Effective combination of microfiltration and intermittent ozonation for high permeation flux and VFAs recovery from coagulated raw sludge

This research was conducted to investigate the effect of intermittent ozona tion on permeation flux recovery and production for soluble organic materia ls in a membrane-coupled anaerobic VFAs fermenter (MCAVF) system. Flux reco very ratio exceeded 80% with 22.2 gO(3) l(-1) of ozone injection and then s howed nearly 95% with 43 gO(3) l(-1) in batch experiment. Under the same oz one concentration, extending contact time was more effective than increasin g bubbling dose rate for flux recovery. In continuous-flow operation, the v alue of average permeation flux was 0.69 m(3) m(-2) d(-1) during without oz onation period, while average permeation flux for 70 days with intermittent ozone bubbling was 1.17 m(3) m(-2) d(-1) that corresponds to 1.7 times tha t with no ozonation period. Moreover, in spite of intermittent ozone bubbli ng for 70 days, significant inhibition was not observed for volatile fatty acids (VFAs) producing bacteria and VFAs production. It was found that the average value of [permeates total organic carbon (TOC) concentration: Influ ent TOC concentration] with ozonation period was about 1.5 times higher tha n that of no ozonation period. Consequently, it is believed that a membrane -coupled anaerobic VFAs fermenter (MCAVF) process combined with intermitten t ozonation is suitable to overcome the flux decline of membrane and simult aneously is useful to the recovery of soluble organic materials from coagul ated raw sludge.