The ornamental design for an ovalwastewaterpurifyingdevice, as shown and described.
FIG. 1 is a top perspective of an oval waste water purifying device embodying our design;
FIG. 2 is a top view of the oval waste water purifying device shown in FIG. 1;
FIG. 3 is a bottom view of the oval waste water purifying device shown in FIGS. 1 and 2;
FIG. 4 is a front perspective of the oval waste water purifying device shown in FIGS. 1-3, with the opposite rear perspective being a mirror image thereof;
FIG. 5 is a side perspective of the oval waste water purifying device shown in FIGS. 1-4, with the opposite side perspective being a mirror image thereof; and,
FIG. 6 is another top perspective of the oval waste water purifying device shown in FIGS. 1-5.