Disinfection of Wastewater by Microwaves

摘要

Results from a laboratory study show that microwave energy can be used for disinfection of wastewater. The time required for destruction of bacteria by microwaves was reduced over that of conventional heating. Destruction of wastewater bacteria and a cell-suspension of E. Coli B. was logarithmic after an initial lag phase, which was dependent upon the volume used. Thermophilic B. stearothermophilus cells were used to try to determine if the mechanism of destruction was thermal. The microwave oven was set at optimum growth temperature of this species (60 C). Destruction was much more rapid in the microwave oven than in a 60 C waterbath. More than 90% of the cells were destroyed by heating 30 minutes in a microwave oven, although continued heating had little further effect. Repeated microwave treatment for 1-hour periods also did not increase the number of cells destroyed. It was thought that by using chilled cells prior to heating or chilled buffer for dilutions after heating, increased thermal shock might be observed. However, neither the temperature of the cells before treatment with microwaves nor the temperature of the diluent buffer showed any effect on the rate and extent of bacterial destruction. (Author)