Biodegradation of nonylphenol by novel bacterial strains isolated from sewage sludge

Póster presentado en el 7th International Conference on Sustainable Solid Waste Management Crete Island, Greece, 26–29 June 2019.- El texto se puede ver en http://uest.ntua.gr/heraklion2019/proceedings/proceedings.html
Nonylphenol (NP) and nonylphenol mono (NP1EO) and diethoxylates (NP2EO; referred as NPE) are used as nonionic surfactants in a large variety of industrial and domestic applications. Although the use of NPEs has been banned under Council Directive 2003/53/EC (European Union 2003), their environmental presence and risk is still high because of its historical and pervasive widespread use. In the waste water treatments plants (WWTPs) the biodegradation of NPEs leads to an increase in the concentration of NP, much more hydrophobic. As a consequence, NP has high affinity for sludge flocs, and is recalcitrant to wastewater and sludge treatment. This is why NP is the main alkylphenol associated with sewage sludge (90%; Soares et al. 2008). Sewage sludge is rich in organic matter and nutrients, and can be utilized in land applications as fertilizer, soil conditioner and composting material. NP in sludge may harm the environment due to its endocrine disrupting properties. It can be accumulated in agricultural soils and contaminate surface water and groundwater, and even concentrate in plants and animals. Different methods have been proposed to remove organic contaminants from sewage sludge (Semblante et al., 2015), such as ozonation, Fenton treatment, UV oxidation, ultrasonication or thermal treatment, but these are expensive treatments. On the contrary, bioaugmentation, which is a procedure that involves the addition of exogenous or endogenous microorganisms to enhance the biodegradation of contaminants, is being considered as a relatively cheap and ecological treatment to further improve organic contaminants biodegradation in sewage sludge and biosolids. The aim of this work was to add NP amendments on sewage sludge to obtain degrading bacterial consortia, and then to isolate bacteria from the NP enrichment cultures in order to test for their ability to degrade it, in a search for strains appropriated for bioremediation uses. The better NP-degrading bacteria obtained will be tested for NP biodegradation in solution and on sewage sludge. The final objective of this research is to use specific NP-degrading bacteria during the period of sewage sludge composting to reduce the NP content in the final biosolids obtained.
This work was supported by the Spanish Ministry of Science, Innovation and Universities (co-funded by the Fondo Europeo de Desarrollo Regional, FEDER), under the research project CTM2017-82472-C2-1-R