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Email the author (Login required) Treatment of Litopenaeus vannamei farming effluents by sedimentation and oyster Crassostrea rhizophorae filtration
DOI: https://doi.org/10.3856/vol36-issue2-fulltext-6
Abstract
Efficiency in removing particulate matter and dissolved nutrients from Litopenaeus vannamei shrimp farming effluents was evaluated at laboratory scale employing a combined two-stage system of sedimentation and filtration by the oyster Crassostrea rhizophorae; three hydraulic residence times (HRT) were used: 6, 12, and 24 h. For the sedimentation process, 100-L tanks were filled with 90 L of the effluent. For the filtration process, 50-L tanks were filled with 20 L of the effluent supernatant corresponding to each HRT of the sedimentation stage. All experimental units were seeded with 15 adult oysters with a mean weight of 80 g and a biomass of 1200 g tank-1. One tank with empty oyster shells was used as a control for each HRT. The results showed that, in the sedimentation process, the best performance was obtained at 24 h, with 56.1% removal by turbidity, 36.3% by total volatile solids, 31.0% by BOD5, and 21.4% by ammonium. In the filtration process, removal efficiency was highest at 6 h, with 62.1% removal by turbidity, 69.4% by total suspended solids, 35.4% by total volatile solids, 100% by chlorophyll a, and 17.2% by BOD5, when compared with the control tank. In the filtration process, the ammonium concentration increased for all HRTs. The integrated removal efficiency for the sedimentation and filtration processes showed significantly improved performance at 6 h, as compared to the untreated effluent, reaching 69.3% removal by turbidity, 69.0% by total suspended solids, 41.3% by total volatile solids, and 100% by chlorophyll a.
