Occurrence, environmental impacts and removal of legacy and emerging contaminants from two wastewater and one water treatment plant in Southern Ontario. Part II: environmental impacts Shahram Tabe a, b, *, Joanne Parrott c , Monica Nowierski a , Vince Pileggi a , Sonya Kleywegt a and Paul Yang a a Ministry of the Environment and Climate Change, 40 St. Clair Ave. West, Toronto, Ontario M4 V 1M2, Canada b Department of Civil and Environmental Engineering, University of Windsor, Windsor, Ontario N9B 3A8, Canada c Environment Canada, 867 Lakeshore Rd., Burlington Ontario L7R 4A6, Canada *Corresponding author. E-mail: shahram.tabe@ontario.ca Abstract This is part two of a paper about the potential environmental impacts of treated effluent from a wastewater treat- ment plant (WWTP) discharging to the Detroit River in Windsor, Ontario, Canada. The WWTP uses conventional activated sludge with nitrification. The assessment was conducted over six months using a variety of established tests, including in vitro cell- based screening assays, as well as acute, chronic and full-life cycle in vivo exposures. Effluent monitoring included pharmaceutically active compounds and endocrine disrupting compounds. No tests reported significant toxicity. However, enhanced algal growth was observed in a Pseudokerchneriella subcapitata growth inhibition test. In full life-cycle fathead minnow exposure, liver-somatic index changes were noted in exposed fish – increases for males, decreases for females – and production of viable fry decreased. Neither alteration is thought biologically significant. Because the effluent is diluted substantially by the receiving water, the level of risk posed to aquatic receptors and the environment is probably negligible. Key words: emerging contaminants, endocrine disrupting compounds (EDCs), pharmaceutically active compounds (PhACs), wastewater treatment, in vitro assay, fish life-cycle exposure INTRODUCTION This is the second of two papers on the occurrence, removal, and assessment of environmental impacts of many emerging and legacy contaminants, in water sources and drinking water. The study comprised two sets of experiments including occurrence and removal of endocrine disrupting compounds (EDCs) and pharmaceutically active compounds (PhACs) at two wastewater treatment plants (WWTPs) and one WTP in Windsor, Ontario, Canada (Part I), and the environmental impacts of the effluent from one of the WWTPs, referred to as WWTP-1 (this paper). Although WWTPs are not designed to treat PhACs/EDCs, a portion of the substances is removed or transformed by conventional processes. However, a number of PhACs/EDCs persist through the treatment processes and are discharged with the final effluent. Even if the substances degrade or trans- form quickly, continuous discharge can result in pseudo-persistence in aquatic environments. Such discharge may harm the environment. © IWA Publishing 2016 Water Practice & Technology Vol 11 No 2 315 doi: 10.2166/wpt.2016.036 Downloaded from https://iwaponline.com/wpt/article-pdf/11/2/315/381578/wpt0110315.pdf by guest on 13 June 2020