Ammonia in poultry barns produced by microbial action on the birds’ excreta can be removed by scrubbing into aqueous solution at pH ∼4. However, disposal of the resulting solution remains a problem. In this work, ammonia was oxidized electrochemically in the presence of unreactive electrolytes (NaClO4, Na2SO4), but the conditions were not compatible with treatment inside or outside a poultry barn (high pH, closed electrochemical reactor, and high ammonia concentration). Efficient denitrification is possible without pH adjustment of the scrubbed solution when chloride ion is also present in the scrubbing solution. This reaction is based on electrochemical hypochlorination, which is similar to breakpoint chlorination for the chemical elimination of ammonia. This work confirms a recent mechanistic proposal that efficient denitrification at pH ∼3 is the result of concomitant oxidation of water and acidification at the anode, but shows in addition that the mechanisms of both chemical and electrochemical hypochlorination are similar at acidic pH. These results allow us to propose that ammonia scrubbed into acidic brine can be oxidized to elemental nitrogen with high current efficiency without pH adjustment and without chemical additives, providing a “green” solution to the problem at hand.

Polymer extraction is a key step of the metal injection moulding (MIM) process. An innovative method for extracting an organic binder involves the use of supercritical fluid instead of a regular solvent. The supercritical fluid selected was carbon dioxide due to its affinity toward polyethylene glycol. The supercritical carbon dioxide parameters were optimised in order to complete the extraction of this polymer from the Inconel 718 superalloy feedstock. The effects on the surface quality of the components and on the microstructure of the densified component were also investigated. A finite element model, which combines the fluid model and structural mechanics , enabled the estimation of the stress distribution during the supercritical debinding step. The study was completed by a parametric analysis of the pressure variation inside the equipment with respect to the processing parameters for the MIM components.