Incorporation of biofilm activity in river biodegradation modeling: A casestudy for linear alkylbenzene sulphonate (LAS)

A mathematical model was constructed which considers both biofilm and suspe nded biomass activity in relation to the biodegradation of individual chemi cals in rivers, To calibrate this model for the surfactant LAS (linear alky lbenzene sulphonate), experimental data were obtained in a lab-scale artifi cial river system, which allowed to collect accurate and reproducible river biodegradation data next to the required river characteristics. Biofilm pr ocesses were shown to be by far the most significant removal mechanism of L AS in the considered system which had a high surface area to volume ratio. The biodegradation model could be fitted to the data using realistic parame ter values. Subsequently, the model was corroborated by comparing its predi ctions to a field study in the Red Beck, a small Yorkshire river. Only easy to collect or default data were used as model parameters. The predicted LA S first-order removal rate coefficient (without any calibration using the f ield data) was 0.25 h(-1), which is less than 20% slower than removal measu red in the field. (C) 2000 Elsevier Science Ltd. All rights reserved.