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Sint-Truiden, Belgium

Sniegowski K.,Catholic University of Leuven | Sniegowski K.,Limburg Catholic University College | Bers K.,Catholic University of Leuven | Ryckeboer J.,Catholic University of Leuven | And 3 more authors.
Applied and Environmental Microbiology | Year: 2011

On-farm biopurification systems (BPS) treat pesticide-contaminated wastewater of farms through biodegradation. Adding pesticide-primed soil has been shown to be beneficial for the establishment of pesticidedegrading populations in BPS. However, no data exist on the response of pesticide-degrading microbiota, either endogenous or introduced with pesticide-primed soil, when BPS are exposed to expected less favorable environmental conditions like cold periods, drought periods, and periods without a pesticide supply. Therefore, the response of microbiota mineralizing the herbicide linuron in BPS microcosm setups inoculated either with a linuron-primed soil or a nonprimed soil to a sequence of such less favorable conditions was examined. A period without linuron supply or a drought period reduced the size of the linuron-mineralizing community in both setups. The most severe effect was recorded for the setup containing nonprimed soil, in which stopping the linuron supply decreased the linuron degradation capacity to nondetectable levels. In both systems, linuron mineralization rapidly reestablished after conventional operation conditions were restored. A cold period and feeding with a pesticide mixture did not affect linuron mineralization. The changes in the linuron-mineralizing capacity in microcosms containing primed soil were associated with the dynamics of a particular Variovorax phylotype that previously had been associated with linuron mineralization. This study suggests that the pesticide-mineralizing community in BPS is robust in stress situations imposed by changes in environmental conditions expected to occur on farms. Moreover, it suggests that, in cases where effects do occur, recovery is rapid after restoring conventional operation conditions. © 2011, American Society for Microbiology.

de Wilde T.,Ghent University | Debaer C.,PCF Royal Research Station of Gorsem | Ryckeboer J.,Catholic University of Leuven | Springael D.,Catholic University of Leuven | Spanoghe P.,Ghent University
Journal of the Science of Food and Agriculture | Year: 2010

Background: Pesticides are efficiently retained and degraded in the organic matrix of a biopurification system. However, as this matrix mineralizes slowly over time, nutrients will start to become depleted and thus a decay in biomasswill probably occur. At that moment, the efficiency of the system decreases and the matrix should be replaced. The spentmatrixmight still contain residues of pesticides. Hence treatment of this matrix is essential. In this study we opted to use composting or incubation as an effective and environmentally friendly treatment strategy. Results: Small- and large-scale composting/incubation trialswere set up to treat the presence of linuron, bentazone, metalaxyl and bifenthrin in a contaminated matrix. Large-scale composting, performed in an industrial composting facility, resulted in decreased concentrations of metalaxyl, linuron and bentazone. Degradation of bifenthrin was very limited. In the smallscale incubation process, a decrease in concentration was noted for bifenthrin, metalaxyl and bentazone. A reduction in extractable pesticide concentration does not, however, always indicate degradation but could be attributed to the formation of non-extractable residues. Conclusion: Industrial and small-scale composting/incubation reduced the concentration of some pesticides during the timeframe studied, although little reduction was obtained for the persistent pesticide bifenthrin in the industrial composting process and for linuron in barrel incubation. © 2010 Society of Chemical Industry.

De Wilde T.,Ghent University | Spanoghe P.,Ghent University | Sniegowksi K.,Catholic University of Leuven | Ryckeboer J.,Catholic University of Leuven | And 2 more authors.
Chemosphere | Year: 2010

Laboratory column displacement experiments were performed to examine whether addition of pesticide-primed material to the matrix of an on-farm biopurification system (BPS), intended to remove pesticides from agricultural waste water, positively affects the degradation of mobile pesticides in the system. Percolated column microcosms with varying types and amounts of metalaxyl and/or isoproturon-primed material or non-primed material were irrigated with water artificially contaminated with isoproturon and/or metalaxyl. Transport of isoproturon was well described using the convection dispersion equation and no dissipation was observed, even in columns inoculated with isoproturon-primed material. On the other hand, delayed dissipation of metalaxyl, i.e., after an initial lag phase, was encountered in all columns receiving metalaxyl. In all systems, dissipation could be described using the Monod model indicating that a metalaxyl degrading population grew in the systems. There was a clear correlation between the lag phase and the amount of metalaxyl-primed material added to the system, i.e., increasing amounts of added material resulted into shorter lag phases and hence more rapid initiation of growth-associated metalaxyl degradation in the system. Our observations suggest that indeed pesticide-primed material can reduce the start-up phase of degradation of mobile pesticides in a BPS and as such can increase its efficiency. However, the primed material should be chosen carefully and preferentially beforehand tested for its capacity to degrade the pesticide. © 2009 Elsevier Ltd. All rights reserved.

De Wilde T.,Ghent University | Spanoghe P.,Ghent University | Ryckeboer J.,Catholic University of Leuven | Jaeken P.,PCF Royal Research Station of Gorsem | Springael D.,Catholic University of Leuven
Environmental Pollution | Year: 2010

Transport of bentazone, isoproturon, linuron, metamitron and metalaxyl were studied under three different flows in macrocosms. The aim was to verify the observations from Part I of the accompanying paper, with an increase in column volume and decrease in chemical and hydraulic load. Very limited breakthrough occurred in the macrocosms for all pesticides, except bentazone, at all flows. From batch degradation experiments, it was observed that the lag time of metamitron and linuron decreased drastically in time for all flows, indicating a growth in the pesticide degrading population. This in contrast to isoproturon and metalaxyl, where an increase in lag time could be observed in time for all flows. From the batch degradation experiments, it could be concluded that the influence of flow on the lag time was minimal and that the inoculation of the pesticide-primed soil had a little surplus value on degradation. © 2010 Elsevier Ltd. All rights reserved.

De Wilde T.,Ghent University | Spanoghe P.,Ghent University | Ryckeboer J.,Catholic University of Leuven | Jaeken P.,PCF Royal Research Station of Gorsem | Springael D.,Catholic University of Leuven
Environmental Pollution | Year: 2010

The efficiency of a biopurification system, developed to treat pesticide contaminated water, is to a large extent determined by the chemical and hydraulic load. Insight into the behaviour of pesticides under different fluxes is necessary. The behaviour of metalaxyl, bentazone, linuron, isoproturon and metamitron was studied under three different fluxes with or without the presence of pesticide-primed soil in column experiments. Due to the time-dependent sorption process, retention of the pesticides with intermediate mobility was significantly influenced by the flux. The higher the flux, the slower pesticides will be sorbed, which resulted in a lower retention. Degradation of the intermediate mobile pesticides was also submissive to variations in flux. An increase in flux, led to a decrease in retention, which in turn decreased the opportunity time for biodegradation. Finally, the presence of pesticide-primed soil was only beneficial for the degradation of metalaxyl. © 2010 Elsevier Ltd. All rights reserved.

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