Recovery of carbohydrate fraction from microalgal biomass grown in wastewater treatment photobioreactors: a biorefinery approach

En los últimos años, la búsqueda de nuevas materias primas renovables ha aumentado exponencialmente debido al gran consumo de materiales y los limitados recursos fósiles. Al mismo tiempo, un importante esfuerzo de investigación se centra en la gestión de las grandes cantidades de desechos generadas por las actividades humanas. Combinando ambos objetivos de investigación, la recuperación y la valorización de los componentes procedentes de desechos parecen ser la única solución sostenible. Las aguas residuales, que contienen gran cantidad de materia orgánica y nutrientes, son uno de los mayores residuos generados en nuestra sociedad. Se están estudiando procesos biotecnológicos con consorcios de microalgas y bacterias para el tratamiento de aguas residuales con el objetivo de mejorar los rendimientos de recuperación de los nutrientes (C, N, P, S ...), así como con el fin de obtener agua limpia para otras aplicaciones. Por lo tanto, esta tesis tiene como objetivo abordar la valorización de la biomasa de microalgas-bacterias cultivadas en fotobiorreactores de tratamiento de aguas residuales. Este trabajo se centra en la valorización de la fracción de carbohidratos de esta biomasa para producir biogás y monosacáridos fermentables, pero considerando el efecto de este proceso en otras fracciones valiosas de la biomasa, como proteínas y lípidos, y la generación de otros subproductos. El estudio de la recuperación de carbohidratos se aborda como una primera etapa de un proceso secuencial para la valorización integral de la biomasa, aplicando un concepto de biorrefinería.Departamento de Ingeniería Química y Tecnología del Medio AmbienteDoctorado en Ingeniería Química y Ambienta

PhD Conference in Chemical and environmental Enginering

Alternativas de valorización de biomasa algal crecida en plantas de tratamiento de purine

5ª Jornada de Doctorandos

Valorization of wastewaters via bioenergy and bioproducts using carbohydrates from microalga

Jornada Técnica Agroalimentaria: Alternativas a la Gestión Sostenible de los purines de cerdo.

Alternativas de valorización de biomasa algal procedente del tratamiento de purine

Study of steam explosion pretreatment and preservation methods of commercial cellulose

Steam explosion (150 – 200 ºC, 5 – 30 min) was performed on a commercial cellulose presented in two configurations (fiberized and compact sheet) and its effect on their chemical and physical properties was studied, along with the influence of two different preservation methods (acetone drying and freezing) after pretreatment. No degradation compounds were produced during pretreatment, although solid recovery (RS) decreased with temperature from 90% to 62%. Similar particle size and surface conditions (increased porosity) were found for both types of pretreated samples despite the extremely different initial configuration. Crystallinity diminished for 150 ºC samples, but 200 ºC pretreatment promoted recrystallization. Pretreatment also reduced polymerization degree, although enzymatic accessibility did not improve. Both acetone and freezing processes extremely affected cellulose properties. Acetone drying counterbalanced crystallinity and enzymatic accessibility variations of pretreated samples, while decreasing polymerization degree to 302. Freezing dramatically decreased enzymatic accessibility of pretreated samples down to 15.8%.UIC-Consejería de Educación Junta de Castilla y León, University of Valladoli

Optimisation of the production of fermentable monosaccharides from algal biomass grown in photobioreactors treating wastewater

Producción CientíficaBiomass grown in wastewater treatment photobioreactors is a cheap raw material with high contents of carbohydrates, proteins and lipids. This work studies the production of fermentable monosaccharides from three biomasses grown in piggery wastewater (P), domestic wastewater (W) and synthetic medium (S) by applying chemical pretreatment and enzymatic hydrolysis, using a Taguchi design. ANOVA identified temperature, chemical reagent type and chemical reagent concentration as significant operational parameters. However, the biomass concentration, pretreatment time, enzyme dosage and enzymatic hydrolysis time had no remarkable effect. The bacterial content of the biomass had no relevant impact on carbohydrate and protein solubilisation but had a remarkable effect on the degradation of the released carbohydrates (57, 60 and 37% for P, W and S), while also affecting lipid solubilisation. Pretreatment with HCl 2 M at 120 °C resulted the optimal conditions, achieving a monosaccharide recovery of 53, 59 and 80% for P, W and S biomasses, respectively.Gobierno regional de Castilla y León (UIC 071, CLU 2017-09 and VA080G18)Ministerio de Ciencia, Innovación y Universidades (project CTQ2017-84006-C3-1-R)Unión Europea - FEDER (CLU 2017-09 and CTQ2017-84006-C3-1-R

Ozonolysis: an advantageous pretreatment for lignocellulosic biomass revisited.

Ozonolysis, as a lignocellulosic biomass pretreatment, goes back to 80s; however, in the last years it is becoming widespread again owing to its efficiency and mild operation conditions. Ozone reacts preferably with lignin than carbohydrates, promoting biomass destructuration and delignification, and so the sugar release by enzymatic hydrolysis. The hydrolysate from pretreated biomass has being used as sugars source for second-generation fuels production, mainly ethanol, methane and hydrogen. Short-chain carboxylic acids are the main inhibitory compounds generated, being properly removed by water washing. The most common inhibitory compounds reported for other pretreatments, furfural and HMF (5-hydroxymethylfurfural) , are not found in ozone-pretreated hydrolysates. Composition of pretreated biomass and ozone consumption depends on several process parameters: reactor design, moisture content, particle size, pH, reaction time, ozone/air flow and ozone concentration. Additional studies are necessary to clarify process parameters effec

Breakthroughs in bioalcohol production from microalgae: Solving the hurdles

Bioethanol production from microalgae biomass has been proposed as an innovative alternative to substitute fossil fuel sources. Unlike other renewable sources (e.g., lignocellulosic materials), microalgae biomass has no lignin, which makes the carbohydrate extraction process easier and eventually it should help to develop cleaner and safer bioethanol production processes. Carbohydrates in microalgae can be present in a variety of forms (cellulose, starch, and/or glycogen) and located in different regions of the cells (inner, inside, outside). Carbohydrate type, location, and concentration will strongly depend on cultivation and operation conditions with concentrations ranging from 15% to 50%. Several steps must be applied to obtain bioethanol from this biomass. First, different methods can be employed to disrupt the cell wall and release the carbohydrates such as physical-mechanicals, chemicals, and/or a combination of them. After that, enzymatic hydrolysis could be required to convert the carbohydrates into simple sugars. Finally, a yeast or bacteria fermentation stage is performed to transform these sugars into ethanol. However, it is imperative that the principal parameters of these different steps should be optimized during the bioethanol production before industrial implementation, and more research on economic and life cycle analysis is needed to ensure the economic feasibility of the process.COS

Saccharification of microalgae biomass obtained from wastewater treatment by enzymatic hydrolysis. Effect of alkaline-peroxide pretreatment

An enzymatic method for the carbohydrate hydrolysis of different microalgae biomass cultivated in domestic (DWB) and pig manure (PMWB) wastewaters, at different storage conditions (fresh, freeze-dried and reconstituted), was evaluated. The DWB provided sugars yields between 40 and 63%, although low xylose yields (< 23.5%). Approximately 2% of this biomass was converted to byproducts as succinic, acetic and formic acids. For PMWB, a high fraction of the sugars (up to 87%) was extracted, but mainly converted into acetic, butyric and formic acids, which was attributed to the bacterial action. In addition, the performance of an alkaline-peroxide pretreatment, conducted for 1 hour, 50ºC and H2O2 concentrations from 1 to 7.5% (w/w), was essayed. The hydrolysis of pretreated microalgae supported a wide range of sugars extraction for DWB (55-90%), and 100% for PMWB. Nevertheless, a large fraction of these sugars (~30% for DWB and 100% for PMWB) was transformed to byproducts.INIA MICINN Junta de Castilla y Leó

24th European Biomass Conference & Exhibition

As a result of the current oil crisis, there is an increasing interest in the development of alternative energy sources characterized for being renewable, economically competitive and environmentally friendly. The production of biofuels through biomass conversion from lignocellulosic materials, or more recently, from microalgae biomass, seems to be an attractive option among them. Within the biofuel production, enzymatic hydrolysis represents a key point that must be carefully considered, as the costs derived from the commercial enzymes used during the hydrolysis can compromise the economical feasibility of the process. The microalgae biomass has proved to be an effective wastewater treatment with high nutrient contents. The nutrients accumulation (N and P) in the biomass, which was produced in these processes of treatment, becomes an attractive substrate for the enzyme production. This work aims at implementing the biorefinery concept by valorising the microalgae biomass produced from agro-food industry wastewater treatment as a substrate for enzyme production and the subsequent biofuel generation through enzymatic hydrolysis. Thus, the production of cellulases and xylanases has been tested for the fungal specie Trichoderma reesei QM9414 using microalgae biomass through solid-state fermentation (SSF). The microalgae biomass was obtained from a mixture of primary wastewater and fertilizer treatment in raceway reactor and thin layer, respectively. This biomass produced was a cocktail of microalgae, principally Scenedesmus obliquus with a content of 45.03% C, 7.80% N and 1.99% P. The fungus, initially stocked at 4ºC in the private collection, was inoculated in commercial potato dextrose agar (PDA) at 28ºC during 7 days, and was suspended in water using it as pre-inoculum. Enzyme production was conducted with different substrates: microalgae, 1:1 sugarcane bagasse:microalgae and 1:1 sugarcane bagasse:wheat bran. It was worked by adding different concentrations of saline solution at 28ºC during 7 days, reducing the external nutrients supply, demonstrating the advantages of using microalgae as a substrate for enzyme production. Each 24 hours two flasks were taken and the enzymes were suspended in water at 150 rpm during 1 h and then centrifuged at 20000xg during 20 min. The supernatants were used for enzyme activity assays that were conducted according to IUPAC recommendations. The enzymes, produced during this process, were used for the enzymatic hydrolysis of microalgae biomass, and other lignocellulosic materials such as sugarcane bagasse; reporting promising results compared with the commercial enzymes