Improved method and system for cleansing a filter bed.

摘要

There is provided an improved method of cleansing a filter bed utilizing a backwash pump (l2) having an inlet line (l4) and an outlet line (l6). The improved method and system includes two cycle operations. Initially,the filter bed is backwashed to remove contaminants from the filter bed with the backwash pump (l2)drawing liquid from an effluent channel (32) through a first diverter valve (l8). The fluid flows through a second diverter valve (2O)and a first throttling control valve (36) for insert into a backwash shoe(38) . In the purging cycle, fluid may be recirculated from the backwash pump (l2) through the backwash shoe (38) and then back to the backwash pump (l2) with a portion of the fluid being diverted through a second diverter valve(2O')into an egress line (42). In an embodiment of the purging cycle method and system(lO'),during the purging cycle fluid is passed on backwash filter pump outlet line (l6)from backwash pump (l2) directly to an egress line (42) through the second diverter valve (2O''). The pressure head of the backwash pump (l2) is controlled by a second control valve (44)located in the egress line (42).