Biobeds for Environmental Protection from Pesticide Use—A Review

Abstract

Biobeds originated in Sweden in response to the need for simple and effective methods to minimize environmental contamination from pesticide use, especially when filling spraying equipment, a typical point source of contamination. The biobed system has attracted attention in several countries, where work is being conducted to adapt it to local conditions and applications. As a consequence, the biobed system has been more or less modified and sometimes renamed, for example, as biomassbed in Italy, biofilter in Belgium, and Phytobac and biobac in France. The effectiveness and simplicity of the biobed also make it suitable for use in developing countries, and different adaptations of the biobed concept now exist in, for instance, Peru, Guatemala, and Ecuador. When the modification of the biobed includes an intention to use it for retention and degradation of pesticides in sprayer washings, the construction has to be adapted to, for example, lined biobeds to ensure that no pesticide leaching will occur. Replacement of some of the original materials in the Swedish biomixture (straw, peat, and soil) can also change the performance of the system, for instance, the amount, activity, and composition of the microbial community that develops. This review presents the state of the art of biobeds and similar systems in Sweden and worldwide and identifies future research needs. Factors affecting the efficiency of biobeds in terms of degradation and retention of pesticides are discussed, with particular emphasis on the microbial processes involved.

Chlorpyrifos degradation in a Biomix: Effect of pre-incubation and water holding capacity

“…Straw stimulates growth of ligninolytic microorganisms and the production of extracellular ligninolytic enzymes as peroxidases and phenoloxidases. In addition, straw promotes growth of microorganisms, such as white-rot fungi, with the ability to degrade those pesticides characterized by an aromatic ring structure (Castillo et al, 2008). On the other hand, peat provides sorption capacity, high water retention ability regulating moisture in the biobed and, also abiotic degradation of pesticides (Torstensson and Castillo, 1997;Castillo et al, 2008).…”

“…In addition, straw promotes growth of microorganisms, such as white-rot fungi, with the ability to degrade those pesticides characterized by an aromatic ring structure (Castillo et al, 2008). On the other hand, peat provides sorption capacity, high water retention ability regulating moisture in the biobed and, also abiotic degradation of pesticides (Torstensson and Castillo, 1997;Castillo et al, 2008). Soil is an important source of microorganisms in the biomix and bacteria can act synergistically with fungi to degrade pesticides (Castillo et al, 2008).…”

“…On the other hand, peat provides sorption capacity, high water retention ability regulating moisture in the biobed and, also abiotic degradation of pesticides (Torstensson and Castillo, 1997;Castillo et al, 2008). Soil is an important source of microorganisms in the biomix and bacteria can act synergistically with fungi to degrade pesticides (Castillo et al, 2008). The presence of soil bacteria can enhance the extent of pesticide degradation (Maya et al, 2011) as well as degradation of other organic pollutants (Kotterman et al, 1998;Castillo et al, 2008).…”

“…Soil is an important source of microorganisms in the biomix and bacteria can act synergistically with fungi to degrade pesticides (Castillo et al, 2008). The presence of soil bacteria can enhance the extent of pesticide degradation (Maya et al, 2011) as well as degradation of other organic pollutants (Kotterman et al, 1998;Castillo et al, 2008).…”

Assessing the effectiveness of a three-stage on-farm biobed in treating pesticide contaminated wastewater

“…Lastly, compost is 77 added to increase sorption capacity, improve moisture content and decrease the pH to make 78 conditions favourable for fungi growth. The surface grass layer aids water regulation and prevents 79 surface crusting, thus limiting the formation of cracks that would open up preferential pathways for 80 pesticides to escape the biobed prior to degradation (Fogg et al, 2004;Castillo and Torstensson, 81 2007; Castillo et al, 2008). In lined biobed systems, common in the United Kingdom (UK), the 82 leachate is typically collected from the bottom of the biobed and re-used for either irrigation, 83 sprayer washing or as a carrier for further herbicide applications.…”