The possible importance of wind aeration in controlling odours from piggery slurry stored after aerobic treatment

An experiment to measure the respiration rate of treated piggery slurry is described. Calculations using data from the experiment estimate the effect that the wind-mediated transfer of oxygen from the atmosphere into the slurry in a storage tank or lagoon might have upon the time of the return of an offensive odour.

The study shows that the effect of wind aeration is potentially far greater than that of even a fourfold increase in the solids residence time of the prior aerobic treatment. For example, storing aerobically-treated piggery slurry in a lagoon of maximum depth 2 m could permit wind aeration sufficient to increase the period for which the odours would not be offensive from a maximum of 30 days after a 4-day solids retention time (SRT) treatment to more than 180 days, even when the slurry had had only a 1-day SRT treatment.