Design and peroormance of paddle wheel aerators
ABSTRACT 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 O2 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 O2 h−1) and SAE (2·7–2·9 kg O2 kWh−1) and were much more efficient than other aerators used in channel catfish farming.
Full-textDOI: · Available from: Claude E. Boyd, Nov 05, 2014
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- "A wide variation in performance of aerators in terms of standard aeration efficiency was found, like, Taiwanese aerator (1.17 kg 0 2 /kWh), Japanese aerator (1.03 kg 0 2 /kWh) and Auburn university design (2.25 kg 0 2 /kWh) (Busch et al. 1974; Boyd and Watten 1989; Boyd, 1998; Colt, 2000a; 2000b). Ahmad and Boyd (1988) provided optimum designs of paddle wheels and Moulick et al. (2002) used similarity criteria in predicting the oxygen transfer performance of paddle wheel aerators. The centrifugal surface aerator along with the paddle wheel surface aerator had been traditionally used in wastewater treatment (Stukenberg et al., 1977; ASCE, 1997). "
ABSTRACT: Oxidation ditch process is used to treat the municipal and domestic sewage. The untreated sewage generates fouling smell, harmful bacteria, etc. which is hazardous for public health and degrades the environment by librating noxious gases. This paper examines the use of curved blade aerator for oxidation ditch process. The rotor, which controls the aeration, is the main component of the aeration process. Therefore, the objective of this study is to find out the variations in overall oxygen transfer coefficient and aeration efficiency for different configurations of aerators by varying the parameters like speed of aerator, depth of immersion and blade tip angles so as to yield higher values of overall oxygen transfer coefficient and aeration efficiency. Four aerators of different configuration were developed and fabricated in the laboratory and were tested for above mentioned parameters. A mathematical model is developed for predicting the values of kLa and aeration efficiency which has R2 values of 0.97 and 0.99 for experimentally determined and calculated values. In laboratory studies, the optimum value of overall oxygen transfer coefficient and aeration efficiency were observed to be 10.33/h and 2.269 kg O2/kWh for aerator speed of 48 rpm, 5.5 cm depth of immersion and 47o blade tip angle for curved blade aerator.International journal of Environmental Science and Technology 01/2009; 6(1). DOI:10.1007/BF03326065 · 1.79 Impact Factor
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ABSTRACT: Paddle wheel aerators made of polyvinyl chloride (PVC) pipe had standard aeration efficiencies (SAE) of 2·0–2·6 kg O2 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 O2 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.Aquacultural Engineering 01/1988; 7(1):63-72. DOI:10.1016/0144-8609(88)90038-6 · 1.23 Impact Factor
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ABSTRACT: Gas phase axial dispersion was characterized within an enclosed packed column receiving oxygen and water under counter-current flow conditions. Steady-state gas phase profiles (longitudinal) were measured during a series of 90 column runs in which, at each of three bed depths (0·362, 0·699, and 1·041 m), all combinations of the following independent variables were tested: influent volumetric oxygen-liquid ratio, 0·8, 1·6, 2·6, 4·0, and 8·0%; hydraulic loading, 32·0 and 61·2 kg/m2 s; and packing type, 2·54 cm Tri-Pack®, 3·81 cm Nor-Pac® and 5·08 cm Nor-Pac®. Over the range of operating conditions tested, gas phase mixing was extensive and for all practical purposes could be considered complete. A homogeneous gas phase within the column, unlike true counter-current flow, results in an exponential decay in dissolved gas deficits as the liquid passes through the packing. Thus, increases in packed bed depth will result in diminishing increases in gas absorption/desorption.Aquacultural Engineering 01/1989; 8(6):421-434. DOI:10.1016/0144-8609(89)90035-6 · 1.23 Impact Factor