FORMATION AND FRACTAL CHARACTERISTICS OF FLOCS AND BUBBLES IN ELECTROCOAGULATION TREATMENT OF FRACTURING WASTEWATER

In this study, the fractal theory was used to describe fractal growth characteristics of granular flocs and bubbles in the electrochemical treatment of polyacrylamide fracturing flow-back wastewater. Also the effect of electrocoagulation treatment time on its formation was evaluated, and influences of treatment time on flocs and bubbles were characterized by fractal dimension. The results showed that the morphology of flocs and bubbles had a good positive correlation with their fractal dimension and equivalent circle diameter, and it had negative correlation with the turbidity of wastewater. When the fractal dimension D-f of flocs larger than 1.906, the change of fractal dimension is small, and the aggregated flocs were more compact and easy to be settled down. The fractal dimension of the bubbles basically did not change with time. D-f had a slight fluctuation at 2.0, and the equivalent circle diameter of bubbles was 39.31 similar to 44.74 mu m which significantly effected micro-air flotation and the rapid separation of flocs was obtained by bubbles strengthened. The turbidity dropped to 18.3 NTU after 21 min of electrocoagulation treatment.