engleski

Settling Characterization of Electrocoagulated Flocs

This paper deals with the characterization of settling properties of flocs generated within the electrocoagulation process. Characterization of the settling properties involves the determination of the settling regimes, sludge index, batch settling curve, settling velocity and relation of the suspended matter concentration to settling velocity. An experimental analysis of the settling properties of electrocoagulated flocs was carried out with several tests by using aluminum and iron electrodes with different currents (I1 = 10 [A], I2 = 5 [A]) and different duration of the process (t1 = 60 [min], t2 = 90 [min]). The phosphate contamination was generated by the addition of potassium dihydrogen phosphate (KH2PO4). The characterization of settling properties was performed for each test. Other water quality parameters, such as dissolved oxygen concentration, water temperature, pH and conductivity were also monitored. Settling properties were analyzed by standard settling tests used for the settling characterization of active sludge. During the tests it was not possible to make diluted sludge volume index test (DSVI) and stirred specific volume index test (SVI3.5) due to the low initial concentration of the electrocoagulated flocs. Maximum concentration of electrocoagulated flocs after 90 min was only 1.6 [g/L]. Also, pre-defined intervals in batch settling curve test, in which the height of the water-sludge surface level is read, are too long, especially for longer intervals of 5, 10 and 15 minutes. These intervals can’t be used because all the settling occurs quickly after the flocs are merged and the time differences between readings is just too high, resulting in poor and imprecise batch settling curves. Therefore, some of the standard settling tests are most likely not applicable for electrocoagulated sludge, because electrocoagulation results with significantly less sludge than a biological wastewater treatment process. Thus, further tests on actual sewage samples should be carried out so that more accurate conclusion is reached.

settling characterization, electrocoagulated flocs, batch settling curve

nije evidentirano