Maria Margarida Gonçalves

• PhD
• Universidade NOVA de Lisboa

In this study, RDF was pelletized, co-pelletized with lignocellulosic biomass (1:1), and then used as a feedstock in CO2 gasification simulation tests using a TGA apparatus to verify its behavior and feasibility for syngas production. The RDF pellets had lower moisture content (5.42%) and better physical characteristics, such as durability (99.53%)...

In this work, dry carbonization (DC) and hydrothermal carbonization (HTC) of refuse-derived fuel (RDF) pellets were conducted to evaluate the physical, chemical, and fuel properties of the produced chars. In the dry carbonization tests, biomass sawdust was incorporated in different proportions on the samples to minimize agglomeration caused by the...

This study investigates the thermochemical decomposition and gasification performance of biochars produced from blends of waste lignocellulosic biomass and waste insulation electrical cables at varying temperatures. Characterization tests revealed changes, particularly in ash content (27.5 %–34 %) and elemental composition, with nitrogen content in...

Pine nutshells (PNSs) are lignocellulosic waste materials with limited use in domestic heating. However, a biorefinery approach may be applied to fractionate PNSs and produce chemicals, materials, and improved solid fuels. In this study, we fractionated PNSs and produced antioxidant extracts, lignins, polysaccharides, chars, and activated carbons a...

This research evaluates the feasibility of using eucalyptus oil blended with conventional diesel fuel in diesel engines. Eucalyptus globulus is one of the main tree species cultivated for paper pulp in western European countries such as Portugal, and eucalyptus oil is one of the byproducts that so far has not been sufficiently evaluated as a biofue...

The production of heterogeneous solid waste, such as municipal solid waste (MSW), construction and demolition waste (CDW), and industrial solid waste (ISW), has increased dramatically in recent decades, and its management is one of today’s biggest concerns. Using waste as a resource to produce value-added materials such as char is one of the most p...

In this work, dry and hydrothermal carbonization (DC and HTC) of RDF pellets were conducted to evaluate the physical, chemical, and fuel properties of the produced chars. In the dry carbonization tests, biomass sawdust was incorporated in different proportions on the samples to minimize agglomeration caused by the melting of the plastic fraction. T...

The growing increase in intensive swine production has huge environmental impacts. In addition to the high organic load and nutrients, swine effluents have large amounts of suspended solids, which hinder and limit several treatment technologies. Solid–liquid separation using filtration or centrifugation is often used as pre-treatment to reduce susp...

The passive contribution of indoor coatings to improve interior comfort is an eco-efficient challenge nowadays. Gypsum is one of the more eco-efficient binders available to produce plasters. Acacia dealbata is an invasive plant species in many countries, and the management of its wood waste for fires prevention is imperative. This study intends to...

The present study aims to test several conditions of the thermochemical pretreatment of torrefaction and carbonization to improve the physical and combustible properties of the Portuguese RDF. Therefore, two different types of RDF were submitted alone or mixed in 25%, 50%, and 75% proportions to dry carbonization processes in a range of temperature...

Waste-grade cork samples of Quercus cerris were subjected to maceration extraction using 7 different solvents, including pure water (I), pure acetone (II), 75% aqueous ethanol (III), 75% aqueous methanol (IV), 75% aqueous acetone (V), 50% aqueous acetone (VI), and 25% aqueous acetone (VII). The extract yields, extract compositions, as well as antio...

The need for reducing fossil fuel consumption and greenhouse gas (GHG) emissions in internal combustion engines has raised the opportunity for the use of renewable energy sources. For the progressive replacement of fossil fuels like diesel, those derived from the sustainable management of forest resources may be a good option. In Portugal, pine tre...

Testing Alternative Fuels and Internal Combustion Engines

A large part of municipal solid waste (MSW) still goes to landfills, representing an environmental concern. A circular economy approach can enable safe management of MSW while mitigating the increasing energy needs when waste is used as a feedstock in energy production processes (waste to energy). Currently, MSW can be converted into refuse-derived...

Quercus cerris phloem is a lignocellulosic waste fraction obtained from bark fractionation. Biochars are technologically interesting functional materials that may be produced from lignocellulosic solid materials. This study explores the solid material properties of Quercus cerris phloem, evaluates biochar production from it, and explores its applic...

Due to the energy crisis that some countries are facing nowadays, the gasification process appears to be a good alternative to produce some energy from solid materials. Increasingly, gasification involves using wastes as a solid fuel, making the process green and reusing some materials that otherwise could end up in a landfill. However, the process...

The construction industry is responsible for a large amount of CO2 emissions and an intensive energy consumption. Cement production is the third largest source of anthropogenic CO2 emissions and is responsible for about 1.8 Gt of CO2 emissions into the atmosphere. The use of waste materials to replace a fraction of cement in the mortar makes it mor...

Coal gasification is a mature technology for conversion of fossil coal to syngas and subsequentially produce chemicals and fuels. In recent years, gasification has been proposed as a suitable technology for conversion of biomass and waste materials, to promote renewable energy sources and circular economy. Gasification of polymeric and miscellaneou...

In this work, the carbonization process was applied as a pretreatment to valorize mixed wastes by producing chars with better fuel properties and more suitable to be used as feed in gasification processes. For this purpose, different types of wastes (Refused Derived Fuel, dry sewage sludge, and pinewood waste) and their blends (RDF/sludge, RDF/biom...

This work aims to review the contribution of biofuels as complement or alternative to gasoline in spark ignition (SI) engines, taking into account the chemical nature and properties of these renewable fuels and describing their effects on engine performance and exhaust emissions. The limits imposed by the legislation, regarding the use of first-gen...

Pig farming effluents usually present high levels of suspended solids as well as organic and biological contaminants that hinder the application of conventional treatment methods. Thus, novel treatment alternatives are needed to solve the problems of point source pollution arising from pig farms. In this paper, the integrated treatment of pig farmi...

Thermochemical conversion of solid fuels depends on the devolatilization rate of the volatile compounds. Depending on the process, the temperature is the key variable that controls such a process. Refuse Derived Fuels (RDFs) are fuels that can have a positive impact on the energy mix while contributing to the reduction of landfill material. Due to...

Faced with climate change and the search for mitigation of CO2 emissions, biomass presents itself as a promising raw material to diversify the renewable energy matrix, as an example, cassava wastewater. In the present study, an analysis of the energy and economic viability of a hybrid solar-PV biogas system (HRES) for the generation of bioenergy fr...

Pine nut shells are waste lignocellulosic residues from the production of edible pine nut kernels that are generally only used for energy production by combustion. Lignocellulosic feedstocks, such as pine nut shells, may be valorized namely by their integration into biorefinery schemes. This article set out to analyze the chemical composition, morp...

The purpose of this work was to evaluate the recovery of bioactive extracts from Acacia dealbata leaves and twigs and to characterize their chemical composition and functional properties. Fresh and air-dried samples were extracted by maceration at room temperature and by hot extraction at 60 °C using aqueous solutions of acetone, ethanol, and metha...

Gasification is a promising thermochemical technology used to convert waste materials into energy with the introduction of low amounts of an oxidant agent, therefore producing an environmental impact that is lower when compared to incineration and landfilling. Moreover, gasification allows a sustainable management of wastes and reduces the use of f...

Waste cork and phloem fractions from the bark of Turkey oak (Quercus cerris) were subject to low-temperature pyrolysis between 250 and 325 °C and residence times of 30 or 60 min. The fuel, leaching, and methylene blue adsorption properties of the produced biochars were evaluated for the first time. The results indicate that cork and phloem containi...

Studying the thermal decomposition of wood pellets is an important subject in order to understand the behavior of wood pellets during the combustion process. In fact, wood pellets have become an important fuel used in boiler combustion. The objective of this study is to investigate the mass loss and elemental analysis of pine wood pellets at variou...

The valorization of noble metals from the recycling of electric cables, generates a negative effect with regard to the production of polymeric residues, mainly composed of polyvinyl chloride (PVC), polyethylene (PE) and polypropylene (PP). Waste insulation electrical cables (WIEC) can be recovered thermochemical, in combustion or gasification proce...

Thermochemical conversion of solid fuels depends on the devolatilization rate of the volatile compounds. Depending on the process, the temperature is the key variable that controls such a process. Refuse Derived Fuels (RDFs) are fuels that can have a positive impact on the energy mix while contributing to the reduction of landfill material. Due to...

Objective: Propolis has been used since antiquity, but recent reports of its biological properties hint that it could be employed as a topical pharmaceutical and cosmetic ingredient. This work aims to probe the action of Portuguese propolis extracts on skin cells, providing mechanistic insights into its mode of action and preliminarily assessing i...

In recent decades, interest in the eco-efficiency of building materials has led to numerous research projects focused on the replacement of raw materials with mineral and biomass wastes, and on the production of mortars with low-energy-consuming binders, such as gypsum. In this context, five different fractions (bark, wood, branchlets, leaves, and...

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 define...

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...

The use of biofuels for spark ignition engines is proposed to diversify fuel sources and reduce fossil fuel consumption, optimize engine performance, and reduce pollutant emissions. Additionally, when these biofuels are produced from low-grade wastes, they constitute valorisation pathways for these otherwise unprofitable wastes. In this study, etha...

The energetic valorisation of wastes through gasification is a promising solution with a better environmental impact in terms of pollutant emissions compared with incineration, landfilling, and heat and power generation from fossil fuels. However, techno-economic studies are imperative to define the viability of these technologies and to optimise h...

The growing production of non-recyclable urban wastes generates environmental problems that impose new alternatives for their energetic valorisation. Nonetheless, some of these wastes do not have adequate properties to be directly used in waste-to-energy technologies, thus requiring adequate pre-treatments to improve their fuel properties. This wor...

Animal production leads to effluents with high loads of macro and micronutrients, and therefore with a huge potential of water bodies eutrophication. Conventional wastewater treatments are expensive, energy-consuming, release greenhouse gases (GHG), and produce a residual sludge. The use of microalgae for wastewater treatment allows recovery of nut...

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 ni...

The behavior of chars from the carbonization process were studied when the lignocellulosic biomass was incorporated into the waste of electrical and electronic equipment for chlorine removal. Tests were performed at 300°C with a heating rate of 15°C/min and residence time of 60 min. Compositions studied had 100, 75, 50, 25 and 0% of waste electrica...

In this work the characteristics and combustion behavior of pellets produced with residual forestry biomass and their mixtures with pine biomass were studied. The tested biomasses were collected in the Algarve region (southern Portugal). Pellets produced with Eucalyptus globulus and Cistus ladanifer wastes presented low carbon content (with 38.0 an...

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 d ⁻¹ (12 days) for Chlorella protothecoides and Tetradesmus obliquus, respectively...

In this study, hydrothermal carbonization (HTC) was used as a thermochemical conversion process to upgrade Refuse Derived Fuel (RDF). The effect of process temperature (250 °C, 275 °C and 300 °C), residence time (30 min and 120 min), and RDF-to-water ratio (1:15 and 1:5) on the main characteristics of the produced hydrochars and process waters was...

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 experiment...

In recent years, there has been growing interest in the pyrolysis of biomass due to economic and environmental reasons. Low-temperature pyrolysis is one of the most straightforward and low-cost pyrolysis processes that may be used to produce added-value biochars as well as liquid and gas products from waste biomass. Lignocellulosic biomass obtained...

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 bioreme-diation through microalgae treatment for effluent disposal. Optimal pre-treatment conditions were determined through batch experimen...

Acacia spp. are widespread all over the Portuguese territory, representing a threat to local biodiversity and to the productivity of the forest sector. The measures adopted in some countries for their eradication or to control their propagation are expensive, have been considered unfeasible from practical and economical perspectives, and have gener...

Featured Application Summer Savory extracts could be a promising pharmacological tool not only in the management of inflammation associated to Inflammatory Bowel Disease (IBD) but also in managing the impaired secondary inflammatory mechanisms related with colorectal cancer progression, with a potential clinical use as a supplement to standard of c...

The use of alternative biofuels for Spark Ignition (SI) engines is done to diversify fuel sources, optimize engine performance and reduce fossil fuel consumption, as well as pollutant and CO2 emissions. Additionally, when these biofuels are extracted from low grade wastes, they solve an important environmental problem while providing value to an ot...

The partial replacement of fossil fuels by biofuels contributes to a reduction of CO2 emissions, alleviating the greenhouse effect and climate changes. Furthermore, fuels produced from waste biomass materials have no impact on agricultural land use and reduce deposition of such wastes in landfills. In this paper we evaluate the addition of pyrolysi...

Refuse derived fuel (RDF) was carbonized at 300 °C for 30 minutes and the resulting RDF char was used as additive for biomass pellets. Pine waste pellets with 0, 5 and 10 % incorporation of RDF char were prepared and characterized. RDF char incorporation caused an increase in fixed carbon and ash contents of the pellets. The pellets were subjected...

Stemphylium vesicarium (Wallr.) E. G. Simmons is the pathogen responsible of brown spot disease in pear and has become one of the main concerns for European pear producers. In Portugal, S. vesicarium is responsible for significant yield reduction and economic losses in “Rocha” pear (Pyrus communis L. cv Rocha) production. Considering the antimicrob...

Due to increased energy demands and environmental concerns, biomass has become an increasingly attractive primary source in the energy mix. It can be used as heat supply to both domestic and industrial sectors, but also as fuel in dedicated or co-generation-based power plants and it is also considered CO2 neutral. Amongst the most widely used forma...

In this work was evaluated the potential of dried biomass from prickly pear cactus cladodes and of the corresponding biochars as low cost and eco-friendly biosorbents for the removal of methylene blue (MB), from aqueous solutions. Dried biomass samples were produced from cladodes of Opuntia ficus indica (OFI), varieties green, orange and red, and f...

This work addresses the application of Refuse Derived Fuel (RDF) char as a low-cost ad-sorbent for methylene blue (MB) in batch mode, as an approach to remediate pigment contaminated effluents and a model for the adsorption of cationic analytes. The RDF char was tested without pre-treatment and after a cold alkali treatment to enhance adsorption. T...

This work aimed to assess the effect of dry (DC) and hydrothermal carbonisation (HTC) in the upgrading of a refuse-derived fuel (RDF) produced with municipal solid wastes (MSW) and construction and demolitions wastes (CDW). Tests were performed at temperatures in the range of 250 ºC to 350 ºC for 30 min. The obtained chars had improved fuel propert...

Mixtures of used cooking oil (UCO) and pine biomass (PB) were subject to pyrolysis at 300 ºC and 350 ºC. PB concentration in the feed varied from 0% to 38 %, and the pyrolysis products obtained were bio-oils, aqueous phase, biochars and gases. The formation of gas products, aqueous phase and biochar was favored by the incorporation of PB and by the...

Purpose: Little is known about the pharmacological effects of the phenolic compounds of Pennyroyal (Mentha pulegium). This Mediterranean aromatic plant, used as a gastronomic spice and as food preservative by the food industry has been studied mainly due to its essential oil antibacterial properties, composed primarily by monoterpenes. With this w...

Pine wood transformation generates large amounts of pine wastes that are currently underexploited, however, their high content in polyphenols makes them attractive raw materials for biorefinery applications. In this work, the extraction of different phenolic compounds from pine bark was investigated varying the solvent, extraction temperature and t...

Persimmon (Diospyros kaki L.), a fruit rich in phenolic compounds (PCs), has been considered effective in mitigating oxidative damage induced by an excess of reactive oxygen species. Due to large molecular weight and intrinsic instability in some physiological fluids, PCs’ passage through biological membranes is very limited. Carriers like phytosom...

Background: Inflammatory Bowel Diseases (IBD) encompasses both Crohn's Disease and Ulcerative Colitis, known to be connected to an enlarged risk for developing colorectal cancer (CRC). Spearmint (Mentha spicata L.) is a Mediterranean plant used as an aromatic agent, and studies have mainly focused on the essential oil suggesting an anti-inflammator...

Hydrothermal carbonization (HTC) was employed as an upgrading thermochemical conversion process for Refuse Derived Fuel (RDF). The effect of process temperature and residence time on the main characteristics of the produced hydrochars was studied. Results illustrated that the HTC process yielded hydrochars with upgraded characteristics such as redu...

The present work aims to study the thermochemical conversion of lignocellulosic wastes and their mixtures with lipid wastes through hydrothermal carbonization (HTC). The raw materials used were a mixture of forestry wastes and lipid waste (resulting from the filtration of used cooking oils). HTC was studied by varying temperature (200 ° C to 300 °...

Refuse derived fuel (RDF) is produced in large amounts but its heterogeneous nature and low calorific value reduce the potential for energetic valorization of this material. In this work, the torrefaction and carbonization of RDF was studied in a temperature range of 200–400 °C and residence times from 15 to 60 min, yielding chars with increased de...

Refuse derived fuel containing non-hazardous industrial wastes was subjected to torrefaction and carbonization in an industrial furnace. The RDF samples were heated at 300 °C and 400 °C, for 30 min, yielding solid products (chars) as well as gases and liquids. Proximate and ultimate composition, mineral composition, chlorine content and high heatin...

Gasification of wastes is considered a promising alternative for energy generation due to its lower environmental impacts when compared with conventional landfilling and incineration. Valorisation of such wastes improves sustainability of resource management and of energy production. However, an appropriate characterisation of wastes in terms of ph...

A new process for the torrefaction of mixtures of biomass and oily sludges is proposed. A fossil fuel (gasoline or diesel) was added to mixtures of biomass and hydrocarbon-rich sludge (10:1), and this mixture was subject to distillation until all liquids are recovered. The fossil fuel partially dissolved the sludge components and promoted their eve...

Refuse derived fuel (RDF) represents a very robust and endogenous resource that has the potential to minimize landfilling of solid waste, reduce greenhouse gas emissions through its biogenic component and contribute to national energy provision whilst diversifying solid fuel supplies. This waste derived fuel can be produced from different waste str...

In this work, the gasification of pellets produced from residual pine biomass and their mixtures with cork wastes, polymeric wastes and polymer derived char pellets was studied. The gasification tests were performed in a fixed bed downdraft gasifier at the temperatures of 700 °C and 800 °C. The influence of pellet combinations and gasification temp...

Low quality waste oils and fats, with elevated levels of acidity, water and other contaminants are not appropriate for biodiesel production or other material recycling processes. Nevertheless, they can be converted to energy-dense bio-oils by pyrolysis, in an oxygen deficient atmosphere. These bio-oils may be used in combustion or upgraded to yield...

Scope & Goals: This article presents a coupled review of scientific literature on environmental impact, as well as occupational safety and health, of gasification plants using residues of sewage sludge and refuse-derived fuel. Methods: The survey, covering a 10-year time span, was made through a typical systematic review of literature, retrieved fr...

Refuse derived fuel (RDF) is a highly heterogeneous material that contains carbonaceous components with a good calorific value but also significant moisture and ash contents. The torrefaction process can help to upgrade RDF and obtain a fuel with improved properties for combustion or gasification because the RDF char is easier to grind, more hydrop...

Non-hazardous industrial waste (IW) is a source of refuse-derived fuels (RDF). RDF production is considered a priority solution regarding waste management in industrialized countries. It allows significant reductions on the amount of end-of-life materials sent to landfills and it enhances energy recovery from different wastes. Nevertheless, the het...

In this work bottom ash from the combustion of solid biofuels used in ceramic furnaces was applied as a precipitating agent for the pretreatment of industrial landfill leachate. The optimal pretreatment conditions were determined in batch experiments, varying contact time, ash-to-leachate ratio, ash granulometry and agitation regime. COD, OD (600 n...

In this study the remediation of landfill leachate was evaluated by combination of physical-chemical and biological treatments. Calcium hydroxide (Ca(OH)2) and biomass ash were used as chemical precipitation agents for pH adjustment and formation of insoluble complexes with organic contaminants. This treatment resulted in reductions of 93.2% and 87...

Solid wastes from combustion and gasification processes include ashes and biochars that may pose an environmental problem if not correctly managed or valorised. These wastes can have interesting adsorption properties that may be exploited in the remediation of effluents and recovery of valuable solutes. In this work the decontamination of a landfil...

In this study the remediation of bovine wastewater by a combination of physicalchemical pre-treatment and bioremediation with microalgae was evaluated. Calcium hydroxide (Ca(OH)2) was used as a precipitation agent using different ratios of Ca(OH)2 mass to wastewater volume (4, 10 and 20 g/L). Optical density at 540 nm, ammonia nitrogen, phosphorus,...

The present work evaluated three different pretreatments for the recovery of cellulose from two different lignocellulosic wastes: residue A - a lignocellulosic powder with polymeric and mineral contamination and residue B - milled waste pine biomass. The low fixed carbon of these wastes (10.0 % to 16.6% wt, db) and their high ash content (12.0% to...

In this work, the extraction of phenolic compounds from low-grade coffee was evaluated by solid-liquid extraction using acetone, water and mixtures of these solvents. Refluxing with acetone and water mixtures yielded extracts rich in phenolic compounds, reaching 615.6 mgGAE /gextract, for the extract produced with 60% acetone and 594.2 mg GAE/gextr...

Residual pine biomass and waste derived chars were used to prepare biomass pellets with 10% char incorporation. The chars were produced from mixtures of pine biomass and hy-drocarbon-rich oily sludges and vegetable oil sludge in oxygen deficient conditions. The chars had high heating values higher than 34 MJ/kg, therefore their incorporation result...