Removal of nonylphenol, pyrene and phenanthrene from sewage sludge and biosolids by cyclodextrins and rhamnolipids
| Autor: | Madrid Díaz, Fernando, Rubio Bellido, Marina, Villaverde Capellán, J., Morillo González, Esmeralda |
|---|---|
| Přispěvatelé: | Ministerio de Ciencia, Innovación y Universidades (España), Agencia Estatal de Investigación (España), European Commission |
| Rok vydání: | 2019 |
| Zdroj: | Digital.CSIC. Repositorio Institucional del CSIC instname |
| ISSN: | 2017-8247 |
| Popis: | 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 After the progressive implementation of the EU Directives 91/271/EEC and 98/15/EEC concerning urban wastewater treatment, many countries have increased the number of wastewater treatment plants (WWTP), and large amounts of sewage sludge are generated which require disposal. A useful and interesting option is the production of compost and the direct application of stabilised sludge to land. It has positive effects on soil, such as modification of soil structure and addition of organic matter and nutrients for plants, but there are potential hazards in this practice, such as spread of pathogens, odours, heavy metals and persistent organic contaminants. The use of sewage sludge in agriculture is regulated by the European Union¿s Council Directive 86/278/EEC, but it has not yet established maximum values for organic contaminants. However, the third draft of a working document on sludge to revise this Directive (EC 2010), although not being a formal regulation, limits the values for some organic compounds, such as some PAHs and nonylphenols (maximum concentration limits 6 and 450 mg kg-1 dry matter). PAHs are formed and released into the environment as by-products of incomplete combustions through natural and man-made sources (Morillo et al. 2007). They are highly toxic, present high persistence in the environment, low biodegradability and high lipophilicity. PAHs enter to wastewater-treatment plants through the sewerage and are almost completely concentrated in sludge because of their poor solubility in water and high adsorption capacity on solid particles. NP is a biotransformation product of nonylphenol ethoxylates (NPnEOs), an important group of non-ionic surfactants that are widely used in many commercial and household functions (detergents, cosmetic products, textiles). Due to its formation in sewer system, NP is commonly detected in influent wastewater of sewage treatment plants. NP causes estrogenic responses on aquatic organisms and it was listed as a priority substance in the Water Framework Directive (EU, 2001). Different methods are being proposed to remove PAHs and NPs from contaminated sewage sludge. Among these techniques, biological ones, based on their degradation by microorganisms are considered cost effective and environmentally friendly. However, the sequestration of these compounds in the sludge matrix declines their bioavailability and reduces the biodegradation of the contaminants. The reduction of bioavailability can be avoided with the use of amendments that increase the solubility of the contaminants. Recently, biogenic compounds as cyclodextrins (CDs) or biosurfactants (BSs) have been used in environmental applications, because they increase the solubility of hydrophobic organic contaminants (Morillo and Villaverde, 2017). CDs form inclusion complexes with a wide range of guest hydrophobic molecules, which are located in the interior cavity of the CDs. The hydrophilic properties of the outer zone of the CDs solubilize the resulting complex, increasing its bioavailability. CDs are formed by glucose monomers, so microorganisms could also use CDs as a biostimulant. Biosurfactants are also biodegradable compounds produced by bacteria or yeast, and also from plants and animals. Their amphiphilic properties reduce interfacial tension and increase solubility and bioavailability of hydrophobic compounds. Rhamnolipids (RLs) are a type of BSs synthesized by Pseudomonas aeruginosa. Due to their special hydrophilic and lipophilic moieties, RLs have enhanced PAH extractability from soils (Madrid et al., 2019). The objective of this study was to evaluate the performance of several CDs and a RL on the removal of Pyrene, Phenanthrene and Nonylphenol from several sewage sludge samples from different WWTPs located in Sevilla (Spain) and from a composted sludge. 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. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|