A messy situation: effects of treated human wastewater on aquatic biota

Abstract

Removal of personal care products (PCPs), pharmaceuticals and other substances from human wastewater is often unsuccessful and released back in to receiving water. This includes anti-psychotics and cosmetic additives, and inorganic nitrogen. These substances are capable of producing unintended biological changes in aquatic biota located downstream from wastewater treatment plants. The present study examined whether wastewater would cause adverse effects in aquatic biota. Medaka (Oryzias latipes) and the zooplankton (Daphnia magna) were used in a controlled laboratory study. Medaka and Daphnia were exposed to 0 %, 50 % and 90 % wastewater. Mortality, development, and reproduction (only in Daphnia) were observed. Daphnia were exposed as neonates and the medaka were exposed as eggs and hatched larvae. There was a significant beneficial effect of wastewater on Daphnia mortality, growth and reproduction (p < 0.001). While in contrast, wastewater had a significant negative effect on the medaka rate of hatching and embryo mortality (p < 0.05). These outcomes suggest that there are ecologically important changes occurring as a result of the release of wastewater into natural water bodies. In addition, this study also iterates the significance of using multiple organisms in environmental toxicological studies.