Electricity and disinfectant production from wastewater: Microbial Fuel Cell as a self-powered electrolyser

This study presents a simple and sustainable Microbial Fuel Cell as a standalone, self-powered reactor for in situ wastewater electrolysis, recovering nitrogen from wastewater. A process is proposed whereby the MFC electrical performance drives the electrolysis of wastewater towards the self-generation of catholyte within the same reactor. The MFCs were designed to harvest the generated catholyte in the internal chamber, which showed that liquid production rates are largely proportional to electrical current generation. The catholyte demonstrated bactericidal properties, compared to the control (open-circuit) diffusate, and reduced observable biofilm formation on the cathode electrode. Killing effects were confirmed using bacterial kill curves constructed by exposing a bioluminescent Escherichia coli target, as a surrogate coliform, to catholyte where a rapid kill rate was observed. Therefore, MFCs could serve as a water recovery system, a disinfectant/cleaner generator that limits undesired biofilm formation and as a washing agent in waterless urinals to improve sanitation. This simple and ready to implement MFC system can convert organic waste directly into electricity and self-driven nitrogen along with water recovery. This could lead to the development of energy positive bioprocesses for sustainable wastewater treatment

Interaction of epitope-related and -unrelated peptides with anti-p24 (HIV-1) monoclonal antibody CB4-1 and its Fab fragment

The binding of four epitope-related peptides and three library-derived, epitope-unrelated peptides of different lengths (10-14 amino acids) and sequence by anti-p24 (HIV-1) monoclonal antibody CB4-1 and its Fab fragment was studied by isothermal titration calorimetry. The binding constants KA at 25°C vary between 5.1 × 107 M-1 for the strongest and 1.4 × 105 M-1 for the weakest binder. For each of the peptides complex formation is enthalpicaily driven and connected with unfavorable entropic contributions; however, the ratio of enthalpy and entropy contributions to ΔG0 differs markedly for the individual peptides. A plot of -ΔH0 vs -TΔS0 shows a linear correlation of the data for a wide variety of experimental conditions as expected for a process with ΔCp much larger than ΔS0. The dissimilarity of ΔCp and AS0 also explains why ΔH0 and TΔS0 show similar temperature dependences resulting in relatively small changes of ΔG0 with temperature. The heat capacity changes ΔCp upon antibody-peptide complex formation determined for three selected peptides vary only in a small range, indicating basic thermodynamic similarity despite different key residues interacting in the complexes. Furthermore, the comparison of van't Hoff and calorimetric enthaipies point to a non-two-state binding mechanism. Protonation effects were excluded by measurements in buffers of different ionization enthaipies. Differences in the solution conformation of the peptides as demonstrated by circular dichroic measurements do not explain different binding affinities of the peptides; specifically a high helix content in solution is not essential for high binding affinity despite the helical epitope conformation in the crystal structure of p24