Indagine sperimentale sull'accumulo di acque reflue in serbatoi: il caso studio di Caltagirone

This paper presents the results of a research aiming at evaluating the effects of storage onwastewater characteristics. Wastewater discharged from the Caltagirone (Eastern Sicily)plant after secondary treatment was stored in an earth reservoir with a capacity of about25,000 m3 and a depth of 5 m. Wastewater inflow in the reservoir was continuosthroughout the experimental activities, while discharge was discontinuous, depending onirrigation demand. Removal efficiency resulted highly influenced by operation regime ofthe reservoir and by influent wastewater characteristics. BOD5 and COD removalefficiency was above 50%. Removal efficiency of faecal coliforms, faecal streptococci andEscherichia coli was between 2 and 5 log units. Single and multiple regressions weretested to determine the reservoir design characteristics and operation parameters thatmost significantly affected water quality changes.