Development of wastewater treatment system based on cascade dielectric barrier discharge plasma atomizers

A novel design for a cascade dielectric barrier discharge (DBD) atomizer was applied for treating samples of water containing biological and organic contaminants. Several experimental investigations were conducted on artificial samples and real sample (digested sludge collected from a wastewater treatment plant, WWTP). The artificial water samples were prepared by using different concentrations of E. coli for biological samples, whereas acetic acid was used to prepare the organic samples. The biological samples were subjected to the plasma effect for different treatment periods, and the growth curves of E. coli were generated for 24 h after treatment. Moreover, the viable cells were counted after each treatment period and the change in E. coli morphology was monitored. The results showed that a significant reduction in the viable cell number, by 3 orders of magnitude, occurred for an artificial biological sample after only 5-min treatment. The treatment of organic samples for 10 min showed a significant reduction in the concentration of acetic acid by 50%. In consequence, treatment of real wastewater sample for 10 min resulted in more than 70% reduction in BOD5 and 30% reduction in COD.