Efficacy of sedimentation basins of a nematology laboratory in retaining plant-parasitic nematodes

Laboratories working with regulated plant-parasitic nematodes need to ensure that those nematodes are contained within the quarantine facility. Solid or liquid waste produced during the nematode extraction process has to be deposited in such a way that there is no risk of nematodes spreading. Autoclaving works well for solid waste but uses substantial amounts of energy and thus is often considered too expensive for the enormous amount of wastewater accumulating during nematode extraction. Therefore, there is considerable interest in using less energy-consuming alternatives, such as sedimentation basins. However, published information on the efficacy of sedimentation basins in retaining plant-parasitic nematodes is almost non-existent. In this study, the efficacy of a three-step sedimentation system under routine and artificially nematode-enriched conditions was investigated. Under all experimental conditions, nematode cysts or part of cysts were never found to escape the sedimentation system. This also accounts for plant-parasitic nematodes (eggs and vermiform stages) during routine operation. However, under artificially nematode-enriched conditions (supply of up to several million nematodes) and maximum water flow rates, single specimens of plant-parasitic nematodes were detected in the effluent of the last sedimentation basin that feeds into the closed municipal sewage system. Although wastewater treatment was not investigated in this study, the combination of a system of sedimentation basins plus subsequent wastewater treatment in sewage plants is considered a cost-effective method to contain plant-parasitic nematodes during routine operation.