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- 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.
- A circular approach for landfill leachate treatment: chemical precipitation with biomass ash followed by bioremediation through microalgaePublication . Viegas, Catarina; Nobre, Catarina; Mota, André; Vilarinho, Cândida; Gouveia, Luisa; Gonçalves, Maria MargaridaABSTRACT: The aim of this work was to study an integrated approach for landfill leachate remediation comprising chemical precipitation with biomass bottom ash as a pre-treatment to reduce color and turbidity followed by bioremediation through microalgae treatment for effluent disposal. Optimal pre-treatment conditions were determined through batch experiments and were found to be 160 g L-1 ash dose, 96 h of contact time, overhead agitation at 15 rpm and ash particle size below 500 mu m. These conditions led to removal efficiencies of 74.3% for chemical oxygen demand and 98.5% for color. Large quantities of sludge containing excess biomass ash and precipitated compounds were formed during the pre-treatment. To minimize solid disposal, this sludge was tested as a raw material for cementitious and aggregate substitute in mortar formulations. Following the pre-treatment, the leachate was inoculated with six different microalgae species to evaluate their ability to grow in such a recalcitrant effluent and remediate it. After a period of 27 days biomass concentration from 0.4 to 1.2 g L-1 were achieved for the tested microalgae. Removal efficiencies were in the range of 18-62% for COD, 63-71% for N, and 15-100% for P. At the end of the treatment, algal biomass was characterized regarding protein, lipid, fatty acids, carbohydrate, and ash contents. This approach allows a low-cost remediation of these recalcitrant effluents when compared with the present options that include inverse osmosis, and the valorization of ash-rich precipitates and microalgae biomass improves the sustainability of the overall process.
- Social Awareness as a Catalyst for Biochar Adoption in the Agricultural and Forestry SectorsPublication . Janiszewska-Latterini, Dominika; Ortigueira, Joana; Lopes, Tiago; Gościańska-Łowińska, Julia; Augustyniak-Wysocka, Dobrochna; Leszczyszyn, Ewa; Nobre, CatarinaABSTRACT: Biochar, a carbon-rich material produced from the pyrolysis of organic matter, has garnered attention for its potential agricultural and environmental benefits, including soil improvement, enhanced crop yields and climate change mitigation. Despite its promise, biochar adoption has been hindered by limited social awareness, particularly in industrialised countries. This review explores the factors influencing biochar's acceptance in agriculture and forestry, focusing on the social aspects that affect its integration. A systematic literature review was conducted to identify studies on social awareness and acceptance, revealing significant barriers such as a lack of knowledge among farmers, high production costs and insufficient infrastructure. In industrialised countries, while technical research on biochar has progressed, farmers often remain unfamiliar with its benefits, and resistance to adoption is common. Studies show that social factors such as age, education level and access to funding play a crucial role in biochar adoption. Furthermore, a lack of government incentives and unclear regulatory frameworks exacerbate the challenge. Conversely, studies from lower-income countries suggest that small-scale, cost-effective biochar production systems may hold promise. The review also identifies strategies to enhance biochar's social acceptance, including targeted education programs, financial incentives and clearer regulatory standards. Despite varying levels of social awareness, the literature suggests that with increased outreach, biochar could significantly contribute to sustainable agricultural practices globally. This review underscores the need for further research into the social dimensions of biochar adoption and the implementation of policies to foster its widespread use.