The dental wastewater can contribute to the total daily mercury load on environment. Factorial design of experiments is useful to
analysis of factors that influence in this mobility. The aim of the present study was to design experiments to examine the effects of
operational variables – temperature, pH and contact time - which may affect the mobility of mercury in form of dental amalgam
residue in reduction process in the sediments of the Pirapó River. Based on the factorial design of experiments and the analysis of
variance, the temperature was the most significant factor in this process, followed by the pH and contact time. The parameters
affecting the mobility of total mercury showed that when the temperature and contact time increases and pH decreases there is an
important increase of mercury concentration in process. For the tested conditions, the high total mercury concentration was obtained
using the temperature = 35oC, pH = 4.0 and contact time = 10 days.
