A novel salt-tolerant mutant YWL-01 for the treatment of saline wastewater

The treatment of high-saline wastewater from some salt-end markets including agro-food industry is a serious problem yet to be solved in some coastal cities. The conventional physical–chemical techniques are energy-consuming and their startup and running costs are still high. Biological methods using salt-tolerant bacterial strains for the treatment of hypersaline wastewater provide one possible solution. In this study, one salt-tolerant mutant named YWL-01 was screened out by sewage treatment and proved to be a genetically stable salt-tolerant strain for saline wastewater treatment. First, combined mutagenesis was done on an isolated sewage treatment strain Bacillus Y for the screening of salt tolerance, and 11 mutants were obtained after subculture for many times. Then, a secondary screening test was performed for COD (chemical oxygen demand) and TOC (total organic carbon) removal efficiency analyses. At last, the best mutant YWL-01 with increased capacity to treat saline wastewater was chosen for use. RAPD (Random Amplified Polymorphic DNA) analysis of genetic stability on the mutant YWL-01 showed that it is a hereditary mutant for the treatment of high-saline wastewater.