This study assesses wastewater from eleven WWTPs in South Australia and Oman, highlighting challenges from persistent contaminants of emerging concern (CECs) using advanced in vitro CALUX and fish cell bioassays. The cell lines included peroxisome proliferator-activated receptor gamma (PPARγ), estrogen receptor-α (ERα), androgen receptor (AR), glucocorticoid receptor (GR), progestogenic receptor (PR) and genotoxic (P53) human CALUX cells and epithelial fish-derived cells (EPC). No effects were observed on EPC cells. Significant ERα activity was detected in effluents at Sites G1 and B1 in South Australia (0.073 and 0.054 ng/L E2 equivalent, respectively) and at Site D in Oman (0.045 ng/L E2 equivalent). GR activity remained significant (0.43 ng/L dexamethasone equivalent) at Site G in Oman. Significant AR activity was observed at G1a (0.045 ng/L DHT eq.) and B1a (0.016 ng/L DHT eq.) in South Australia but decreased to levels below the LOQ and reporting limit. Similarly, in Oman, influent samples showed significant AR activity, which was significantly reduced after wastewater treatment. Removal efficiencies of detected activities were comparable, with significant AR removal (67–99.8 %). For ERα activity, most treatment processes in Oman achieved significant removal (84–99.8 %), while those in South Australia showed partial to negative efficiencies (17 to −20 %).