Assessing the risk associated with the presence of emerging organic contaminants in sludge-amended soil: A country-level analysis

Greece was used as case study and the environmental risk associated with the existence of 99 emerging organic contaminants (EOCs) in sludge-amended soil was estimated using risk quotient (RQ) approach. Data on the concentration levels of EOCs in sewage sludge was collected after literature review. Chemical analyses were also conducted for 50 pharmaceuticals and illicit drugs in sludge samples from Athens Sewage Treatment Plant. Risk assessment was based on both terrestrial and aquatic acute toxicity data, using both the maximum and the average measured concentrations of the target compounds. EC50/LC50 values were collected through literature review or using the ECOSAR program in cases that experimental values were not available. Triclosan seems to pose an environmental risk on the soil environment, as its RQ values exceeded 1, both in terrestrial and aquatic toxicity data based risk assessment. Calculations based on aquatic toxicity data showed that another eleven compounds had RQs higher than 1, most of them belonging to the classes of synthetic phenolic compounds and siloxanes. Tetradecamethylhexasiloxane presented the highest RQ, while high RQs were also calculated for decamethylcyclopentasiloxane and caffeine. No environmental risk for the terrestrial environment is expected due to the individual action of illicit drugs, perfluorinated compounds and benzotriazoles. The sludge source and the day of sampling affected the estimated threat due to nonylphenolic compounds; however these factors did not affect the estimated risk for siloxanes, caffeine and ofloxacin. Calculation of RQ values for the mixture of EOCs, using either the maximum or the average concentrations, far exceeded 1 (253 and 209, respectively), indicating a presumable threat for the terrestrial environment due to the baseline toxicity of these compounds. Countries that reuse sludge for agricultural purposes should include specific EOCs in national monitoring campaigns and study more thoroughly on their effects to the terrestrial environment. © 2016 Elsevier B.V

Wide-scope target analysis of emerging contaminants in landfill leachates and risk assessment using Risk Quotient methodology

Raw and treated leachate samples were collected from different landfills in Greece and analyzed for several groups of emerging contaminants using high resolution mass spectrometric workflows to investigate the possible threat from their discharge to the aquatic environment. Fifty-eight compounds were detected; 2−OH-benzothiazole was found at 84 % of the samples and perfluorooctanoic acid at 68 %. Bisphenol A, valsartan and 2−OH-benzothiazole had the highest average concentrations in raw leachates, after biological treatment and after reverse osmosis, respectively. In untreated leachates, Risk Quotients > 1 were calculated for 35 and 18 compounds when maximum and average concentrations were used, indicating an ecological threat for the aquatic environment. Leachates’ biological treatment partially removed COD and NH4+-N, as well as 52.3 % of total emerging contaminants. The application of reverse osmosis resulted in a 98 % removal of major pollutants, 99 % removal of total emerging contaminants and a significant decrease of ecotoxicity to Lemna minor. Beside the decrease of the detected micropollutants during treatment, RQs > 1 were still calculated for 13 and 3 compounds after biological treatment and reverse osmosis, respectively. Among these, special attention should be given to 2−OH-benzothiazole and bisphenol A that had RQ values much higher than 1 for all tested organisms. © 2020 Elsevier B.V