Wastes from the olive oil production in sustainable bioremediation systems to prevent pesticides water contamination

Abstract

Installation of biobed biopurification systems at farm level, traditionally composed of soil, peat and straw, to reduce point source contamination is difficult in some countries where peat is not environmentally or economically feasible. This study evaluates the use of local organic wastes from olive oil production such as wet olive cake and its vermicompost as substitutes of peat and olive tree pruning as substitute of straw to perform robust biobeds capable of removing mixtures of pesticides at high concentrations. Adsorption capacity of the novel biomixtures was comparable to or higher than traditional one. The biomixture with soil and olive tree pruning showed the highest pesticides adsorption, except for imidacloprid. The biomixture with soil, vermicompost and olive tree pruning showed dissipation efficiency of dimethoate, imidacloprid and oxyfluorfen (>73%) higher than traditional biobed. Meanwhile, the biomixture with soil and vermicompost was the alternative biomixture with the highest dissipation of diuron (54%) and tebuconazole (35%) but it was lower than traditional biomixture (59 and 47% for diuron and tebuconazole, respectively). The low dissipation of these compounds (<60%) is probably due to competitive and/or inhibitory phenomena between the pesticides in the mixture. Labile organic compounds from biomixture components such as water-soluble carbon constitute a more available carbon source for microorganisms that may counteracted the negative impact of high pesticide load on biomixture microbial populations, but they may have limited the pesticides dissipation. Novel biomixtures composed of olive oil mill waste may be a sustainable and less expensive alternative to traditional biomixture.