Modelling of bacterial removal in wastewater storage for irrigation purposes: a case study in Sicily

In arid and semiarid regions the reclamation and reuse of municipal wastewater can play a strategic role in alleviating water resources shortages. Public awareness is growing about the need torecycle and reuse water for increasing supply availability. Many wastewater reuse projects have been put inoperation in European and Mediterranean countries adopting extensive treatment systems such as aquiferrecharge, lagooning, constructed wetlands, and storage reservoirs, mainly for landscape and agriculturalirrigation. In agricultural reuse systems, there is an increasing interest in extensive technologies because oftheir high reliability, and easy and low cost operation and maintenance. Wastewater storage reservoirs havebecome the option selected in many countries because of the advantages they present in comparison withother treatment alternatives, namely the coupling of two purposes, stabilization and seasonal regulation. Thispaper describes an example of a wastewater storage system, built in Caltagirone (Sicily, Italy). The storageresults in a tertiary treatment of a continuous inlet flow of activated sludge effluents. The prediction of themicrobiological water quality has been evaluated by means of a non-steady-state first-order kinetic model.Single and multiple regressions were applied to determine the main variables that most significantly affecteddie-off coefficients. The proposed model has been calibrated using the results of a field monitoring carriedout during a period from March to October 2000.