Determination of sorption properties of micropollutants: What is the ă most suitable activated sludge inhibition technique to preserve the ă biomass structure?

Abstract : Apart from providing a total activated sludge (AS) inhibition, an ă efficient AS inhibition technique must preserve the biomass structure in ă order to maintain the real sorption phenomenon. Many inhibition ă techniques with different modes of action were used in previous studies ă for AS inhibition. But, the effectiveness of AS deactivation and the ă adverse effects on the biomass structure were rarely related. In this ă paper, five common AS inhibition techniques were evaluated: thermal, ă three chemical and gas purging techniques. The lowest chemical effective ă concentrations were determined in order to limit the negative impact on ă the AS structure. 100 mgHg(2)SO(4) g(TSS)(-1) and 30 mgHgCl(2) ă g(TSS)(-1) within 2 h of reaction were enough to provide a complete AS ă inhibition. However, after 20 h of reaction a full AS inhibition has ă never been achieved with sodium azide at 200 mgNaN(3) g(TSS)(-1), even ă by increasing NaN3 concentration. ă The analysis of the AS apparent viscosity, the median size D-50 of the ă flocs and the supernatant turbidity showed that the thermal technique ă destructured the AS completely. A significant AS deflocculation is ă induced by the three chemical reagents depending on the mode of action ă and the concentration used. Thermal and chemical inactivations are ă therefore not suitable to determine sorption properties. The only ă technique which kept the initial AS structure unchanged has several ă drawbacks since (i) a reaction might occur between the gas and the ă analyte of interest, and (ii) anaerobic activated sludge are not ă inhibited by this technique. Therefore, the establishment of anaerobic ă conditions without gas injection is recommended for implementing ă sorption experiments on aerobic AS. (C) 2013 Elsevier B.V. All rights ă reserved.
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Pierre Hamon, Maud Villain, Benoît Marrot. Determination of sorption properties of micropollutants: What is the ă most suitable activated sludge inhibition technique to preserve the ă biomass structure?. Chemical Engineering Journal, Elsevier, 2014, 242, pp.260-268. ⟨10.1016/j.cej.2013.07.017⟩. ⟨hal-01464699⟩

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