Tertiary-treated wastewater as a potential water source for sustainable aquaculture: A laboratory-scale experiment with Cyprinus carpio

Aquaculture in treated wastewater (TWW) has been practiced around the world, yet this field of research is backed with only scant scientific data, especially the aspect of the bioaccumulation of organic micropollutants (OMPs) in fish. The objectives of this study were to evaluate how fish culture in tertiary TWW (TTWW) affects commercially important traits, such as fish survival, growth rate and health, and to assess the potential risks associated with food safety and consumer protection. Cyprinus carpio juveniles were raised in 0%, 50% and 100% TTWW, for five months. Fish performance and health parameters were not affected by exposure to TTWW. The levels of heavy metals in the fish muscle were below the FAO and EU maximal permitted levels in edible fish. Seven out of 40 screened OMPs were detected in the TTWW samples at least once. Out of the 19 analyzed OMPs in fish tissues, four were detected in exposed fish. Carbamazepine and diclofenac were detected in the muscles and livers of fish grown in 50% and 100% TTWW at measurable concentrations. Carbamazepine-epoxide and diphenhydramine concentrations were below the limit of quantification (LOQ) in the muscle of the exposed fish, while diphenhydramine was detected above the LOQ level in two liver samples of fish grown in 100% TTWW. Based on the presented findings, TTWW can be successfully used for growing fish, and TTWW-grown fish met all the existing standards for heavy metals accumulation. However, the issue of OMP's bioaccumulation needs to be further studied in different fish species and culture conditions to broaden the perspective of the findings.