استفاده از باكتري ها در تجزيه آلكيل بنزن سولفانات هاي خطي موجود در پاب واحدهاي توليدكننده مواد شوينده

Using Bacteria for Degrading of Linear Alkyl Benzene Sulfonates in Wastewaters of Detergent Producing Factories

Background and Objectives. Linear alkyl benzene sulfonate ( LABS ) is a substance, that is used in anionic detergents as a surfactant. Nowadays, LABS is the most widely used surfactant in household detergents products after soap. Everyday, LABS enters into the nature as a pollutant by industrial and domestic wastewaters. A bacterial consortium is capable of LABS mineralization under aerobic conditions. This study carried out to consider the role of Pseudomonas and Aeromonas bacteria in degrading of LABS in wastewaters of detergent producing factories. Materials and Methods: In this research, gram-negative rods consisting of three Pseudomonas strains and one Aeromonas strain were used. For determining LABS biodegradation degrees, the method of methylene blue active substance (MBAS) was used. In this method, the microorganisms were inoculated in a container including culture medium and test surfactant. After two adaptive phases, percentages of biodegraded LABS were measured for the test bacteria or the bacterial consortium. Results: Results showed that LABS biodegradation degree was 23.1% by Aeromonas sp., whereas Pseudomonas fluorescens biodegraded 77.95% of this substance which indicates high ability of this bacterium in LABS biodegradation in sewage systems. P. aeruginosa biodegraded 44.85% of LABS which is nearly half of available LABS in growth medium. Also, P. putida could biodegrade 67.5% of LABS. Approximately, 90% of LABS was biodegraded by bacterial consortium in 8 days of biodegradation period which this level was reduced to 85.2% by eliminating Aeromonas sp. Conclusion: Aeromonas sp. as compared to other bacterial strains of Pseudomonas genus, had the lowest ability for LABS biodegradation. Comparing bacteria with one another, P. fluorescens had more ability to biodegrade LABS. The highest degree of biodegradation ( >88% ) in this survey, was related to aerobic bacterial consortium. The test gram-negative bacilli were able to biodegrade LABS and according to our findings, the bacterial consortium can be used in detergent producing factories refineries, for eliminating LABS from wastewater to acheive low harm in environment as the result of LABS entry into the nature.