Effect of Dissolved Air Flotation Process on Thickening of Activated Sludge

Document Type : Original Article


1 Environmental Health Engineering Department, Public Health School, Kashan University of Medical Sciences, Kashan, Iran

2 Biostatistics & Public Health Department, Health Faculty, Kashan University of Medical Sciences, Kashan, Iran


Aims: Sludge is an inescapable component of all wastewaters that originated
from their treatment. dissolved air flotation (DAF) process as an alternative
clarifier is used in treatment of drinking water, pretreatment of wastewater,
and as a phase separator in sludge activation processes. This study aimed to
calibrated the usage of DAF process in a laboratory scale and under various
conditions, to achieve the optimum efficiency in recycling the activated sludge.
Instrument & Methods: In this experimental study, of Kashan's Shahid
Beheshti hospital and immediately transported to the laboratory. The optimal
dose of polyaluminum chloride coagulant and pH was determined and then
applied in DAF process. Finally turbidity, electrical conductivity (EC) and total
solids (TS) parameters were measured and compared with control sample.
Findings: The optimal pH and optimal dose of coagulant were 6.5 and 25mg/l,
respectively. Also Optimal process efficiency to reduce EC, TS and turbidity
parameters were 23.4, 44.5 and 88%, respectively.
Conclusion: Dissolved air flotation process removes the turbidity, EC and TS
effectively; however, it has minimal impact on EC and TS.