Innovative Water Reuse Process Using Photocatalysis and Catalytic Ceramic Membrane Filtratio

Water scarcity has become one of the most challenging problems that humanity must address. Cost-effective water and wastewater treatment technologies are imperative to protect public health and the environment. The objectives of this work were to assess catalytic ceramic membrane filtration-ozonation processes for the mitigation of fouling and calculate the energy cost and environmental impacts of the process; to efficiently use sunlight as energy source for photodegradation and the removal of persistent organics in wastewater; finally, to propose an innovative process that combines photodegradation and membrane filtration process for emerging contaminants removal and industrial water reuse. The first part of the study analyzed the effect of ozone dosage on membrane fouling using catalytic ceramic membranes, and used life-cycle-assessment to assess the energy consumption and environmental impacts of the catalytic ceramic membrane system and compared that to hollow fiber membrane filtration. Results showed that membrane fouling was effectively controlled at ozone dosages of 10 microg/s or greater using manganese oxide coated membranes. At least 15 microg ozone/s was necessary to control membrane fouling with uncoated titianium oxide membranes. Catalytic ceramic membrane filtration resulted in less energy consumption of pressurization and backwashing as compared with hollow fiber membrane filtration, and had a slightly lower environmental impact than hollow fiber membrane filtration. In photodegradation study, three photocatalysts were synthesized and characterized. Photodegradation abilities were compared using with methylene blue as a model contaminant. Moreover, the deactivation mechanism and photo-deactivation of photocatalysts were also studied. The order of photocatalysis degradation efficacies of methylene blue during illumination was CdS > NiFe2O4 ? ZnFe2O4. It was found that the methylene blue removal efficacy is affected by the absorption range of the photocatalysts, initial dye concentrations, amount of photocatalysts added, and photoreactor conditions. The proposed water reuse process combining photocatalytic reaction and ceramic membrane filtration to achieve safe and high efficient water reuse and reduce energy consumption and operating costs was evaluated using caffeine as a target contaminant. Results show that by using photodegradation and membrane filtration, caffeine could be degraded and photocatalysts could be recovered.