Performance evaluation of charcoal, charcoal-gravel, and gravel biofilters for aquaculture applications

Date

4-2009

Degree

Bachelor of Science in Agricultural Engineering

Major Course

Major in Land & Water Resources Engineering

College

College of Engineering and Agro-Industrial Technology (CEAT)

Adviser/Committee Chair

Aurelio A. Delos Reyes

Committee Member

Rosa B. Delos Reyes, Leila T. Dominguez

Abstract

The performance of prototype bucket biofilters of charcoal, charcoal-gravel and gravel were evaluated and compared head-to-head using actual fish culture water from a 7.0m³ tank. The tank was stocked with African catfish, Clarias gariepinus, at a total of 20 kg fish, fed with 31% crude protein feed at 200-400g/day. The media were randomly assigned to six identical bucket filters and were evaluated in terms of Total Ammonia Nitrogen (TAN) Conversion Rate and Nitrate-Nitrogen Conversion Rate. The main objective of the study was to establish if commercially available, ordinary wooden charcoal can be an effective biofilter. The study was set-up in the Bureau of Fisheries and Aquatic Resources-Los Baños Freshwater Fisheries Research Station (BFAR-LBFFRS).Filter effectiveness in solids removal was indirectly indicated by the large reduction in apparent color of 65%-97%. Relatively higher values for charcoal was obtained but the Volumetric TAN Removal Rate (VTR), Volumetric Nitrite Removal Rate (VNR), Areal TAN Removal Rate (ATR) and Areal Nitrite Removal Rate (ANR) do not have statistically significant differences due to their wide variationThe range for VTR(g TAN/m³-day)values was from 17.67 to 71.14 for charcoal, 16.37-85.39 for charcoal-gravel and 13.90-110.48 for gravel. The range of VNR (g N O₂ -N/m³-day) values for charcoal, charcoal-gravel and gravel biofilters were 14.46-50.52, 18.51-43.38 and 21.40-41.44 respectively. On areal basis, the range of TAN removal (ATR, g TAN/m²-day) for charcoal was -0.08-0.62, 0.07-0.36 for charcoal-gravel and 0.06-024 for gravel.For NO₂-N removal (ANR,g NO₂-N/m²-day), the range for charcoal was 0.08-0.29, 0.08-0.18 for charcoal-gravel and 0.07-0,14 for gravel.Overall mean VTR and ATR for the filters were 41.0 g TAN/m³-day and 0.18 gTAN/m²-day, respectively. These values were attained at operational conditions with flow rate ranging from 6.71 to 25.84 per min (Lpm), temperature of 27.3-33.9°C and ammonia levels ranging from 0.24-1mg/L. The VTR values of existing biofilters except Rotating Biological Contractor (RBC) were higher than those obtained in the study. The ATR of the biofilter media studied compared well with the RBC value obtained in the literature.The TAN removal rates may be used as criteria for sizing charcoal biofilters for aquacultural applications with an equivalent hydraulic flux of 29.47L/min-m² observed. Keywords: biofilter, charcoal, gravel, ammonia removal, nitrate removal, aquaculture, recirculating system.

Language

English

Location

UPLB College of Engineering and Agro-Industrial Technology

Call Number

LG 993.5 2009 A2 L33

Document Type

Thesis

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