X-BR Dye Wastewater Treatment By Membrane Bioreactor Combined With Different Pre-Treatment Methods

Anthraquinone dyes which are characterized by carcinogenicity and toxicity contains the molecular structure of one or more carbonyl (C=O) conjugation generally. Due to the stable structure of polycyclic aromatic hydrocarbons, it is always hardly biodegradable. As an environmental friendly technology for wastewater treatment and reuse,membrane bioreactor (MBR) which integrating the traits of membrane filtration and activated sludge exhibits incomparable advantages. In this paper, MBR coupled with three types of pre-treatment including A/A/O, Fenton oxidation and iron inner electrolysis membrane bioreactor were used for the degradation of Reactive Blue X-BR. The membrane module was self-made PVDF hollow fiber membrane. The coupling system was continuously operated by the microcomputer controlling system. Effects of three coupling system on waste treatment were investigated. The degradation mechanism was analyzed and the variation of microbial activity was characterized. Meanwhile, membrane fouling and relative cleaning methods were also explored.During the experiments, the devices coupling with membrane bioreactor were designed and built. After operating more than half years, the removal efficiency of CODCr, TOC and turbidity in all these three systems of pretreatment was stable at 90%, and the pH of the effluent was nearly at neutral point. In the iron inner electrolysis system, whose operating conditions were set as reaction time within 30min, influent pH of 6-7, Fe/C ratio of 2, solid to liquid ratio of 180g/L and stirring speed at 300r/min, the decolor rate was highest, reaching 98.8%. In Fenton system, the decolor rate reached 90% when pH = 5, H2O2 = 0.2g/L, FeSO4 = 100mg/L. Among three systems, the decolor rate of A/A/O method was the lowest, merely 60%. Serious membrane fouling mainly contained bacteria and organics was found through SEM in all these three methods. It was observed that the flux easily restored 90% after chemical cleaning. The presence of Fe3+ could cause the increase of EPS and enlarge sludge particle size that leading to flocculation and the removal of organisms.