Modelling of Drinking Water Recarbonization in Fluidized Bed Reactor

Abstract

Calcium and magnesium are important not only for human health but also for reducing problems related to the corrosive and aggressive effects of soft water on drinking water distribution materials. Experimental and mathematical modeling of the recarbonization process aimed at increasing the content of these biogenic elements in water was carried out using the novelty of continuous laboratory- and pilot-scale fluidized bed reactors. A methodology for scaling-up the modeled system was extended with mathematical modeling. Water remineralization was performed using half-calcined dolomite (HCD) and CO2. The influence of operating conditions, i.e., Q(CO2), freshwater inflow, and HCD dose, on quality indicators of treated drinking water (c(Ca2+), c(Mg2+), c(Ca2+ + Mg2+) and Ca/Mg) was studied. Results show that the Mg2+ concentration is more significantly affected by the amount of HCD in the system and the flow of CO2, while the effect of freshwater inflow is less significant. At constant CO2 flow, the Ca2+ content decreases and the Mg2+ content increases as the tap water inflow increases, which results in a decrease in the Ca/Mg molar ratio. However, the Ca/Mg ratio can be effectively controlled by adding an appropriate amount of HCD at certain time intervals. Overproduction of ions is easily controlled by the CO2 flow.