Effects of fine bubble aeration in improvement of Bacillus spp. Density in rearing culture

Abstract

This study aimed to examine the effect of fine bubble diffuser on visibility of the Bacillus spp. density in rearing culture of the whiteleg shrimp, Litopenaeus vannamei. The research consisted of 2 trials. In the first trial, the oxygen transfer efficiencies of different diffusers were evaluated. In the second trial, the selective Bacillus sp. was added into aerated rearing water of the whiteleg shrimp using different diffusers and then the density of Bacillus spp. and water quality of water were assessed. Results showed that no significant differences were observed in oxygen transfer efficiency of bottom diffuser and fine bubble diffuser at different flow rate (0.025, 0.05, 0.1 MPa). Therefore, it is recommended that the pressure at 0.025 MPa could be more suitable for the fine bubble diffuser under small tank experiment. In addition, with adding Bacillus spp. at the dose of 1.43104 CFU/L, no significant differences in COD, pH, TSS and Bacillus spp. density were found among control (no aeration), bottom diffuser, and fine bubble diffuser treatment after 7 days. However, concentrations of NO2-, TAN, DO, and BOD were significantly different among all treatments. The next study should apply the fine bubble aeration to culture shrimp.