Stormwater purification via progressive freeze concentration: effect of initial concentration and stirring speed: article

Water is one of basic needs and is essential for every living organism on Earth to survive. With increasing population, water has become scarce resource since the water demand is more than water supply. There are several methods to treat water such as evaporation, membrane processes and ultraviolet disinfection. However, these methods have limitations. Thus, researches have to find alternative way and this lead to progressive freeze concentration (PFC) process. This research aims to study the effect of initial concentration and stirring speed in stormwater purification via progressive freeze concentration (PFC) towards effective partition constant (K) value, solute recovery (Y) and concentration efficiency. The range of initial concentration and stirring speed were determined at 2, 4, 6, 8 and 10 ppm and 150, 200, 250, 300 and 350 rpm. Simulated stormwater was created by using zinc chloride instead of actual stormwater to ease the process. Each effect was run at constant coolant temperature and time, -8ᵒC and 15 minutes. The results show at lowest initial concentration, the lowest K value obtained is 0.25 and the highest Y value of 0.686. It was found that at stirring speed of 350 rpm produced lowest K value, 0.2305 and utmost value of Y, 0.85. Best efficiency of PFC system achieved at 2 ppm initial concentration which is 75% and 350 rpm stirring speed which is 76.95%.