DDE is one of the main transformation products of the insecticide DDT which has been largely used in agriculture after 1945 against a wide range of arthropods. Although the utilization of DDT has been banned in most world countries, DDE is still found as an environmental contaminant. Microbial Fuel Cells (MFCs) represent a promising technology for contaminated soils recovering based on the conversion of the energy stored in the chemical bonds of organic compounds into electrical energy. Here, MFCs were used to test their effectiveness on the complex degradation of DDE in presence/absence of compost. The compost was used a possible energy source. MFCs transform the energy stored in the chemical bonds of different organic compounds into electrical energy thanks to reactions catalyzed by microorganisms through oxidation and reduction reactions which take place at the anode and the cathode, respectively. The bacterial community, in anaerobic conditions, forms a biofilm at the anode. The microorganisms in the biofilm oxidize the organic matter that is present as carbon source, producing electrons and protons. Electrons flow from the anode to the cathode through an external circuit while protons flow through the soil (that works as an electrolyte) and migrate directly to the cathode where, in aerobic conditions, electrons and protons react with oxygen (present in the air) to produce water. The questions arising are if such process can influence, possibly accelerate, DDE degradation and if the presence of compost can intensify both DDE degradation and energy generation due to the higher content in nutrients. To evaluate DDE degradation four experimental conditions using MFCs have been carried out: a) natural soil; b) soil plus compost; c) soil plus DDE; d) soil plus compost and DDE. Each experimental condition was realized in triplicates. Moreover, the last two conditions were tested using both an open and close circuit condition (made through an electrical resistance in order to obtain the maximum power value corresponding to the highest DDE degradation rate). Chemical and microbiological analyses have been performed at three sampling times: 0 day, 2 months and 4 months. In addition, electrical measurements were performed for the whole duration of the experiment. Preliminary results (at 2 months) showed that the maximum OCV (open circuit voltage) was obtained in b) condition suggesting that the compost increased the reaction mechanism while in d) condition the pesticide partially reduced the performance. Regarding the CCV (closed circuit voltage) configuration, the maximum power generation was obtained in the b) configuration suggesting that the compost accelerated the reactions while the DDE limited them in accordance with the results achieved in the OCV configuration.
DDE degradation in soil by using Microbial Fuel Cells (MFCs)
Aimola G;Campanale C;Grenni P;Barra Caracciolo A;Ancona V;
2019
Abstract
DDE is one of the main transformation products of the insecticide DDT which has been largely used in agriculture after 1945 against a wide range of arthropods. Although the utilization of DDT has been banned in most world countries, DDE is still found as an environmental contaminant. Microbial Fuel Cells (MFCs) represent a promising technology for contaminated soils recovering based on the conversion of the energy stored in the chemical bonds of organic compounds into electrical energy. Here, MFCs were used to test their effectiveness on the complex degradation of DDE in presence/absence of compost. The compost was used a possible energy source. MFCs transform the energy stored in the chemical bonds of different organic compounds into electrical energy thanks to reactions catalyzed by microorganisms through oxidation and reduction reactions which take place at the anode and the cathode, respectively. The bacterial community, in anaerobic conditions, forms a biofilm at the anode. The microorganisms in the biofilm oxidize the organic matter that is present as carbon source, producing electrons and protons. Electrons flow from the anode to the cathode through an external circuit while protons flow through the soil (that works as an electrolyte) and migrate directly to the cathode where, in aerobic conditions, electrons and protons react with oxygen (present in the air) to produce water. The questions arising are if such process can influence, possibly accelerate, DDE degradation and if the presence of compost can intensify both DDE degradation and energy generation due to the higher content in nutrients. To evaluate DDE degradation four experimental conditions using MFCs have been carried out: a) natural soil; b) soil plus compost; c) soil plus DDE; d) soil plus compost and DDE. Each experimental condition was realized in triplicates. Moreover, the last two conditions were tested using both an open and close circuit condition (made through an electrical resistance in order to obtain the maximum power value corresponding to the highest DDE degradation rate). Chemical and microbiological analyses have been performed at three sampling times: 0 day, 2 months and 4 months. In addition, electrical measurements were performed for the whole duration of the experiment. Preliminary results (at 2 months) showed that the maximum OCV (open circuit voltage) was obtained in b) condition suggesting that the compost increased the reaction mechanism while in d) condition the pesticide partially reduced the performance. Regarding the CCV (closed circuit voltage) configuration, the maximum power generation was obtained in the b) configuration suggesting that the compost accelerated the reactions while the DDE limited them in accordance with the results achieved in the OCV configuration.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
