Ammonia recovery from anaerobically digested cattle manure effluents through steam stripping was studied at a stripping tower temperature of 98-99 degrees C and a steam-water ratio approximately 56-72 g/L. The digested manure effluents were first treated by microfiltration and then the permeate was used as feed in steam stripping. The stripping performance was evaluated under different feed pH values, ammonia concentrations and temperatures. The increase of the initial feed pH does not significantly improve ammonia stripping efficiency due to the fact that the stripped effluent pH is increased during steam stripping. This suggests that steam stripping of anaerobically digested manure effluents for ammonia recovery may not need pre-raised pH. In contrast, the pH value of the synthetic ammonia wastewater containing NH4Cl dramatically decreases after steam stripping. Increasing the feed temperature slightly improves ammonia stripping efficiency, but reduces the concentration of the recovered ammonia in the condensate due to an increased condensate volume at a higher feed temperature. Therefore, the feed temperature should be controlled at an optimum point that can compromise the condensate ammonia concentration and the ammonia stripping efficiency. Experimental results indicate that recovery of ammonia from anaerobically digested cattle manure effluents as NH4OH is technically feasible.

Pt/CeO2/CNT catalysts were prepared by adsorbing Pt nanoparticles on the supports of CNTs coated with CeO2. The electrocatalytic performances in respect to the electrooxidation of chemisorbed CO were tested using potential step and stripping voltammetry methods under variable sweep rate and temperature conditions. At 10 mV s–1, the CO stripping voltammogram exhibited the peak splitting phenomenon. The oxidation charge and the peak potential of the two voltammetric peaks changed regularly with the number of Pt and CeO2 neighbours, the sweep rate, and the temperature. We considered that the low potential peak originated from the reaction of COads with hydroxyl groups on CeO2 adjacent to Pt sites, while the high potential peak came from the reaction of COads with hydroxyl groups produced on pure Pt. Furthermore, the experimental results of the peak potential against the logarithm of the sweep rate and the logarithm of the current maximum time against the step potential were plotted and intersecting lines with different slopes in high and low potential regions in the plot were observed. The lines intersected at lower potentials on the Pt/CeO2/CNT electrode than on the Pt/CNT electrode, which was attributed to the contribution of hydroxyl groups on CeO2.

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