[Effect of feed residues on the release of nitrogen and phosphorus of pond sediment].

The effect of feed residues on release law of nitrogen and phosphorus in water-sediment interface was studied under the simulated condition in laboratory. Two sets of conditions were applied in this study, static condition (A group) and feed add condition (B group). The results show that DO in A group is higher than that in B group (P < 0.05). The pH value is neutral in A group, but pH value of B group became weak acidic. After adding the feed, nitrate nitrogen concentration in A group is higher than that in B group (P < 0.05), but orthophosphate concentration in A group is lower than that in B group (P < 0.05). At the 2-14th day of experiment, ammonia concentration in A group is higher than that in B group (P < 0.05), but since then the ammonia concentration in B group begins to rise. At the end of the test, ammonia concentration in B group is higher than that in A group (P < 0.05). At the beginning of the experiment, ammonia and nitrate nitrogen release restrained in B group. Nitrogen increases first, and then decreases in A group, but the changing regulation is completely opposite in B group. Feed decomposition can produce a large amount of phosphorus in B group, at the same time, orthophosphate changing regulation increases first and then decreases.

Removal of Cl adsorbed on Mn-Ce-La solid solution catalysts during CVOC combustion.

Mn-Ce-La oxide-mixed catalysts prepared by the method of complexation followed by calcination at 750°C were tested in the catalytic combustion of chlorobenzene (CB) taken as a model of chlorinated aromatics. XRD analyses show that Mn and La enter CeO2 matrix with a fluorite-like structure to form solid solution. The catalysts with high ratio of Mn/Mn+Ce+La exhibit high activity for CB combustion, due to high oxygen mobility. For all Mn-Ce-La catalysts, deactivation due to Cl adsorption is observed at different temperatures, depending on composition. At 330°C or higher temperature, the removal of Cl species from the surface in the forms of Cl2 (produced through Deacon reaction) and HCl (produced through hydrolysis of Cl) occurs and the activity of catalysts for CB combustion becomes thus stable. Either the addition of water or the increase in gaseous oxygen concentration can promote the removal of Cl species, and thus to increase the activity for CB combustion. High stable activity of Mn-Ce-La catalysts can be related to the combination of good oxidation and Deacon reaction performances.