BOD reduction by bacterial strains isolated from rosewater industry wastewater

Abstract

Abstract Bacteria can break down organic materials, obtain energy and building material for cell growth. Wastewater treatment plants try to optimize this ability of bacteria to eat the organics [1]. Material and Method In this study, samples were collected in an aseptic manner. Serial dilutions of the samples up to 10-6 were prepared for proper isolation of individual colony forming units [1]. Bacterial isolates were cultured on Lysogeny broth (LB) medium [2] and incubation at 30 oC for 24 hours [3]. Phenotypic characteristics of individual isolates including gram-staining, cell morphology, catalase and oxidase activities were determined using standard methods [4]. Then the bacteria were used for reduction BOD5. Result After several dilutions and repeated sub-culturing, 84 pure bacterial cultures isolated includ- ing grampositive bacilli and cocci, gram-negative bacilli and cocci. Morphological variation was observed when colonies were compared including smooth, circular, low-convex, trans- parent or translucent and different colors like red, orange-red, pale-pink, yellowish, cream or white. Isolates were identified by biochemical tests. Of these, three bacterial isolates were se- lected to reduce BOD5 include K21, K53 and K70. K21 isolates were catalase and oxidase positive, gram-positive bacilli, containing spores, hy- drolyzed starch, positive Voges-Proskauer (VP) test and do not have the ability to ferment glucose, negative mannitol, citrate positive and negative indole. K53 isolates were catalase and oxidase negative, gram-positive bacilli, containing spores, hydrolyzed starch, VP positive and do not have the ability to ferment glucose, negative mannitol, citrate positive and negative indole. K70 isolates were catalase and oxidase positive, gram-positive cocci, not containing, positive mannitol. Three isolates had ability to reduce BOD. Conclusion Results showed that K21 had the greatest ability (79 percent) to reduce BOD5.