A Case Study on Identifying the Toxicant in Effluent Discharged from a Chemical Plant

Three phase procedures of toxicity identification evaluation (TIE) were conducted using Daphnia magna to identify the toxicant in effluent discharged from a chemical plant in Nanjing. Phase I toxicity characterization procedures suggested nonpolar organic compounds were responsible for the whole effluent toxicity. In phase II toxicity identification procedures, the effluent toxicity was recovered by C18 solid-phase extraction and concentration steps. Gas chromatography–mass spectrometry (GC/MS) of the concentrate indicated that benzopyrone and phenol were present in the effluent at sufficient concentrations to cause the effluent toxicity. In phase III toxicity confirmation procedures, benzopyrone and phenol mixture tests and mass balance determinations with toxic units (TU) confirmed these compounds were the key toxicants accounting for 44.6% and 32.9% of the whole effluent toxicity, respectively.