(376a) Advanced Wastewater Treatment by Corona Discharge

Advanced wastewater treatment, overwhelmingly based on photochemical, photocatalytical, electrochemical processes and combinations of electrochemical and photochemical measures, is an expensive technique still. The main reason for the high cost of operation is caused by the low concentration of target .constituents on the one hand and, on the other hand operation efficiency expressed in terms of specific overall energy demand is low due to low current efficiency as well as low radiation efficiency of photochemical processes. Fouling of electrodes and radiation sources is a significant obstacle preventing these processes from general application.

With these disadvantages of state of the art treatment processes in mind wastewater treatment by corona discharge is a very promising technical measure because discharge area and target effluent are separated through a gaseous gap and fouling of the electron emission source is avoided.

This project investigates the design parameters of corona discharge facilities with consideration of the effect of the design of discharge electrodes and the effect of flow conditions on the current/ voltage characteristics as well as pollutant degradation.

Several discharge electrodes were investigated. The current/voltage characteristics derived from experiments have been modeled. According to Figure 1 discharge electrodes of optimized shape generate significantly higher corona discharge currents compared with wire type electrodes with a positive effect on degradation of pollutants. Yield of ozone formation can easily be adjusted to individual needs according to a widely adjustable operation range between corona onset and corona break through voltage.  

Figure 1: Comparison of the specific current/voltage characteristic; (T, P: ambient)