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- A novel approach for nutrients recovery from municipal waste as biofertilizers by combining electrodialytic and gas permeable membrane technologiesPublication . Oliveira, Verónica; Ferreira, Célia; González-García, Isabel; Labrincha, João; Horta, Carmo; García-González, María CruzThe recovery of valuable materials from waste fits the principle of circular economy and sustainable use of resources, but contaminants in the waste are still a major obstacle. This works proposes a novel approach to recover high-purity phosphorus (P) and nitrogen (N) from digestate of municipal solid waste based on the combination of two independent membrane processes: electrodialytic (ED) process to extract P, and gas permeable membranes (GPM) for N extraction. A laboratory ED cell was adapted to accommodate a GPM. The length of waste compartment (10 cm; 15 cm), current intensity (50 mA; 75 mA) and operation time (9 days; 12 days) were the variables tested. 81% of P in the waste was successfully extracted to the anolyte when an electric current of 75 mA was applied for 9 days, and 74% of NH4 + was extracted into an acid-trapping solution. The two purified nutrient solutions were subsequently used in the synthesis of a biofertilizer (secondary struvite) through precipitation, achieving an efficiency of 99.5%. The properties of the secondary struvite synthesized using N and P recovered from the waste were similar to secondary struvite formed using synthetic chemicals but the costs were higher due to the need to neutralize the acid-trapping solution, highlighting the need to further tune the process and make it economically more competitive. The high recycling rates of P and N achieved are encouraging and widen the possibility of replacing synthetic fertilizers, manufactured from finite sources, by secondary biofertilizers produced using nutrients extracted from wastes.
- Electrodialytic process combined with gas permeable membrane for phosphorus and nitrogem recovery from municipal waste as biofertilizerPublication . Oliveira, Veóonica; Ferreira, Célia; González-Garcia, Isabel; Labrincha, João; Horta, Carmo; Garcia-González, María Cruz
- Polypyrrole-TiO2 composite for removal of 4-chlorophenol and diclofenacPublication . Silvestri, Siara; Burgo, Thiago Augusto Lima; Ferreira, Célia; Labrincha, João; Tobaldi, DavidIn this work, we successfully synthesized TiO2-polypyrrole (PPy) composite material via polymerization method using the sulfuric acid (H2SO4) as an oxidizing agent. Different characterization techniques, including electrostatic force microscopy, confirmed that TiO2 was intimately attached on PPy. The photocatalytic activity of PPyTiO2 composite was studied experimentally for the conversion of diclofenac (DCF)– one of the most frequently detected pharmaceutical compounds in the aquatic environment – and 4-chlorophenol (4-CP) - largely used in the bleaching of cellulose pulp in the paper industry, as herbicide and pesticide - under simulated solar light irradiation at environmental conditions. This is the first time that a composite PPy-TiO2 was used as photocatalyst for the conversion of 4-CP. Results showed that the PPy-TiO2 was able to convert more than 90% of DCF and 40% of 4-CP in just 60 min, showing stability and efficiency over five consecutive cycles of reuse for both pollutants. The produced PPy-TiO2 showed higher photocatalytic efficiency compared to that of TiO2, thus proving itself to be a promising photocatalyst.