Influence of distinct processes on the quality of water in distribution systems.

A new mathematical model has been introduced (Pianese et al, 1995) to evaluate the changes, in time and space, of quality characteristics of the water flowing through a complex water distribution system composed of free water surface tanks, pumping stations and pipes connecting the to one another and carring water to delivering modes. The model is able to give a highly detailed description of all the phenomena that may arise in the water system, such as: mixing, transportation of the inlet substances (through advection, eddy diffusion, molecular diffusion), volatilisation in the tanks, reactions with substances contained in the water and/or present on the pipes' internal walls. The capabilities of the proposed model in order to evaluate the concentrations, in steady-state conditions, of non conservative substances in a water system have been already illustrated (Pianese et al., 1997). The present paper reports the results of a sensitivity analysis carried out with reference to a case-study already described in literature, in order to explain the influence, even on the steady-state concentration values, of a series of phenomena frequently neglected by other models.