Desludging Interval in a Waste Stabilization Pond: a Markov Approach

The nature of sludge deposits and their effects on pond performance are discussed. A cost-objective function is minimized to obtain an equation for the optimal desludging interval. The objective function is formulated in terms of the waste stabilization treatment cost incurred at every level of maintenance and the total cost of desludging. The desludging and treatment costs are functions of the underlying finite states, while the optimization criterion is the expected average cost per unit time period. Transition to the terminal state is both gradual and sudden ("catastrophic") depending on the efficiency of the maintenance adopted in the pond. The results obtained are discussed and compared with the conventional desludging interval.