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One of the primary problems related to pesticide use is disposal of the lowconcentration pesticidecontaminated wastewater resulting from leftover mixes, equipment rinsing, and general cleanup. The costs, safety issues, and potential environmental impacts associated with this pesticidecontaminated waste are major concerns for most applicators. As part of a broad effort by the University of Tennessee Agricultural Experiment Station and the Tennessee Agricultural Extension Service, researchers have been carrying out a series of projects that will result in construction of fullscale wastewater handling facilities on branch research stations. This study reports on the first project phase, whose objectives were: to choose a wastewater disposal technique from alternatives presented in the scientific literature, and to propose an optimal set of operating conditions that could reasonably be followed by typical pesticide applicators. The wastewater disposal technique selected by the study was designated the SoilBased BioReactor, or SBBR. This method, which has been in use for quite some time, involves application of pesticidecontaminated wastewater to soil beds. The water evaporates from the moist soil surface, and the pesticide is adsorbed to the soil and then broken down by chemical and biological activity. Earlier studies found this to be an effective technique with no longterm accumulation of pesticide, no measurable volatilization of pesticide, and low management requirements. These earlier studies, however, made no attempt to optimize the system, so that became the second study objective. The optimum system resulting from this study used a mediumfine textured soil (a silt loam), operated at a temperature elevated above the ambient much as would be the case in a greenhouse, and used an application method providing five days of nearsaturation followed by five days of drying. Under these conditions, and assuming 180 days of wastewater application followed by 120 days of clean water application, over 98% of atrazine and over 90% of fluometuron active ingredients applied with the wastewater had dissipated. The study results indicate that an SBBR system using simple construction and management techniques can effectively dispose of pesticidecontaminated wastewater on a research farm or for a typical small to mediumsize applicator.