Single pass solids removal by a hydrocyclone separator at varying flow rates from pond water used as a flow-through water source for catfish pond bank spawning tanks

Abstract

Catfish spawning is typically conducted by placing spawning containers in the shallow area of a pond where there is 0.6–0.9 m of water and when temperatures reach 24° C. The fish spawn in the containers, and the eggs are usually removed and incubated indoors. Currently, at the Warmwater Aquaculture Research unit (Stoneville, MS) fish biologists are using round polytanks placed on the pond bank for spawning container placement with pond water pumped through the tank and aeration diffusers in the tanks to assure the pond water is well oxygenated. Depending on how and where the water is obtained from in the pond there can be a heavy solids loads associated with the incoming water. A hydrocyclone was evaluated as a simple and easily managed unit to reduce the solids load of the incoming water flow. The pond water flowed to a line of one hundred polytanks (1.5 m Ø, 1.5m³). The mean total suspended solids (TSS) concentration in the incoming pond water ranged from 26.3 to 37.1 mg/L. Mean daily single pass solids removal rates were compared at four different flow rates, 114 lpm, 170 lpm, 227 lpm, and 303 lpm (30, 45, 60, and 80 gpm, respectively). The pump output flow was limited by the suction pressure of the water flow from the in-pond floating skimmer and the reduced diameter (3.18 cm) of the inlet pipe to the pump intake. The mean single pass solids removal efficiency, RE (%)from four consecutive days of sampling at each flow rate (n = 4) ranged from 12.0 % at 114 lpm to 23.9 % at 303 lpm. Removal rates increased with increasing flow but the test statistic with α at 0.05 indicated no observable significant difference. The mean amount of solids from the hydrocyclone underflow purge volume ranged from 24.4 g at 114 lpm to 31.6 g at 170 lpm. Significant greated solids amount were observed (α at 0.05) in the purge volumes at te 170 and 227 lpm flow rates, respectively. Scatter plots of RE % versus influent TSS (mg/L) and RE (%) versus grams of purged solids had a observable positive linear correlation (R² = 0.0.7628 and 0.80748, respectively) but the test statistic t was less than the table critical value at an α of 0.05. Implementing the hydrocyclone was a useful management technique in reducing the solids load from the incoming pond water source used for the seasonal catfish spawning purposes.