Analysis of cyanide bioremediation using cyanobacterium; Chroococcus isolated from steel manufacturing industrial wastewater

Abstract

Cyanide and its derivates contamination of waste waters is one of the problems in steel manufacturing industries. Increasing usage of this toxic element is leading to its accumulation and contamination of the environment. In the present study, cyanide resistant cyanobacterium has been isolated from the waste water of steel manufacturing industrial area in Iran and identified based on the morphological characteristics. For this purpose, contaminated samples achieved from different parts of waste water containing lagoons and inoculated to BG11 culture medium. The antibiotics cycloheximide and imipenem used for removing the fungi and other bacteria. The isolated cyanobacterium has been identified based on the microscopic morphological characteristics and amplification of 16S rDNA sequence. For in vitro analysis of cyanide resistance, different concentration of potassium cyanide (5-15 mg L-1) prepared in BG11 media and the microorganism inoculated to the media. The bacterial growth assessment was done based on the cell counting, culture turbidity, dry weight and the amount of chlorophyll a. The cyanide removal was estimated after 16 h incubation in 25°C and shaking at 140 rpm and the presence of light (16 h lightening in 3 Klux and 8 h darkness continuously), using cyanide ion characterization electrode. Also the purified cyanobacterium inoculated to the samples obtained from the lagoons and the cyanide removal has been analyzed in waste water samples. The isolated cyanobacterium identified as a species of Chroococcus in the family Chroococcaceae. The bacterium was able to grow in the presence of 5-30 mg L-1 KCN. The results of direct studies showed that the isolated Chroococcus sp. removed a mean of 14.06% of free cyanide from the steel manufacturing waste water samples. © 2012 Academic Journals Inc.