Bioaugmentation of halophilic consortium for degradation of 1,4 dioxane (1,4-DE) and treatment of cosmetic industrial wastewater in continuous stirred tank reactor under saline condition

Abstract

The heterocyclic ether 1,4-Dioxane (1,4-DE) is a toxic by-product used widely in various industrial activities as a solvent or stabilizer. 1,4-DE was classified as a probable human carcinogen according to the United States Environmental Protection Agency (USEPA) due to its chemical and physical properties. Emerging pollutants in industrial wastewater is the major challenge for the operation of effluent treatment plant. The bioremediation of 1,4-DE is an effective approach to treat the industrial wastewater. The bacterial consortium was obtained from industrial sludge samples, Yanbu, Saudi Arabia and enriched in 1,4-DE supported basal salt saline medium. Biodegradation of 1,4-DE was studied at several concentrations ranging from 200 to 1200 mg/L. Complete mineralization of 1,4-DE from 200 to 800 mg/L was achieved in 4 to 8 days at 4% salinity. 1,4-DE utilization was studied at different salinity (4% and 6%), the results exhibited complete mineralization of 1,4-DE at 4 days and 6 days respectively. Increase in salinity to 8% displayed 92% degradation of 1,4-DE. Addition of yeast extract accelerated the biomass production correspondingly reduced the time required for biodegradation under saline condition. The bacterial consortium showed the ability to degrade 1,4-DE completely at various range of concentrations. Lab scale continuous stirred tank reactor (CSTR) was used to evaluate the industrial wastewater treatment efficacy of the bacterial consortium under saline condition. CSTR operated for 36 days displayed chemical oxygen demand (COD) removal and 1,4-DE degradation of 96% under saline condition. THF (Tetrahydrofuran) which accelerated the degradation process of 1,4-DE was completely degraded in 28 days. Bacterial analysis with high throughput sequencing technique confirmed the existence of bacterial strains like Ochrobactrum (45%), Marinobacter (21%), Stenotrophomonas (16%), Pseuodomonas (9%), Sphingomonas (4%), Bacillus (3.5%) and Sedimentibacter (1.5%).