Abstract

A. Lemerhyeratte, M. Zougagh, O.Id El Mouden, R. Salghi, L. Bazzi, A. Hormatallah and S. Zine

A potential method for cleaning water from point-source pollution by organic compounds using biological reactors. In this study, five reactors were tested for their ability to retain and degrade pesticides. The pesticides tested were the insecticide chlorpyriphos ethyl (CE), malathion (MAL), dimethoate (DIM) and methamidophos (MET). The reactors were filled with differing mixtures of soil, bleaching earth and straw. The reactor volume was 10 L. Forced circulation of the contaminated solution was programmed to decontaminate the solution. Both retention and degradation of the compounds by the reactors was studied. The degradation rate of the pesticides in the reactors was fast. The reactors retained CE, MAL and DIM very strongly, and retained MET less strongly. The half-life of all pesticides in the reactors was less than 21 days, compared to literature values of 60–70 days in soil. The combined retention and fast degradation make the biofilter a feasible technique to reduce spill-related and point environmental contamination by pesticides. The technique is most effective against persistent pesticides, while for mobile pesticides, the efficiency can be improved with several passages of the contaminated solution through biofilters.

Biobeds; pesticides; soil; bleaching earth and straw

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