Novel processing routes for effective sewage sludge management (ROUTES)

The ROUTES project aimed to evaluate new routes of sewage sludge treatment and management matching the needs of different wastewater origins and different digested sludge utilisations. Elimination of micropollutants was targeted for agricultural sludge application, and minimising the production volume for other sludge disposal routes. Research of ECT in sludge-soil interactions focussed on three aspects: characterising the ecotoxicity of selected sludge-associated pollutants, assessing and comparing the ecotoxicity of digested sludge samples from different novel sludge stabilisation processes, and investigating in the field the abundance and community structure of the soil fauna after several years of sewage sludge application.

Biotests with the azoles ketoconazole, climbazole and fluconazole and the quaternary ammonia compound benzyldimethyldodecylammonium chloride provided evidence that these ingredients of pharmaceuticals and personal care products are similarly toxic to plants as fungicides used in agriculture.

All digested sludge samples showed negative effects on the tested soil bacteria and earthworms only at concentrations exceeding those resulting from common European sludge application rates by at least factor 30. Correlation of effects with the sludge concentrations of some pollutants indicate that an efficient stabilisation of the digested sludge may be more relevant for reducing its toxicity than minimising the total concentration of single pollutants.

A  description and discussion of the applied methods and the obtained results can be found in the following publications:

Coors, A., Richter, E., Lorenz, P., Römbke, J., Gianico, A. (2013). Ecotoxicity of sewage sludge. Minimization, recycling of materials, enhanced stabilisation, disposal after recovery. In: Mininni, M. (ed.), Effective sewage sludge management. Quaderni de ‘la Ricerca Scientifica’ 120, Istituto di Ricerca sulle Acque, Rome, p. 211-223.

Braguglia, C.M., Coors, A., Gallipoli, A., Gianico, A., Guillon, E., Kunkel, U., Mascolo, G., Richter, E., Ternes, T.A., Tomei, M.C., Mininni, G. (2015). Quality assessment of digested sludges produced by advanced stabilization processes. Environmental Science and Pollution Research 22, 7216-7235.

Richter, E., Roller, E., Kunkel, U., Ternes, T.A., Coors, A. (2016). Phytotoxicity of wastewater-born micropollutants – characterisation of three antimycotics and a cationic surfactant. Environmental Pollution 208, 512-522. [read more]