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From three different sewage treatment plants, three effluent samples were collected to demonstrate applicability of a non-targeted mass spectrometric analysis for exploration and identification of organic ecotoxicants in the samples. Five known organic ecotoxicants were added to these samples to simulate toxic samples. The non-targeted analyses of the simulated samples were conducted with a liquid chromatograph-high resolution mass spectrometer. The whole effluent toxicity tests were conducted by using Raphidocelis subcapitata as the test organism. The number of components detected by the analyses was 3,427. Relationships between peak volumes of these detected components and the samples' toxicities were analyzed by the orthogonal projections to latent structure-regression analysis, the correlation analysis and the multiple regression analysis. An ion of m/z 286.9436 was found as a possible monoisotopic ion of the added toxicant. A molecular formula of the ion was determined by its accurate mass and natural isotopic pattern. The determined molecular formula was searched in an advanced mass spectral database. The database suggested that the found toxicant is triclosan (an antibacterial and antifungal agent). It was identified as triclosan by a co-chromatography using a reference standard reagent. Because a dominant toxicant was triclosan among the added five toxicants, the applicability was successfully demonstrated.

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The effect of anionic surfactants on organic matter degradation during enhanced in-sewer purification by porous media was evaluated in this study. Surfactants, wherein the anionic subgroup comprises a significant portion of surfactant load in domestic wastewater, are anticipated to affect biofilm activity during enhanced in-sewer purification negatively. To evaluate this, synthetic feed containing a fixed concentration of readily biodegradable organic matter and different anionic surfactant concentrations was supplied intermittently to an airtight channel intended for enhanced in-sewer purification for 32 days. Dodecylbenzene sulfonate, as sodium dodecylbenzene sulfonate, was used as a model anionic surfactant. Results showed that increased anionic surfactant concentration up to 160 mg L −1 decreased aerobic organic matter degradation rate by up to 36% of the initial rate. It was inferred from the compositional analysis of effluent surfactants by liquid chromatography tandem mass spectrometry that the accumulation of possible inhibitory intermediate products may have caused decline in rates over time. Recovery of aerobic activity related to organic matter degradation was observed with continued operation under decreasing influent anionic surfactant concentration. Findings highlight that although increased surfactants concentrations negatively affected aerobic activity, aerobic organic matter was still continuously degraded aerobically.