1 Department of Environmental Engineering, Technical University of Denmark2 Environmental Chemistry, Department of Environmental Engineering, Technical University of Denmark3 Department of Environmental Science and Engineering, Technical University of Denmark4 Technical University of Denmark5 Lund University6 Lund University
Application of sludge from wastewater treatment plants (WWTPs) on agricultural land is an approach for nutrient recycling that rise challenges due to recalcitrant and harmful pollutants. In this study we assessed the feasibility of a seed germination test to evaluate sludge ecotoxicity and compared germination responses from two test parameters, root elongation and seed germination (sprouts elongation) of the barley (Hordeum vulgare). 2nd objective was to evaluate sewage sludge pre-treatments at batch-scale of sludge samples from two WWTPs using anaerobic digestion, and thermal and ozonation pre-treatments. Glyphosate and eco-labelled soil were used as references. Inhibition of germination of seeds exposed to the glyphosate and sludge was registered and thus germination was successfully applied for sludge ecotoxicity assessment, and using the root elongation as the end-point was both faster and more precise than the sprout elongation. In comparison of pre-treated raw samples and pre-treaded and subsequently digested sludge the effects of the pre-treatments were limited and hence, the anaerobic digestion in it-self gave the foremost detoxification.