Artificial destratification of Dipotamos reservoir in Northern Greece by low energy air injection

The aims of this study were to investigate the Dipotamos water reservoir destratification process that used the low-energy method of air injection, and evaluate its potential to suppress the presence of nuisance compounds to within permitted drinking water limits. The selection of optimum design parameters for the application of air injection through perforated pipes was based on the Davis model. Data collected throughout a 4-year operation period showed that artificial mixing by air injection may be adequate for the complete destratification of the reservoir. The air injection method had a low energy demand, estimated to be around 55 Wh/10³m³/d. Upon air injection start-up, water column homogenization occurred relatively quickly, as deduced by the values of temperature and dissolved oxygen concentration recorded at various sampling points within the reservoir. After the 1st week of operation, the oxygen concentration at 20 m depth increased from nearly zero to 2 mg/L, and doubled 1 week later, reaching equilibrium after 30 d of continuous operation. The air injection method resulted in the improvement of water quality.