Decolorization And Biodegradation Of The Congo Red By Acinetobacter Baumannii And Its Polymer Production’s Flocculation And Dewatering Potential

Azo dyes are broadly utilized especially in the textile industry, however, they pose a major threat to the environment, human health and aquatic life. Therefore, there is an urgent need to search economical, environment friendly and sustainable treatment. Biological treatment of azo dyes wastewater has been extensively studied, but an anaerobic condition is vital to degrade azo dyes in prokaryote kingdom. Since the presence of oxygen would lead to the lack of available electron donors for azo dyes degradation under aerobic conditions, and the azo bonds (-N=N-) would not be cleaved. In this study, novel Acinetobacter baumannii YNWH 226 can degrade typical azo dye-Congo red (CR)-under aerobic conditions. And then CR was employed as the sole carbon source instead of expensive conventional media substrates to produce EPS which was utilized as a kind of potent bioflocculant.The decolorization and biodegradation of the Congo red by YNWH 226 under aerobic conditions were performed using a high performance liquid chromatography (HPLC), a total organic carbon (TOC) analyzer, a UV-Vis spectrophotometer (UV-Vis), a Fourier transform infrared spectroscopy (FTIR) analyzer, a high resolution mass spectrometer (HRMS). Congo red and its intermediate byproducts and the possible pathways of Congo red degradation were identified. Total 98.62% CR was removed during 48-h decoloration experiments of the Congo red (100 mg/L). Total 83% of bioadsorption and 65% of biodegradation were responsible for the decoloration and degradation of the CR by the strain.Congo red was first used as the sole carbon source instead of expensive conventional media substrates for production of bioflocculant. And flocculation activities and dewatering capacity of its EPS were investigated in existence of divalent cations (Ca2+). The bioflocculant showed high flocculation activity and dewaterability on textile dyeing sludge. Maximum flocculation activity up to 78.62%, minimum SBF up to 3.07×109 s2/g and CST of 58.4 s were achieved. We investigated the internal relations between decolorization efficiency of YNWH 226 and flocculation activities, dewatering capacity of its EPS. The components and structure of the strain’s EPS have great influence on decolorization efficiency of CR and flocculation activities, dewatering capacity on sludge.