Process intensification with a hybrid system: A tubular packed bed bioreactor with immobilized activated sludge culture coupled with membrane filtration

Performance of a hybrid system consisting of a tubular bioreactor and a membrane filter was studied for removing carbohydrate and protein. Microporous polyurethane (sponge) was used as the packing medium for immobilization activated sludge culture. The bioreactor was operated in series with a cross flow ultrafiltration system to study the effect of influent flow rate and chemical oxygen demand (COD) concentration on the overall system performance. The removal efficiency in the bioreactor decreased linearly with increase in loading. The decline of removal efficiency at higher loadings was more significant for protein than carbohydrate. Coupling the bioreactor with a membrane separation process increased the overall removal rates and provided a consistent effluent quality. The flux through ultrafiltration membrane did not change significantly even when the bioreactor effluent had high levels of protein. Morphological examination of the packing medium both visually and by SEM showed significant accumulation of organisms on the surface which indicates that biofilm thickness was controlled by diffusion limitations. Advantages of the hybrid system include small footprint, economical packing medium, and space savings by coupling the bioreactor with a membrane filtration process.     

Electropolymerization, characterization and corrosion performance of poly(N-ethylaniline) on copper

Poly(N-ethylaniline) (PNEA) coatings were grown by cyclic voltammetry technique on copper from 0.1 M N-ethylaniline (NEA) in 0.3 M oxalic acid solution. The optimum conditions (e.g. upper potential limit, scan rate and cycle number) effect on corrosion performance of synthesized PNEA films were determined in order to obtain best protection results against corrosion. The electrodeposited coatings were characterized by cyclic voltammetry (CV), Fourier Transform Infrared-Attenuated Total Reflectance (FTIR-ATR) spectroscopy and scanning electron microscopy (SEM). Redox parameters were found after electrochemical tests and results of stability tests of these films impart an electroactive behavior that is composed of both diffusion control and thin film behavior. In addition, corrosion performance of PNEA coatings were investigated in 0.1 M H₂SO₄ by Tafel extrapolation and electrochemical impedance spectroscopy (EIS) techniques.