Browsing by Issue Date, starting with "2024-09-24"
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- Beyond bioremediation: the untapped potential of microalgae in wastewater treatmentPublication . Liberti, Davide; Pinheiro, Filipa; Simões, Beatriz; Varela, João; Barreira, LuísaMicroalgae-based wastewater bioremediation has emerged as a promising and sustainable solution for water purification by harnessing the natural ability of microalgae to absorb and transform pollutants. In the literature, it is possible to find diverse microalgae applications in wastewater treatment, highlighting their efficiency in nutrient removal, heavy metal sequestration, and overall water quality enhancement. Although microalgae demonstrate remarkable potential for wastewater treatment, there is a critical gap in research concerning the utilization of biomass produced during the treatment process, including large-scale biomass harvesting methods, economic viability assessments, and the exploration of innovative downstream applications. By shedding light on these deficiencies, the aim of this review is to encourage further research and development to maximize the potential of microalgae in removing wastewater pollution and the application of biomass derived from the treatment. In conclusion, this review not only underscores the overall efficiency of microalgae in wastewater bioremediation but also emphasizes the necessity of a more comprehensive approach that considers the full lifecycle of microalgae, from wastewater treatment to innovative applications of biomass, addressing both environmental and economic concerns.
- Microalgae flocculation: assessment of extraction yields and biological activityPublication . Imbimbo, Paola; Ferrara, Alfonso; Giustino, Enrica; Liberti, Davide; Monti, Daria MariaDownstream costs represent one of the main obstacles to enabling microalgae to become widespread. The development of an economical, easily scaled-up strategy could reduce the overall process costs. Here, different flocculants were tested on different microalgae strains and a cyanobacterium. The results indicate that flocculation could be an alternative to centrifugation, as CaCl2 induced a complete flocculation of green and red marine strains (96 +/- 4% and 87.0 +/- 0.5%, respectively), whereas Chitosan was the only agent able to induce flocculation on the cyanobacterium (46 +/- 1%). As for the thermoacidophilic red microalga, 100% flocculation was achieved only by increasing the pH. Carotenoids were extracted from the flocculated biomass, and the strategy improved with the use of the wet biomass. The results indicate that flocculation does not affect carotenoid yield, which is at least the same than that obtained upon centrifugation and extraction from the wet biomass. Then, for the first time, the biological activity of the extracts obtained from the flocculated biomasses was evaluated. The results indicate that only the green microalga extract shows increased antioxidant activity. In conclusion, this work highlights that a general downstream procedure cannot be developed for microalgae strains but should be rationally tailored.
- The monitoring of pharmaceutical pollutants in wastewater treatment plants in the Algarve, PortugalPublication . Mathaba, Hopolang Jonase; Pinto, Patrícia Isabel Silvestre; Power, DeborahThe occurrence of pharmaceutical compounds in wastewaters of Faro-Olhão and Faro-Noroeste wastewater treatment plants was monitored over summer and winter seasons from 2021 to 2024, to contribute to monitor marine pollution. A total of 26 pharmaceutical pollutants were analysed in the influent wastewater and in treated effluents by liquid-chromatography coupled with tandem mass-spectrometry (LC-MS/MS). The results showed quantifiable occurrences of 17 of the 26 pharmaceutical pollutants with outstanding levels of acetaminophen and caffeine (average 50-55 and 63.8-65 μg/L, respectively), and no quantifiable presence of sex hormones or contraceptives. These influent and effluent occurrence concentrations were used to compare the treatment performance between the classical activated sludge and the aerobic granular sludge wastewater treatment systems deployed in Faro-Noroeste and in Faro-Olhão wastewater treatment plants, respectively. The conventional activated sludge treatment exhibited relatively higher treatment efficiencies for most of the monitored pollutants than the aerated granular sludge. The majority of the quantifiable pharmaceutical pollutants were removed effectively by the wastewater treatment plants, with over 60% removal for ten pharmaceutical pollutants in Faro-Noroeste and five in Faro-Olhão. The high occurring caffeine and recalcitrant diclofenac were the only pollutants found at quantifiable levels in the surrounding Ria Formosa environment. Resistance to removal from the wastewater was observed greatly for the anticonvulsants carbamazepine and diclofenac leading to the investigation of carbamazepine, phytoestrogen coumestrol, and wastewater effects on the marine invertebrate Artemia sp. using an immobilisation/lethality assay. The assay showed high toxicity potential for coumestrol and lower for carbamazepine with LC50 values of 39.87 and 94.53 mg/L, respectively, in artificial seawater, and 5.09 and 26.47 mg/L in natural seawater, respectively. The toxicity levels were, however, multiple times (approximately 1.9x104) higher than their existence in the wastewater.