1 research outputs found
Effect of coagulation and sonication on the dissolved air flotation (DAF) process for thickening of biological sludge in wastewater treatment
Background: Dissolved air floatation (DAF) is one of the methods has been used for the sludge
thickening in wastewater treatment plants. This study aimed to investigate the effects of coagulation
and sonication processes as additional configurations on the efficiency of a lab-scale DAF process for
thickening of the biological sludge of an industrial wastewater treatment plant in Kashan, Iran.
Methods: The required amounts of sludge samples were collected from a wastewater treatment plant
and kept at temperature of 4°C. Variables, such as pressure (3, 5, and 7 atm), flotation time (5 and 10
minutes), ultrasonic irradiation power (0, 75, and 150 W), and presence/absence of Fe-based coagulant
were considered on a sequencing batch reactor (SBR) included coagulation, flotation, and sonication
processes, respectively.
Results: The use of ultrasonic waves led to an insignificant increase in the DAF efficiency (P > 0.05),
however, the application of coagulant significantly increased the thickening efficiency (P < 0.05). The
maximum efficiency of the process was achieved at flotation time of 5 min, pressure of 3 atm, and
sonication power of 75 W.
Conclusion: According to the results, DAF has a proper efficiency for thickening of biological sludge.
Coagulation compared to sonication has a greater effect on the efficiency of the process.
Keywords: Ultrasonic waves, Industrial effluent, Dissolved air flotation, Sonicatio