Electroflocculation of real raw dairy wastewater under optimum experimental conditions
Table 2 displays the results of electroflocculation for real raw dairy wastewater employing aluminum and iron electrodes under the following experimental conditions: initial pH of 5.0, applied potential intensity of 5 V, electroflocculation time of 60 min and constant stirring at 50 rpm. The COD, turbidity and pH values differed statistically between two different electrode sets, as demonstrated by the t-test with a 95% significance level. Fig. 5 a-b displays the variables for the synthetic
(a) and real raw
(b) dairy wastewater samples prior to the electroflocculation process and Fig. 5 c-d displays the variables for the real raw dairy wastewater samples after the electroflocculation process employing iron
(c) and aluminum
(d) electrodes. A slight darkening of the solid whey flocks was observed in the first 20 min of electroflocculation with
iron electrodes. Starting at 40 min, the formation of yellow gas bubbles was found on the surface of the cathode, along with progressive clarification of the remaining liquid. Starting at 60 min, complete clarification of the remaining aqueous solution was observed, with the subsequent electroflotation of the solid whey.
During the electroflocculation process with aluminum electrodes, no color change was observed in the white solid whey flocks. Moreover, total wastewater clarification occurred. Thus, the whitesolid whey flocks produced could be efficiently employed in the production of animal feed and even food products for humans after being appropriately purified.
These flocks could also be employed as food supplements due to the high levels of protein.
Whey flocks recovered by electroflocculation and electroflotation employing iron electrodes must be previously treated to remove the excess iron. However, this product could be employed as an iron and protein supplement in the production of different foods. The initial and final temperatures of the real raw dairy wastewater were 24.0 ± 0.2 and 27.0 ± 0.2 C, respectively, which is in accordance with the limits established for wastewater disposal in the environment
(Brasil, 2011). Lastly, the remaining aqueous solutions generated after the electroflocculation and electroflotation processes could be disposed without causing environmental problems