A comparison of biologically active filters for the removal of ozone by-products, turbidity, and particles
- Metropolitan Water District of Southern California, La Verne, CA (United States)
Biofiltration tests were performed at the Metropolitan Water District of Southern California`s 5.5-mgd (21,000 m{sup 3}d) demonstration plant using two 400 ft{sup 2} (37 m{sup 2}) anthracite/sand filters and a 6 ft{sup 2} (0.56 m{sup 2}) granular activated carbon (GAC)/sand filter operated in parallel. The empty-bed contact time (EBCT) within the GAC and anthracite ranged from 2.1-3.1 min. The filters were evaluated based on (1) conventional filtration performance (turbidity, particle removal, and headloss); (2) removal of biodegradable ozone by-products (assimilable organic carbon [AOC], aldehydes, and aldoketoacids) after startup; (3) removal of biodegradable ozone by-products at steady state; and (4) resistance to short-term process upsets such as intermittent chlorination or filter out-of-service time. Approximately 80 percent formaldehyde removal was achieved by the anthracite/sand filter operated at a 2.1-min EBCT (6 gpm/ft{sup 2} [15 m/h]) within 8 days of ozone operation. The GAC/sand filter operated at the same rate achieved 80 percent removal within 1 day, possibly as an additive effect of adsorption and biological removal. In-depth aldehyde monitoring at four depths (0.5-min EBCT intervals) provided additional insight into the removal kinetics. During periods of warmer water temperature, from 20 to 48 percent of the AOC was removed in the flocculation/sedimentation basins by 40-75 percent. This percentage removal typically resulted in AOC concentrations within 40 {mu}g C/L of the raw, unozonated water levels.
- OSTI ID:
- 387286
- Report Number(s):
- CONF-951108-; TRN: 96:003589-0011
- Resource Relation:
- Conference: Water quality technology conference, New Orleans, LA (United States), 12-16 Nov 1995; Other Information: PBD: 1996; Related Information: Is Part Of Proceedings: 1995 water quality technology conference. Part I - Sunday seminars through Session 3E includes poster presentations. Part II - Session 4A through ST7; PB: 2562 p.
- Country of Publication:
- United States
- Language:
- English
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