Development of a nebulizing advanced oxidation process
Description
Two chemical oxidation technologies, the OMNIPURE(TM) electrolytic marine sanitation device (MSD) and the Purizer(TM) advanced oxidation process (AOP), were assessed to determine process efficiency enhancements Oxidation reduction potential (ORP), pH and free chlorine measurements indicated chlorine dioxide (ClO2·) and hypochlorite (OCl-) are the main oxidants produced by the OMNIPURE(TM) electrolytic cell. Hydrogen peroxide (H2O2) was produced by the cell in the absence of chlorine oxidants but it was not determined if H2O2 is formed with free chlorine. ORP levels also indicated the cell is capable of producing ferrate (HFeO4 -) from ferrous iron (Fe2+) in tests conducted to determine the quantity of milliequivalents of oxidants transferred to solution. Oxidant production efficiency may be enhanced by optimizing the electrolyte dose The Purizer(TM) Process design goal was to produce peroxone (O 3/H2O2) from oxygen, water and UV radiation; the original process design did not produce significantly more H2O 2 or greater ORP levels in solution than ozone (O3) gas applied to solution. The 254 nm UV lamp was changed to a dual frequency 185/254 nm lamp, the delivery system material was changed to glass (PyrexRTM ) and different configurations of UV radiation use and humidification were tested. Both humidified and dry 185/254 nm photolyzed O3 increased H2O2 production efficiency by up to 50 percent A nebulizing AOP was developed after assessment of existing technology was completed. The design intent in this process is to overcome observed limitations of bulk liquid treatment. It has been demonstrated to be more time efficient than and is cost-comparable to current AOP in bench experiments. Three optimal combinations of nebulized O3 gas, nebulized liquid H2O 2 and UV light were identified using constant liquid and gas flow rates and an excess dose of O3. O3 alone and O3 photolyzed by 254 nm UV degraded 90 percent of 200 mg/L EDTA within 5 minutes. Only the combination of O3 and 254 nm UV light was effective within fifteen minutes in a significant oxidation of chromium (III) to chromium (VI) which was used as an indicator of production of milliequivalents. Process efficiency can be enhanced by reducing the O3 dose and optimizing droplet size