AP--Animal Production Technology Some Intermittent Aeration Kinetics from a Laboratory Study with Pig Slurry

A 0·75 kW aeration system with a venturi air injector was used in this study to examine the properties of the oxygen uptake rate and overall oxygen transfer coefficient in pig slurry. Data showed that both parameters varied with the intermittent aeration process. The oxygen uptake rate increased from 0·46 mgl-1 min-1to about 1·8 mg l-1min-1, while the overall oxygen transfer coefficient decreased from 0·5 min-1to about 0·3 min-1over a total number of 31 tests. The system had a tendency to run continuously since the off-run time decreased from 10 min at the beginning of the test to 3 min at the end of the test. This may imply that an intermittent aeration system, if controlled by dissolved oxygen concentration, might not be able to run intermittently due to increased consumption of oxygen by the manure. The aeration system tested achieved an aeration efficiency of 3·20 kg [O2] kWh-1in this study.