Upflow filter and method of washing same

摘要: A method of washing an upflow filter between service runs employs a bed having non-buoyant particulate layer through which influent to be filtered is directed in upward direction, and liquid employed the operation direction. two-stage includes steps first directing combination air direction with velocity being less than minimum fluidization layer, for disrupting only some floc retained during previous run, thereafter at removing disrupted from while leaving attached said media layer. The process most preferably carried out including coarse, flocculation distributing flow promoting flocculation.