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Types of Biofilters: Advantages

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1st AQUALITY Symposium, April 2 - 7, 2004, Oceanario de Lisboa, Portugal. Types of Biofilters: ... Tidepool (RBC) - skimmer & GAC. Berlin - skimmer, no GAC ... – PowerPoint PPT presentation

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Title: Types of Biofilters: Advantages


1
Types of BiofiltersAdvantages Disadvantages
  • Timothy A. Hovanec, Ph.D.
  • Chief Science Officer
  • Marineland Aquatic Research Labs
  • 6100 Condor Cr.
  • Moorpark, CA 93021
  • 805.553.4446 fax 805.529-0170
  • hovanec_at_marineland.com

2
Definitions
  • Biofilter - The physical location where
    nitrification takes place
  • Nitrification - The oxidation of ammonia to
    nitrite and subsequent oxidation of nitrite to
    nitrate by microorganisms

3
Goal of a Perfect Biofilter
  • Provide a high surface area per volume for the
    nitrifying bacteria
  • Maintain a thin nitrifying biofilm
  • Does not clog smothering the nitrifiers
  • Low maintenance requirement
  • Lower operating cost

4
Sewage Treatment Facilities
  • However -
  • Much higher ammonia loading TAN gt 50 mg/L
  • Much higher organic loading SS gt 750 ml/L
  • Single pass system

5
Biofilter Types and Classification
6
Rapid Sand Filter
Main purpose - generally to maintain water clarity
7
Sand Filters
  • Advantages
  • Long history in the industry - known
  • Easy to operate
  • Easy to construct
  • Disadvantages
  • Requires large water pumps
  • Operation smothers the nitrifying biofilm
  • Needs frequent backwashing

8
Trickle Filters
9
Trickle Filters
  • Disadvantages
  • Uneven surface wetting
  • May promote solids retention be hard to clean
  • Advantages
  • Good air exchange
  • Simple to construct
  • Almost any material will work

10
Rotating Biological Contractor- RBC
11
Industrial RBC
  • Advantages
  • Good air exchange
  • Least maintenance of all biofilters
  • Automatically maintains a thin biofilm
  • Most efficient Biofilter
  • Disadvantages
  • No solids removal
  • Have to maintain rotation
  • Needs space

12
Fluidized Beds
13
Cut Away of Fluidized Bed
14
Fluidized Beds
  • Advantages
  • Constant movement of beads promotes thin biofilm
  • Large surface for nitrification
  • Disadvantages
  • Hard to maintain constant bead movement
  • Beads tend to stick together
  • Loss of Beads from the filter
  • May promote growth of heterotrophic bacteria

15
Bead Filters
16
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17
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18
Traditional and Tidepool (RBC) - skimmer GAC
Berlin - skimmer, no GAC Jaubert - no skimmer,
no GAC
19
Filter Comparison
20
Biofilm micro-electrode probing
21
Oxidation of 1mg Ammonia
22
Optimal Water Conditions
  • Temperature
  • range 5 to 50 C
  • optimal 25 to 30 C
  • pH
  • range 5 to 10
  • optimal 7 to 8.5
  • Particulate organics nitrifiers do not mix

23
Some Case Studies
  • Greiner Timmons. 1998. AE 18189-200
  • Trickle filter nitrification rate 7.5x than
    downflow microbead filter
  • Nitrification not affected for hydraulic loading
    rates between 469 and 1,231 m3/m2/day
  • Biofilm growth on the microbeads expanded the
    media volume between 15 and 32
  • Sastry et al. AE 1998. AE 19105-117
  • Studied bubble washed bead filters at 3 loading
    rates (16, 24, and 32 kg/day/m3 of beads
  • to maintain DO gt 2mg/L needed flow gt 50
    L/min/kgfeed/day
  • Al-Hafedh et al. 2003. AE 29139-154
  • compared scrub pads, plastic hair rolls,and PVC
    pipe
  • hair rolls best, scrub pads clog, pipe was a good
    inexpensive alternative

AEAquacultural Engineering www.aesweb.org
24
Ammonia Oxidation Rates
25
Which Biofilter is the Best?
  • Miller and Libey. 1985. J. World Mari. Soc.
    16-158-168 TAN removal efficiencies
  • RBC 74-83
  • Trickle Filter 23-51
  • Fluidized Bed 8 - 32
  • Westermann et al 1996. AE 39723-727
  • RBC most reliable
  • Bead Filter high CO2 and TAN
  • Fluidized Bed clogged, beds packed
  • Sand Filters clogged, poor water quality, high
    maintenance
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