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In 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.

The biomass growth, pharmaceutical removal and light conversion efficiency of Chlorella sorokiniana under the presence of paracetamol (PC) and salicylic acid (SaC) were assessed and compared at two different concentrations of these pharmaceuticals (I: 25 mg l-1, II: 250 mg l-1). Microalgae were resistant to these concentrations and, moreover, their growth was significantly stimulated (p ≤ 0.05) under these drugs (biomass concentration increased above 33% PCI, 35% SaCI, 13% PCII and 45% SaCII, as compared with the respective positive controls). At the steady state of the semicontinuous culture, C. sorokiniana showed removal efficiencies above 41% and 69% for PCI and PCII, respectively; and above 93% and 98% for SaCI and SaCII, respectively. Under an irradiance of 370 μE m-2 s-1, higher quantum yields were reached by microalgae under the presence of drugs, either at dose I or II, than by the respective positive controls. These results point to C. sorokiniana as a robust strain for the bioremediation of paracetamol and salicylic acid concentrated wastewaters.

This work aimed to investigate thermal decomposition of microalgae throughout the different culture stages. For this purpose, Chlorella sorokiniana was cultured in photobioreactors, and microalgae biomass was sampled at different days throughout the development of the culture. The aim was to analyze the energetic value of this biomass by thermogravimetric analysis as well as to calculate combustion characteristic indexes during the different culture stages. In all cases, thermal decomposition of microalgae biomass during combustion denoted two stages. The first one encompassed the carbohydrates and proteins decomposition and the breakdown of hydrocarbon chains of fatty acids, whereas the second step was closely related to the combustion of the formed char. Fuel composition analysis denoted a microalgae HHV value quite similar to that of Poplar (considered as an energy crop) biomass and slightly higher than published values for herbaceous biomass. In relation with the culture stages, a better combustion performance was found (higher thermal indexes as well as higher DTGmax values) for microalgae biomass sampled at days 19 and 21. These results point to the importance of the culture stage for the thermal valorization of microalgae biomass.

Thermal conversion of biomass derived from energy crops is one alternative for the production of energy. In this work, thermogravimetric analysis of poplar biomass was carried out and both the kinetic parameters (activation energy and frequency factor) and characteristic indexes were determined. Four poplar clones (UNAL, I-214, AF-2 and AF-8) under no fertilization (CONTROL) or under fertilization with either dehydrated composted sewage sludge (BIOSOLIDS) or sludge from dairy wastewater treatment (MUD) were used in this work. Five weight loss stages were identified in the DTG pyrolysis curves: moisture loss, active pyrolysis (two phases), passive pyrolysis and a high-rank pyrolysis phase. Among them, the second pyrolysis active phase was the most representative one. For this stage, BIOSOLIDS-UNAL poplars biomass was the one that achieved the highest weight loss values. The characteristic parameters and indexes (especially P and Pi indexes) also pointed to UNAL poplars under BIOSOLIDS fertilization as the most favourable for pyrolytic thermal conversion.

In 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&minus, 1) was larger than for ibuprofen (12 mg g&minus, 1), which was also verified for a commercial activated carbon used as reference (with capacities of 250 and 147 mg g&minus, 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.

In this work, zebrafish embryo bioassays were performed to assess the efficiency of microalgae in the removal of acetaminophen from water. Chlorella sorokiniana (CS), Chlorella vulgaris (CV) and Scenedesmus obliquus (SO) were the strains used for water treatment. Toxic effects on zebrafish embryo caused by effluents from microalgae treatment were compared with those observed under exposure to experimental solutions with known concentrations of acetaminophen. The three microalgae strains allowed for the reduction of acetaminophen concentration and its toxic effects, but CS was the most efficient one. At the end of the batch culture, a 67% removal was provided by CS with a reduction of 62% in the total abnormalities on the exposed zebrafish embryo. On the other hand, toxic effects observed under exposure to effluents treated by microalgae were alike to those determined for acetaminophen experimental solutions with equivalent concentration. Thus, it may be inferred that microalgae biodegradation of acetaminophen did not involve an increased toxicity for zebrafish embryo.

The objective of this work was to assess and compare the removal efficiency of paracetamol and salicylic acid from aqueous medium by a microalgae-based treatment, using either Chlorella vulgaris or Tetradesmus obliquus. Moreover, considering microalgae application in wastewater treatment, the influence of these pharmaceuticals in the algal nutrient removal capacity was evaluated. The removal of paracetamol by T. obliquus (>40 %) was larger than by C. vulgaris (>21 %) in batch culture, and this was also observed for salicylic acid (>93 % by T. obliquus and >25 % by C. vulgaris). Both strains removed nutrients (phosphate and nitrate) almost completely by the end of the batch culture, but T. obliquus showed the highest efficiency at the steady state conditions of the semicontinuous culture. In spite of this, under the flocculants here tested, the efficiency in the recovery of biomass was much higher for C. vulgaris. These results highlight the importance of strain selection in the application of microalgae for wastewater treatment and, particularly, for the removal of pharmaceuticals.

Diclofenac has recently been included in the first watch list of substances to be monitored in all member states so as to evaluate its future inclusion in the priority substances list by the Water Framework Directive. Therefore, in view of upcoming limitations on diclofenac discharge, the objective of this work was to assess its removal from water by a microalgae-based treatment. Moreover, considering microalgae application in wastewater treatment, it was aimed to verify if their nutrient removal capacity was affected by the presence of diclofenac. For a comparison purpose, three different microalgae strains, namely Chlorella sorokiniana , Chlorella vulgaris and Scenedesmus obliquus , were cultured in photobioreactors under identical controlled conditions. For the three strains, the addition of diclofenac meant an organic carbon source and provided higher biomass concentration. C. sorokiniana was the strain showing the largest increase of growth rate and microalgae density, which were above 25% and 31%, respectively, compared with the positive control. However, S. obliquus showed the highest efficiency in the removal of diclofenac (> 79%) and nutrients (> 87% nitrates, > 99% phosphates) per litre and per gram of biomass. These results pointed to the potential application of microalgae for the removal of pharmaceuticals in the bioremediation of wastewater.

Energy crops and thermal conversion of the obtained biomass is a feasible route for the production of energy. In this work, dehydrated composted sewage sludge (BIOSOLIDS) and sludge from dairy wastewater treatment (MUD) were used as organic amendments on four different poplar clones (UNAL, I-214, AF-2 and AF-8) and. These amendments were yearly applied throughout a four years' study aiming to find out the effects on both agronomic (diameter, height and biomass volume of the trees) and thermal (fuel and thermogravimetric analysis) properties of the poplars. The application of MUD improved the agronomic characteristics of the poplars, especially those of UNAL and AF-2. Thermal results were not as conclusive, but pointed to an improvement of the thermal behavior of UNAL under BIOSOLIDS treatment and of AF-2 and AF-8 under MUD fertilization. On the whole, the most favorable case was that of the AF-2 under fertilization with MUD.

This work aimed to compare the adsorptive removal of diclofenac from ultrapure and wastewater by different adsorbents. Batch kinetic and equilibrium experiments were carried out using two different activated carbons (GPP20 and WP70, from Chemviron Carbon) and a non-ionic polymeric resin (SP207, from Resindion). The pseudo-second-order equation fitted the kinetic experimental results and the corresponding k2 (g mg−1 min−1) determined for the activated carbons was one order of magnitude higher than for the polymeric resin. The equilibrium results were fitted by the Langmuir–Freundlich isotherm. The determined maximum adsorption capacity (Qm, mg g−1) and the adsorbent–adsorbate affinity parameter (KLF, mg g−1 (mg L−1)−1/n) were one order of magnitude higher for the activated carbons than for the polymeric resin. With respect to the influence of the aqueous matrix, both the k2 and the Qm remained the same in ultrapure as in wastewater. Differently, the KLF showed one order of magnitude higher values i...

At the pulp and paper industries, large volumes of primary and secondary sludge are generated from wastewater treatment. Aiming to assess the co-processing of each type of sludge with coal, thermogravimetric (TG) analysis has been used in this work. First, combustion and pyrolysis TG curves of coal (C), primary (L1) and secondary (L2) pulp mill sludge were obtained under oxidizing and inert atmosphere, respectively. Then, under identical experimental conditions, TG analysis was carried out on the primary sludge–coal (CL1) and the secondary sludge–coal (CL2) blends. The corresponding differential thermogravimetric (DTG) curves showed evident differences between C, L1 and L2, which were mainly related to the relative large fixed carbon and low volatiles content of C. However these differences, the combustion of CL1 and CL2 mostly resembled that of C. Meanwhile, the pyrolysis of CL1 and CL2 showed lower devolatilization temperatures and char yields than that of C. Non-isothermal kinetic analysis of TG data showed slightly lower apparent activation energy (E) for the combustion of C than for the combustion of either CL1 or CL2. Contrarily, much lower E values were determined for the pyrolysis of CL1 and CL2 than for the pyrolysis of C. Yet, lower E values than the weighted calculated ones were determined for the combustion and, especially, for the pyrolysis of the blends.

Pharmaceuticals represent an especially worrying class of micropollutants because they are biologically active. Thus, their occurrence in the aquatic environment may cause undesirable effects in living organisms and, if present in water sources for human consumption, may constitute a public health issue. Actually, wastewater treatment plants (WWTP), which were not designed for the removal of pharmaceuticals and cannot guarantee their full elimination, are considered hotspots for their dissemination in natural waters. In this context, the present Special Issue (SI) was launched to contribute to the assessment of the current challenges and advances on the removal of pharmaceuticals from wastewater. The SI consists of seven works with any of two different perspectives: (i) fate and removal of pharmaceuticals by conventional treatments applied in existing WWTP; (ii) advanced and alternative green approaches to remove pharmaceuticals from water. The papers in this SI included five experimental works, two literature reviews, and one case study, all of them presenting unconventional approaches, original views, innovative research and/or novel methodologies. We hope that readers of this SI published by Water may find these papers useful for their research or actual activity and may share the findings with their colleagues and community stakeholders.

In the present work, the adsorptive removal of diclofenac from water by biosorption onto non-living microalgae biomass was assessed. Kinetic and equilibrium experiments were carried out using biomass of two different microalgae strains, namely Synechocystis sp. and Scenedesmus sp. Also, for comparison purposes, a commercial activated carbon was used under identical experimental conditions. The kinetics of the diclofenac adsorption fitted the pseudo-second order equation, and the corresponding kinetic constants indicating that adsorption was faster onto microalgae biomass than onto the activated carbon. Regarding the equilibrium results, which mostly fitted the Langmuir isotherm model, these pointed to significant differences between the adsorbent materials. The Langmuir maximum capacity (Qmax) of the activated carbon (232 mg∙g&minus, 1) was higher than that of Scenedesmus sp. (28 mg∙g&minus, 1) and of Synechocystis sp. (20 mg∙g&minus, 1). In any case, the Qmax values determined here were within the values published in the recent scientific literature on the utilization of different adsorbents for the removal of diclofenac from water. Still, Synechocystis sp. showed the largest KL fitted values, which points to the affinity of this strain for diclofenac at relative low equilibrium concentrations in solution. Overall, the results obtained point to the possible utilization of microalgae biomass waste in the treatment of water, namely for the adsorption of pharmaceuticals.

The performance of a polymeric resin (Sepabeads SP207, from Resindion, Binasco, Italy) was compared with that of an activated carbon (GPP20, from Chemviron Carbon, Feluy, Belgium) in the adsorption of acetaminophen and ibuprofen from either ultrapure or waste water. Kinetic and equilibrium adsorption experiments were carried out under batch operation conditions, and fittings of the obtained results to different models were determined. The kinetic experimental results fitted the pseudo-first and -second order equations, and the corresponding kinetic rates evidenced that the pharmaceuticals adsorption was faster onto GPP20 than onto Sepabeads SP207, but was mostly unaffected by the aqueous matrix. The equilibrium results fitted the Langmuir-Freundlich isotherm model. The corresponding maximum adsorption capacity (Qm, mg&minus, 1) was larger onto GPP20 (202 mg g&minus, 1 &le, Qm &le, 273 mg g&minus, 1) than onto the polymeric resin (7 mg g&minus, 18 mg g&minus, 1). With respect to the parameter KLF (mg g&minus, 1 (mg L&minus, 1)&minus, 1/n), which points to the adsorbent-adsorbate affinity, greater values were determined for the pharmaceuticals adsorption onto GPP20 than onto Sepabeads SP207. For both adsorbents and pharmaceuticals, neither Qm or KLF were affected by the aqueous matrix.

This work deals with a preliminary study aimed at evaluating the efficiency of three different microalgae strains, namely Chlorella sorokiniana, Chlorella vulgaris and Scenedesmus obliquus in the bioremediation of diclofenac contaminated water. For this purpose, microalgae were cultured in bubbling column photobioreactors (PBRs) under batch operation until the end of the exponential growth phase. For the three strains, the concentration of diclofenac in the PBRs aquatic medium decreased along microalgae growing, which pointed to biodegradation as the main removal mechanism. Among the three strains, S. obliquus was the most capable to reduce diclofenac concentration (99% removal from an initial concentration of 25,000 μg l−1). However, such a large removal does not guarantee an efficient treatment since transformation products (TPs) exceeding the concentration and/or toxicity of the parent compound may be generated during biodegradation of diclofenac. Thus, for a comprehensive evaluation of the microalgae treatments efficiency, the final effluents from the PBRs were tested for their effects on the embryonic development of zebrafish. Again, the S. obliquus treatment was the most efficient in the reduction of toxicity, with the corresponding effluents having no effects on the embryo's mortality or abnormalities incidence (at 80 h post fertilization). In any case, for the three strains, the toxicity effects of effluents were equal or lower than those determined for diclofenac solutions with the same concentration. Therefore, it may be stated that, at the end of the batch culture, the removal of diclofenac by the considered strains did not involve the generation of toxic TPs to zebrafish embryos.

Properties of primary and secondary pulp mill sludge are unalike and are also very different from those of coal. Thermogravimetric analysis was used to assess the separate combustion of coal, primary and secondary pulp mill sludge. Then, the co-combustion of coal with primary and with secondary pulp mill sludge was studied under identical experimental conditions. Both Differential Thermogravimetry burning profiles (DTG) and Differential Scanning Calorimetric analysis (DSC) showed remarkable differences between the combustion of coal, primary and secondary paper mill sludge. However, compared with the combustion of coal, the effects of adding a 10 wt.% of either primary or secondary paper mill sludge were not relevant in terms of weight loss or heat release. This was further proved by non-isothermal kinetic analysis, which was used to evaluate the apparent activation energy corresponding to the single combustions and to the co-combustion of blends.

A continuous method to produce monolayer lay-flat hoses is described in this work. Our first goal was to develop a new continuous method for the production of a polymeric matrix reinforced with fabric ( monolayer lay-flat hoses). Then, we faced the big challenge of achieving the same properties as the existing products obtained by the current uncontinuous method that prevails in the market. These important properties are bursting and working pressures, adhesion between polymer matrix and fabric, tensile strength and modulus, weight per metre and maximum load. Another crucial matter is the economical side. Therefore, the proposed method was evaluated in terms of production costs and tangible assets (machinery investments). It was concluded that the final product by the proposed continuous production method is highly competitive from a quality and economic point of view.

This work aimed to study both the removal of nutrients and pharmaceuticals, namely salicylic acid or paracetamol, from water by the culture of Chlorella sorokiniana . The removal of nutrients was nearly complete at the end of the batch culture; above 70% for nitrates and 89% for phosphates in the semicontinuous culture. The pharmaceuticals removal kinetics were 2.3 times greater for the salicylic acid than paracetamol, reaching volumetric efficiencies above 93% for salicylic acid in the semicontinuous culture. Finally, to separate the microalgae biomass from treated water, metal salts, synthetic polyelectrolytes and a biopolymer were tested as coagulants–flocculants. The best flocculation results were achieved with AlCl 3 (95.23% with 200 mg g −1 , 1 min incubation time). However, given that resulting flocs had different characteristics, flocculants must be chosen on the basis of the subsequent use of the biomass.

Energy valorization of rice straw is possible by thermal conversion. The aim of this paper was to study the emissions throughout heating of rice straw under seven different atmospheres (simulating combustion, gasification and pyrolysis). For this purpose, combustion, gasification and pyrolysis of rice straw were studied by simultaneous TG/MS dynamic runs at 15 °C min−1. Results showed that a partially inert atmosphere is more advisable from an environmental point of view due to the lower emission of contaminants.

This work presents the application of a new system for wastewater treatment in the food industry, which is based in the injection of pure oxygen in the homogenization tank of a traditional physicochemical treatment. This system operates stably under a wide variety of both input chemical oxygen demand (COD) and total suspended solids (TSS). Compared with the previous physicochemical system, it has been proved that the new one is more efficient and implies important economic savings for the dairy. Compared with a traditional anaerobic treatment, it has been shown that the oxygen injection system avoids the relatively high costs associated to the initial investment and operating costs and is environmentally friendlier. In this work it is shown that oxygen injection may be an interesting option for the dairy industry wastewater treatment.

Benzotriazole is used as corrosion inhibitor in many industrial sectors, such as the dairy industry. Due to its widespread use in various applications and everyday consumer products, this chemical easily reaches the aquatic environment, where it may have deleterious effects. In fact, benzotriazole has been included among the so-called emerging contaminants. In this work, the occurrence and fate of a benzotriazole based anticorrosive (BTA-A) during wastewater treatment in a dairy industry has been assessed. At this dairy, a new system for wastewater treatment based on the injection of pure oxygen was recently started. This system has been proved to be efficient, economic and able to stably operate under a wide range of chemical oxygen demand and total suspended solids inputs. Then, after detecting the presence of BTA-A in the effluent of the wastewater treatment plant, it was aimed to optimize oxygen injection for the removal of this anticorrosive together with the regulated parameters. The performance of the system was evaluated at a real scale during a month period, during which the mean removal performance of the oxygen injection based treatment was 91%, 90% and 99% for chemical oxygen demand, total suspended solids and BTA-A, respectively.

The purpose of this study was to investigate the fate of three tetracyclines (TCs), namely oxytetracycline (OTC), chlortetracycline (CTC) and doxycycline (DC) at two different full-scale swine manure-activated sludge treatment plants. Throughout treatment, OTC, CTC and DC were removed by 71–76%, 75–80% and 95%, respectively. Removal of these TCs under physical treatment was deniable. On the contrary, the flocculation–coagulation and the secondary clarification resulted in a relevant reduction of the concentration of these TCs.

Thermal valorization of organic wastes by co-processing with coal may be a management option for such wastes. In this work, the separate pyrolysis of coal and primary and secondary pulp mill sludge was assessed by thermogravimetric (TG) analysis. Then, under the same experimental conditions, the pyrolysis TG curves of the coal blends with a 10 mass% of either primary or secondary pulp mill sludge were obtained. The corresponding differential thermogravimetry curves made evident that the devolatilization of coal starts at higher temperature and reaches higher char yields than that of primary or secondary paper mill sludge. Under blending, lower devolatilization temperatures and char yields, close to the weighted calculated ones, are observed. Non-isothermal kinetic analysis showed that the Arrhenius activation energy (E) corresponding to the pyrolysis of coal was lower than that corresponding to either L1 or L2. Moreover, lower E than the weighted calculated ones was determined for the co-pyrolysis of the blends.

Microalgae are aquatic photosynthetic prokaryotic or eukaryotic microorganisms which cultivation for the fixation of CO2 and the production of biofuels has received large attention. However, the sustainable development of an algal biorefinery is still a challenge. In this context, the valorization of microalgae biomass for a wastewater adsorptive treatment may be an option to explore. Recently, the presence of emerging contaminants (ECs) in natural waters and the associated risks have led to a great concern, especially in the case of pharmaceuticals. In the present work, the elimination of paracetamol from water by biosorption onto microalgae, namely Synechocystis sp., has been studied. Kinetic and equilibrium parameters have been determined and compared with those obtained when using a commercial activated carbon under the same experimental conditions. Although the adsorption kinetics are very similar onto both materials, at the equilibrium, the Langmuir maximum capacity of the activated carbon (278 mg g−1) is five times higher than that of Synechocystis sp. (53 mg g−1). In any case, it must be considered that the utilization of microalgae may be considered an environmentally friendly process with important associated savings.