pipe diameter for better cost-effectiveness is one of the inputs to financkdly and technically optimising the water pumping and supply process. But this so-called "cost-effective" diameter may vary greatly according to certain project constraints, other than simply the rate of flow and suction lift. Amongst such parameters to be accounted for are the possible evolution of rugosity, the status and future prospects of demand plus the network-related constraints.

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