محسن معمارزاده

The purpose of this study was to investigate the effect of using tubular settlers on the energy required for backwashing filters and the frequency of backwashing.

In this experimental study, two accelerator clarifiers connected to the raw water transfer channel No. 1 of the Isfahan Water Treatment Plant (WPT), Iran, were equipped with approximately 350 tubular settlers at an installation angle of 60 degrees.

The results of sampling the outlets showed that the average concentration of suspended solids in the clarifiers with tubular settlers was 3.20 ± 16.00 mg/l, while in clarifiers without tubular settlers, it was 4.41 ± 20.00 mg/l. The average removal efficiency of suspended solids in clarifiers equipped with tubular settlers was 64.86 ± 34.00%, compared to 52.10 ± 46.00% in other clarifiers. Additionally, the number of backwashing cycles of filters decreased by 25%, and energy consumption was reduced by 50%-60%.

The use of tube settlers to improve the quality of water entering filters reduces the number of backwashing cycles per day and ultimately saves energy for backwashing filters, which is very effective.

The Isfahan water treatment plant, with a final capacity of 12.5 cubic meters per second, is one of the largest water treatment plants in the Middle East. It has 10 sedimentation basins with a retention time ranging from 1.91 to 2.75 hours; each basin has a volume of 9172 cubic meters and a surface load of 14.2 to 2.85 cubic meters per square meter per hour. This research was conducted to investigate the efficiency of the combined use of accelerator sedimentation basins equipped with tube settlers on a full and field scale. The goal was to achieve greater efficiency in improving the quality of output water and managing the reduction of water wastage, backwashing time wastage, as well as reducing the need for repairs and maintenance of treatment plant equipment. In this study, the accelerator sedimentation ponds related to two stream 1 clarifiers from the first phase of the treatment plant were equipped with rapid tubular settlers made of food-grade polypropylene. These settlers are hexagonal in shape with a hydraulic diameter of 50 to 80 mm; placed at a 60-degree angle to the surface, and have a length of 90 cm. Stream 2 was operated without the simultaneous use of rapid tube settlers in the circuit. The amount of backwashing’s of filters, the number of times the aerators and backwashing pumps are engaged in the circuit, the amount of water wastage, and the time required for each wash in streams 1 and 2 were compared with each other. The results of this study showed that the number of times of reverse washing of filters was reduced by an average of 25% compared to stream 2. This action also reduced the amount of water used for backwashing the filters and consequently reduced the number of working hours of the electrical and mechanical equipment of the water treatment plant.

There are many methods for increasing efficiency of turbidity removal such as tube settler, rotating plate or gradient parallel plate. In this study was evaluated conventional sedimentation basin which equipped by lamella system. The pilot used in the study was made up of poleax glass hexagonal having effective height of 1.2m with hydraulic diameter of 50-80 mm. The slope of sedimentation basin was 600 at the basis of horizon. The lamella system was installed onto a segment which located 150 at the basis of center of sedimentation basin. The pilot was located in Isfahan Water Treatment Plant. In fact the segment isolates sedimentation basin into two compartments, first with lamella and another without it.The turbidity of influent and effluent in two compartments were evaluated by SPSS software and T-Student.The result showed that at same condition without lamella, the minimum, maximum and average turbidity removal efficiency in Isfahan Water Treatment Plant were about 0.9%, 54% and 18.9% respectively. But in compartment equipped by lamella system The removal were about 20%, 65% and 35.3%. It can be concluded that the turbidity removal efficiency will be increased if the sedimentation basin would equipped by lamella system.