We report recent results achieved by applying in the field a dynamical model of in situ bioremediation that has been developed within the Colombo project, one of the major european endeavours in bioremediation modelling.Our approach relies upon the CabCol methodology, which is based upon the use of adaptive models, which are tailored to the case at hand in the pilot plant phase. The model is then used to forecast the results of real field interventions. A further original feature is that the model is based upon the cellular automata framework, instead of relying upon partial differential equations. A software environment for these models has been developed, which can make use of parallel as well as sequential hardware. Further discussion of the methodology and of the CA model can be found in the literature and in the 1999 Battelle Conference Proceedings, alongside with comparisons with experimental results on the pilot scale.We discuss here the results which have been achieved in the first two applications of the methodology to real cases, referring to two sites in Germany: one (site A) was contaminated mainly by TPH, the other (site B) by PAH. Pilot scale studies have been performed in both cases, where the indigenous bacteria were stimulated by the flow of an aqueous solution of nutrients and hydrogen peroxide. The pilot plants were composed by a series of three cylinders filled with contaminated soil coming from the site. The model has been adapted to the two different cases, in order to match both the overall degradation rate and its space-time profile. After adaptation, the model has been applied in the field without any further change. The major results are as follows: in site A, the overall degradation rate is predicted with reasonable accuracy, while the detailed spatial distribution on its boundaries is not satisfactory. This is likely to be due to the fact that site A is actually a part of a larger site, and the boundaries are affected by operations taking place outside the monitored area and not considered in the model. In site B, both the overall degradation rate and the spatial distribution are correctly forecasted.What is particularly worth noticing is that the overall pilot-plant degradation rate is similar in the two cases, while the kinetics in the field differ by about an order of magnitude. The model correctly forecasts this difference, and it also allows one to understand the reason of the difference. So, while a naive approach would have predicted similar rate constants in the two cases, the use of CabCol allows to forecast the different rates in the field. The importance of such a forecast for determining the duration and the cost of the remediation is obvious.Since two cases have been so far fully worked out, we cannot claim a general validity of the methodology; however, these first real field applications show very promising and potentially useful results in the scale-up from the lab to the field.
|Data di pubblicazione:||2001|
|Titolo:||Bioremediation modelling: from the pilot plant to the field|
|Autore/i:||Villani, Marco; M., Padovani; M., Andretta; Serra, Roberto; B., Muller; H. P., Ratzke; R., Rongo; W., Spataro; S., Di Gregorio|
|Nome del convegno:||The Sixth International in Situ and On-Site Bioremediation Symposium|
|Luogo del convegno:||San Diego - California|
|Data del convegno:||June 4-7|
|Citazione:||Bioremediation modelling: from the pilot plant to the field / Villani, Marco; M., Padovani; M., Andretta; Serra, Roberto; B., Muller; H. P., Ratzke; R., Rongo; W., Spataro; S., Di Gregorio. - STAMPA. - (2001), pp. 131-138. ((Intervento presentato al convegno The Sixth International in Situ and On-Site Bioremediation Symposium tenutosi a San Diego - California nel June 4-7.|
|Tipologia||Relazione in Atti di Convegno|
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