Membrane filtration of suspended solids in a semi-closed aquafarming system
A problem confronting semi-closed circuit aquaculture is the need for continuous elimination of suspended matter (SM) and nitrogenous substances. Conventional processes used to retain SM (settling tanks, hydrocyclones, rotating-drum mechanical filters, gravity filtration) are not entirely satisfacto...
| Published in: | Revue des sciences de l'eau |
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| Main Authors: | , , , , , |
| Format: | Article in Journal/Newspaper |
| Language: | unknown |
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Consortium Erudit
2005
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| Subjects: | |
| Online Access: | http://www.erudit.org/fr/revues/rseau/2001-v14-n1-rseau3303/705406ar.pdf https://www.erudit.org/fr/revues/rseau/2001-v14-n1-rseau3303/705406ar.pdf https://doi.org/10.7202/705406ar https://www.erudit.org/en/journals/rseau/2001-v14-n1-rseau3303/705406ar/ https://core.ac.uk/display/59610181 https://academic.microsoft.com/#/detail/2167688964 https://id.erudit.org/iderudit/705406ar |
| Summary: | A problem confronting semi-closed circuit aquaculture is the need for continuous elimination of suspended matter (SM) and nitrogenous substances. Conventional processes used to retain SM (settling tanks, hydrocyclones, rotating-drum mechanical filters, gravity filtration) are not entirely satisfactory. However, membrane filtration has recently been shown to allow removal of suspended particles and bacteria. The present study evaluates the performance of different ultrafiltration and microfiltration membranes for water processing in a semi-closed aquaculture system. A brief economic analysis of treatment costs is proposed based on the results.The marine aquafarm studied produces about 5 tons of turbot per year with a plant volume of about 100 m3. The water processing line is fitted with a rotating-drum mechanical filter that stops the largest particles and ejects 1 m3 h-1 of loaded water into the surrounding environment. Another 2 m3 h-1 are cleared out by overflowing the pumping pit. These volumes are renewed at a rate of 3% per hour by pumping saltwater from an underground source. Crossflow filtration was performed on rejections from both the mechanical filter and pumping pit overflow. SM contents and granulometric distributions determined by laser diffractometry were found to vary with sample source and withdrawal time, and size of fish in the pens. A comparison of granulometric distributions in volume percent and numerical percent underscores the presence of a great number (> 98 %) of submicron particles.To limit the risk of mechanical-pore fouling due to blockage by particles, organic membranes in the form of internal-skin capillaries (pore diameters of about 10 to 20 nm) were initially employed. These membranes, used in drinking water production, are relatively inexpensive. The experimental device was fitted with an interchangeable volumetric pump (with gears or monoscrew). Adjustable parameters were transmembrane pressure and circulation velocity within the module. Analysis of the influence of these ... |
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