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Microbial fuel cells are devices that convert chemical energy stored into the bonds of organic compounds in electric energy using microorganisms. The advantages of these devices are the capability of water treatment and cleaning. We report, as proof of concept, the construction and performance of a microbial fuel cell, employing reusable and low-cost materials. Microbial Consortium was isolated from Amaluza sludge, Cuenca-Ecuador. The microbial fuel cell was tested using domestic residual water, sampled from Ubilus's neighborhood, at the canton Quito, Ecuador. A power density of ca. 40 mW/m2 and an 80 % of organic matter remotion were obtained with the final microbial fuel cell. On the concept of circular economy, nitrogen, phosphorus, and potassium were measured into the produced biomass, as possible applications in agronomy., Las celdas de combustible microbianas son dispositivos que permiten transformar energía química almacenada en compuestos orgánicos en energía eléctrica, utilizando microrganismos depositados sobre un electrodo. Entre las ventajas que posee esta tecnología se destaca la posibilidad de limpiar o tratar matrices acuosas como aguas residuales. A continuación se reporta, como prueba de concepto, la construcción de una celda de combustible microbiana empleando materiales reciclados o de bajo costo. El consorcio de bacterias electrogénicas utilizadas se aisló de sedimentos del embalse Amaluza, en Cuenca, Ecuador. La celda se puso en funcionamiento utilizando aguas residuales domésticas reales, obtenidas del barrio Ubilus de la parroquia Pintag del cantón Quito, Ecuador. La celda de combustible construida generó una densidad de potencia de 40 mW/m2 con un porcentaje de remoción de materia orgánica cercano al 80 %. Siguiendo el concepto de economía circular, se midió la concentración de nitrógeno, fosforo y potasio en la biomasa producida por la celda para su posible aplicación como aditivo ecológico de fertilizantes.

Membrane fouling and biofouling, which arises from the nonspecific interaction between the membrane surface and foulants, significantly impedes the efficient application of membrane technology. The addition of nanoparticles could have an impact on the properties of membranes used for nanofiltration. Nanoparticles can provide various functionalities to a membrane but, there are very few studies of the effect of mixing catalysts in PDA-modified membranes. In this study, polydopamine has been used to firmly bind a combination of nanoparticles on thin film composite (TFC) membranes. Two simple methods (a one-step and a two-step method) to assemble a multifunctional (TiO2, ZnO) layer of nanoparticles onto a commercial NF membrane as support have been evaluated by applying fast deposition of polydopamine (PDA). The membrane performance was evaluated based on the relative flux decline. Results show that the modification methods did not compromise the rejection of MgSO4, combined with an increase ∼15% in the rejection of NaCl. A 25% increase in the hydrophilicity of the modified membranes compared to pristine membrane was evidenced. In addition, the two-step modification method has antimicrobial activity for an ultralow load of 0.03 wt% ZnO nanoparticles; the antimicrobial activity increased when the membrane had a combination of TiO2:ZnO nanoparticles at 1:2 and 2:1 ratios using Bacillus Subtilis as model bacteria. The photocatalytic activity of the nanoparticles layer was demonstrated through the removal of methylene blue from a solution contacting the membrane when exposed to solar radiation.

Highly cross-linked dense structure of integrally skinned asymmetric (ISA) organic solvent nanofiltration (OSN) membranes limits the permeability of organic solvent. Herein, a new porous nanocomposite OSN membrane was constructed based on one-dimensional nanofibers and a modified zeolitic imidazole framework, ZIF-8. Aramid nanofibers (ANFs) were exfoliated from Kevlar fiber in potassium hydroxide (KOH)/dimethyl sulfoxide (DMSO). The coordinative binding of branched polyethyleneimine (BPEI) on ZIF-8 surface gave rise to a good dispersion of ZIF-8 in the ANFs dope solution. The membrane was prepared by non-solvent induced phase inversion and thermal post-treatment. The effect of ZIF-8 on membrane physicochemical properties was inferred by SEM, XRD, AFM, FTIR, TGA, contact angle analysis and tensile strength measurement. The results demonstrated that the ZIF-8 intercalated among ANFs and produced a porous nanofibrous network. The porosity of the membrane increased from 23.3% to 56.9%. As consequences, the prepared ANF nanocomposite membrane showed two times higher permeances for polar (methanol, ethanol, isopropanol, acetone, tetrahydrofuran) as well as non-polar solvents (hexane, carbon tetrachloride) than that of the pristine membrane. It was found that the nanocomposite membrane has promising applications in nanofiltration of organic liquids for molecular separation. The long-term OSN filtration showed that the membrane had an ethanol and isopropanol permeance of 2.9 L m−1 h−1 bar−1, 1.8 L m−1 h−1 bar−1 respectively, with erythrosin B (EB, 836 g mol−1) rejections over 90%. The architecture of one-dimensional nanofibers and porous nanomaterials provides a new route for fabrication of nanocomposite OSN membranes.