In this paper the experimental results of laboratory anaerobic dechlorination tests on a groundwater polluted by chlorinated solvents are presented and discussed. Batch tests, performed in parallel, were carried out using two carbon substrates as electron donor (sucrose and milk serum) at equimolar concentration and at selected excess with respect the total chlorinated organics. The purpose of the tests was to evaluate which of the two substrates was capable to provide optimal operative conditions for chlorinated solvents degradations. The effect of the addition of yield extract was also evaluated. Eight digesters were operated along two months at the site conditions: at selected time intervals they were sampled and the nitrate, sulphate, iron ad manganese content were determined, together with the main physical-chemical parameters. At the same time, the evolution of gas composition in the head space was determined. Results indicate that the overall pathway of the process involved the initial denitrification, followed by sulfate reduction and methane production, that occurred almost simultaneously. The process was faster when using milk serum rather than sucrose as electron donor, though, in the tests when the milk serum was in the larger excess, a faster pH lowering caused a partial inhibition of methanogenic bacteria activity, thus retarding the beginning of methane production. In the reactors fed with milk serum and with an excess of electron donor with respect to the total chlorinated organics of 5:1 and 20:1, methanogenesis started after 17-20 days of incubation. Mass balances performed in both liquid and gaseous phase at the end of the experiments showed that a total removal of up to about 60% of the total chlorinated organics was achieved in the liquid phase. This was attributed both to the reduction to CVM (that was not detected in the gaseous phase), and, at a lower extent, to volatilisation induced by gas developing in the digester.
Experimental tests of anaerobic dechlorination of a polluted groundwater / DE FILIPPIS, Paolo; DI PALMA, Luca; D., Lausdei. - ELETTRONICO. - B:(2009), pp. 15/1-15/6. (Intervento presentato al convegno 2nd International Conference on Polluted Sites Remediation, Bosicon 2009 tenutosi a Rome, Italy nel 13-15 Maggio 2009).
Experimental tests of anaerobic dechlorination of a polluted groundwater
DE FILIPPIS, Paolo;DI PALMA, Luca;
2009
Abstract
In this paper the experimental results of laboratory anaerobic dechlorination tests on a groundwater polluted by chlorinated solvents are presented and discussed. Batch tests, performed in parallel, were carried out using two carbon substrates as electron donor (sucrose and milk serum) at equimolar concentration and at selected excess with respect the total chlorinated organics. The purpose of the tests was to evaluate which of the two substrates was capable to provide optimal operative conditions for chlorinated solvents degradations. The effect of the addition of yield extract was also evaluated. Eight digesters were operated along two months at the site conditions: at selected time intervals they were sampled and the nitrate, sulphate, iron ad manganese content were determined, together with the main physical-chemical parameters. At the same time, the evolution of gas composition in the head space was determined. Results indicate that the overall pathway of the process involved the initial denitrification, followed by sulfate reduction and methane production, that occurred almost simultaneously. The process was faster when using milk serum rather than sucrose as electron donor, though, in the tests when the milk serum was in the larger excess, a faster pH lowering caused a partial inhibition of methanogenic bacteria activity, thus retarding the beginning of methane production. In the reactors fed with milk serum and with an excess of electron donor with respect to the total chlorinated organics of 5:1 and 20:1, methanogenesis started after 17-20 days of incubation. Mass balances performed in both liquid and gaseous phase at the end of the experiments showed that a total removal of up to about 60% of the total chlorinated organics was achieved in the liquid phase. This was attributed both to the reduction to CVM (that was not detected in the gaseous phase), and, at a lower extent, to volatilisation induced by gas developing in the digester.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
