The study looked at how well waste stabilization ponds in Brazil can remove intestinal worm eggs from wastewater. They found that certain ponds can remove 88-100% of Ascaris spp. eggs and 91-100% of hookworm eggs. One pond combination produced egg-free water with a 18.9-day retention time. Effluents with less than or equal to 1 egg per liter can be made with a 1-day anaerobic pond, followed by a 5-day secondary facultative and a 5-day maturation pond.