Process and apparatus for subsurface washing

Claim 1

THE PROCESS OF WASHING A LIQUID TREATMENT BED OF PARTICLES OF LIQUID TREATING MEDIUM FOLLOWING A SERVICE PAHSE OF THE CYCLE IN WHICH LIQUID TO BE TREATED IS PASSED DOWNWARDLY THROUGH THE BED, WHICH COMPRISES INTRODUCING LIQUID WHIRLING IN ONE DIRECTION ON A GENERALLY VERTICAL AXIS AT A LEVEL BENEATH AND ADJACENT TO THE SURFACE OF SAID BED, CONCURRENTLY INTRODUCING A RELATIVELY SMALLER VOLUME OF LIQUID FORCEFULLY FROM A PLURALITY OF DISTRIBUTED STATIONARY JETS DIRECTED GENERALLY TANGENTIALLY IN THE OPPOSITE DIRECTION, SAID INTRODUCED LIQUID BEING WITHDRAWN UPWARDLY THROUGH SAID BED WITHOUT DISTRUBING THE BOTTOM, THEREBY LOCALLY BACKWASHING THE UPPER PORTION OF THE BED.