A filtering unit for the removal of pesticide residues from aqueous solutions

Pesticide loss during filling and washing spray tanks can be considerable especially where cooperative pesticide distribution centres exist (up to 200 1000-litre tanks daily). A filtering unit using readily available organic media (peat, moss and manure) was designed to filter out a variety of commonly-used pesticides in apple orchards. Each filtering unit received residues from 20 pesticide applications consisting of a typical pesticide treatment schedule for apples. Initial concentration of the pesticides in the wastewater was between 26 and 1820 mg 1 −1. Average removal efficiencies were > 99% for dodine. copper oxychloride, azinphos methyl, triadimefon, bitertanol, dithianon, fenarimol, chlorpyrifos ethyl, cyhexatin, benzomate, dinocap and benomyl. Removal efficiency for vamidothion averaged 61%; removal for sulphur was 73%. Bioassays with Daphnia magna and Gloeosporium sp. were performed to evaluate effluent toxicity.