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- The Use of Algae and Fungi for Removal of Pharmaceuticals by Bioremediation and Biosorption Processes: A ReviewPublication . Silva, Andreia; Delerue-Matos, Cristina; Figueiredo, Sónia; Freitas, OlgaThe occurrence and fate of pharmaceuticals in the aquatic environment is recognized as one of the emerging issues in environmental chemistry. Conventional wastewater treatment plants (WWTPs) are not designed to remove pharmaceuticals (and their metabolites) from domestic wastewaters. The treatability of pharmaceutical compounds in WWTPs varies considerably depending on the type of compound since their biodegradability can differ significantly. As a consequence, they may reach the aquatic environment, directly or by leaching of the sludge produced by these facilities. Currently, the technologies under research for the removal of pharmaceuticals, namely membrane technologies and advanced oxidation processes, have high operation costs related to energy and chemical consumption. When chemical reactions are involved, other aspects to consider include the formation of harmful reaction by-products and the management of the toxic sludge produced. Research is needed in order to develop economic and sustainable treatment processes, such as bioremediation and biosorption. The use of low-cost materials, such as biological matrices (e.g., algae and fungi), has advantages such as low capital investment, easy operation, low operation costs, and the non-formation of degradation by-products. An extensive review of existing research on this subject is presented.
- Ecotoxicological evaluation of chemical indicator substances present as micropollutants in laboratory wastewatersPublication . Silva, A.; Santos, Lúcia H.M.L.M.; Antão, C.; Delerue-Matos, Cristina; Figueiredo, SóniaLaboratories produce a large volume of wastewaters containing different chemical indicators, organic species for which there is no complete knowledge about their effects in the aquatic environment. The aim of this work was to evaluate the ecotoxicity of four chemical indicator substances commonly used in titrations (sodium diphenylamine-4-sulfonate, phenolphthalein, methyl orange, and eriochrome black T) by applying two distinct bioassays that evaluated the growth inhibition of the microalga Chlorella vulgaris and the acute immobilization of the microcrustacean Daphnia magna. All the indicators showed growth inhibition rates in the chronic test performed with the alga C. vulgaris. Only phenolphthalein and eriochrome black-T showed high immobilization rates on the acute test for D. magna. C. vulgaris showed higher sensitivity to the chemical indicators tested than D. magna. Eriochrome black T was the most toxic for both test organisms and, according to the effective concentration that causes inhibition on 50% of C. vulgaris population, it can be considered as “highly toxic to aquatic organisms”. Phenolphthalein and methyl orange may be classified as “toxic to aquatic organisms” and sodium diphenylamine-4-sulfonate is the least toxic, only being considered as “harmful”. This work increases the awareness of the hazardous effects of these chemical indicators and reinforces the need of improved solutions to manage and treat laboratory effluents.
- Evaluation of the adsorption potential of biochars prepared from forest and agri-food wastes for the removal of fluoxetinePublication . Fernandes, Maria João; Moreira, Manuela M.; Paíga, Paula; Dias, Diogo; Bernardo, Maria; Carvalho, Maria Manuela; Lapa, Nuno; Fonseca, Isabel; Morais, Simone; Figueiredo, Sónia; Delerue-Matos, CristinaTwelve biochars from forest and agri-food wastes (pruning of Quercus ilex, Eucalyptus grandis, Pinus pinaster, Quercus suber, Malus pumila, Prunus spinosa, Cydonia oblonga, Eriobotrya japonica, Juglans regia, Actinidia deliciosa, Citrus sinensis and Vitis vinifera) were investigated as potential low-cost and renewable adsorbents for removal of a commonly used pharmaceutical, fluoxetine. Preliminary adsorption experiments allowed to select the most promising adsorbents, Quercus ilex, Cydonia oblonga, Eucalyptus, Juglans regia and Vitis vinifera pruning material. They were characterized by proximate, elemental and mineral analysis, thermogravimetric analysis, Fourier transform infrared spectroscopy, determination of specific surface area and pH at the point of zero charge. Batch and equilibrium studies were performed, and the influence of pH was evaluated. The equilibrium was reached in less than 15 min in all systems. The maximum adsorption capacity obtained was 6.41 mg/g for the Eucalyptus biochar, which also demonstrated a good behavior in continuous mode (packed column).
- Green Microalgae Scenedesmus Obliquus Utilization for the Adsorptive Removal of Nonsteroidal Anti-Inflammatory Drugs (NSAIDs) from Water SamplesPublication . Silva, Andreia; Coimbra, Ricardo N.; Escapa, Carla; Figueiredo, Sónia; Freitas, Olga; Otero, MartaIn view of the valorisation of the green microalga Scenedesmus obliquus biomass, it was used for the biosorption of two nonsteroidal anti-inflammatory drugs, namely salicylic acid and ibuprofen, from water. Microalgae biomass was characterized, namely by the determination of the point of zero charge (pHPZC), by Fourier transform infrared (FT-IR) analysis, simultaneous thermal analysis (STA) and scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS). Kinetic and equilibrium batch experiments were carried out and results were found to fit the pseudo-second order equation and the Langmuir isotherm model, respectively. The Langmuir maximum capacity determined for salicylic acid (63 mg g−1) was larger than for ibuprofen (12 mg g−1), which was also verified for a commercial activated carbon used as reference (with capacities of 250 and 147 mg g−1, respectively). For both pharmaceuticals, the determination of thermodynamic parameters allowed us to infer that adsorption onto microalgae biomass was spontaneous, favourable and exothermic. Furthermore, based on the biomass characterization after adsorption and energy associated with the process, it was deduced that the removal of salicylic acid and ibuprofen by Scenedesmus obliquus biomass occurred by physical interaction.
- Vermiculite as a potential functional additive for water treatment bioreactors inhibiting toxic action of heavy metal cations upsetting the microbial balancePublication . Węgrzyn, Agnieszka; Tsurtsumia, Avtandil; Witkowski, Stefan; Freitas, Olga; Figueiredo, Sónia; Cybińska, Joanna; Stawiński, WojciechA new adsorbent that combines mineral vermiculite with the yeast Saccharomyces cerevisiae, was used for Cd2+ removal. The influence of vermiculite presence on the toxic effects of Cd2+ to Saccharomyces cerevisiae yeast was evaluated as a function of the microorganisms' respiratory activity (CO2 production). The Cd2+ toxicity increased with prolonged exposure time reaching the LC50 value of 857 and 489 mg L−1 after 30 and 120 min, respectively. The yeast managed to bioaccumulate 25.0 ± 0.6 mg g−1 of Cd2+ at the initial Cd2+ concentration of 741.9 mg L−1; the maximum Cd2+ adsorption capacity of vermiculite reached 25 ± 5 mg g−1. The addition of the mineral decreased the cations toxic effect; the LC20 value in vermiculite absence attained approximately 200 mg L−1 after 30 min and decreased to 80 mg L−1 after 2 h, while in the bio-mineral system it was at the level of 435 ± 50 mg L−1 without a significant change in time. The mineral provided a superior living environment for the yeast by removing part of the cations, releasing essential microelements and providing a protective, clay hutch-like habitat for the cells
- Study of adsorptive materials obtained by wet fine milling and acid activation of vermiculitePublication . Węgrzyn, Agnieszka; Stawiński, Wojciech; Freitas, Olga; Komędera, Kamila; Błachowski, Artur; Jęczmionek, Łukasz; Dańko, Tomasz; Mordarski, Grzegorz; Figueiredo, SóniaWet fine milling, as a pretreatment step to acid activation of vermiculite, was applied in order to decrease the environmental impact of the procedure commonly used to increase the mineral's adsorption capacity. Milling caused fragmentation of the material and several changes in its structure: edges of the flocks became frayed, the surface cracked, cation exchange capacity (CEC) increased, and most of the iron in oligonuclear and bulk form was removed. At the same time the specific surface area, crystallinity, chemical composition and adsorption capacity did not change significantly. Fine ground material was more susceptible to acid activation, which caused a decrease in the crystallinity and CEC, development of meso- and microporosity, an increase in the total volume of pores, in the specific surface and external surface areas. Micropores were developed faster in lower acid concentrations in the rough ground material, while the external surface area and total pores volume increased faster in the fine ground vermiculite. The latter material also had a higher CEC. Application of 0.5 mol L− 1 HNO3 to rough ground vermiculite did not change its adsorption capacity, however it changed from 55 ± 7 to 110 ± 8 mg g− 1 when the material was fine ground. The optimal treatment conditions for both materials were obtained for 1.0 mol L− 1 HNO3, however the adsorption capacity for the fine ground vermiculite increased more (i.e., from 55 ± 7 to 136 ± 7 mg g− 1) than for its rough ground counterpart (i.e., 52 ± 7 to 93 ± 7 mg g− 1). Concentrations higher than 1.0 mol L− 1 resulted in deterioration of the adsorption capacities in both cases. Considering all the experimental outcomes, it can be concluded that the environmental impact of acid activation of vermiculite may be diminished by application of fine grinding of the material before the chemical activation process. Such treatment resulted in higher adsorption capacity at a given acid concentration compared to the rough ground material.
- Electro-Fenton degradation of a ternary pharmaceutical mixture and its application in the regeneration of spent biocharPublication . Puga, Antón; Moreira, Manuela M.; Figueiredo, Sónia A.; Delerue-Matos, Cristina; Pazos, Marta; Rosales, Emilio; Sanromán, M. ÁngelesThis study proposed an integrated valorisation system, by combining adsorption and electro-Fenton processes for fast and effective micropollutant remediation of a complex pharmaceutical mixture. The pharmaceuticals venlafaxine, fluoxetine and trazodone, commonly detected in the environment (river water and sediment), were selected in this study as target pollutants. Initially, the electro-Fenton degradation process of the ternary mixture was optimised. For this, a Box-Behnken experimental design was used and the degradation of each pollutant, as a response function, was evaluated using three key operational process parameters (iron concentration, current intensity and solution pH). The pharmaceutical mixture was removed by total adsorption onto the biochar, the regeneration of which was then carried out under the optimal electro-Fenton conditions (0.24 mA, 0.33 mM Fe2+ and pH 3.2). In addition, different options in relation to the presence of iron were considered: i) iron dissolved in aqueous solution; ii) iron supported on the biochar; iii) no addition of iron (“self-cleaning”). The results confirmed that the natural content of iron in the biochar was enough to catalyse the electro-Fenton regeneration. The adsorption-electro-Fenton regeneration process was repeated over several cycles with no reduction in the efficiency of either process. Finally, this combination (adsorption and electro-Fenton process) was tested using an aqueous matrix from a wastewater treatment plant.
- Acid-base treated vermiculite as high performance adsorbent: Insights into the mechanism of cationic dyes adsorption, regeneration, recyclability and stability studiesPublication . Stawiński, Wojciech; Węgrzyn, Agnieszka; Dańko, Tomasz; Freitas, Olga; Figueiredo, Sónia; Chmielarz, LucjanAdditional treatment with NaOH of acid activated vermiculite results in even higher increase in the adsorption capacity in comparison to samples modified only in acidic solution (first step of activation) with respect to raw material. Optimization of treatment conditions and adsorption capacity for two cationic dyes (methylene blue (MB) and astrazon red (AR)), also as binary mixture, was evaluated. The capacity, based on column studies, increased from 48 ± 2 to 203 ± 4 mg g-1 in the case of methylene blue and from 51 ± 1 to 127 ± 2 mg g-1 in the case of astrazon red on starting and acid-base treated material, respectively. It was shown that adsorption mechanism changes for both cationic dyes after NaOH treatment and it results in decrease of adsorption rate. In binary mixtures methylene blue is bound stronger by adsorbent and astrazon red may be removed in initial stage of adsorption. Extensive studies on desorption/regeneration process proved high efficiency in recyclable use of all materials. Although cation exchange capacity decreases due to acid treatment, after base treatment exchange properties are used more efficiently. On the other hand, increased specific surface area has less significant contribution into the adsorption potential of studied materials. Obtained adsorbents worked efficiently in 7 adsorption-regeneration cycles and loss of adsorption capacity was observed only in two first cycles.
- Removal of diclofenac and sulfamethoxazole from aqueous solutions and wastewaters using a three-dimensional electrochemical processPublication . Soares, Cristina; Correia-Sá, Luísa; Paíga, Paula; Barbosa, Carlos; Remor, Paula Verônica; Freitas, Olga; Moreira, Manuela M.; Nouws, Henri; Correia, Manuela; Ghanbari, Amir; Rodrigues, António J.; Oliveira, Carlos M.; Figueiredo, Sónia; Delerue-Matos, CristinaThe three-dimensional (3D) electrochemical treatment process was studied for the removal of two pharmaceuticals, diclofenac (anti-inflammatory) and sulfamethoxazole (antibiotic), in mono and bi-component systems. Adsorption and conventional two-dimensional electrochemical processes were initially studied and then combined to develop the 3D process. The influence of different operating parameters on the removal efficiency was studied: the distance between the cathode and the anode, the pharmaceutical and electrolyte (NaCl) concentrations, the pH, and the (carbon-based) adsorbent used as particulate electrode (biochar and commercial activated carbon, granulometry, and amount). The energy consumption and the electric energy per order were evaluated. The results demonstrate the efficiency of the 3D process for the removal of diclofenac and sulfamethoxazole from aqueous solutions, both for mono- and bi-component systems, achieving their complete removal respectively in 10 and 30 min, using a Mixed Metal Oxide anode (titanium-coated with RuO2-IrO2-TiO2), a stainless steel cathode, a biochar particulate electrode (1–2 mm), an initial pharmaceutical concentration of 10 mg/L, an inter-electrode distance of 7.5 cm, a pH value of 7 and a current density of 7 mA/cm2. The optimised 3D process was also successfully applied to a wastewater treatment plant effluent, but lower removal efficiencies were observed (after 30 min) for bi-component fortified samples; 49% for DCF and 86% for SMX, with energy consumptions of 1224 and 613 Wh/g and an electric energy per order of 19.1 and 8.77 kWh/m3 respectively. On the other hand, the pharmaceuticals were completely removed from the effluent when real concentrations (i.e. without their addition) were used
- Sustainable adsorbents formed from by-product of acid activation of vermiculite and leached-vermiculite-LDH hybrids for removal of industrial dyes and metal cationsPublication . Stawiński, Wojciech; Węgrzyn, Agnieszka; Mordarski, Grzegorz; Skiba, Michał; Freitas, Olga; Figueiredo, SóniaHydrotalcite-like layered double hydroxide (LDH) materials were synthesized from liquid waste by-product produced during acid activation of vermiculite (raw (W) and expanded (Ve)), and by combining the waste with the activated mineral, novel hybrid vermiculite-hydrotalcite-like materials were obtained in one-pot synthesis. Batch system adsorption experiments were performed on fresh and calcined (at 450 °C) materials using two anionic dyes (Congo Red - CR, and Reactive Red 184 - R), a cationic dye (Astrazon Red - AR), and Cu2+. Calcination significantly increased the materials' adsorption capacities for all the pollutants. The highest adsorption capacities of the LDH derived from W were 289 ± 2, 137 ± 2, 38.2 ± 0.6 and 64 ± 2 mg g−1, while for the ones derived from Ve were 214 ± 2, 119.5 ± 0.3, 35.9 ± 0.7 and 66 ± 3 mg g−1 for CR, R, AR and Cu2+, respectively. The hybrids obtained from W attained removal levels of 238 ± 3, 111 ± 2, 44 ± 1 and 70 ± 1 mg g−1 and their counterparts derived from Ve reached 84 ± 1, 34.1 ± 0.5, 43 ± 2 and 75 ± 1 mg g−1 for CR, R, AR and Cu2+, respectively. Strong synergic effect on adsorption was observed in the hybrid materials, especially in these derived from Ve. These adsorbents had higher (up to 400%) adsorption capacities than theoretical ones prepared by mixing ex-situ appropriate amounts of activated vermiculite and LDH. All the materials were characterized by XRD, SEM-EDS, and ATR techniques. The proposed procedure is a sustainable approach to clay minerals valorization and my open new possibilities in fields such as wastewater treatment or catalysis.