pollution treatment

Nitrate contamination of drinking water is a common problem in many parts of the world that poses a serious threat to public health and environment. In this research, the performance of a new rotary electrocoagulation reactor model for removal of nitrate in presence or absence of turbidity has been investigated.

In this study, aluminum and iron electrodes were analyzed in parallel and monopolar arrangement. At each test time, a sample of 370 liters was prepared and the effects of operating parameters such as initial nitrate concentration, current density, annular reactor speed, optimum time, electrode materials and presence of turbidity on nitrate removal were evaluated.

The results indicated that the optimum utilization parameters were material of aluminum electrode, current density of 22.8 A/m2, annular reactor speed of 13.3 rpm and optimum time of 90 min, under which removal efficiency was 95.7%. The presence of turbidity has decreasing effect on nitrate removal and at nitrate concentration of 225 mg and with increasing in turbidity, the removal efficiency decreased from 81% to 48%. For aluminum electrode, the consumed energy in optimum utilization condition was 0.74 kWh/m3.

The results of this study showed that the introduced batch rotary reactor model was able to remove the high nitrate content from aquatic environments with ease of use and this model is recommended to be used for drinking water treatment plants.

One of the most important problems facing the water treatment plants is seasonal turbidity removal from the drinking surface waters. In this work, the efficiency of turbidity removal from water surface has been studied using a batch rotary reactor model and electrocoagulation process and different electrodes including iron and aluminum were tested. Finally, the optimum values of the studied parameters were evaluated at different operating conditions.

In order to eliminate the turbidity from drinking water, the discontinuous rotary reactor model with monopolar electrodes was used in parallel connection. The sample volume in the experiments was 377 liters, and the rotation of the model caused all fluid particles, sediments, and contaminants to be homogeneously touched with the electrodes. This model provided a higher efficiency of turbidity removal due to not having pump blades and return pipes.

Results of this study showed that the maximum efficiency of turbidity removal from drinking water would be achieved by using the material of aluminum for electrode and considering time duration of 60 min,  rotation speed of the model equal to 1.3 rpm, current density of 18.8 A/m2 in pH=7.4 and electrode gap distance of 3 cm. At these conditions the maximum turbidity removal efficiency was obtained 84.1 and 93.3% for the iron and aluminum electrodes, respectively.

Results of this work showed that the proposed batch rotary reactor model, in addition to its easy application, is able to remove turbidity from the aqueous solutions at a the high efficiency. Therefore this model would be strongly suggested for application in drinking water treatment plants.