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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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The kinetic model of Vandepitte and Schowanek shows that hypochlorite is degraded during transport in the sewer within the first minutes.

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Hypochlorite decay model in the environment

The kinetic model of Vandepitte and Schowanek shows that hypochlorite is degraded during transport in the sewer within the first minutes. The abundance of reaction partners allows a very quick reaction. For a hypochlorite concentration of 75 mg/L (expressed as free available chlorine, FAC) a concentration at the end of the sewer below 1 x 10-32 µg/L was calculated. The drop of FAC occurs in parallel with a sharp increase of the chloramine concentration, which can be explained by the high availability of ammonia in the sewer. Chloramine further reacts as an oxidant during further transport in the sewer, the STP and in the surface water (river). The extensive degradation of chloramine in the activated sludge can be explained by the presence of reduced organic material. Chloramine is calculated to fall below a concentration of 5 x 10-10 µg/L in the river.

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