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- Hydrogenation of rapeseed oil for production of liquid bio-chemicalsPublication . Pinto, Filomena; Martins, Susana; Gonçalves, Maria Margarida; Costa, Paula; Gulyurtlu, Ibrahim; Alves, Andreia; Mendes, BenildeThe main objective of rapeseed oil hydrogenation tests was the production of liquid bio-chemicals to be used as renewable raw material for the production of several chemicals and in chemical synthesis to substitute petroleum derived stuff. As, hydrogenation of vegetable oils is already applied for the production of biofuels, the work done focused in producing aromatic compounds, due to their economic value. The effect of experimental conditions on rapeseed oil hydrogenation was studied, namely, reaction temperature and time with the aim of selecting the most favourable conditions to convert rapeseed oil into liquid valuable bio-chemicals. Rapeseed oil was hydrogenated at a hydrogen initial pressure of 1.10 MPa. Reaction temperature varied in the range from 200 C to 400 C, while reaction times between 6 and 180 min were tested. The performance of a commercial cobalt and molybdenum catalyst was also studied. The highest hydrocarbons yields were obtained at the highest temperature and reaction times tested. At a temperature of 400 C and at the reaction time of 120 min hydrocarbons yield was about 92% in catalyst presence, while in the absence of the catalyst this value decreased to 85%. Hydrocarbons yield was even higher when the reaction time of 180 min was used in the presence of catalyst, as the yield of 97% was observed. At these conditions hydrocarbons formed had a high content of aromatic compounds, around 50%. For this reason, the viscosity values of hydrogenated oils were lower than that established by EN590, which together with hydrogenated liquids composition prevented its use as direct liquid fuel to substitute fossil gas oil for transport sector. However, hydrocarbons analysis showed the presence of several valuable compounds that encourages their use as a raw material for the production of several chemicals and in chemical synthesis.
- Chemical and bioassay fractionation of chars obtained in the co-pyrolysis of different wastesPublication . Bernardo, Maria; Lapa, Nuno; Gonçalves, Maria Margarida; Mendes, Benilde; Pinto, FilomenaThe present work is devoted to the study chars obtained in the co-pyrolisis of plastics, biomass and tyres wastes. The composition of these chars is not yet well studied and only recent an attempt was made by the aithors to provide some information about the composition and risk assessment of these materials. The objectives of this work were to perform solvent extractions, using differents, in chars obtained in the co-pyrolysis process to evaluate the extraction efficiency by characterising the different solvent extracts obtained as well as the extracted chars, to perform a chemical ans bioassay franctionation in the most toxic crude extraction in order to study the chemical composition of the fractions as well as their individual contribution to the global toxicity of the crude extarct. The results will allow to conclude which solvent should be used in the decontamination of the pyrolysis chars.
- Evaluation of the environmental hazard of char residues produced in the co-pyrolysis of different wastes :chemical and ecotoxicological characterizationPublication . Bernardo, Maria; Lapa, Nuno; Gonçalves, Maria Margarida; Barbosa, Rui; Mendes, Benilde; Pinto, Filomena; Gulyurtlu, IbrahimChar residues produced in co-pyrolysis of different wastes were characterized through chemical and toxicity tests. A fraction of the solid chars was treated by extraction with dichloromethane. Different volatilit fractions present in the extracted and non extrated char were evaluated. A selected group of heavy metals was determined in both chars. Chars were subjected to the leaching test ISO/TS 21268-2 and resulting eluates were further characterized by determining a group of inorganic parameters and concentrations of several organic contaminants. An ecotoxicological characterization was performed by using the bio-indicator Vibrio fischeri. The chemical and ecotoxicological characterization led to a classification on the chars as ecotoxic
- Evaluation of the toxicity of char residues produced in the co-pyrolysis of different wastesPublication . Bernardo, Maria; Lapa, Nuno; Gonçalves, Maria Margarida; Barbosa, Rui; Mendes, Benilde; Pinto, FilomenaThe high amounts of solid waste produced in industrial installations and in urban centers is a complex problem of today's society. The traditional strategies for solid waste transformation and disposal include and filling or incineration. Other approaches are being exploited namely waste selective collection and recycling on the energetic valorization of solid wastes through pyrolysis. In the pyrolytic process, the wastes are converted into a gaseous and liquid phase that can be used in energy production or as feedstock in chemistry industries. A solid residue (char) is also produced in a proportion that depends on the pyrolysis conditions. Even when the operating condiions are optimized in order to minimize the solid fraction, a resonable amount of chars are obtained. Those chars are mainly composed of a carbon-rich matrix that contains the mineral matter initially present in the wastes as well as components of the liquid fraction. Therefore, these solid residues have a toxicity potential due to the presence of heavy metals or organic compounds that must be assessed in order to define their safe reutilization or disposal. In the present study, the chars produced in the co-pyrolysis of plastics, pine biomass and tyres were characterized through chemical and ecotoxicological tests. A fraction of the solid chars was treated by extraction with dichloromethane. Different volatibility groups of compounds present in the extracted and non extracted char were evaluated. A selected group of heavy metals was determined in both chars. Chars were subjected to the leaching test ISO/TS 21268-2 and the resulting eluates were further characterized by determining a group of inorganic and organic parameters. An ecotoxicological characterization was performed by using he bio-indicator Vibrio fischeri. The chemical and ecotoxicological results were compared and analysed according to the council Decision 2003/33/CE and the Criteria on the Evaluation Methods of Waste Ecotoxicity (CEMWE). The results of the chemical characterization indicate that the extraction of the char residues with an appropriate organic solvent allows the sufficient elimination of the volatile organic contaminants thus decreasing the potential toxicity of these chars. The semi-volatile and non-volatile fractions were not, apparently, affected by this pre-treatment. Regarding the release of heavy metals from extracted and non-extracted chars during the leaching tests, a strong contamination with Zn was found in both eluates, which contribute to a classification of the corresponding chars as hazardous and ecotoxic materials. Also the results of the ecotoxicological characterization of the eluates led to a classification of these chars as ecotoxic materials.
- Evaluation of microalgae as bioremediation agent for poultry effluent and biostimulant for germinationPublication . Viegas, Catarina; Gouveia, Luisa; Gonçalves, Maria MargaridaABSTRACT: This work addresses how a pre-treatment involving biomass ash influences the poultry effluent's bioremediation using three microalga strains, such as Chlorella vulgaris, Chlorella protothecoides and Tetradesmus obliquus. The undiluted effluent served as the culture medium for the growth, both in batch and semi continuous modes, and the remediation efficiency and biomass production yield were quantified. The combination strategy in batch mode, allowed removal efficiency of 100% for total nitrogen, more than 80% for total phosphorus and over 70% for chemical oxygen demand. Average biomass productivities for 10 days of 94.9, 76.2 and 72.0 mg L-1 day(-1) were obtained for T. obliquus, C. vulgaris and C. protothecoides, respectively. Regarding semi-continuous strategy (28 days), the biomass productivities achieved were 245 and 194 mg L-1 day(-1) for T. obliquus and C. vulgaris, respectively. Remediation rates of 100% for total nitrogen and phosphorus, and over 92% for COD were attained. The microalga composition was assessed for protein, sugar, lipid, and ash contents. The produced biomasses were tested as biostimulant and showed a 147% increase in wheat germination index, for the C. vulgaris microalga. The use of the precipitate from the biomass ash pre-treatment as fertilizer in germination tests was also assessed and results in an increase of 26%, for 10% of precipitate incorporation.
- Production of bio-hydrocarbons by hydrotreating of pomace oilPublication . Pinto, Filomena; Varela, Francisco; Gonçalves, Maria Margarida; Andre, Rui N.; Costa, Paula; Mendes, BenildeOlive pomace oil is a by-product from the olive oil industry that is still being used in the food industry as a low value vegetable oil. Crude olive pomace oil needs to be refined and is blended with virgin olive oils before being used as edible oil. The detection of toxic compounds led to more restricted legislation and to the search of alternative valorisation processes, such as hydrotreating to obtain bio-hydrocarbons. Hydrotreating of olive pomace oil at moderate temperatures (from 300 to 430 C) and in presence of initial hydrogen pressure of 1.1 MPa led to triglycerides destruction and to their conversion into a large range of organic compounds with predominance to hydrocarbons. Even without any catalyst, conversions into hydrocarbons were always higher than 90% (v/v). Catalyst presence, such as: CoMo/Al2O3, FCC (fluid catalytic cracking) or HZSM-5 changed hydrogenated liquids composition. The highest content of alkanes was obtained with CoMo catalyst, while FCC and HZSM-5 led to the highest contents of aromatic compounds. The results obtained showed that olive pomace oil can be efficiently converted into bio-hydrocarbons with a wide range of applications. It was also studied the effect of pyrolysing olive pomace oil prior to its hydrotreating. Pyrolysis pre-treatment seems to have favoured hydrotreating process by promoting initial cracking reactions. Thus, it was possible to increase the production of liquid compounds with a higher content of light molecules. However, the advantages of using a more complex two steps process still need to be proven.
- Leaching behaviour and ecotoxicity evaluation of chars from the pyrolysis of forestry biomass and polymeric materialsPublication . Bernardo, Maria; Mendes, S.; Lapa, Nuno; Gonçalves, Maria Margarida; Mendes, Benilde; Pinto, Filomena; Lopes, HelenaThe main objective of this study was to assess the environmental risk of chars derived from the pyrolysis of mixtures of pine, plastics, and scrap tires, by studying their leaching potential and ecotoxicity. Relationships between chemical composition and ecotoxicity were established to identify contaminants responsible for toxicity. Since metallic contaminants were the focus of the present study, an EDTA washing step was applied to the chars to selectively remove metals that can be responsible for the observed toxicity. The results indicated that the introduction of biomass to the pyrolysis feedstock enhanced the acidity of chars and promote the mobilisation of inorganic compounds. Chars resulting from the pyrolysis of blends of pine and plastics did not produce ecotoxic eluates. A relationship between zinc concentrations in eluates and their ecotoxicity was found for chars obtained from mixtures with tires. A significant reduction in ecotoxicity was found when the chars were treated with EDTA, which was due to a significant reduction in zinc in chars after EDTA washing.
- Optimization of Biochar Production by Co-Torrefaction of Microalgae and Lignocellulosic Biomass Using Response Surface MethodologyPublication . Viegas, Catarina; Nobre, Catarina; Correia, Ricardo; Gouveia, Luisa; Gonçalves, Maria MargaridaABSTRACT: Co-torrefaction of microalgae and lignocellulosic biomass was evaluated as a method to process microalgae sludge produced from various effluents and to obtain biochars with suitable properties for energy or material valorization. The influence of four independent variables on biochar yield and properties was evaluated by a set of experiments defined by response surface methodology (RSM). The biochars were characterized for proximate and ultimate composition, HHV, and methylene blue adsorption capacity. HHV of the biochars was positively correlated with carbonization temperature, residence time, and lignocellulosic biomass content in the feed. Co-torrefaction conditions that led to a higher yield of biochar (76.5%) with good calorific value (17.4 MJ Kg(-1)) were 250 & DEG;C, 60 min of residence time, 5% feed moisture, and 50% lignocellulosic biomass. The energy efficiency of the process was higher for lower temperatures (92.6%) but decreased abruptly with the increase of the moisture content of the feed mixture (16.9 to 57.3% for 70% moisture). Biochars produced using algal biomass grown in contaminated effluents presented high ash content and low calorific value. Dye removal efficiency by the produced biochars was tested, reaching 95% methylene blue adsorption capacity for the biochars produced with the least severe torrefaction conditions.Co-torrefaction of microalgae and lignocellulosic biomass was evaluated as a method to process microalgae sludge produced from various effluents and to obtain biochars with suitable properties for energy or material valorization. The influence of four independent variables on biochar yield and properties was evaluated by a set of experiments defined by response surface methodology (RSM). The biochars were characterized for proximate and ultimate composition, HHV, and methylene blue adsorption capacity. HHV of the biochars was positively correlated with carbonization temperature, residence time, and lignocellulosic biomass content in the feed. Co-torrefaction conditions that led to a higher yield of biochar (76.5%) with good calorific value (17.4 MJ Kg(-1)) were 250 & DEG;C, 60 min of residence time, 5% feed moisture, and 50% lignocellulosic biomass. The energy efficiency of the process was higher for lower temperatures (92.6%) but decreased abruptly with the increase of the moisture content of the feed mixture (16.9 to 57.3% for 70% moisture). Biochars produced using algal biomass grown in contaminated effluents presented high ash content and low calorific value. Dye removal efficiency by the produced biochars was tested, reaching 95% methylene blue adsorption capacity for the biochars produced with the least severe torrefaction conditions.
- Aquaculture wastewater treatment through microalgal: biomass potential applications on animal feed, agriculture, and energyPublication . Viegas, Catarina; Gouveia, Luisa; Gonçalves, Maria MargaridaABSTRACT: The use of microalgae to remediate raw effluent from brown crab aquaculture was evaluated by performing batch mode growth tests using separately the microalgae Chlorella vulgaris (Cv), Scenedesmus obliquus (Sc), Isochrysis galbana (Ig), Nannocloropsis salina (Ns), and Spirulina major (Sp). Removal efficiencies in batch growth were 100% for total nitrogen and total phosphorus for all microalgae. Chemical oxygen demand (COD) remediations were all above 72%. Biomass productivity varied from 20.9 mg L-1 day- 1 (N. salina) to 146.4 mg L-1 day- 1 (C. vulgaris). The two best performing algae were C. vulgaris and S. obliquus and they were tested in semicontinuous growth, reaching productivities of 879.8 mg L-1 day- 1 and 811.7 mg L-1 day- 1, respectively. The bioremediation of the effluent was tested with a transfer system consisting of three independent containers and compared with the use of a single container. The single container had the same capacity and received weekly the same volume of effluent as the three containers together. The remediation capacity of the 3 containers was much higher than the single one. The supplementation with NaNO3 was tested to improve the nutrient removal microalgae? capacity, with positive results. The removal efficiencies were 100% for total nitrogen and total phosphorus and higher than 96% for COD. The obtained C. vulgaris and S. obliquus biomass were composed of 31 and 35% proteins, 6 and 8% lipids, 39 and 30% carbohydrates, respectively. The composition of these biomass suggest that it can be used as novel and sustainable ingredients in aquaculture feeds. The algal biomass of Cv and Sc were used as biostimulants in the germination of wheat and watercress, and very promising results were attained, with increases in the germination index for Cv and Sc of 175% and 48% in watercress and 84% and 98% in wheat, respectively. The biomasses of Cv and Sc were also subjected to a torrefaction process with 72.5 ? 1.7% char yields. The obtained biochars were tested as biostimulants for germination seeds (wheat and watercress) and as bio-adsorbent of dye solutions.
- Bioremediation of cattle manure using microalgae after pre-treatment with biomass ashPublication . Viegas, Catarina; Gouveia, Luisa; Margarida Gonçalves, MariaABSTRACT: In this work, cattle manure was diluted and pre-treated with biomass ash to yield a liquid fraction and a solid precipitate. Microalgae grown in the liquid fraction, in batch and semi-continuous mode, achieved maximum biomass productivities of 522.9 and 554.3 mg L−1 day−1 (12 days) for Chlorella protothecoides and Tetradesmus obliquus, respectively. Nutrient removal efficiency was highest for the semicontinuous mode with replacement of 10% of reactor volume every 48 h. The produced algal biomass was characterized for its nutrient composition. Both, algal biomass, and precipitate aqueous extracts, were evaluated as biostimulants for wheat and watercress seeds Increments in the germination index were 177% for wheat with Chlorella protothecoides and 34% for watercress with Tetradesmus obliquus. The strategy adopted in this work is coherent with circular economy principles, combining effluent treatment with the production of added-value materials that could be used as biostimulants or animal feed additives.