AWWA WQTC60660

The objective of this work was to determine the technical feasibility of using a diffused aeration process for finalpH adjustment at the City of Houston Southeast Water Purification Plant (SEWPP), evaluate the aeration efficiency at various air-to-waterratios, and the impacts of water depths and detention time on aeration process. The aeration for pH adjustment pilot plant was designed by CDM, Inc. and consists of an aeration tank with a nominal capacity of 10,250 US gallons, an aeration system, arotary lobe PD blower skids with a VFD drive, an orifice plate flow meter, and an ultrasonic flow meter.A fine bubble aeration system by Sanitaire was selected as testing aeration system. Pilot testing was performed at SEWPP. Thesettled water from existing treatment module settle water channel was used as testing water and isintroduced to the aeration tank though 10-inch PVC pipe. Air is supplied by the blower and transportedto the air diffuser system through 4-inch carbon steel pipe. Treated water is discharged into the existing54-inch sedimentation basin drain pipe and flows back to the plant process overflow basin.Water flow rate is manually controlled by adjusting the influent butterfly valve and monitored by theultrasonic flow meter. Air flow rate is controlled by adjusting the blower motor speed and monitored bythe orifice flow meter. Sample tap has been installed on the discharge line to collect effluent sample foranalyzing pH and water quality.Aeration pilot-scale testing was conducted under both batch and continuous flow conditions. Varioushydraulic detention times, water depths, and air to water ratios were tested to evaluate pH changes undereach testing condition. The initial pH of the settled water ranged from 7.1 to 7.4 during the testingperiod. For each test condition, the initial and final pH values, alkalinity, hardness, total Cl₂ residual,dissolved oxygen (DO), UV transmittance, and volatile organic carbon (VOC) were recorded.Given the large volume of testing water, water temperature is not expected to change much during eachtest. The water temperature was measured at the tank inlet and outlet sample taps during the aerationprocess and the difference was less than 1°C. Includes 5 references, tables, figures.

Product Details

Edition:

Vol. - No.

Published:

11/15/2004

Number of Pages:

13

File Size:

1 file , 1000 KB