The Hybrid process of preozonation and CNTs modification on hollow fiber membrane for fouling control

Abstract

The preozonation and carbon nanotubes (CNTs) modification of hollow fiber membranes for fouling control was systematically evaluated when treating real sewage effluent. The hybrid process was operated in cyclical flow filtration system, involving filtrating and backwashing processes. The results revealed that preozonation and CNTs modification improved fouling control and permeate quality. After preozonation, the fouling rate of the CNTs modified membrane was reduced and its recoverability was effectively improved. With increased ozone dosage, the hybrid effectiveness of preozonation and CNTs modification on fouling control was enhanced. The recoverability of CNTs modified membranes in the hybrid process was improved by increasing the frequency of backwashing. Compared with CNTs’ adsorption effect, the interception effect of CNTs layer pre-deposited during membrane modification increased permeate quality and reduced membrane fouling. The interception effect of CNTs layer was enhanced after preozonation. Confocal laser scanning microscope results demonstrated that the hybrid preozonation and CNTs modification membrane process effectively controlled biofouling. After preozonation, the presence of CNT layers on membrane surfaces could further decrease the amount of living bacteria. The attachment of dead bacteria to CNTs modified membrane was also decreased after preozonation.