In regard to reduce the influence of air bubbles inside the sand filter column, CO2 was added into the filter column. It was expected that the CO2 will be dissolved in water and the air bubbles will no longer disturb the flow of the water. Two columns that have the same configurations were tested for their flow behavior especially in their hydraulic loading rate. The filter columns were operated intermittently with variable supernatant level (decreasing level). As can be seen in the figure, those two columns have the different behavior although they have the same condition. Those two columns were operated during the day only and in the night they stay saturated without any operation. Every time the filter columns were started in operation on the next day, the hydraulic loading rate decreased and increased along with the number of filtration. Generally, the hydraulic loading rate decreased slightly along with the number of filtration. Does anyone have any experiences on this matter? How could we explain this behavior?
Dear Agustina,
A very interesting question. I think the reduction of hydraulic load rate at the beginning of experiments caused by the sediments or effluents that has been stabilized or actually stuck among the porous media of the sand columns. After passing a little while and according the water flow through the columns, these sediments probably move and dislocate from their previous position and make the column more porous. However, I believe that if the experiment last for several days the curve shape would become more logical and display the precise results.
Dear Amir,
Thank you for your answer. I'm sorry for not mentioning the type of water that I used during the experiment. I only used distilled water. The focus was only to observe the behavior of the column without adding some sediments or particles into the filter column. Then do you have any idea on the differences of behavior? I mean both columns have the same configuration. However they produce different hydraulic loading rate although operated under the same method.
Regards,
Kiky
Dear Kiky,
I apologize for misunderstanding your question. I'm sorry I have no idea about that. But I appreciate that you let me know the reason if you find it.
Sincerely
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