Abstract:
The objective of this research is to analyze the turbidity removal efficiency and the suitable operating condition obtained with Air-Lift Reactor (ALR) as the hybrid process of coagulation, flocculation and sedimentation processes. The synthetic wastewater prepared by 1 and 0.1 g/l of kaolin concentration was used in this work. The results showed that removal efficiencies of the ALR are greater than those of bubble column reactor (BCR) with lower mixing energy and time. Moreover, the applied gas flow rate has been proven as an important parameter for classifying the appropriate flow regime, interaction among of bubble, coagulant (alum) and suspended particle and thus overall treatment. From batch process, the highest treatment efficiency (97.67%) can be obtained with the ALR at 3 LPM of gas flow rate and 1 minute of mixing time: this was close to jar test experiments. Note that, due to the higher amount of target for sweep-floc coagulation, higher efficiencies were found in case of 1 g/L. In order to improve the ALR performance, the application of cone-device has provided the insignificant effect, whereas the increasing of internal tube from 10 cm (ALR[subscript 10]) to 12 cm (ALR[subscript 12 ]) can enhance the removal efficiency (98.03%) with lower gas flow rate (2 LPM) and 1 minute mixing time: this condition was thus applied for the continuous process. The maximum removal efficiencies (85%) can be obtained with the ALR combined with special cone-device which separates the reactor zone and controls the turbulent condition and thus sedimentation. It can be noted that flowshortcut and shear force occurred in continuous system could be responsible for the lower efficiency (15%) than in batch system. Even some limitations in terms of removal efficiency obtained with very low particle concentration and of achievement for water supply standard, the ALR can be possibly apply as the pre-treatment for raw water for reducing the size of treatment process, chemical dosage and also the sludge generated in case of high turbid water.