Fate of methidathion residues in biological waste during anaerobic digestion

• Published in: Chemosphere (Oxford) Vol. 48; no. 3; pp. 287 - 297
• Main Authors: Vorkamp, Katrin, Kellner, Esther, Taube, Jörg, Möller, Kai D, Herrmann, Reimer
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.07.2002; Elsevier
• Subjects: Agriculture, rearing and food industries wastes; Anaerobic digestion; Applied sciences; Bacteria, Anaerobic; Biodegradation, Environmental; Biological and medical sciences; Biological treatment of sewage sludges and wastes; Biological waste; Biotechnology; Carbon - metabolism; Environment and pollution; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Hydrogen-Ion Concentration; Hydrolysis; Industrial applications and implications. Economical aspects; Insecticides - metabolism; Methidathion; Organothiophosphorus compounds; Organothiophosphorus Compounds - metabolism; Pesticide residues; Pollution; Refuse Disposal; Solubility; Temperature; Wastes; Hydrolysis; Methidathion; Pesticide residues; Anaerobic digestion; Organothiophosphorus compounds; Biological waste; Insecticide; Biodegradability; Pollutant behavior; Waste treatment; Pesticides; Temperature effect; Thermophily; Organic wastes; Organic dithiophosphonate; Composting; Medium effect; Mesophily; pH; Biological wastes; Organophosphorus compounds; Biological treatment
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/S0045-6535(02)00095-4

The aim of this study was to examine the fate of the organothiophosphorus pesticide methidathion during anaerobic digestion of biological waste. Three reactor experiments were conducted under various conditions of temperature, pH and retention time. The influence of pH and temperature as well as the partitioning between solid and aqueous phase were studied in batch experiments. The mesophilic (25, 35 °C) reactor experiments showed a decline to about 10% of the maximum methidathion concentration within 30–80 d. In the thermophilic (55 °C) reactor experiment, methidathion disappeared within 20 d. The batch experiments showed an abiotic hydrolysis of methidathion over the experiment period of 4 d, accelerated by alkaline conditions (pH 10.5 and 12.8) and high temperatures (55 °C). The hydrolysis was also noticeable at a neutral pH, while methidathion was most stable at weakly acid pH values. Methidathion bonded strongly to the biological waste, and the amount released into the water phase was below the maximum aqueous solubility. About 10% of methidathion remained non-extractable. High concentrations of dissolved organic carbon and yeast extract as a model substance for disintegrated cells further reduced the content of methidathion in the water phase, possibly caused by co-sorption to the solid organic matter.