Conference proceeding
Reducing the environmental impact of high density fish production: An integrated approach to solids treatment for recirculating aquaculture systems using expandable granular biofilters
UNJR TECH. REP. Jan 1997, pp.157-164
U.S.-Japan Aquaculture Panel Symposium, 24 (1995)
01/01/1997
Handle:
https://hdl.handle.net/2376/118474
Abstract
Over the past decade, regulatory agencies have begun to view the environmental impact of wastes discharged from high density flow-through fish production systems with increasing concern. At the same time, recirculating aquaculture systems have gained wider acceptance because of their ability to reduce waste discharges, improve quality control and reduce costs. The crucial processes that must be addressed in treating recirculating water are solids capture, biofiltration, aeration, degasification and ion balance. Designs that integrate two or more of these processes provide the greatest potential for cost reduction. The technology that is the focus of this paper is an expandable granular biofilter (EGB), which integrates solids capture and biofiltration in a single unit process. Backwash frequency is a major operational parameter of EGBs, influencing the volume of sludge produced and the nitrification rate. Computer and mass balance models are used to describe the relationship between solids residence time, sludge production and nitrification rates. The models show that infrequent backflushing decreases water loss and sludge production, although nitrification rates decline for extended solids residence times. Declining nitrification rates reflect decay of the accreting solids mass - which creates an internal ammonia and BOD load, decreasing the oxygen available to the nitrifiers because of heterotrophic competition for oxygen and impeded mass transfer as the bed becomes occluded. Nitrification appears to be optimized with solids residence time in the range of 2-3 days, for filters utilized as the primary solids capture device. The focus of this paper is: (1) primary in-filter solids stabilization; (2) the effect of in-filter solids stabilization on nitrification; and (3) post-discharge, pre-disposal digestion of aquacultural solids.
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Details
- Title
- Reducing the environmental impact of high density fish production: An integrated approach to solids treatment for recirculating aquaculture systems using expandable granular biofilters
- Creators
- W GolzR F MaloneShulin Chen
- Contributors
- B J Keller (Editor)Kazumi Hosoya (Editor)J P McVey (Editor)Kazufumi Takayanagi (Editor)P K Park (Editor)
- Publication Details
- UNJR TECH. REP. Jan 1997, pp.157-164
- Conference
- U.S.-Japan Aquaculture Panel Symposium, 24 (1995)
- Academic Unit
- Biological Systems Engineering, Department of
- Identifiers
- 99900583061301842
- Language
- English
- Resource Type
- Conference proceeding