1995-2009: what have we learned about effluent biotreatment in relation to environmental protection?

effl uent biotreatment regarding environmental protection, such as the reproductive capacity of fi sh. To address these concerns, a series of before-after studies were undertaken during the past decade. These included i) comparisons of effl uents before and after biotreatment by means of fi sh (vitellogenin activity and egg production) and Ceriodaphnia (young production) tests done in the laboratory and ii) comparisons of fi sh communities in a river before and after the installation of effl uent biotreatment at two mill sites. In all laboratory tests and with respect to all endpoints examined in these tests, the effects of the effl uents after biotreatment were less or nonexistent when compared with the effects of the effl uents before biotreatment. The assessment of the fi sh communities based on various metrics (e.g., percent piscivores, percent fi sh with anomalies) indicated improved conditions after the installation of biotreatment. Taken overall, the results indicated that biotreatment has improved effl uent quality and this has resulted in clear improvements for the receiving environment.