Evaluation of biofilter performance with alternative local biomedia in pilot scale recirculating aquaculture systems
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Date
2022
Journal Title
Journal ISSN
Volume Title
Publisher
Elsevier
Abstract
Plastic is commonly used as biofilter media in recirculating aquaculture systems. Because plastic is relatively
expensive and may erode and emit microplastics to the environment, efforts are being made to test and develop
more sustainable materials. Five alternative locally available biofilter media were compared with commercial
plastic media and evaluated in duplicate in 1 m 3 two pilot scale Recirculation aquaculture system. Ammonium
chloride and sodium nitrite were added to the systems for 4 weeks followed by stocking 20 kg of Nile tilapia in
each system. Volumetric total ammonia nitrogen (TAN), nitrite and oxygen conversion rates were assessed for ten
weeks. All biofilters with local media matured and reached full capacity after six weeks, while commercial plastic
biomedia matured after seven weeks. This study found that the performance of commercial plastic biomedia was
similar to performance of coconut shells in terms of volumetric TAN conversion rate (VTR), volumetric nitrite
conversion rate (VNR) and volumetric oxygen conversion rate (VOCR). The highest VTR recorded in this study
was 599 ± 15.8 g TAN/m 3 /d from coconut shells while the lowest was 343 ± 8.9 g TAN/m 3 /d from cattle horns.
Biofilters with commercial plastic media had the highest VNR (704 ± 50.3 g NO 2 –N/m 3 /d) while media made of
cattle horns was the lowest (457 ± 46.1 g NO 2 –N/m 3 /d). Biofilters containing coconut shells demonstrated the
highest oxygen consumption around 3.0 g/m 3 /d and biofilters containing charcoal consumed less than 1.0 g/m 3 /
d of oxygen. This study suggests that coconut shells can be used in place of plastic materials in simple recir
culation aquaculture system biofiltration. This study also recommends further studies on comparing coconut
shells with other biomedia and assessing its effects on water quality parameters and durability.
Description
Journal Article
Keywords
Biofiltration, Biomedia, TAN removal, Recirculating aquaculture system, Water quality parameters