Treatment of rainbow trout ( Oncorhynchus mykiss) raceway effluent using baffled sedimentation and artificial substrates

The treatment performance of a 6 m wide by 67 m long by 0.8 m deep, baffled sedimentation basin receiving rainbow trout ( Oncorhynchus mykiss) raceway effluent was evaluated with and without the installation of artificial substrates (Aquamats ®). Treatment efficiency was also determined using normal...

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Veröffentlicht in:Aquacultural engineering 2006-08, Vol.35 (2), p.166-178
Hauptverfasser: Stewart, Nathan T., Boardman, Gregory D., Helfrich, Louis A.
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Sprache:eng
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Zusammenfassung:The treatment performance of a 6 m wide by 67 m long by 0.8 m deep, baffled sedimentation basin receiving rainbow trout ( Oncorhynchus mykiss) raceway effluent was evaluated with and without the installation of artificial substrates (Aquamats ®). Treatment efficiency was also determined using normal rearing condition effluent loading versus cleaning and harvesting events. Total suspended solids (TSS) removal for the total basin averaged 79% and 71% during normal rearing conditions, as compared to 92% and 79% during cleaning and harvesting operations, when the Aquamats ® were installed versus removed, respectively. Total phosphorus (TP) removal by the total basin, with and without Aquamats ®, was 20% and 23% during normal rearing conditions as compared to 55% and 65% under cleaning and harvesting conditions, respectively. Higher TP removal during cleaning operations was attributed to sedimentation of particulate fractions. Dissolved nutrient removal ( ortho-phosphate (OP), total ammonia nitrogen (TAN), nitrate, nitrite, and total organic carbon (TOC)) was not consistent throughout the basin and did not improve when the Aquamats ® were installed. A short contact time and periphyton grazing by isopods may have limited the capacity of the Aquamats ®. Calculated retention times with and without Aquamats ® for the first half and total basin were 37% and 32% and 27% and 17% less than theoretical values, respectively based on a rhodamine WT dye study. Average surface overflow rates were adjusted accordingly and measured 19.1 m 3/m 2 day when the Aquamats ® were installed, versus 14.8 m 3/m 2 day when the Aquamats ® were removed for the overall basin. These rates are lower than previous recommendations for treating aquaculture effluents, but resulted in high solids removal and consistently low TSS effluent (average 2 mg/L by 50%. For the first half of the sedimentation basin, the overflow rate averaged 44.1 m 3/m 2 day with Aquamats ® versus 35.8 m 3/m 2 day without Aquamats ®. The majority of effluent treatment occurred within the first half of the basin, which was responsible for 84% and 94% of overall TSS removal, 42% and 100% of overall NH 3-N removal and 61% and 80% of overall TP removal during normal and cleaning/harvesting conditions, respectively.
ISSN:0144-8609
1873-5614
DOI:10.1016/j.aquaeng.2006.01.001