Paddlewheel Aerators Research Articles

Experimental pond grow-out of red drum, Sciaenops ocellatus, in South Carolina

This study assessed the production potential of red drum, Sciaenops ocellatus, in intensive pond culture. Six 0.1-ha saltwater ponds at the Waddell Mariculture Center were stocked in April 1986 with juvenile red drum (1.7 – 4.3 g) produced from captive South Carolina brood stock. Stocking densities of 7500, 15 000 and 22 500 fingerlings/ha were compared in duplicate ponds. The fish were fed a 38% protein commercial trout diet (Zeigler Bros.). Salinity averaged 28±3 ppt, and mean water exchange rates were 16.4%, 17.5% and 27.4% per day for the 7500, 15 000 and 22 500 fish/ha densities, respectively, during the 18-month study. A 0.75-hp fountain-type aerator was utilized in the two high density ponds during warm weather in year 1 (1986), and 1-hp paddlewheel aerators were used on a near continuous basis in all ponds during year 2 (1987). An infestation of the parasitic dinoflagellate, Amyloodinium, caused complete mortality of fish reared in one of the highest density ponds on day 146, and a dissolved oxygen depletion resulted in an estimated 35% loss in one medium density pond on day 432. At harvest (28 September–5 October 1987), mean fish weights were 1.3, 1.0, and 1.2 kg, respectively, at the three densities. Harvested biomass averaged 8997.5 kg/ha at the 7500 fish/ha density, with a mean survival of 88.7%. Survival, mean fish weight and crop size at harvest for the medium density (15 000 fish/ha) pond affected by low dissolved oxygen levels were 54.7%, 0.9 kg, and 7251.3 kg/ha, respectively. In contrast, fish in the other medium density pond exhibited 94.9% survival, 1.1 kg mean fish weight and 15 011.3 kg/ha at harvest. The single remaining high density (22 500 fish/ha) pond produced 24 082.5 kg/ha of 1.2 kg fish with 90.6% survival. Food conversion averaged 2.43 (range 2.15 – 2.60). The fish were sold whole at pond bank to commercial dealers for $1.65 – 2.75/kg.

Preliminary Comparisons of the Native Penaeus setiferus and Pacific P. vannamei White Shrimp for Pond Culture in South Carolina, USA

AbstractTwo pond experiments were conducted at the Waddell Mariculture Center to compare production characteristics of the native Penaeus setiferus and Pacific P. vannamei white shrimp in South Carolina. In 1985, 7–9 day old postlarval P. setiferus were stocked in one 0.1 and one 0.25 ha ponds, while P. vannamei of the same age were stocked in one 0.1 and one 0.25 ha ponds, while P. vannamei of the same age were stocked in one 0.1, one 0.25, and one 0.5 ha ponds. Both species were stocked at 12 shrimp/m2. The shrimp were fed a 25% protein commercial food and harvested by draining after 147 d. Sarvival in all ponds was > go%, but growth and production of the P. setiferus were considerably lower than values obtained for P. vannamei: 12.8 g and 1,555 kg/ha/crop for P. satiferus versus 19.7 g and 2,477 kg/ha/crop for P. vannamei. In 1989, duplicate 0.1 ha ponds were stocked with P. setiferus and P. vannamei at 60 shrimp/m2, and two additional 0.1 ha ponds were stocked with P. setiferus at 40/m2. The P. setiferus postlarvae were produced at the Waddell Center from captive‐reared and wild South Carolina brood stock. Rearing procedures involved paddlewheel aeration (10 hp/ha), regular water exchange (averaging 16–21%/d in all ponds), and use of a 40% protein feed. Due to the availability of postlarvae, the various treatments were stocked at different times. Both P. setiferus treatments were reared for 145 d, while the P. vannamei were reared for 165 d. P. setiferus at the 40/m2 density attained mean size, survival, and standing crop biomass at harvest of 13.5 g, 97.5% and 5,259 kg/ha/crop, respectively. The 60/m2P. setiferus treatment was stocked 2 wk earlier and yielded 15.2 g mean weight, 87.5% survival, and 7,995 kg/ha/crop at harvest. The P. vannamei 60/m2 treatment, which was stocked 3 wk earlier than any of the P. setiferus, produced mean size, survival and standing crop biomass at harvest of 17.1 g, 69.5% and 7,187 kg/ha/crop. Both survival and production levels would have been higher had not one replicate experienced a partial mortality due to a feeding accident. The 1989 study yielded what is thought to be the highest production levels yet achieved with P. setiferus in pond culture. These results suggest that P. setiferus may be a viable alternative to P. vannamei for intensive cultivation in the continental U.S. when P. vannamei are unavailable. Further evaluation of this potential is needed.

Design of small paddle wheel aerators

The oxygen-transfer rate and power input to the aerator shaft were determined for paddle wheel aerators of different paddle wheel diameters (61–91 cm), paddle wheel lengths (15–75 cm), paddle depths (8–18 cm), and paddle wheel rotational speeds (75–125 rev min −1). These data allowed selection of the best design criteria for 0·25-, 0·33-, 0·5-, 0·75-, 1·0-, 1·5-, and 2·0-hp paddle wheel aerators. These aerators had standard aeration efficiencies of 2·0–2·6 kg O 2 kW h −1. Small paddle wheel aerators made according to this design would be slightly less efficient in transfering oxygen to pond water than large wheel aerators commonly used in channel catfish ponds, but they would be more efficient than most other types of small aerators.

Effect of salinity on oxygen transfer by propeller-aspirator-pump and paddle wheel aerators used in shrimp farming

Propeller-aspirator-pump aerators transferred oxygen to water more efficiently at salinities of 10–30 ppt than at lower salinities. Oxygen transfer by Taiwan-style paddle wheel aerators was unaffected by salinity in the range of 0–30 ppt. One brand of propeller-aspirator-pump aerator had an aeration efficiency about 1·5 times greater than the Taiwan-style paddle wheel aerators at salinities of 10–30 ppt (aeration efficiencies averaged 1·20 and 0·85 kg O 2/kWh −1, respectively). In the same salinity range, the second brand of propeller-aspirator-pump aerator had aeration efficiencies roughly equal to the Taiwan-style paddle wheel aerators.

The relationship between feeding rate, paddlewheel aeration rate and expected dawn dissolved oxygen in intensive shrimp ponds

Determination of the proper level of supplemental aeration in intensive shrimp culture is critical for maintaining adequate concentrations of dissolved oxygen while minimizing equipment and operating costs. Little quantitative information is available on sizing the amount of aeration equipment to various levels of intensification. Results indicate that dawn dissolved oxygen (mg/liter) can be predicted based upon the amount of feed applied (kg/ha day) per unit aeration (hpday/ha). The amount of feed which can be applied with a given amount of supplemental aeration and a reasonable expectation that dawn dissolved oxygen will not be below a targeted concentration is expressed by the equation F A = 28·83 − (4·31 × DO) .

Paddlewheel Effects on Shrimp Growth, Production and Crop Value in Commercial Earthen Ponds

AbstractThe effects of continuous paddlewheel operation on shrimp growth, yield and crop value were studied in Hawaii. Six 0.4 ha earthen ponds were stocked with Penaeus vannamei at 25 postlarvae/m2. Three ponds served as controls with no mechanical aeration or mixing. Each of the other three ponds had two 1 hp paddlewheel aerators (3.7 kw/ha) running continuously throughout the five month trial (29 April‐8 October 1986). All other management factors were applied uniformly.Daily water temperature and use were significantly different between treatments. Paddlewheel ponds had lower water temperatures (28.3 vs. 28.5 C) and lower water use (0.8% exchange per day vs. 2.2% exchange per day) than control ponds.Faster shrimp growth in paddlewheel ponds was evident in week 8. At week 14, mean shrimp body weights and growth rates were significantly greater. Shrimp at harvest were 21.2 ± 2.6 g in paddlewheel ponds versus 15.3 ± 2.6 g in control ponds. Mean shrimp production was 2,852 ± 222 kg/ha in paddlewheel ponds compared to only 2,061 ± 558 kg/ha in controls. Mean crop value was $13,719 per pond per crop for paddlewheel ponds versus $9,111 for control ponds. Hence, paddlewheels afforded an increase of 42% in net crop value after subtracting purchase and operating costs.

Design and peroormance of paddle wheel aerators

An apparatus was constructed for testing the influence of paddle shape and depth and paddle wheel speed and diameter on oxygen-transfer characteristics of paddle wheel aerators. Paddles triangular in crosssection were more efficient than other paddle shapes. Standard oxygen transfer rate (SOTR) increased with increasing paddle depth and paddle wheel speed while standard aeration efficiency (SAE) declined. For a particular depth and speed, SOTR increased with increasing paddle wheel diameter. The greatest SAE (2·96 kg O 2 kWh −1) was achieved with a 91 cm diameter paddle wheel with triangular paddles operated at 77 rev min −1 and 12·5 cm paddle depth. Three companies made floating, 7·5 kW electric paddle wheel aerators according to design specifications developed in this research. These commercial aerators had high values for SOTR (18·8–21·8 kg O 2 h −1) and SAE (2·7–2·9 kg O 2 kWh −1) and were much more efficient than other aerators used in channel catfish farming.

Evaluation of plastic pipe, paddle wheel aerators

Paddle wheel aerators made of polyvinyl chloride (PVC) pipe had standard aeration efficiencies (SAE) of 2·0–2·6 kg O 2 kWh −1 when paddle wheel diameter was 71–81 cm, paddle wheel speed was < 90 rev min −1, and paddle depth was < 15 cm. The standard oxygen transfer rate (SOTR) was low (1·15–1·85 kg O 2 h −1 per 1-m length of paddle wheel). To supply enough oxygen for large ponds, PVC paddle wheels would be impractically long, and, even then, values for SOTR per unit length of paddle wheel and SAE would be lower than those obtained for steel paddle wheels currently used in aquaculture. PVC paddle wheels might have application in small ponds and especially in mariculture ponds where construction of noncorrosive material would be beneficial.

Intensive Culture Potential of Penaeus vannamei

AbstractTank and pond rearing studies were conducted to assess the potential for intensive culture of Penaeus vannamei in South Carolina. Postlarvae were stocked in intensive nursery tanks at 500/ m2. Growth and survival were compared for shrimp reared in control fiberglass tanks and in tanks with artificial substrates (fiberglass screen). Addition of substrate improved survival (82% versus 58%), but not growth. Juvenile shrimp (mean weight, 1.3 g) from the nursery trial were stocked into 6 m diameter tanks at densities of 10, 20 and 40/m2. Growth rate was inversely related to stocking density, with mean sizes of 33.9, 32.5, and 26.7 g attained at the low, medium, and high densities respectively after 168 days. At harvest, standing crop biomass averaged 225.6, 442.0, and 685.4 g/m2 for the three densities. To further test the intensive culture potential, two 0.1 ha ponds were stocked with hatchery‐reared postlarvae at densities of approximately 40 and 45/m2. The ponds were managed intensively using paddlewheel aerators and water exchange averaging 16–17%/day. The ponds were harvested after 138 and 169 days and yielded 6,010 kg/ha of 16.7 g (mean weight) shrimp and 7,503 kg/ha of 17.9 g shrimp, respectively. Average production was 6,757 kg/ha with a food conversion of 2.51. These data suggest good potential for intensive pond culture of P. vannamei in South Carolina and other areas of the continental United States.

Comparisons of oxygen-transfer rates and water-circulating capabilities of emergency aerators for fish ponds

Oxygen-transfer rates (tap water, 0 mg/l dissolved oxygen, 20°C) for four tractorpowered emergency aerators tested in a 820-m 3 pond were: blower-fan aerator, 12.2 kg O 2/h; Crisafulli ® pump and sprayer, 12.3 kg O 2/h; Airmaster ® aerator (centrifugal pump and sprayer), 21.3 kg O 2/h; paddlewheel aerator, 26.3 kg O 2/h. Times required for aerators to homogeneously mix salt in a 6000-m 3 pond were: blower-fan aerator, 96 min; Crisafulli pump and sprayer, 94 min; paddlewheel aerator, 53 min; and Airmaster aerator, 38 min. The Airmaster aerator and the paddlewheel aerator did not differ in their abilities to transfer oxygen and circulate pond water ( P > 0.05); they were both superior to the blower-fan aerator and the Crisafulli pump and sprayer ( P < 0.01).

An evaluation of three paddlewheel aerators used for emergency aeration of channel catfish ponds

Oxygen transfer rate, power requirement and fuel consumption were determined for three paddlewheel aerators used for emergency aeration of channel catfish ponds. The power requirement of the tractor-powered units was directly related to the diameter of the paddlewheel drum and the paddle immersion depth. Oxygen transfer rates ranged from 6·9 to 41 kg h −1 and increased linearly with the power requirement. The largest paddlewheel aerator, operated at the maximum paddle depth, produced the highest oxygen transfer rate (41 kg h −1). Oxygen transfer efficiencies ranged from 1·29 to 1·97 kg kWh −1.

Growth and food habits of hybrid carp, Ctenopharyngodon idella×Aristichthys nobilis, from aerated and non‐ aerated ponds

Hybrid grass carp fry (Ctenopharyngodon idella×Aristichthys nobilis) were stocked into 0·04 ha ponds with and without paddlewheel aeration. Fish in the paddlewheel and non‐paddlewheel pond, preyed upon identical organisms, but in different proportions. Fish in the paddlewheel ponds grew at significantly greater rates.

Oxygen Transfer Calculations for a Tractor-Powered Paddlewheel Aerator

Standardized aeration tests were conducted for a tractor-powered paddlewheel aerator of the type often used for emergency aeration of fish ponds. The greatest oxygen transfer coefficient (30.0 hour−1) and oxygen transfer rate (35.1 kg of oxygen per hour) were obtained at 108 rpm (revolutions per minute) and 54 cm paddle depth. All trials at 108 or 128 rpm with paddle depths of 36 cm or more had oxygen transfer coefficients and rates greater than 20 hour−1 and 20 kg of oxygen per hour, respectively. There was good agreement between the size and shape of spray patterns and oxygen transfer coefficients and rates.

Emergency Aeration of Fish Ponds

Abstract Dissolved oxygen (DO) concentrations were depressed in 0.57-hectare fish ponds through algicide treatment and the effectiveness of different techniques of emergency aeration was compared. The most effective device for emergency aeration was a paddlewheel aerator powered by a tractor. A tractor-powered Crisafulli pump with a discharge capacity of 18.9 m3/minute was also a relatively effective aeration device when used either to spray DO-deficient water into the air and back into the pond or to pump fresh, oxygenated water from another pond into the one with low DO concentration. A lower capacity Rainmaster pump (3.8 m3/minute) was much less effective than the Crisafulli pump when used to discharge oxygenated water into a DO-depleted pond. Neither of the pumps raised DO concentrations appreciably when used to circulate DO-deficient water in ponds. Three sizes (0.25, 2.2, and 3.7 kilowatts) of spray-type surface aerators failed to appreciably increase DO concentrations.