Avances hacia un desarrollo sostenible mediante el tratamiento y revalorización de residuosestudio de la aplicación industrial de los productos obtenidos

Abstract

Un desarrollo sostenible pasa por satisfacer las necesidades de las generaciones presentes sin comprometer las posibilidades de las del futuro para atender sus propias necesidades. Por tanto desde este punto de vista es interesante, el buscar materias primas y fuentes de energías renovables que nos permitan que el medio ambiente pueda recuperarse al mismo ritmo que es afectado por la actividad humana. Nuestra comunidad Autónoma genera gran cantidad de residuos agroindustriales, por ejemplo de naturaleza lignocelulósica, que pueden potenciar el desarrollo de ciertos problemas medioambientales como, el efecto invernadero o la destrucción de la capa de ozono, cuando estos no son tratados de una forma adecuada. En este sentido es necesario concienciar a la sociedad y a los distintos sectores empresariales que algunos residuos agroindustriales pueden ser utilizados como materia prima para la obtención de productos de interés como el ácido láctico, biosurfactantes o bioemulsionantes etc. El grupo de investigación donde se desarrollará este proyecto de Tesis es experto en el fraccionamiento de residuos de naturaleza lignocelulósica para la obtención de diferentes aditivos químicos y alimentarios, ya sea mediante procesos biotecnológicos o a través de procesos de extracción, aunque de momento no se ha profundizado demasiado en la aplicación industrial de estos productos obtenidos. Por tanto los objetivos de esta Tesis Doctoral se pueden resumir en los siguientes apartados: 1-Búsqueda de nuevas tecnologías que nos puedan facilitar el tratamiento de residuos agroindustriales de una forma sostenible con el medio ambiente 2-Extracción, caracterización y purificación de los metabolitos obtenidos tas el fraccionamiento y posterior tratamiento biotecnológico de los residuos agroindustriales. 3- Estudio de diferentes aplicaciones industriales de metabolitos obtenidos a partir del fraccionamiento y posterior tratamiento biotecnológico de los residuos agroindustriales seleccionados, entre los que se encuentran por ejemplo los residuos procedentes de la industria vitivinícola. Serán objeto de estudio metabolitos como el ácido láctico, biosurfactantes, biemulsionantes, antioxidantes etcUn desenvolvemento sostenible pasa por satisfacer as necesidades das xeracións presentes sen comprometer as posibilidades das do futuro para atender as súas propias necesidades. Xa que logo desde este punto de vista é interesante, o buscar materias primas e fontes de enerxías renovables que nos permitan que o medio ambiente poida recuperarse ao mesmo ritmo que é afectado pola actividade humana. A nosa comunidade Autónoma xera gran cantidade de residuos agroindustriales, por exemplo de natureza lignocelulósica, que poden potenciar o desenvolvemento de certos problemas medioambientales como, o efecto invernadero ou a destrución da capa de ozono, cando estes non son tratados dunha forma adecuada. Neste sentido é necesario concienciar á sociedade e aos distintos sectores empresariais que algúns residuos agroindustriales poden ser utilizados como materia prima para a obtención de produtos de interese como o ácido láctico, biosurfactantes ou bioemulsionantes etc. O grupo de investigación onde se desenvolverá este proxecto de Tese é experto no fraccionamiento de residuos de natureza lignocelulósica para a obtención de diferentes aditivos químicos e alimentarios, xa sexa mediante procesos biotecnológicos ou a través de procesos de extracción, aínda que de momento non se profundou demasiado na aplicación industrial destes produtos obtidos. Xa que logo os obxectivos desta Tese Doctoral pódense resumir nos seguintes apartados: 1-Procura de novas tecnoloxías que nos poidan facilitar o tratamento de residuos agroindustriales dunha forma sostenible co medio ambiente 2-Extracción, caracterización e purificación dos metabolitos obtidos tas o fraccionamiento e posterior tratamento biotecnológico dos residuos agroindustriales. 3- Estudo de diferentes aplicacións industriais de metabolitos obtidos a partir do fraccionamiento e posterior tratamento biotecnológico dos residuos agroindustriales seleccionados, entre os que se atopan por exemplo os residuos procedentes da industria vitivinícola. Serán obxecto de estudo metabolitos como o ácido láctico, biosurfactantes, biemulsionantes, antioxidantes etcFrom several decades agro-industrial wastes have been a focus of attention for several researchers worldwide, because they can be used as raw material to generate diverse products of commercial interest, this situation follows prevailing in the actuality and it is expected that it will continue in the future. Besides of the economic interest that it supposes for the production of products of high value, the utilization of agro-industrial waste or by-products has incidences in the preservation of the environment when considering the development of technologies oriented to a sustainable transformation of the natural resources. In this Thesis it has been studied the revalorization and the integral utilization of two agro-industrial wastes or by-products, vineyard pruning waste and corn steep liquor, obtained from the wine industry and from the corn industry respectively. Vineyard pruning waste is a lignocellulosic material of polymeric nature constituted mainly by lignin, cellulose and hemicelluloses. During the activity of wine industry vineyard pruning waste is obtained after the stage of vineyard pruning and traditionally is burned in the field generating some gases like CO2, CH4 and N2O that favors the green house effect. Besides, the lignocellulosic materials, and in this case vineyard pruning waste is composed by lignin that when it is burned gives place to some aromatic compounds of polycyclic nature which can inhibit the synthesis of DNA and induce the development of tumors in the animal species. Thus, it would be interesting to improve the environmental management of lignocellulosic wastes, avoiding the indiscriminate burnt of these materials. Vineyard pruning waste is an especially attractive source by its content in compounds of different nature (like sugars, pigments, fiber, protein, polyphenols, cellulose or lignin) and can be potentially useful when these compounds are transformed in products of high value by means of the appropriate reactions. Thus, the production of biosurfactants and bioadsorbents can revalorize this agricultural residue providing useful products with application in the food, pharmaceutical, cosmetic, agricultural and environmental industries. The prehydrolysis of vineyard prunning waste with sulphuric acid followed of a neutralization stage of hemicellulosic sugars and fermentation of this sugars by the lactic acid bacterium Lactobacillus pentosus is the method employed in this Thesis for obtaining biosurfactants with emulsify capacity. Following, after lactic acid fermentation, the microbial biomass is subjected to an extraction with saline buffer phosphate, that allows to obtain the biosurfactant that it was cell bounded to the plasmatic membrane of lactic acid bacterium. In this Thesis it has been optimized the extraction, in absence of salt, of the biosurfactant produced by L. pentosus and it has been carried out the characterization of the lipophilic chain. The importance of the extraction of these compounds in absence of salt, is related to the direct application of the biosurfactant extract to the soil in order to avoid the phytotoxic effect produced by salt. Regarding its applications in the pharmaceutical and cosmetic industry as well as in the environmental industry, it has been evaluated the emulsify capacity of the biosurfactant produced by L. pentosus to stabilize aqueous emulsions containing rosemary oil, gasoline or fluorene. Also, it has been studied the adsorption of the biosurfactant produced by L. pentosus on sediments for possible application in froth flotation processes. During the acid hydrolysis of vineyard pruning waste, in addition to the hemicellulosic liquors is generated a solid fraction composed mainly by cellulose and lignin. This fraction has been proposed for the formulation of bioadsorbents with application in the treatment of wastewater for winery industry contaminated with color compounds and micronutrients. Thus it is aimed the formulation of a low-cost bioadsorbent of biodegradable nature. On the other hand, in the corn wet milling industry, during the extraction of flour, a residual stream, corn steep liquor (CSL) is generated, whose usual applications, until the moment, has based on the utilization of these liquors as low-cost nitrogen source in fermentative processes or like supplement for animal feed. In this Thesis, based on the knowledge of the presence of lactic acid bacteria in this stream, corn steep liquor has been evaluated as source for obtaining low-cost biosurfactant and a process for the extraction and characterization of this surface-active compound has been developed. Besides, corn steep liquor has been evaluated as nutritional supplement for lactic acid bacteria after the biosurfactant extraction.